ascorbic-acid and malic-acid

Patients complaining of a dry mouth can present themselves to various clinicians such as the primary care physician, dentists, otolaryngologists and/or oral surgeons. The aim of our review is to provide a systematic method of assessing and managing these patients based on current best evidence published in the literature.. A literature search was performed on 20th April 2009 using MEDLINE and EMBASE using the terms dry mouth and xerostomia in combination with diagnosis, management, investigations and treatment.. There appears to be little correlation between patient symptoms and objectives tests of salivary flow. Therefore clinical management should be based on patient symptoms. There is good evidence to support that xerostomia is commonly associated with anticholinergic drugs, and altering such agents plays an important role in the management of these patients. In patients with residual salivary gland function, the use of salivary stimulants appears to be more beneficial than salivary substitutes.. Xerostomia can be debilitating and primarily affects the middle aged and elderly population. The most common causes of xerostomia include medications with anticholinergic properties, dehydration, diabetes and radiotherapy for head and neck cancer. Treatment of xerostomia essentially involves addressing the cause followed by salivary substitutes and/or salivary stimulants.

Topics: Acupuncture Therapy; Ascorbic Acid; Chewing Gum; Humans; Malates; Medical History Taking; Muscarinic Agonists; Parasympathomimetics; Physical Examination; Pilocarpine; Radiation-Protective Agents; Referral and Consultation; Saliva, Artificial; Xerostomia

Two homeopathic pathogenetic trials (HPTs, provings), of identical design were conducted: of Acidum malicum 12 cH and Acidum ascorbicum 12 cH. Each trial included 20 healthy volunteers. Both were of double-blind, placebo-controlled, randomised, four period crossover design, with two sequences. 'Healthy' was defined in terms of SF-36 scores, medical judgement and blood tests. All volunteers had regular interviews with the same supervisor. No serious adverse reactions occurred. The causal relationship of each symptom with treatment was judged, blind, by the volunteer, the supervisor and a 9-item pathogenetic index. For Acidum malicum 79 symptoms were identified by the supervisor, 57 were included in the final analysis, 22 occurred in verum treatment periods. For Acidum ascorbicum, of 55 symptoms, 39 were included in the analysis. 16 occurred in verum treatment periods.

Topics: Adult; Antioxidants; Ascorbic Acid; Cross-Over Studies; Double-Blind Method; Follow-Up Studies; Humans; Malates; Male; Materia Medica; Middle Aged; Patient Compliance; Reference Values; Treatment Outcome

The type strain of the species Alicyclobacillus acidoterrestris (DSM 3922) and the strain CB1 (accession number: KP144333) were studied in this research to assess the effects of three weak acids (malic, citric, and ascorbic acids), pH (3 or 4), and spore status (spores, and activated spores). Acids were used to prepare 7 different blends, and the blends used to reduce the pH of Malt Extract broth to 3 and 4; then, media were inoculated with spores or activated spores, stored at 45 °C (optimal temperature for A. acidoterrestris growth), and analyzed immediately and after 2 and 7 days. Data were preliminary standardized as increase/reduction of microbial population, compared to the initial concentration, and modelled through two different statistical approaches (multifactorial ANOVA, and multiple regression). Finally, a binary code (0-no growth or reduction of viable count; 1-growth) was used to perform a multiple regression analysis on the growth probability of A. acidoterrestris. Generally, ascorbic acid was the most effective compound, but other acids (e.g., malic acid) could contribute to increase the inactivation ratio; concerning spore status, the highest sensitivity of activated spores suggests that acids probably act during the outgrowing phase. Finally, the two strains showed different trends at pH 3.0, being the type strain the most resistant one.

Topics: Analysis of Variance; Ascorbic Acid; Citric Acid; Malates; Spores

Maternal diets during pregnancy and lactation are key determinants that regulate the development of metabolic syndrome (MetS) in offspring. l-malic acid (MA) was previously reported to improve antioxidant capacity and aerobic metabolism. However, the effects of maternal MA consumption on the metabolic features of offspring remain largely unexplored. Herein, through pig models consuming MA-enriched diets during late pregnancy and lactation, we found that maternal MA consumption potentiated the anti-inflammatory and antioxidant capacity of sows, thereby improving their reproductive performance and the growth performance of piglets. Maternal MA consumption also induced a transition of slow-twitch to fast-twitch fibers in the early life of offspring. Along with muscle growth and fiber-type transition, insulin sensitivity and glucose metabolism, including aerobic metabolism and glycolysis, were improved in the skeletal muscle of offspring. An untargeted metabolomic analysis further revealed the contribution of modified amino acid metabolism to the improved aerobic metabolism. Mechanistically, maternal MA consumption remodeled colonic microbiota of their offspring. Briefly, the abundance of Colidextribacter, Romboutsia, and Family_XIII_AD3011_group increased, which were positively associated with the antioxidant capacity and glucose metabolism of skeletal muscles. A decreased abundance of Prevotella, Blautia, Prevotellaceae_NK3B31_group, and Collinsella was also detected, which were involved in less insulin sensitivity. Notably, milk metabolites, such as ascorbic acid (AA) and granisetron (GS), were found as key effectors regulating the gut microbiota composition of piglets. The properties of AA and GS in alleviating insulin resistance, inflammation, and oxidative stress were further verified through mice treated with high-fat diets. Overall, this study revealed that maternal MA consumption could modulate the inflammatory response, antioxidant capacity, and glucose metabolism by regulating the gut microbiota of offspring through the vertical transmission of milk metabolites. These findings suggest the potential of MA in the prevention and treatment of MetS in early life.

Topics: Animals; Antioxidants; Ascorbic Acid; Diet, High-Fat; Female; Gastrointestinal Microbiome; Glucose; Insulin Resistance; Metabolic Syndrome; Mice; Pregnancy; Swine

The impact of long-term chronic cadmium stress (ChS, 0.1 µM Cd, 85 days) or short-term acute cadmium stress (AS, 10 µM Cd, 4 days) on

Topics: Antioxidants; Ascorbic Acid; Asteraceae; Biomass; Cadmium; Chelating Agents; Chlorogenic Acid; Chromatography, High Pressure Liquid; Citric Acid; Glutathione; Hormesis; Malates; Oxidative Stress; Phenols; Phytochelatins; Plant Leaves; Plant Roots; Plant Shoots; Stress, Physiological; Trichomes; Triterpenes; Ursolic Acid

Our results reveal both soil drought and PEG can enhance malate, glutathione and ascorbate metabolism, and proline biosynthesis, whereas soil drought induced these metabolic pathways to a greater degree than PEG. Polyethylene glycol (PEG) is widely used to simulate osmotic stress, but little is known about the different responses of wheat to PEG stress and soil drought. In this study, isobaric tags for relative quantification (iTRAQ)-based proteomic techniques were used to determine both the proteomic and physiological responses of wheat seedlings to soil drought and PEG. The results showed that photosynthetic rate, stomatal conductance, intercellular CO

Topics: Ascorbic Acid; Droughts; Glutathione; Malates; Metabolic Networks and Pathways; Osmotic Pressure; Polyethylene Glycols; Proline; Proteomics; Stress, Physiological; Triticum; Water

Physicochemical characteristics and phytochemical profiles of red (Physalis alkekengi L., RP) and yellow (P. pubescens L., YP) Physalis fruits cultivated in three provinces of China were characterized. YP fruits showed significantly lower levels of total organic acids and elevated total sugars than those of RP. A total of 18 compounds was tentatively identified in hydromethanolic extracts of Physalis fruits applying HPLC-DAD-ESI-MS

Topics: Amino Acids; Ascorbic Acid; China; Chromatography, High Pressure Liquid; Citric Acid; Color; Consumer Behavior; Coumaric Acids; Food Analysis; Food Quality; Fructose; Fruit; Glucose; Hardness; Hydrogen-Ion Concentration; Malates; Mass Spectrometry; Physalis; Phytochemicals; Quinic Acid; Sucrose; Tartrates; Taste

Carbapenems are widely regarded as the drugs of choice for the treatment of severe infections caused by extended-spectrum beta lactamases producing Enterobacteriaceae. The emergence of carbapenem-resistant organisms is worrisome due to the limited treatment options. Detection of carbapenemase-producing bacteria is critical for the choice of appropriate therapy. However, Inhibition of carbapenemases is an alternative approach to combat resistance to carbapenms. In this study, Escherichia coli and Klebsiella pneumoniae carbapenem resistant isolates were recovered from 300 clinical isolates. They were subjected phenotypically for detection of class B metallo-carbapenemase (MBL) producers (by carbapenem disks with or without EDTA), and were subjected for confirmation genotypically by PCR. In addition, the synergistic activities of MBL-inhibitors in combination with carbapenems were elucidated. Two E. coli and 15 K. pneumoniae isolates were carbapenem resistant. The genes encoding blaNDM-1 carbapenemase were detected in 16/17 isolates solely, or collaboratively with either blaVIM, or blaIMP or both in all carbapenem resistant isolates, by PCR method. The VIM-carbapenemase was encoded by one isolate. In pre-clinical trials for development of MBL-specific inhibitors, Sub-inhibitory concentrations of citric acid, malic acid, ascorbic acid and ciprofloxacin in combination with imipenem or meropenem exerted synergistic activities against metallo-carbapenemases. Their activities are probably attributed to the chelation of zinc ions in the active site of carbapenemase. Conclusively, these promising combined therapies might represent a new strategy for combating such serious infections caused by metallo-B-carbapenemase producers of K. pneumoniae and E. coli isolates.

Topics: Anti-Bacterial Agents; Ascorbic Acid; Bacterial Proteins; beta-Lactamases; Carbapenem-Resistant Enterobacteriaceae; Carbapenems; Catalytic Domain; Ciprofloxacin; Citric Acid; Drug Combinations; Drug Synergism; Escherichia coli; Humans; Imipenem; Klebsiella pneumoniae; Malates; Meropenem; Microbial Sensitivity Tests; Zinc

Topics: Ascorbic Acid; Glutathione; Hydrogen Peroxide; Ketoglutaric Acids; Lichens; Malates; Nickel; Oxidative Stress; Phytochelatins

Kei-apple (Dovyalis caffra) is an evergreen tree indigenous to Southern Africa. The fruit contains high concentrations of l-malic acid, ascorbic acid, and phenolic acids. Kei-apple juice was sequentially inoculated with Schizosaccharomyces pombe and Saccharomyces cerevisiae yeasts. A reference fermentation using only S. cerevisiae was included. The fermentation was monitored by recording mass loss. At the end of fermentation, twelve untrained judges conducted free choice aroma profiling on the fruit wines. The Kei-apple juice and wines were analysed for total titratable acidity, total soluble solids, pH, alcohol, l-malic acid, and phenolic acids. Total titratable acidity was ca. 70% lower in Kei-apple wines produced with S. pombe+S. cerevisiae than in Kei-apple juice. Kei-apple wines produced with S. pombe+S. cerevisiae showed substantially lower concentrations of l-malic acid than Kei-apple wines produced with S. cerevisiae only. Wines produced with S. cerevisiae only proved higher in phenolic acid concentrations than wines produced with S. pombe+S. cerevisiae. Chlorogenic acid was the most abundant phenolic acid measured in the Kei-apple wines, followed by protocatechuic acid. Judges described the Kei-apple wines produced with S. pombe+S. cerevisiae as having noticeable off-odours, while wines produced with S. cerevisiae were described as fresh and fruity. Kei-apple wines (S. pombe+S. cerevisiae and S. cerevisiae) were of comparable vegetative and organic character. Saccharomyces cerevisiae produced Kei-apple wine with increased caffeic, chlorogenic, protocatechuic, and sinapic acids, whereas S. pombe+S. cerevisiae produced Kei-apple wines with increased ferulic, and p-coumaric acids and low l-malic acid.

Topics: Ascorbic Acid; Bioreactors; Chlorogenic Acid; Ethanol; Fermentation; Flavoring Agents; Fruit; Hydroxybenzoates; Malates; Odorants; Saccharomyces cerevisiae; Salicaceae; Schizosaccharomyces; Wine

Ascorbic acid (AsA) content in mature fruits of 457 apple accessions were measured, and a great variation in AsA concentration was detected. Wild fruits showed significantly higher level of AsA than cultivated fruits. Fruit AsA content was positively correlated with malic acid content, but negatively correlated with fruit weight and soluble solid content. Thus, the difference in AsA content between the wild and cultivated fruits could be attributed to an indirect consequence of human selection for larger fruit size, less acidity, and increased sweetness during apple domestication. Additionally, AsA concentration was extremely high in fruit at the juvenile stage, but dramatically decreased at the expanding and mature stages. The expression levels of three genes controlling AsA accumulation, MdGGP1, MdDHAR3-3, and MdNAT7-2, were significantly negatively correlated with AsA contents in fruits, suggesting a feedback regulation mechanism in AsA-related gene expression. Our results could be helpful for future apple breeding.

Topics: Ascorbic Acid; Fruit; Gene Expression Regulation, Plant; Malates; Malus; Plant Breeding; Plant Proteins

Postharvest ultraviolet-C (UV-C) hormesis has been shown effective for the treatment of the edible part of several horticultural crops such as strawberry fruit; however, there is a lack of information on its potential preharvest impact. In the present study three strawberry cultivars (Fragaria × ananassa Duch. 'Albion', 'Charlotte' and 'Seascape') were exposed to UV-C during two growth seasons for a period of three weeks. Treatment begins when the first flowers were wide open and fruits at commercial maturity were harvested within one week after UV treatment. The physicochemical quality parameters of the fruits harvested from the treated plants were compared to those of the fruits of the untreated control plants. Preharvest UV-C treatment tended to increase fruit firmness in all cultivars with significant differences declared only for 'Albion' and 'Seascape' in season 2. Fruits from treated plants were generally redder but a significant difference was observed only for cultivar 'Charlotte' in the second growing season. Other color attributes were not affected by UV-C, neither were organic acids, simple sugars, soluble solids content (SSC), titratable acidity (TA) and pH, although in most cases slight decreases were noticed. Cultivar and growing season were the factors that mostly influenced on the parameters under study. The present study show that cumulative preharvest UV-C treatment of 3.6 kJ m

Topics: Ascorbic Acid; Citric Acid; Color; Food Quality; Fragaria; Fruit; Malates; Monosaccharides; Ultraviolet Rays

Tomato is sensitive to ozone. Fruit growth and composition are altered under ozone stress by modification of reproductive development. Fifty-one-day-old plants were exposed to three concentrations of ozone (200, 350 and 500 µg m(-3)) for 4 h.. Ozone reduced well-developed fruit number and fruit size, but it did not significantly affect flowering rate and fruit setting rate. The effect of ozone depends on organ developmental stage at the time of ozone application, as flowers and young fruits at the time of ozone exposure were more affected. Contents of total soluble sugars (total SS), total organic acids (total OA) and ascorbic acid (AsA) increased in fruits harvested from ozone-treated plants. Tomato fruit composition was altered under ozone stress, leading to a lower sugar:acid ratio. These changes were mostly due to increased contents of malic acid, ascorbate and glucose despite a decrease in sucrose.. Acute ozone exposure up to 500 µg m(-3) greatly influences tomato fruit quality. As final fruit yield was not significantly reduced, it highlighted that there may be compensatory mechanisms present in the reproductive structures of tomato. Further research would be necessary to determine how reproductive traits are affected by repeated ozone exposure or longer-term exposure.

Topics: Ascorbic Acid; Flowers; Fruit; Glucose; Malates; Ozone; Reproduction; Solanum lycopersicum; Stress, Physiological; Sucrose

To introduce a direct method for estimating relaxation and kinetic parameter values from rapid dissolution dynamic nuclear polarization (RD-DNP) NMR time courses.. The analysis relied on a kinetic model that is often used to analyze data in these studies-a unidirectional (bio)chemical reaction with rate constant k1 , coupled to longitudinal relaxation of the magnetization of substrate and product that is characterized by the time constant T1 . The latter value was estimated from the width of the product curve (peak) at the height α relative to the maximum height. We showed α ∼ 0.8 under most conditions, so we measured the interval between the falling and rising parts of the curve at the relative height 0.8. We called this the "fall-minus-rise time at height α," or FmRα , and found that FmR0.8 ∼ T1 . The ratio β = (product signal/substrate signal) when the product is maximal was shown to be equal to k1 T1 . Therefore, k1 = β/FmR0.8 .. FmRα analysis was demonstrated with (13) C NMR RD-DNP data recorded from hemolysates and from previously published data.. FmRα analysis enables immediate estimates of kinetic and relaxation parameters from (13) C NMR RD-DNP data. The values can be used as initial estimates in more extensive computer-based data-regression analysis.

Topics: Animals; Ascorbic Acid; Carbon Isotopes; Fumarates; Glutathione; Humans; Kinetics; Lactic Acid; Magnetic Resonance Spectroscopy; Malates; Mice; Models, Chemical; Models, Statistical; Pyruvic Acid

Carboxylate-rich organic acids play an important role in controlling the growth of apatite crystals and the extent of mineralization in the natural bone. The objective of this work was to investigate the effect of organic acids on calcium phosphate (CaP) nucleation on nanofiber microsheets functionalized with a glutamic acid peptide and osteogenic differentiation of human mesenchymal stem cells (hMSCs) seeded on the CaP-nucleated microsheets. High molecular weight poly(dl-lactide) (DL-PLA) was mixed with low molecular weight L-PLA conjugated with Glu-Glu-Gly-Gly-Cys peptide, and the mixture was electrospun to generate aligned nanofiber microsheets. The nanofiber microsheets were incubated in a modified simulated body fluid (mSBF) supplemented with different organic acids for nucleation and growth of CaP crystals on the nanofibers. Organic acids included citric acid (CA), hydroxycitric acid (HCA), tartaric acid (TART), malic acid (MA), ascorbic acid (AsA), and salicylic acid (SalA). HCA microsheets had the highest CaP content at 240 ± 10% followed by TART and CA with 225 ± 8% and 225 ± 10%, respectively. The Ca/P ratio and percent crystallinity of the nucleated CaP in TART microsheets was closest to that of stoichiometric hydroxyapatite. The extent of CaP nucleation and growth on the nanofiber microsheets depended on the acidic strength and number of hydrogen-bonding hydroxyl groups of the organic acids. Compressive modulus and degradation of the CaP nucleated microsheets were related to percent crystallinity and CaP content. Osteogenic differentiation of hMSCs seeded on the microsheets and cultured in osteogenic medium increased only for those microsheets nucleated with CaP by incubation in CA or AsA-supplemented mSBF. Further, only CA microsheets stimulated bone nodule formation by the seeded hMSCs.

Topics: Ascorbic Acid; Calcium Phosphates; Cell Differentiation; Citrates; Citric Acid; Humans; Malates; Mesenchymal Stem Cells; Nanofibers; Oligopeptides; Salicylic Acid; Tartrates

Keratoconus (KC) affects 1:2000 people and is a disorder where cornea thins and assumes a conical shape. Advanced KC requires surgery to maintain vision. The role of oxidative stress in KC remains unclear. We aimed to identify oxidative stress levels between human corneal keratocytes (HCKs), fibroblasts (HCFs) and keratoconus cells (HKCs). Cells were cultured in 2D and 3D systems. Vitamin C (VitC) and TGF-β3 (T3) were used for 4 weeks to stimulate self-assembled extracellular matrix (ECM). No T3 used as controls. Samples were analyzed using qRT-PCR and metabolomics. qRT-PCR data showed low levels of collagen I and V, as well as keratocan for HKCs, indicating differentiation to a myofibroblast phenotype. Collagen type III, a marker for fibrosis, was up regulated in HKCs. We robustly detected more than 150 metabolites of the targeted 250 by LC-MS/MS per condition and among those metabolites several were related to oxidative stress. Lactate levels, lactate/malate and lactate/pyruvate ratios were elevated in HKCs, while arginine and glutathione/oxidized glutathione ratio were reduced. Similar patterns found in both 2D and 3D. Our data shows that fibroblasts exhibit enhanced oxidative stress compared to keratocytes. Furthermore the HKC cells exhibit the greatest level suggesting they may have a myofibroblast phenotype.

Topics: Arginine; Ascorbic Acid; Cell Differentiation; Cells, Cultured; Collagen Type I; Collagen Type III; Collagen Type IV; Cornea; Corneal Keratocytes; Extracellular Matrix; Fibroblasts; Glutathione; Humans; Keratoconus; Lactic Acid; Malates; Metabolomics; Myofibroblasts; Oxidative Stress; Proteoglycans; Pyruvic Acid; Transforming Growth Factor beta3

The therapeutic action of a plant depends on its chemical constituents. In this study, experiments were carried out in order to evaluate the effect of extraction conditions on the antioxidative and antimicrobial activities of Roselle (Hibiscus sabdariffa L.).. Roselle was found to be rich in malic acid, anthocyanins, ascorbic acid and minerals, especially Ca and Fe, but low in glucose. More than 18 volatile compounds were identified by gas chromatography and gas chromatography-mass spectrometry. This herb, which is rich in phenolic compounds and displays DPPH radical scavenging activity, could be a good source of natural antioxidants. The antimicrobial activity of the Roselle water and ethanol extracts was tested with Bacillus subtilis (ATCC6633), Staphylococcus aureus (ATCC6538) and Escherichia coli (ATCC 8739). The inhibition of the Roselle ethanol extract against B. subtilis and S. aureus was slightly higher than that of water extract but this difference was not significant. However, E. coli was strongly inhibited by the Roselle water extract at concentrations of 25 and 50 mg mL(-1) as determined by a paper disc method.. The obtained results indicated that antioxidant and antimicrobial activity was related to different methods of extraction and Roselle extracts could be a source of therapeutically useful products.

Topics: Anthocyanins; Anti-Bacterial Agents; Antioxidants; Ascorbic Acid; Bacillus; Bacteria; Biphenyl Compounds; Escherichia coli; Hibiscus; Malates; Minerals; Oils, Volatile; Phenols; Picrates; Plant Extracts; Staphylococcus aureus

Ageing is associated with skeletal muscle impairment. Changes in mitochondrial homeostasis are thought to play a key role in this process. This study examined whether chronic intake of polyphenols (PPs), which are known to be modulators of oxidative stress, might prevent the age-related decline of mitochondrial functions in skeletal muscle. Three groups of 10 Wistar rats were investigated. Rats aged 16 weeks were compared with rats aged 40 weeks that were given 75 mg kg(-1) day(-1) PPs or solvent in the drinking water starting at week 16. Mitochondrial respiratory chain complex activities were measured in saponin-skinned fibres of soleus muscles using glutamate-malate (V(max)), succinate (V(succ)) and N,N,N',N'-tetramethyl-p-phenylenediamine dihydrochloride-ascorbate (V(TMPD)). Production of reactive oxygen species was assessed using dihydroethidium staining. Transcript levels of genes involved in antioxidant defence were determined using RT-PCR. Ageing reduced muscle V(max) (from 8.8 ± 0.45 to 6.17 ± 0.51 μmol O(2) min(-1) g(-1), -30.5%, P < 0.01), V(TMPD) (from 20.67 ± 1.24 to 16.55 ± 1.16 μmol O(2) min(-1) g(-1), -19.9%, P < 0.05), increased production of reactive oxygen species (from 100 ± 9.9 to 351.1 ± 31.7%) and decreased transcripts of mitochondrial superoxide dismutase 2 (-59.3%, P < 0.01), peroxisome proliferator-activated receptor γ coactivator-1β (PGC-1β; -61.5%, P < 0.05) and sirtuin 1 (-54.2%, P < 0.05). Chronic PP intake normalized V(max) (8.63 ± 0.63 μmol O(2) min(-1) g(-1)), decreased production of reactive oxygen species (141.7 ± 16.7%, P < 0.001) and enhanced antioxidant defence (superoxide dismutase 2 expression, +151.3%, P < 0.05) and PGC-1β expression (+185.7%, P < 0.05) in comparison to age-matched untreated rats. The present data indicate that regular intake of PPs starting at a young age prevents age-related mitochondrial respiratory impairment in skeletal muscle, probably through decreased oxidative stress and enhancement of PGC-1β expression.

Topics: Administration, Oral; Age Factors; Aging; Animals; Antioxidants; Ascorbic Acid; Electron Transport Chain Complex Proteins; Energy Metabolism; Gene Expression Regulation; Glutamic Acid; Malates; Male; Mitochondria, Muscle; Muscle, Skeletal; Oxidation-Reduction; Oxidative Stress; Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; Polyphenols; Rats; Rats, Wistar; Reactive Oxygen Species; Real-Time Polymerase Chain Reaction; RNA-Binding Proteins; RNA, Messenger; Sirtuin 1; Succinic Acid; Superoxide Dismutase; Time Factors; Transcription Factors

Demand for broccoli has increased due to its high content of bioactive compounds. However, broccoli is a perishable commodity with a short shelf life mainly due to dehydration, yellowing and losses of bioactive compounds. Thus, efficient treatments to preserve broccoli quality are needed.. The effect of heat treatment on senescence and antioxidant compounds evolution during storage at 20 °C was evaluated in organic and conventionally grown broccoli. Senescence evolved quickly as manifested by floral head yellowing, which was higher in conventional than in organic broccolis, but senescence was significantly delayed by heat treatment. All organic acids, including ascorbic acid, were found at higher concentrations in organic than in conventional broccoli at harvest but decreased during storage in all broccolis. Phenolic concentration and antioxidant activity (in both hydrophilic and lipophilic fractions) also decreased during storage, although these decreases were higher in conventional than in organic broccolis, and no differences were found attributable to heat treatment.. Heat treatment was effective in delaying broccoli senescence, manifested by chlorophyll retention. In addition, organic broccoli maintained higher concentrations of bioactive compounds (ascorbic acid and phenolics) and antioxidant potential during storage than conventional broccoli, with higher potential health beneficial effects.

Topics: Antioxidants; Ascorbic Acid; Brassica; Chlorophyll; Flowering Tops; Food Preservation; Food Quality; Food Storage; Food, Organic; Hot Temperature; Hydrophobic and Hydrophilic Interactions; Malates; Phenols; Pigments, Biological; Plant Stems; Spain; Tartrates; Time Factors

Treatment of melasma and postinflammatory hyperpigmentation is often challenging. No ideal short-term and long-term treatment is available. Vitamin C alone and in combination with iontophoresis has been studied and found to be useful; however, no long-term studies have been published.. In this study, 35 patients (34 female, 1 male) were treated with a novel full-face iontophoresis mask (FFIM) and a proprietary vitamin C (ascorbyl glucoside) preparation. Patients received one in-office treatment and 12 to 24 at-home treatments over 1 to 2 months in conjunction with a strict maintenance regimen consisting of a mandelic/malic acid skin care regimen, broad-spectrum ultraviolet A/ultraviolet B sunblock, a wide-brimmed hat, and sun-avoidance behavior. Follow-up after the initial in-office treatment ranged from 1 to 54 months (mean, 26 months). Four independent observers graded improvement of melasma and PIH using a 4-point scale. Before the study, high-performance liquid chromatography was used to verify iontophoretic penetration of vitamin C into the skin to a level of 0.2 cm in healthy volunteers (2 male, 2 female).. A mean 73% improvement in abnormal pigmentation was observed at the end of FFIM/vitamin C treatment. Greater than 25% improvement was observed in 32 of 35 patients, and greater than 50% improvement in 22 of 35 patients. Melasma Area and Severity Index scores demonstrated substantial improvement from baseline for all patients, with a mean improvement of 15.7.. Full-face iontophoresis of vitamin C appears to be an effective short-term treatment for melasma and postinflammatory hyperpigmentation. A protocol of strict sun avoidance in combination with a mandelic/malic acid skin care regimen appears to be useful in maintaining the improvement.

Topics: Adult; Ascorbic Acid; Chromatography, High Pressure Liquid; Female; Follow-Up Studies; Humans; Hyperpigmentation; Iontophoresis; Malates; Male; Mandelic Acids; Masks; Melanosis; Middle Aged; Skin; Skin Absorption; Sunscreening Agents; Treatment Outcome; Vitamins

Sea buckthorn berries (Hippophaë rhamnoides ssp. mongolica) of nine varieties were collected from three growth locations in five inconsecutive years (n = 152) to study the compositional differences of sugars, sugar alcohols, fruit acids, and ascorbic acid in berries of different genotypes. Fructose and glucose (major sugars) were highest in Chuiskaya and Vitaminaya among the varieties studied, respectively. Malic acid and quinic acid (major acids) were highest in Pertsik and Vitaminaya, respectively. Ascorbic acid was highest in Oranzhevaya and lowest in Vitaminaya. Berry samples of nine varieties collected from two growth locations in five years (n = 124) were combined to study the effects of latitude and weather conditions on the composition of H. rhamnoides ssp. mongolica. Sea buckthorn berries grown at lower latitude had higher levels of total sugar and sugar/acid ratio and a lower level of total acid and were supposed to have better sensory properties than those grown at higher latitude. Glucose, quinic acid, and ascorbic acid were hardly influenced by weather conditions. The other components showed various correlations with temperature, radiation, precipitation, and humidity variables. In addition, fructose, sucrose, and myo-inositol correlated positively with each other and showed negative correlation with malic acid on the basis of all the samples studied (n = 152).

Topics: Ascorbic Acid; Beverages; Carbohydrates; Environment; Fructose; Fruit; Genotype; Glucose; Hippophae; Malates; Quinic Acid; Sugar Alcohols; Weather

Ten promising jujubes were analyzed for textural characteristic (hardness), antioxidant activity, sugar, organic acid, and phenolic profiles. Total phenolic content (TP) measured by Folin-Ciocalteu method ranged from 275.6 to 541.8 mg of gallic acid equivalents per 100 g fresh weight (mg GAE/100 g FW). Four sugars (rhamnose, fructose, sucrose, and glucose), 3 organic acids (malic, citric, and succinic acids), and 11 phenolic compounds (gallic acid, protocatechuic acid, cinnamic acid, chlorogenic acid, caffeic acid, ferulic acid, ellagic acid, catechin, epicatechin, rutin, and quercetin) were identified and quantified by high-performance liquid chromatography in jujube fruits. The results showed that ascorbic acid and proanthocyanidins contents were positively correlated with hardness, and antioxidant activity was well correlated with TP content. Among 10 jujube cultivars, Zizyphus jujuba cv. Qingjianmuzao is good for direct consumption containing high levels of total soluble solids, total sugars, fructose, and glucose, while Zizyphus jujuba cv. Jiaxianmuzao could be an important dietary source of natural antioxidants.. Genotype is the main factor influencing the composition of bioactive compounds in jujubes. Zizyphus jujuba cv. Qingjianmuzao is good for direct consumption, while Zizyphus jujuba cv. Jiaxianmuzao could be an important dietary source of natural antioxidants for prevention of diseases caused by oxidative stress.

Topics: Antioxidants; Ascorbic Acid; Carbohydrates; Chemical Phenomena; Chromatography, High Pressure Liquid; Citric Acid; Fruit; Genotype; Malates; Oxidative Stress; Phenols; Proanthocyanidins; Succinic Acid; Ziziphus

Burbank and Norkotah potato slices were dipped into 3% sodium acid sulfate (SAS), citric acid (CA), sodium erythorbate (SE), malic acid (MA), sodium acid pyrophosphate (SAPP), or a combination of SAS-CA-SE. Browning by polyphenol oxidase (PPO) obtained from potato extract with 0.04 to 0.016 g/mL of antibrowning solutions at pH 2.0 to 6.9 were measured by UV-Vis spectroscopy. The color of slices dipped in antibrowning solutions at pHs 2 to 7 and stored at 4 °C for 15 d was measured every 5 d by colorimeter. Headspace analysis of volatiles in raw and cooked potato samples was performed by selected ion flow tube mass spectrometer (SIFT-MS) and soft independent modelling by class analogy (SIMCA) analysis of the calculated odor activity values (OAV) determined interclass distances. Microbial growth was measured at 15 d. At unadjusted pHs (1.1 to 7.1), the PPO browning of the control and samples with SAPP was not significantly different, SAS, CA, and MA produced some inhibition and SE and SAS-CA-SE prevented browning. At pH 5 to 7, only SE and SAS-CA-SE were effective browning inhibitors. Based on the color of potato slices, SE was the most effective at pH 2 to 7, but SAS was most effective at unadjusted pH. Cooking increased volatile levels in the treated potatoes and decreased differences between volatile profiles. Differences between cooked samples may not be noticeable by the consumer because volatiles with high discriminating powers have low OAVs. SAS, CA, and SAS-CA-SE treatments inhibited microbial growth but SAPP, control, and SE did not, most likely due to pH.. Antibrowning agents inhibit polyphenol oxidase, increasing shelf life and consumer acceptability of processed raw potato products by preserving the color. Their effectiveness was shown to be mainly due to a pH effect, except SE, which was not pH dependent. MA, CA, and SAS-CA-SE are better acidulants for inhibition of color change as well as growth of spoilage bacteria, yeast, and mold than SAPP, the industry standard.

Topics: Ascorbic Acid; Catechol Oxidase; Citric Acid; Colony Count, Microbial; Color; Consumer Behavior; Diphosphates; Food Contamination; Food Handling; Food Microbiology; Food Preservation; Hydrogen-Ion Concentration; Maillard Reaction; Malates; Odorants; Solanum tuberosum; Sulfates; Volatile Organic Compounds

Hydrocolloid-based materials have been extensively used to coat fruit and vegetables to prolong shelf-life. The effects of different concentrations of acidic washing (acetic, ascorbic, citric and malic acids) followed by coating with gum arabic (GA), carboxymethyl cellulose and emulsified gum arabic (EGA) were evaluated on the weight loss (WL), firmness and color of mushroom. The WL of the uncoated mushrooms was significantly (p < 0.05) greater than that of the coated ones, and the minimum WL was obtained with EGA coating. The mushrooms washed with malic and ascorbic acids showed minimum and maximum of WL, respectively. Loss in firmness of the EGA-coated mushrooms was by 21% (the minimum of loss), while loss value of the uncoated ones was by 39% (the maximum of loss). Firmness of mushrooms was not influenced by the acid type. Concentration of the acid significantly (p < 0.05) influenced the firmness of mushrooms, and at the lowest concentration of acid (1%), the mushrooms tissue was firmest. The L* value of the mushrooms coated with GA was higher than that of others. A significant (p < 0.05) decrease in L* value and a significant (p < 0.05) increase in a* and b* values occurred in the mushrooms washed with acetic acid. Overall, washing with 1% citric or malic acid followed by coating with EGA resulted in minimum decrease in WL and firmness of the mushrooms.

Topics: Acetic Acid; Agaricus; Ascorbic Acid; Carboxymethylcellulose Sodium; Chemical Phenomena; Citric Acid; Colloids; Emulsifying Agents; Food Handling; Food Preservatives; Food Storage; Gum Arabic; Maillard Reaction; Malates; Mechanical Phenomena; Osmolar Concentration; Polysorbates; Soybean Oil; Surface Properties; Water

In this study, changes in quality and various biochemical parameters of 'Idared' apples during prolonged shelf life period after ultra-low oxygen (ULO) storage were investigated. Additionally, the impact of the postharvest application of 1-methylcyclopropene (1-MCP) on different parameters was evaluated. After the harvest, apples were stored in the ULO storage for 6 months and then exposed to room temperature. Fruit firmness, peel color, and changes in sugars, organic acids and phenolics were monitored during the 3 weeks of shelf life. Malic acid, sugars and firmness decreased at room temperature. However, the color of the apples remained unchanged. The level of citric and ascorbic acid remained constant. Levels of phenolics in the peel increased significantly, whereas remained constant in the pulp of apples. 1-MCP treatment resulted in higher amounts of fructose and glucose, malic acid and greater firmness of apples. However, 1-MCP did not influence the phenolic content, ascorbic acid or color. The results obtained indicate that the content of different health-promoting compounds of apples does not change dramatically at room temperature. At the same time these results suggest that 1-MCP could be useful for maintaining certain quality and biochemical parameters and might extend the shelf life of apples.

Topics: Ascorbic Acid; Chemical Phenomena; Citric Acid; Cyclopropanes; Dietary Carbohydrates; Food Preservatives; Food Quality; Food Storage; Fructose; Fruit; Functional Food; Glucose; Malates; Malus; Mechanical Phenomena; Phenols; Pigmentation; Plant Epidermis; Refrigeration; Slovenia

Ultraviolet radiation induced degradation of ascorbic acid in a model apple juice system and in apple juice was studied using a collimated beam batch UV reactor. In the model system, ascorbic acid degradation was more rapid at higher dose levels and the reaction accelerated with increasing exposure time. Ascorbic acid degradation significantly (P < 0.05) increased as the pH was raised from 2.4 to 5.5, although no difference was observed between 2.4 and 3.3. Increasing malic acid concentration between 0.1 and 1%, increased ascorbic acid degradation (P < 0.05) although there was no difference between 0.5 and 1.0%. Solution absorbance, varied by addition of tannic acid, decreased ascorbic acid degradation with increasing concentration due to absorption of UV radiation. Fructose at levels found in apple juice significantly increased ascorbic acid degradation while glucose and sucrose did not. Factors identified that accelerate ascorbic acid degradation may at least partially explain why ascorbic acid degradation occurred more rapidly in UV-treated apple juice than in the 0.5% malic acid model system. Ascorbic acid degradation continued after UV treatments during dark storage. Storage decreases were faster at higher initial UV dose levels and higher storage temperature.. The present study shows the effect of UV processing on ascorbic acid, a key vitamin found in many fruit juices. Process developers and researchers can use this study as a model for designing experiments to identify factors that influence the stability of vitamin C and other bioactive compounds during UV processing.

Topics: Ascorbic Acid; Beverages; Food Handling; Food Preservation; Fructose; Glucose; Hydrogen-Ion Concentration; Kinetics; Malates; Malus; Models, Biological; Sucrose; Ultraviolet Rays

The accumulation of L-ascorbate (Asc) in fruits is influenced by environmental factors including light quantity. Fruit exposure to ambient light is often reduced by the surrounding leaf canopy, and can be altered by cultivation practices. The influence of reduced sunlight exposure on the accumulation of Asc and its catabolites was investigated in field-grown berries of the cultivated grapevine Vitis vinifera L. cv. Shiraz.. Growth under sunlight-eliminated conditions resulted in reduced berry fresh weight, chlorosis and a reduced total L-ascorbate pool size. The concentration of the Asc catabolite L-tartaric acid (TA) was reduced in berries grown without light. Conversely, concentrations of oxalic acid (OA), an alternative catabolite of Asc, and malic acid (MA), were unaffected by shading the berries during development. Brief and significant reductions in transcription of the Asc metabolic genes were observed in shade-grown berries after 4 weeks of dark acclimatisation whilst a key TA biosynthetic gene was not regulated by light.. The results demonstrate that light-regulation of Asc and TA occurs only at brief stages of development and that OA and MA accumulation is light independent. Additionally, the comparable ratios of TA product to Asc precursor under both light regimes suggest that the diversion of Asc to TA is driven by factors that are not responsive to light. These findings suggest that an altered light regime is not the key to manipulating TA or MA levels in the harvested berry.

Topics: Acclimatization; Agriculture; Ascorbic Acid; Biomass; Darkness; Fruit; Gene Expression Regulation, Plant; Genes, Plant; Malates; Oxalic Acid; Sunlight; Tartrates; Vitis

The consumption of acidic soft drinks may lead to demineralization and softening of human dental enamel, known as dental erosion. The aims of this in vitro study were to determine: (i) if different acids with a similar sensorial acidic taste lead to different hardness loss of enamel and (ii) if the fruit acids tartaric, malic, lactic or ascorbic acid lead to less hardness loss of enamel than citric or phosphoric acid when their concentration in solution is based on an equivalent sensorial acidic taste.. Enamel samples of non-erupted human third molars were treated with acidic solutions of tartaric (TA), malic (MA), lactic (LA), ascorbic (AA), phosphoric (PA) and citric (CA) acids with a concentration that gave an equivalent sensorial acidic taste. The acidic solutions were characterized by pH value and titratable acidity. Atomic force microscopy (AFM) based nanoindentation was used to study the nano mechanical properties and scanning electron microscopy (SEM) was used to study the morphology of the treated enamel samples and the untreated control areas, respectively.. The investigated acids fell into two groups. The nano hardnesses of MA, TA and CA treated enamel samples (group I) were statistically significantly greater (p<0.05) than the nano hardnesses of PA, AA and LA treated enamel samples (group II). Within each group the nano hardness was not statistically significantly different (p>0.05). The SEM micrographs showed different etch prism morphologies depending on the acid used.. In vitro, the acids investigated led to different erosion effects on human dental enamel, despite their equivalent sensorial acidic taste. This has not been reported previously.

Topics: Acids; Analysis of Variance; Ascorbic Acid; Beverages; Citric Acid; Dental Enamel; Elastic Modulus; Hardness; Humans; Hydrogen-Ion Concentration; Lactic Acid; Malates; Phosphoric Acids; Tartrates; Taste; Tooth Erosion

Recent data demonstrated that hind limb ischemia induces skeletal muscle mitochondrial dysfunctions. Improvement of such metabolic myopathy improves patient's symptomatology, supporting the development of experimental models focused on mitochondrial function analysis. However, although the nonischemic contralateral leg is often used as a control during unilateral leg ischemia, whether it might be useful when assessing ischemia-induced mitochondrial dysfunction remains to be investigated.. Both ischemic (IR) and nonischemic contralateral legs (CTL) of rats (n=13) submitted to 5 h ischemia induced by a rubber band tourniquet applied on the root of the hind limb were studied and compared to that of sham-operated animals (SHAM, n=13). Maximal oxidative capacities (V(max)) and complexes I, II and IV activities of the gastrocnemius mitochondrial respiratory chain were determined, using glutamate-malate, succinate (Vs) and TMPD-ascorbate (V(TMPD)) substrates.. V(max) was decreased in IR (4.6+/-0.4 microM/min/g dry weight) compared to both SHAM and CTL muscles (8.5+/-0.5 and 7.1+/-0.4 microM/min/g dry weight, -46% and -36%, P<0.001, respectively). V(S) and V(TMPD) were reduced in IR muscle (-56% and -48% for V(S); and -25% and -24% for V(TMPD), P<0.001) as compared to SHAM and CTL). V(S) and V(TMPD) were similar in SHAM and CTL muscles.. Five hours ischemia-reperfusion significantly impaired complexes I, II and IV of the ischemic skeletal muscle mitochondrial respiratory chain. Interestingly, only V(max) was slightly altered in the contralateral leg, supporting that the nonischemic leg might be used as a control when assessing mitochondrial function in the experimental setting of unilateral hind limb ischemia.

Topics: Animals; Ascorbic Acid; Cell Respiration; Electron Transport Chain Complex Proteins; Glutamic Acid; Ischemia; Lower Extremity; Malates; Male; Mitochondria, Muscle; Mitochondrial Diseases; Muscle, Skeletal; Rats; Rats, Wistar; Reperfusion Injury; Succinic Acid; Tetramethylphenylenediamine

To study the different and the variety of four organic acids in leaves of Isatis indigotica among different cultivated populations in water stress condition and healthy plant.. Four kinds of organic acids, such as oxalic acid, malic acid, ascorbic acid and citric acid from the leaves, were detected by HPLC.. Significant differences of four organic acids in the leaves of Beijing, Mongolia, Hebei and Shanxi cultivated populations. Compared with the healthy plant, the content of oxalic acid, malic acid and citric acid in water stress were increased, while the content of ascorbic acid was decreased.. Contents of four organic acids can act as the guideline factor in I. indigotica because they were related with the water stress condition.

Topics: Ascorbic Acid; China; Chromatography, High Pressure Liquid; Citric Acid; Dehydration; Isatis; Malates; Oxalic Acid; Plant Leaves

Sulfide oxidation in the lugworm, Arenicola marina (L.), is most likely localized in the mitochondria, which can either produce ATP with sulfide as a substrate or detoxify it via an alternative oxidase. The present study identified selective activators of the energy-conserving and the detoxifying sulfide oxidation pathways respectively. In the presence of the ROS scavengers glutathione (GSH) and ascorbate, isolated lugworm mitochondria rapidly oxidized up to 100 micromoll(-1) sulfide with maximal oxygen consumption rates but did not produce any ATP in the process. Under these conditions, salicylhydroxamic acid (SHAM), which is an inhibitor of the alternative oxidase of plant mitochondria, completely blocked oxygen consumption whereas inhibitors of complex III and IV had hardly any effect. By contrast, dehydroascorbate (DHA) enabled the mitochondria to gain ATP from sulfide oxidation even if the sulfide concentration far exceeded the threshold for inhibition of cytochrome oxidase. In the presence of dehydroascorbate, respiratory rates were independent of sulfide concentrations, with a respiratory control ratio of 2.1+/-0.2, and both oxygen consumption and ATP production were completely inhibited by myxothiazol and sodium azide but only marginally by SHAM. The present data indicate that a redox mechanism may contribute to the regulation of sulfide oxidation in lugworm mitochondria in vivo. Thus, mitochondria are presumably much more sulfide resistant in a cellular context than previously thought.

Topics: Adenosine Triphosphate; Animals; Ascorbic Acid; Cell Respiration; Dehydroascorbic Acid; Glutathione; Malates; Mitochondria; Models, Biological; Oxidation-Reduction; Oxidoreductases; Oxygen; Oxygen Consumption; Polychaeta; Sulfides

An experimental system to measure the carbon dioxide (CO(2)) solubility in liquids at different pressures was designed and tested. Pressure and temperature were controlled in the system, and the design assured an accurate measurement of solubility. Experimental measurements of CO(2) solubility were performed in pure water, model solutions (ascorbic acid-sugars-water, citric acid-sugars-water), and in commercial orange juice (OJ) and apple juice (AJ), as a function of pressure (7.58 to 15.86 MPa) at constant temperature (40 degrees C). Aspen simulation software was used to predict the solubility in simple cases. All experimental results and predictions from simulations were compared with literature data. Measurements of CO(2) solubility in pure water were not significantly different than the literature. CO(2) solubility (g/100 g of liquid) results in the model liquids and in the juices were lower than for pure water, due to the presence of solutes. The software simulation was able to predict the CO(2) solubility in the model systems at low pressures.

Topics: Ascorbic Acid; Beverages; Bicarbonates; Carbon Dioxide; Citric Acid; Citrus sinensis; Equipment Design; Fructose; Malates; Malus; Pressure; Solubility; Sucrose; Temperature

Effects of treatment with dehydroepiandrosterone (DHEA) on oxidative energy metabolism in rat liver and brain mitochondria were examined.. Young adult rats were administered DHEA (0.1, 0.2, 1.0 or 2.0 mg/kg body weight) by subcutaneous route for 7 consecutive days.. DHEA treatment resulted in general, in stimulation of state 3 respiration rates without having any uncoupling effect on ADP/O ratios. The stimulation of state 3 respiration rate for a given substrate was dose dependent in a tissue-specific manner. Parallel increases in the contents of cytochromes aa(3) and b were also noted. DHEA treatment stimulated the glutamate dehydrogenase (GDH) and succinate DCIP reductase (SDR) activities. Under the treatment conditions, mitochondrial ATPase activity was also stimulated.. Treatment with DHEA significantly stimulated oxidative energy metabolism in liver and brain mitochondria.

Topics: Adenosine Triphosphatases; Animals; Ascorbic Acid; Brain; Cytochromes; Cytosol; Dehydroepiandrosterone; Glutamic Acid; Malates; Male; Mitochondria; Mitochondria, Liver; Oxidative Phosphorylation; Oxidoreductases; Pyruvic Acid; Rats; Substrate Specificity; Succinic Acid; Tetramethylphenylenediamine

Bundle sheath chloroplasts of NADP-malic enzyme (NADP-ME) type C4 species have a high demand for ATP, while being deficient in linear electron flow and oxidation of water by photosystem II (PSII). To evaluate electron donors to photosystem I (PSI) and possible pathways of cyclic electron flow (CEF1) in isolated bundle sheath strands of maize (Zea mays L.), an NADP-ME species, light-induced redox kinetics of the reaction center chlorophyll of PSI (P700) were followed under aerobic conditions. Donors of electrons to CEF1 are needed to compensate for electrons lost from the cycle. When stromal electron donors to CEF1 are generated during pre-illumination with actinic light (AL), they retard the subsequent rate of oxidation of P700 by far-red light. Ascorbate was more effective than malate in generating stromal electron donors by AL. The generation of stromal donors by ascorbate was inhibited by DCMU, showing ascorbate donates electrons to the oxidizing side of PSII. The inhibitors of NADPH dehydrogenase (NDH), amytal and rotenone, accelerated the oxidation rate of P700 by far-red light after AL, indicating donation of electrons to the intersystem from stromal donors via NDH. These inhibitors, however, did not affect the steady-state level of P700+ under AL, which represents a balance of input and output of electrons in P700. In contrast, antimycin A, the inhibitor of the ferredoxin-plastoquinone reductase-dependent CEF1, substantially lowered the level of P700+ under AL. Thus, the primary pathway of ATP generation by CEF1 may be through ferredoxin-plastoquinone, while function of CEF1 via NDH may be restricted by low levels of ferredoxin-NADP reductase. NDH may contribute to redox poising of CEF1, or function to generate ATP in linear electron flow to O2 via PSI, utilizing NADPH generated from malate by chloroplastic NADP-ME.

Topics: Ascorbic Acid; Chloroplasts; Diuron; Electron Transport; Kinetics; Light; Malates; Nigericin; Oxidation-Reduction; Paraquat; Photosynthesis; Photosystem I Protein Complex; Plant Proteins; Zea mays

A fast, one-step gas chromatographic method was developed to analyze trimethylsilyl (TMS) derivatives of sugars, fruit acids, and ascorbic acid in sea buckthorn (Hippohaë rhamnoides L.) berries. The method was applied to berry press juice of sea buckthorn of different origins grown in Finland during the 2003 and 2004 seasons. The method gave reliable results for D-fructose, D-glucose, ethyl-D-glucose, and malic, quinic, and ascorbic acids, which are the major sugars and acids in sea buckthorn juice. For the first time in sea buckthorn and evidently in any berry, the presence of ethyl beta-D-glucopyranoside is reported. The structure of ethyl glucose was verified by high-performance liquid chromatography (HPLC), gas chromatography (GC), MS, and NMR analyses of both the isolated and the synthesized compounds. In the GC method, vitamin C was analyzed as ascorbic acid only, and dehydroascorbic acid was thus not taken into account.

Topics: Ascorbic Acid; Carbohydrates; Carboxylic Acids; Chromatography, Gas; Finland; Fructose; Fruit; Glucose; Hippophae; Magnetic Resonance Spectroscopy; Malates; Quinic Acid

The effect of added organic acids on the calcium availability of vegetables was investigated using the dialysis profiles obtained from an in vitro simulated gastrointestinal digestion with continuous-flow dialysis method. Citric acid was the most effective enhancer followed by tartaric, malic, and ascorbic acids. For amaranth, which has a low calcium availability (5.4%), a significant increase of availability was observed with increasing concentrations of all acids studied. With the continuous-flow dialysis approach, organic acids could be observed to promote the dialyzability even at an elevated intestinal pH. An enhancement effect from added organic acids was not clearly observed for Chinese kale, which itself contains a high amount of available calcium (52.9%).

Topics: Ascorbic Acid; Calcium; Carboxylic Acids; Citric Acid; Dialysis; Digestion; Humans; Intestinal Absorption; Malates; Nutritive Value; Tartrates; Vegetables

To develop an HPLC method for the simultaneous separation and determination of oxalic acid (OA), tartaric acid(TA), malic acid(MA), vitamin C (VC), lactic acid (LA), acetic acid (AA) citric acid (CA) and succinic acid (SA) in Fructus mume.. Analytical column was Zorbax Eclipse XDB C18. Mobile phase was 0.5% (NH4) H2PO4 aqueous solution and detection wavelength was 214 nm. The flow rate of mobile phase was 0.5 mL x min(-1).. The regression equations (pH 2. 8, adjusted with phosphoric acid) of eight constituents have been established, r = 0.999 7, 0. 999 8, 0.999 2, 0.999 6, 0.999 1, 0.999 5, 0.999 8, 0.999 2 respectively. Meanwhile, the content and proportion relationship of eight organic acids in Fructus mume which yielded in Fujian (China) were investigated.. This method was simple, accuracy and quick. The method can be used for the purpose of routine analysis and the quality control of a botanic (Fructus mume) containing these organic acid components.

Topics: Acetic Acid; Ascorbic Acid; Carboxylic Acids; Chromatography, High Pressure Liquid; Citric Acid; Fruit; Lactic Acid; Malates; Oxalic Acid; Plants, Medicinal; Prunus; Quality Control; Reproducibility of Results; Succinic Acid; Tartrates

The stereochemical outcome of the intramolecular Diels-Alder reaction of ester-linked 1,3,8-nonatrienes can be controlled by substituents about a stereogenic center attached to C1. The scope and limitations of this approach have been investigated, with variation in substrate structure about the allylic stereocenter and the dienophile. The stereochemical outcomes of these reactions are explained by reference to B3 LYP/6-31G(d) transition structures. New insights into the conformational preferences of allylic alcohol derivatives are reported, results which allow an explanation of the differing levels of pi-diastereofacial selectivity and cis/trans (i.e. endo/exo) selectivity from the reaction.

Topics: Ascorbic Acid; Computers; Lactic Acid; Malates; Models, Chemical; Molecular Structure; Stereoisomerism

The mechanism of citric acid-enhanced Helicobacter pylori urease activity remains unclear.. To compare ascorbic, citric and malic acid given at the same concentration and pH on intragastric urease activity.. Volunteers received 40 mg of famotidine the evening prior to breath testing. After an overnight fast volunteers were randomized to receive 100 mL of water or 100 mm citric, malic, or ascorbic acid, pH 2.3 containing 75 mg of 13C-urea. At 15 min a second 100 mL solution of one of the test solutions was taken without added urea.. Twelve volunteers were studied (eight men, four women, age 19-57, median 50.7) in a randomized-crossover study. The mean breath test result at 30 min with ascorbic (17.5 +/- 5), malic (25.8 +/- 5) and citric acid (29.5 +/- 5) were all significantly greater than with water (9.5 +/- 3). Citric and malic acid were similar (P = 0.699) and significantly greater than ascorbic acid (P < 0.02). When the ascorbic acid was followed by citric acid, the result was similar to that with citrate alone (25.8 +/- 4) and greater than with ascorbic then ascorbic (P = 0.026).. Enhancement of H. pylori urease activity is not strictly a function of the pH. We propose the effect is related to differential effects of the availability of nickel, which is required for urease activity. Citric acid and malic acid were essentially equivalent such that malic acid could substitute for citric acid in the UBT; ascorbic acid would be a poor choice.

Topics: Adult; Ascorbic Acid; Citric Acid; Female; Helicobacter Infections; Helicobacter pylori; Humans; Malates; Male; Middle Aged; Prospective Studies; Stomach Diseases; Urease

The long-lived mutant of Caenorhabditis elegans, clk-1, is unable to synthesize ubiquinone, CoQ(9). Instead, the mutant accumulates demethoxyubiquinone(9) and small amounts of rhodoquinone(9) as well as dietary CoQ(8). We found a profound defect in oxidative phosphorylation, a test of integrated mitochondrial function, in clk-1 mitochondria fueled by NADH-linked electron donors, i.e. complex I-dependent substrates. Electron transfer from complex I to complex III, which requires quinones, is severely depressed, whereas the individual complexes are fully active. In contrast, oxidative phosphorylation initiated through complex II, which also requires quinones, is completely normal. Here we show that complexes I and II differ in their ability to use the quinone pool in clk-1. This is the first direct demonstration of a differential interaction of complex I and complex II with the endogenous quinone pool. This study uses the combined power of molecular genetics and biochemistry to highlight the role of quinones in mitochondrial function and aging.

Topics: Animals; Ascorbic Acid; Caenorhabditis elegans; Electron Transport Complex I; Electron Transport Complex II; Glutamic Acid; Hydroquinones; Malates; Mitochondria; Mutation; Oxidative Phosphorylation; Pyruvic Acid; Quinones; Substrate Specificity; Tetramethylphenylenediamine; Time Factors; Ubiquinone

Pyruvate is an energy substrate with known cardioprotective activity. We know now that this is due not only to its antioxidant activity, but also to its reduction of intracellular acidosis, modulation of intracytosolic calcium and improvement of cardiomyocyte contractility. However, the role of cardiac mitochondria in such positive effects has only recently begun to be understood and the exact mechanisms of the effect of pyruvate on mitochondria are still largely unknown. Aiming to study the effect of pyruvate on cardiac mitochondrial function during acute ischemia, we used an ex-vivo animal model, perfused in a Langendorff system and then subjected to ischemia in the presence and absence of pyruvate. We evaluated the mitochondrial membrane electrical potential, the respiratory chain O2 consumption (and respiratory control ratio) and the energy charges generated with different energy substrates. We conclude that pyruvate has some effect on the mitochondrial oxidative system (by non-significantly improving the respiratory control ratio), but its main action is on the phosphorylation system, significantly decreasing the time taken to complete a phosphorylation cycle (lag phase) and improving ATP production (increase in energy charge), thus allowing better maintenance of mitochondrial membrane structure, with consequent improvement of the electrical potential after a phosphorylation cycle. These findings have enabled better understanding of the mechanisms behind pyruvate cytoprotection in ischemic cardiomyopathy, clearly highlighting the essential role of cardiac mitochondria in this process.

Topics: Animals; Ascorbic Acid; Chemotherapy, Cancer, Regional Perfusion; Female; Glutamic Acid; Intracellular Membranes; Malates; Male; Membrane Potentials; Mitochondria, Heart; Models, Animal; Myocardial Ischemia; Oxidoreductases, N-Demethylating; Oxygen Consumption; Phosphorylation; Pyruvic Acid; Rats; Rats, Wistar; Succinic Acid

Maize malic enzyme was rapidly inactivated by micromolar concentrations of cupric nitrate in the presence of ascorbate at pH, 5.0. Ascorbate or Cu2+ alone had no effect on enzyme activity. The substrate L-malate or NADP individually provided almost total protection against Cu2+-ascorbate inactivation. The loss of enzyme activity was accompanied by cleavage of the enzyme. The cleaved peptides showed molecular mass of 55 kDa, 48 kDa, 38 kDa, and 14 kDa. Addition of EDTA, histidine and imidazole provided protection. The results of protection experiments with sodium azide, DABCO and catalase suggested that reactive oxygen species were generated resulting in loss of enzyme activity. This was further supported by experiments showing that the rate of enzyme inactivation was higher in D2O than in water. It is suggested that maize malic enzyme is modified by reactive oxygen species like singlet oxygen and H2O2 generated by Cu2+-ascorbate system and the modified amino acid residue(s) may be located at or near the substrate-binding site of the enzyme.

Topics: Amino Acids; Ascorbic Acid; Catalase; Copper; Deuterium Oxide; Edetic Acid; Histidine; Hydrogen Peroxide; Hydrogen-Ion Concentration; Imidazoles; Malates; NADP; Oxygen; Piperazines; Reactive Oxygen Species; Zea mays

There is dose-dependent Cd(2+)-evoked swelling of isolated rat liver mitochondria energized by complex I, II, or IV respiratory substrates in sucrose medium in the absence of added Ca(2+) and P(i), which is prevented by Sr(2+). Permeability transition effectors (ADP, CsA, EGTA, RR, DTT, ATR, P(i), and Ca(2+)) affect in a corresponding way Cd(2+)-promoted membrane permeabilization in NH(4)NO(3), KCl, and sucrose media. Maximal depression of Cd(2+)-induced swelling is achieved by simultaneous addition of ADP, Mg(2+), and CsA that produces either synergistic (NH(4)NO(3)) or additive (KCl and sucrose media) action. Sustained activation by low [Cd(2+)] of mitochondrial basal respiration in KCl medium is observed both in the absence and in the presence of rotenone and/or oligomycin but only in the latter case (rotenone+oligomycin) CsA inhibits completely Cd(2+) activation of St 4 respiration and partially reverses DNP-uncoupled respiration depressed by cadmium. Cd(2+) effects are discussed in terms of comparison with those of Zn(2+) and PhAsO.

Topics: 2,4-Dinitrophenol; Adenosine Diphosphate; Adenosine Monophosphate; Animals; Ascorbic Acid; Cadmium; Cell Respiration; Cyclosporine; Fatty Alcohols; In Vitro Techniques; Intracellular Membranes; Magnesium; Malates; Mitochondria, Liver; Oxygen; Permeability; Potassium Chloride; Rats; Succinic Acid

Topics: Adult; Antioxidants; Ascorbic Acid; Body Constitution; Homeopathy; Humans; Malates; Male; Middle Aged; Randomized Controlled Trials as Topic; Reproducibility of Results; Surveys and Questionnaires; Treatment Outcome

Oxalic acid is found in a wide variety of plants. This study showed that oxalic acid suppressed in vitro lipid peroxidation in a concentration-dependent manner. Furthermore, oxalic acid reduced the rate of ascorbic acid oxidation in the presence of hydrogen peroxide and Cu(2+). These results suggest that oxalic acid is available as a natural antioxidant.

Topics: Analysis of Variance; Animals; Antioxidants; Ascorbic Acid; Beta vulgaris; Brain; Copper; Hydrogen Peroxide; Lipid Peroxidation; Malates; Male; Microsomes, Liver; Oxalic Acid; Plant Roots; Plants; Rats; Rats, Wistar; Rheum; Spinacia oleracea; Thiobarbituric Acid Reactive Substances

[reaction: see text] A convergent, highly enantioselective synthesis of the fully functionalized AB sector of cochleamycin A is described. A pair of building blocks, crafted from L-malic and L-ascorbic acids, are conjoined in a manner that gives rise to an (E,Z,E)-1,6,8-nonatriene. On heating, the latter undergoes stereocontrolled intramolecular Diels-Alder cyclization via an endo transition state.

Topics: Antibiotics, Antineoplastic; Ascorbic Acid; Cyclization; Cyclopentanes; Lactones; Malates; Polyenes; Stereoisomerism

A method for the simultaneous separation and direct determination of oxalic acid (OA), tartaric acid (TA), malic acid (MA), vitamin C (VC), citric acid (CA), and succinic acid (SA) in Fructus mume using reversed-phase high-performance liquid chromatography with a UV detector in an acidic medium is presented in this study. In the experiment, the optimization of chromatographic conditions (i.e., the pH and flow rate of the mobile phase, the absorption wavelength, and temperature of column) that affect the separation degree and peak shape of organic acids has been obtained. The linear ranges are found to be 0.05-4.7 microg for OA (r = 0.9999), 0.11-10.5 microg for TA (r = 0.9999), 0.114-11.4 microg for MA (r = 0.9999), 0.033-3.30 microg for VC (r = 0.9999), 0.155-15.5 microg for CA (r = 0.9998), and 0.194-19.4 microg for SA (r = 0.9996). For OA, TA, MA, VC, CA, and SA, the even recovery (n = 3) of six effective components are 100.9%, 99.97%, 101.2%, 102.1%, 101.1%, and 100.7%, respectively, and the largest relative standard deviation (n = 11) for the six components is less than 1.7%. The detection limits are 0.01 microg for OA, TA, and VC; 0.05 microg for MA; 0.03 microg for CA; and 0.1 microg for SA. In a single chromatographic run, OA, TA, MA, VC, CA, and SA can be determined in less than 7 min. The method can be used for the purpose of routine analysis and the quality control of a botanic (Fructus mume) containing these effective components.

Topics: Ascorbic Acid; Chromatography, High Pressure Liquid; Citric Acid; Malates; Oxalic Acid; Rosaceae; Spectrophotometry, Ultraviolet; Succinic Acid; Tartrates

The organic acids present in several samples of quince fruit (pulp and peel) and quince jam (homemade and industrially manufactured) were analyzed by HPLC. The sample preparation was simple, involving only extraction with methanol (40 degrees C) and filtration through a Sep-pack C18 cartridge. The chromatographic separation was achieved using an ion exclusion column, Nucleogel Ion 300 OA (300 x 7.7 mm), in conjunction with a column heating device at 30 degrees C. An isocratic elution with H(2)SO(4) 0.01 N as the mobile phase, with a flow rate of 0.1 mL/min, and UV detection at 214 nm were used. These analyses showed that all samples presented a similar profile composed of at least six identified organic acids: citric, ascorbic, malic, quinic, shikimic, and fumaric acids. Several samples also contained oxalic acid. This study suggests that the organic acids levels and ratios may be useful for the determination of percent fruit content of quince jams. The citric acid value can also be used in the differentiation of the type of manufacture of the commercial quince jams (homemade or industrially manufactured).

Topics: Ascorbic Acid; Carboxylic Acids; Chromatography, Gel; Chromatography, High Pressure Liquid; Citric Acid; Food Handling; Fruit; Fumarates; Malates; Methanol; Oxalic Acid; Quinic Acid; Rosaceae; Shikimic Acid

The involvement of mitochondrial dysfunction promoting neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), has been suggested. Histopathological and biochemical mitochondrial abnormalities have been reported in both sporadic and familial patients and suggest the contention that mitochondria may play a key role promoting ALS. Animal models of ALS provide a unique opportunity to study this incurable and fatal human disease. In the present study we tested the hypothesis that alterations in mitochondrial physiology occur in the brain of wobbler mice. No significant difference was found in the respiratory control index or adenosine diphosphate/oxygen ratio values between isolated mitochondria of wobbler and control mice. When pyruvate and malate were used as substrates, oxygen consumption was decreased significantly by approximately 33% in mitochondria isolated from wobbler mouse brain compared to controls. Oxygen consumption in the presence of ascorbate and N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) was decreased significantly by approximately 21% in wobbler brain mitochondria compared to controls, which suggests impairment in the function of complex IV. These findings are the first demonstration of mitochondrial respiratory chain dysfunction in the brain of the wobbler mouse.

Topics: Amyotrophic Lateral Sclerosis; Animals; Ascorbic Acid; Brain; Cell Respiration; Disease Models, Animal; Electron Transport; Malates; Mice; Mice, Neurologic Mutants; Mitochondria; Oxygen Consumption; Pyruvic Acid

In order to examine if organic acids (OA), a kind of natural food components, will prevent from atherosclerosis formation, the effects of four OA, namely chlorogenic acid (CHA), ascorbic acid (AA), citric acid (CA), and malic acid (MA) on human vascular endothelial cells were studied.. Primary human umbilical vein endothelial cells (EC) were cultured, and the changes of cell morphology, cell growth, lactate dehydrogenase (LDH) released from cells were measured when EC was incubated with oxidized low density lipoprotein (oxLDL) in the presence or not of four OA added at three different conditions, i.e. before 4 hours oxLDL added, at the same time as oxLDL added, and after 3 hours oxLDL added, as well as at the indicated doses (10, 20 or 40 mg/L).. The EC survival rate of the oxLDL control group was lower (P < 0.01) and LDH release rate was higher (P < 0.01) than those of normal control group. CHA, AA, CA and MA protected EC from damage caused by oxLDL when they were added before and/or at the same time of oxLDL, but the same beneficial effects of these four OA added after oxLDL were not observed. The EC survival rates of CHA + oxLDL and AA + oxLDL groups in three doses were higher (P < 0.05) and the LDH release rates were lower (P < 0.05) in a dose-effect manner when compared with those of oxLDL control group, respectively. Similar results were found in the CA + oxLDL and MA + oxLDL of the high dose groups.. Four tested OA could effectively prevent EC from damage induced by oxLDL. CHA and AA had the strongest effects, the next was CA, followed by MA.

Topics: Arteriosclerosis; Ascorbic Acid; Cells, Cultured; Chlorogenic Acid; Citric Acid; Endothelium, Vascular; Humans; Malates; Umbilical Veins

Experiments have been carried out with field-grown pear trees to investigate the effect of iron chlorosis on the composition of the leaf apoplast. Iron deficiency was associated with an increase in the leaf apoplastic pH from the control values of 5.5-5.9 to 6.5-6.6, as judged from direct pH measurements in apoplastic fluid obtained by centrifugation and fluorescence of leaves incubated with 5-CF. The major organic acids found in leaf apoplastic fluid of iron-deficient and iron-sufficient pear leaves were malate, citrate and ascorbate. The total concentration of organic acids was 2.9 mM in the controls and increased to 5.5 mM in Fe-deficient leaves. The total apoplastic concentration of inorganic cations (Ca, K and Mg) increased with Fe deficiency from 15 to 20 mM. The total apoplastic concentration of inorganic anions (Cl-, NO3-, SO4(2-) and HPO4(2-)) did not change with Fe deficiency. Iron concentrations decreased from 4 to 1.6 microM with Fe deficiency. The major Fe species predicted to exist in the apoplast was [FeCitOH](-1) in both Fe-sufficient and deficient leaves. Organic acids in whole leaf homogenates increased from 20 to 40 nmol x m(-2) with Fe deficiency. The accumulation of organic anions in the Fe-deficient leaves does not appear to be associated to an increased C fixation in leaves, but rather it seems to be a consequence of C transport via xylem.

Topics: Anions; Ascorbic Acid; Biological Transport; Carbohydrates; Cations; Chlorophyll; Citric Acid; Enzymes; Fruit; Hydrogen-Ion Concentration; Iron; Iron Chelating Agents; Malates; Nucleotides; Plant Diseases; Plant Leaves; Rosales; Trees

To examine the combined effects of 2-week endurance training and 3-week feeding with beta-guanidinopropionic acid (GPA) on regional adaptability of skeletal muscle mitochondria, intermyofibrillar mitochondria (IFM) and subsarcolemmal mitochondria (SSM) were isolated from quadriceps muscles of sedentary control, trained control, sedentary GPA-fed and trained GPA-fed rats. Mitochondrial oxidative phosphorylation was assessed polarographically by using pyruvate plus malate, succinate (plus rotenone), and ascorbate plus N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) (plus antimycin) as respiratory substrates. Assays of cytochrome c oxidase and F(1)-ATPase activities were also performed. In sedentary control rats, IFM exhibited a higher oxidative capacity than SSM, whereas F(1)-ATPase activities were similar. Training increased the oxidative phosphorylation capacity of mitochondria with both pyruvate plus malate and ascorbate plus TMPD as substrates, with no differences between IFM and SSM. In contrast, the GPA diet mainly improved the overall SSM oxidative phosphorylation capacity, irrespective of the substrate used. Finally, the superimposition of training to feeding with GPA strongly increased both oxidase and enzymic activities in SSM, whereas no cumulative effects were found in IFM mitochondria. It therefore seems that endurance training and feeding with GPA, which are both known to alter the energetic status of the muscle cell, might mediate distinct biochemical adaptations in regional skeletal muscle mitochondria.

Topics: Animals; Antimycin A; Ascorbic Acid; Creatine; Diet; Electron Transport Complex IV; Guanidines; Humans; Malates; Male; Mitochondria; Muscle, Skeletal; Oxidative Phosphorylation; Oxygen Consumption; Physical Conditioning, Animal; Propionates; Proton-Translocating ATPases; Pyruvic Acid; Rats; Rats, Wistar; Rotenone; Sarcolemma; Succinic Acid; Tetramethylphenylenediamine; Time Factors

Taste-preference thresholds for five food-associated sugars and acids, respectively, as well as relative sweet-taste preferences were assessed in six pigtail macaques using two-bottle choice tests of brief duration (1 min). In experiment 1, the animals were found to significantly prefer concentrations as low as 10 mM maltose and sucrose, 20 mM fructose and glucose, and 30 mM lactose over tap water. In experiment 2, the monkeys were given a choice between all binary combinations of the same five saccharides presented in equimolar concentrations of 50, 100, 200, and 400 mM. Preferences for individual sugars were stable across the concentrations tested and indicate the following order of relative effectiveness: maltose>sucrose>glucose> or =fructose> or =lactose. In experiment 3, Macaca nemestrina was found to significantly discriminate concentrations as low as 5 mM malic acid, 10 mM ascorbic acid, 20 mM citric acid and acetic acid, and 0.5 mM tannic acid from the alternative stimulus. With the latter substance, the monkeys rejected all suprathreshold concentrations tested, whereas with the former four substances, the animals showed an inverted U-shaped function of preference. The results showed pigtail macaques to be the first primate species tested so far whose taste-preference threshold for maltose is as low as that for sucrose, and which - similar to rodents - prefers maltose over equimolar concentrations of sucrose and other saccharides. Further, unlike most other primates, pigtail macaques do not generally reject acidic tastants but show a substance- and concentration-dependent change in their behavioral response that may range from rejection to preference. The results support the assumption that the gustatory responsiveness of M. nemestrina to food-associated sugars and acidic tastants might reflect an evolutionary adaptation to its dietary habits.

Topics: Acetic Acid; Acids; Animals; Ascorbic Acid; Behavior, Animal; Choice Behavior; Citric Acid; Dietary Sucrose; Female; Food Preferences; Fructose; Glucose; Hydrolyzable Tannins; Lactose; Macaca nemestrina; Malates; Male; Maltose; Species Specificity; Sucrose; Taste; Taste Threshold

The mitochondrial myopathy associated with long-term AZT therapy limits the clinical efficacy of this drug in AIDS therapy. Thus, in order to determine how AZT can affect mitochondria bioenergetics, the capability of AZT to both uncouple oxidative phosphorylation and inhibit electron flow in isolated rat liver mitochondria was investigated. The failure of AZT to oxidize intramitochondrial pyridine nucleotides, to stimulate mitochondrial swelling in K+-acetate plus valinomycin or to cause ATP hydrolysis shows that AZT is not an uncoupler.

Topics: Animals; Antimetabolites; Ascorbic Acid; Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; Electron Transport; Energy Transfer; Glutamic Acid; Malates; Male; Mitochondria, Liver; NADP; Oxidation-Reduction; Oxygen Consumption; Rats; Rotenone; Succinates; Uncoupling Agents; Zidovudine

Pigeon liver malic enzyme was rapidly inactivated by micromolar concentration of Fe2+ in the presence of ascorbate at neutral pH. The inactivated enzyme was subsequently cleaved by the Fe(2+)-ascorbate system at the chemical bond between Asp258 and Ile259 (Wei, C.H., Chou, W.Y., Huang, S.M., Lin, C.C., and Chang, G.G. (1994) Biochemistry, 33, 7931-7936), which was confirmed by site-specific mutagenesis (Wei, C.H., Chou, W.Y., and Chang, G.G. (1995) Biochemistry 34, 7949-7954). In the present study, at neutral pH, Cu2+ was found to be more reactive in the oxidative modification of malic enzyme and the enzyme was cleaved in a similar manner as Fe2+ did. At acidic pH, however, Fe2+ was found to be ineffective in oxidative modification of the enzyme. Nevertheless, Cu2+ still caused enzyme inactivation and cleaved the enzyme at Asp141-Gly142, Asp194-Pro195, or Asp464-Asp465. Mn2+ and L-malate synergistically protect the enzyme from Cu2+ inactivation at acidic pH. Cu2+ is also a competitive inhibitor versus Mn2+ in the malic enzyme-catalyzed reaction with Ki value 70.3 +/- 5.8 microM. The above results indicated that, in addition to the previously determined Asp258 at neutral pH, Asp141, Asp194, and Asp464 are also the coordination sites for the metal binding of malic enzyme. We suggest that the mechanism of affinity modification and cleavage of malic enzyme by the Cu(2+)-ascorbate system proceed in the following sequence. First, Cu2+ binds with the enzyme at the Mn2+ binding site and reduces to Cu+ by ascorbate. Next, the local oxygen molecules are reduced by Cu+, thereby generating superoxide or other reactive free radicals. These radicals interact with the susceptible essential amino acid residues at the metal-binding site, ultimately causing enzyme inactivation. Finally, the modified enzyme is cleaved into several peptide fragments, allowing the identification of metal site of the enzyme. The pH-dependent different specificities of metal-catalyzed oxidation system may be generally applicable for other enzymes or proteins.

Topics: Amino Acid Sequence; Animals; Ascorbic Acid; Binding Sites; Cations, Divalent; Columbidae; Copper; Enzyme Inhibitors; Liver; Malate Dehydrogenase; Malates; Manganese; Models, Chemical; Molecular Sequence Data; NADP; Oxidation-Reduction; Sequence Homology, Amino Acid

We report the polarographic analysis of subsarcolemmal and intermyofibrillar mitochondria from rat skeletal and cardiac muscle, in order to detect possible biochemical and functional differences. Electron microscopic observation of isolated mitochondria showed normal aspect, with intact membranes. Respiratory control rate with different substrates and state 3 activity did not show differences between subsarcolemmal and intermyofibrillar mitochondria in skeletal muscle and heart.

Topics: Animals; Ascorbic Acid; Glutamic Acid; Malates; Male; Microscopy, Electron; Mitochondria, Muscle; Muscle, Skeletal; Muscles; Myocardium; Myofibrils; Oxidative Phosphorylation; Polarography; Pyruvates; Pyruvic Acid; Rats; Rats, Wistar; Sarcolemma; Succinates; Succinic Acid

Excessive consumption of acidic fruit juices is associated with dental morbidity. The pH and buffering capacities of fruit juices packaged and consumed in Canada were measured, and the implications on dental pathology of consuming juices of these qualities are discussed. Canadian fruit juices have a pH below the critical dissolving pH of enamel, and have buffering capacities similar to juices produced and consumed elsewhere in the world. Citrus, apple, and grape juice, or blends of these juices, are all potentially hazardous to teeth. Erosion, attrition, decay and dentinal hypersensitivity may all result from abusive juice drinking.

Topics: Ascorbic Acid; Beverages; Buffers; Canada; Citrates; Citric Acid; Dentin Sensitivity; Fruit; Humans; Hydrogen-Ion Concentration; Malates; Sodium Hydroxide; Tartrates; Tooth Demineralization; Tooth Erosion

Six patients with progressive supranuclear palsy (PSP) and 12 age-matched disease-free subjects participated in this study designed to compare rates of ATP production by intact mitochondria from biopsied skeletal muscle. When pyruvate and malate were used as metabolic substrates, rates of ATP production were 0.184 +/- 0.025 mumol/min/U of citrate synthase (CS) activity (a mitochondrial marker) in control subjects and 0.131 +/- 0.051 mumol/min/U of CS in PSP patients. In the presence of succinate, rates of ATP formation were 0.137 +/- 0.02 mumol/min/U of CS in controls and 0.109 +/- 0.04 mumol/min/U of CS in patients. With N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) and ascorbate, rates were 0.034 +/- 0.008 mumol/min/U of CS in controls and 0.022 +/- 0.01 mumol/min/U of CS in PSP subjects. Differences between the control and PSP populations reached statistical significance with pyruvate/malate and TMPD/ascorbate. No differences in either muscle histopathology or histochemistry were found between patient and control subjects. Results of this study suggest that oxidative phosphorylation defects occur in muscle mitochondria from patients with PSP.

Topics: Adenosine Triphosphate; Aged; Ascorbic Acid; Humans; Kinetics; Malates; Mitochondria; Muscles; Oxidative Phosphorylation; Pyruvates; Pyruvic Acid; Supranuclear Palsy, Progressive; Tetramethylphenylenediamine

Mitochondrial respiratory systems have been screened in 63 orthopaedic patients of age ranging between 17 and 91 years. The results show a statistically significant definite decrease with ageing of mitochondrial respiratory activity with pyruvate plus malate, succinate and ascorbate plus TMPD. This pattern is associated with an equally significant decrease with age of the enzymatic activity of complex I, II and IV. No significant decrease with age is, on the contrary, observed in the mitochondrial content of cytochromes a+a3, and c+c1. Preliminary Western blot analysis indicates an altered polypeptide pattern in cytochrome c oxidase. This study provides evidence for a decline with age of mitochondrial respiratory activity in human skeletal muscle, affecting complex I, II and IV.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Aging; Ascorbic Acid; Cytochromes; Electron Transport Complex II; Electron Transport Complex IV; Humans; Malates; Middle Aged; Mitochondria, Muscle; Multienzyme Complexes; NAD(P)H Dehydrogenase (Quinone); Oxidation-Reduction; Oxidoreductases; Pyruvates; Pyruvic Acid; Succinate Dehydrogenase; Succinates; Succinic Acid

The meat, seed and pulp of Carica papaya Linn., a popular traditional medicinal herb grown in the tropics, was shown by the agar-cup method to be bacteriostatic against several enteropathogens such as Bacillus subtilis, Enterobacter cloacae, Escherichia coli, Salmonella typhi, Staphylococcus aureus, Proteus vulgaris, Pseudomonas aeruginosa, and Klebsiella pneumoniae. The same parts of papaya were unequivocably demonstrated by electron spin resonance spectrometry to scavenge 1,1-diphenyl-2-picrylhydrazyl (5.8 x 10(14) spins/ml), hydroxyl (5.1 x 10(14) spins/ml) and superoxide (1.2 x 10(14) spins/ml) radicals with the seed giving the highest activity at concentrations (IC50) of 2.1, 10.0 and 8.7 mg/ml, respectively. The superoxide dismutase (SOD)-like activity in the meat, seed and pulp amounts to about 32, 98 and 33 units/ml; comparable to those of soybean paste miso, rice bran and baker's yeast. Vitamin C, malic acid, citric acid and glucose are some of the possible antioxidative components in papaya. Our study correlates the bacteriostatic activity of papaya with its scavenging action on superoxide and hydroxyl radicals which could be part of the cellular metabolism of such enteropathogens. This is indicative of the pathophysiological role of these reactive oxygen species in gastrointestinal diseases and papaya's ability to counteract the oxidative stress.

Topics: Anti-Bacterial Agents; Antioxidants; Ascorbic Acid; Citrates; Citric Acid; Electron Spin Resonance Spectroscopy; Enterobacteriaceae; Fruit; Glucose; Malates; Microbial Sensitivity Tests; Plant Extracts; Plants, Medicinal; Pseudomonas aeruginosa; Staphylococcus aureus

The three steps in the synthesis of aldosterone (11 beta/18-hydroxylations and aldehyde synthetase) were examined in mitochondria from bovine glomerulosa and fasciculata to study the regulation of aldehyde synthetase. Ascorbate plus NADH shows synergism with malate in stimulating aldehyde synthetase without affecting 11 beta/-18-hydroxylations. The concentration of semidehydroascorbate reductase in mitochondria from glomerulosa is more than twice that from fasciculata. We propose that in glomerulosa, ascorbate provides a source of reducing equivalents that specifically support the last step in the synthesis of aldosterone.

Topics: Adrenal Glands; Aldehyde Oxidoreductases; Aldosterone; Animals; Ascorbic Acid; Cattle; Chemical Phenomena; Chemistry; Cytochrome P-450 Enzyme System; Desoxycorticosterone; Drug Interactions; Malates; Mitochondria; NAD; NADP

P/2e- stoichiometries in six assay systems spanning different portions of the respiratory chain were estimated by direct determinations of Pi uptake in suspensions of bovine heart mitochondria containing a hexokinase trap. The electron donors were malate + pyruvate, succinate, and ascorbate + N,N,N',N'-tetramethyl-p-phenylenediamine, and the electron acceptors were ferricyanide (Site 1, Site 2, and Sites 1 + 2) and O2 (Sites 1 + 2 + 3, Sites 2 + 3, and Site 3). A major objective was to find conditions in which the six systems yield results in sufficiently good agreement to allow confidence as to their reliability. This objective was achieved, and maximum values of 1.1, 0.5, and 1.0 were observed in the Sites 1, 2, and 3 systems, respectively. This required that the energy-conserving reactions be relatively nonlimiting and that the P/2e- ratios be estimated from the slopes of plots of respiration rate versus phosphorylation rate obtained by inhibiting oxidative phosphorylation with respiratory chain inhibitors. The latter requirement allows avoidance of the effect of an apparent endogenous uncoupler and is based on the observation (Tsou, C. S., and Van Dam, K. (1969) Biochim. Biophys. Acta 172, 174-176) that uncoupling agents at low concentrations decrease the rate of phosphorylation nearly as much in absolute amount at low rates of respiration as at high rates. The maximum P/2e- stoichiometry at Site 1 is considered to be 1.0, and the value observed in the Site 1 system is suggested to be higher as a result of H+ ejection at the transhydrogenase level. Respiratory control due to carboxyatractyloside inhibition was examined and found to differ greatly among the systems. It is pointed out that this observation is not consistent with the lack of complete control being due primarily to ion cycling and that, in view of this, the relatively meager control at Site 3 is not consistent with O2 being reduced on the matrix side of the coupling membrane.

Topics: Animals; Ascorbic Acid; Atractyloside; Cattle; Electron Transport; Ferricyanides; Malates; Mitochondria, Heart; Oxidative Phosphorylation; Oxygen Consumption; Phosphates; Pyruvates; Pyruvic Acid; Succinates; Succinic Acid; Tetramethylphenylenediamine; Uncoupling Agents

A mitochondrial preparation from duck adrenal gland was used, under aerobic conditions, to show that the oxygen requirement for the last step of aldosterone biosynthesis (transformation of 18-hydroxycorticosterone into aldosterone) is at the cytochrome P-450 level only. Vitamin C and tetramethyl-p-phenylene-diamine (TMPD) were used to increase oxygen consumption at the cytochrome a3 level, thereby decreasing its availability to cytochrome P-450. The vitamin C plus TMPD system acts as an 'oxygen trap'. Results show that despite reducing equivalents provided by L-malate, vitamin C plus TMPD strongly inhibits aldosterone biosynthesis from 18-hydroxycorticosterone (89%). Moreover, we used KCN in order to block oxygen consumption, even in the presence of vitamin C plus TMPD. Under these conditions, the inhibition of aldosterone biosynthesis from 18-hydroxycorticosterone is reduced by 51%. The reversal of this inhibition by KCN was evident but only partial. According to polarographic and electron microscopy studies, the reversal of inhibition can only be explained by an increased availability of oxygen at the cytochrome P-450 level. Experiments performed under aerobic conditions, without a nitrogen atmosphere, show that oxygen is required in the transformation of 18-hydroxycorticosterone into aldosterone, at the cytochrome P-450 level. This suggests that a classical hydroxylating mechanism is involved.

Topics: 18-Hydroxycorticosterone; Adrenal Glands; Aerobiosis; Aldosterone; Animals; Ascorbic Acid; Biotransformation; Corticosterone; Ducks; Electron Transport Complex IV; In Vitro Techniques; Malates; Male; Mitochondria; Oxygen Consumption; Tetramethylphenylenediamine

Oxygen electrode polarographic measurements of the rate of oxygen consumption by isolated rat liver mitochondria revealed that oligomycin inhibition of respiration was offset to different degrees by varying concentrations of perfluidone (1,1,1-trifluoro-N-(2 methyl-4-(phenylsulfonyl) methanesulfonamide). Using any of pyruvate-malate, succinate or ascorbate-TMPD (N,N,N',N'-tetramethyl-p-phenylenediamine) as substrate, this herbicidal and anti-inflammatory agent at 100 microM concentration caused a 5-fold stimulation of oligomycin-inhibited respiration. Higher concentrations of the herbicide (greater than or equal to 120 microM) gave lower stimulatory effects. Similar stimulatory effects were obtained with 1 microM FCCP (carbonylcyanide p-trifluoromethyoxyphenyl-hydrazone), a classical protonophore. Our results also show an enhanced oligomycin-sensitive ATPase action in intact mitochondria incubated with ATP and varying concentrations of perfluidone. Maximum enhancement effect (111.3%) was obtained at 120 microM perfluidone. FCCP (1 microM) stimulated this ATPase action by 130%. An initial inhibition of respiration by oligomycin is due to an interaction with the proton well of FOF1-ATP synthetase (Lardy, H.A. et al., Arch. Biochem. Biophys., 78 (1953) 587). Perfluidone probably increases the proton conductance of mitochondrial inner membrane in the same manner as FCCP and thus causes an increase in mitochondrial respiratory rate. As protons move into the matrix, delta mu H+, the proton electrochemical potential gradient becomes very small and the F0F1-ATP synthetase functions in the direction of hydrolysis of ATP rather than its shnthesis (Mitchell, P., Eur. J. Biochem., 95 (1979) 1). These findings therefore indicate that perfluidone acts in a way similar to FCCP, a classical uncoupler and protonophore.

Topics: Adenosine Triphosphatases; Animals; Ascorbic Acid; Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; Drug Interactions; Electrodes; Enzyme Activation; Herbicides; Malates; Mitochondria, Liver; Oligomycins; Oxygen Consumption; Proteins; Pyruvates; Rats; Rats, Inbred Strains; Succinates; Succinic Acid; Sulfones; Tetramethylphenylenediamine

Phosphorylating mitochondrial preparations were obtained from T. cruzi culture (epimastigote) forms by grinding the cells with glass - beads and differential centrifugation. Using ADP as phosphate acceptor and succinate, L-malate or ascorbate + tetramethyl-p-phenylenediamine (TMPD) as oxidizable substrates, the respiratory control (R.C.) values were (mean +/- S.D.; n = 4, in parenthesis, the substrate): 2.8 +/- 0.10 (succinate): 2.3 +/- 0.13 (L-malate) and 2.0 +/- 0.12 (ascorbate + TMPD). The ADP:O values were 1.68 +/- 0.08, 1.42 +/- 0.08 and 0.66 +/- 0.66 +/- 0.12, respectively. The uncoupler CCCP stimulated substrate oxidation somewhat more than ADP. Succinate oxidation was by malonate and also by oxaloacetate but the latter was effective only after sonicating the mitochondrial preparation. The mitochondrial membranes oxidized also NADH but this oxidation was not subjected to control by the phosphate acceptor. Our results support the existence of two energy-conserving sites in T. cruzi respiratory chain (sites 2 and 3) and confirm previous observations by Stoppani et al. (Mol. Biochem. Parasitol. 2:3-21, 1980) with intact epimastigotes.

Topics: Adenosine Diphosphate; Animals; Ascorbic Acid; Malates; Mitochondria; Oxidative Phosphorylation; Succinates; Succinic Acid; Trypanosoma cruzi

Rat adrenal mitochondria have an active rotenone-insensitive outer mitochondrial membrane NADH-semidehydroascorbate (NADH-SDA) reductase which supports cholesterol side chain cleavage at a rate equal to that supported by malate. Side chain cleavage activity supported by both of these electron donor systems is equally inhibited by cycloheximide. Catalase or butylated hydroxyanisole are required for the NADH-SDA reductase-supported cholesterol side chain cleavage. This requirement can be removed by briefly subjecting the mitochondrial preparations to -20 degrees C. Ascorbic acid alone or with malate is either inhibitory or has no effect on side chain cleavage activity. These observations demonstrate that outer mitochondrial membrane NADH-SDA reductase in rat adrenal functions to provide cytoplasmic reducing equivalents to intramitochondrial cytochrome P-450scc and provides a new explanation for the function of ascorbic acid in corticosteroidogenesis.

Topics: Adrenal Glands; Animals; Ascorbic Acid; Butylated Hydroxyanisole; Catalase; Cholesterol; Cold Temperature; Cosyntropin; Cycloheximide; Female; Malates; Mitochondria; NADH, NADPH Oxidoreductases; Pregnenolone; Rats; Rats, Inbred Strains

Topics: Adult; Aged; Ascorbic Acid; Biological Availability; Calcium Oxalate; Citrates; Citric Acid; Diet; Female; Flavonoids; Humans; Hydrolyzable Tannins; Intestinal Absorption; Iron; Malates; Middle Aged; Oryza; Phenols; Phytic Acid; Polymers; Polyphenols; Tartrates; Vegetables

Vesicles prepared from glucose-grown cells of Pseudomonas putida (ATCC, 12633) retain glucose oxidase (GOX) and gluconate dehydrogenase (GADH) activity and actively transport D-glucose, 2-deoxy-D-glucose (2DOG), 3-deoxy-3-fluoro-D-glucose (3FG), and D-gluconate by saturable processes. The transport of these substrates is stimulated by the addition of L-malate or reduced phenazine methosulphate (PMS). Vesicles prepared from succinate-grown cells of P. putida lose their capacity to transport D-glucose, 2DOG, and 3FG by a saturable process. The transport and accumulation of D-gluconate, however, is retained with a KX value of 65 microM and a Vmax of 1.0 nmol . mg protein-1 . min-1. The rate of D-gluconate transport is stimulated by the addition of reduced PMS of L-malate with a reduction in the KX value to 42.0 microM. Respirometric studies with these vesicles indicate the presence of an active GOX and L-malate dehydrogenase but a defective GADH. Thus a reductase activity is detected in the presence of D-gluconate and either 2,6-dichloroindophenol (DCIP) or ferricyanide, as measured by a decrease in absorbance at 500 and 420 nm, respectively. Measurements on these vesicles with the oxygen electrode, however, indicate that no electron transfer from GADH to oxygen occurs. This is in contrast to the results with glucose-grown vesicles or with L-malate or D-glucose as substrates in the succinate-grown vesicles. A comparison between glucose and gluconate oxidase activity in native and detergent-treated vesicles is made. The significance of these results in relation to the presence of a glucose carrier in P. putida and other pseudomonads is presented.

Topics: Ascorbic Acid; Biological Transport, Active; Deoxyglucose; Gluconates; Glucose; Kinetics; Malates; Methylphenazonium Methosulfate; Oxygen Consumption; Pseudomonas; Spectrophotometry