ascorbic-acid and Dehydration

Urolithiasis is a condition that can cause significant morbidity among patients. Dietary manipulations traditionally advised include fluid, protein, oxalate, calcium, citrate, and sodium changes in the diet. Evidence-based practice guidelines suggest that there is not ample evidence to confidently recommend dietary changes, since inadequate studies have been done to quantify the risks of diet in stone formation. While fluid intake patterns have the weightiest evidence in the literature, not even fluid intake meets the guidelines for evidence-based practice. Health care providers should recognize that current patient education is largely based on intuition. It behooves us as clinicians to look critically at all our practices, review the available literature, and question what we believe we know. A summary of available literature is provided to guide the clinician in educating patients in reducing their risk of recurrent calcium oxalate stone disease.

Topics: Ascorbic Acid; Calcium Oxalate; Calcium, Dietary; Citrates; Dehydration; Diet, Protein-Restricted; Diet, Sodium-Restricted; Evidence-Based Medicine; Feeding Behavior; Fluid Therapy; Humans; Information Services; Internet; Kidney Calculi; Nurse's Role; Nutritional Sciences; Obesity; Oxalates; Patient Education as Topic; Phytotherapy; Practice Guidelines as Topic; Recurrence; Risk Factors

Previous studies have confirmed the safety of polyethylene glycol plus ascorbic acid for healthy middle-aged adults but not for the elderly. The osmotic pressure of polyethylene glycol plus ascorbic acid is approximately twice that of plasma osmolality and may cause dehydration.. In this study, we determined whether dehydration was induced in elderly patients by polyethylene glycol plus ascorbic acid, and we analysed the data obtained in order to identify predictors of dehydration.. This was a prospective, uncontrolled, before-and-after intervention study. All patients older than 65 years who underwent colonoscopies at the Moji Medical Center were administered polyethylene glycol plus ascorbic acid prior to colonoscopy. Clinical variables before and after bowel preparation were measured and analysed statistically. A multiple linear regression analysis was performed to identify predictors of dehydration due to this procedure.. Eighty-three patients were assessed for eligibility, and 74 clinical variables were ultimately analysed. A significant increase in the red blood cell count (4.10 versus 4.25 × 10(6)/mm(3)), haemoglobin level (12.4 versus 13.0 g/dL) and haematocrit (38.1% versus 39.4%) suggested the presence of hypovolaemia after the procedure (P < 0.001). The serum concentration of albumin before bowel preparation was identified as the only significant predictor of hypovolaemia (β = 0.47, P = 0.0001, adjusted R (2) = 0.22).. The serum concentration of albumin before bowel preparation predicted hypovolaemia caused by polyethylene glycol plus ascorbic acid in elderly patients. Therefore, care is needed in order to prevent hypovolaemia, especially in elderly patients with hypoalbuminaemia.. No. 000015724 (University Hospital Medical Information Network Center).

Topics: Aged; Aged, 80 and over; Ascorbic Acid; Cathartics; Colonoscopy; Dehydration; Erythrocyte Count; Female; Hemoglobins; Humans; Male; Patients; Polyethylene Glycols; Prospective Studies; Serum Albumin

This study aimed to evaluate coconut sugar (CS) as an alternative osmotic agent to sucrose for the osmotic dehydration (OD) of strawberries. OD was performed by immersing strawberries cut into 13.6 ± 0.4 mm edge cubes in osmotic solutions of CS or sucrose, at two different concentrations (40% and 60%, w/w), with and without application of vacuum (AV) in the first 20 min of the process. The total OD time was 300 min. Evaluations of the kinetics of solid gain (SG), water loss (WL), and weight reduction (WR) were performed at 30, 60, 120, 180, 240, and 300 min. SG, WL, and WR increased over the OD time and showed values of up to 7.94%, 63.40%, and 55.94%, respectively. AV increased WL, WR, shrinkage, pH, and total color difference and decreased anthocyanin, ascorbic acid (AA), phenolic, and antioxidant contents. The higher concentration led to higher SG, WL, WR, shrinkage, hardness, and lower moisture content, water activity, anthocyanin, AA, phenolic, and antioxidant contents. The use of CS instead of sucrose had little influence on strawberry properties, except pH and color responses. The optimal treatment was using a 60% CS solution without AV, showing a very distinct color change, hardness increased by approximately 4.5 times and maintenance of acidity, anthocyanins, AA, total phenolics, and antioxidants of 38.0%, 39.6%, 11.8%, 30.0%, 31.1%, and 30.3%, respectively, compared to fresh strawberries. PRACTICAL APPLICATION: Osmotic dehydration of fruit is a process traditionally carried out using sucrose. However, increasing health concerns have made consumers seek alternative sugars to sucrose. The use of coconut sugar made it possible to produce osmo-dehydrated strawberries different from the traditional one, maintaining product quality and process efficiency.

Topics: Anthocyanins; Antioxidants; Ascorbic Acid; Cocos; Dehydration; Desiccation; Fragaria; Fruit; Sucrose; Sugars; Water

Color enhancement mechanisms of freeze-dried carrot sample (FDS) treated by ultrasound-assisted osmotic (ascorbic acid-CaCl

Topics: Ascorbic Acid; Calcium Chloride; Color; Daucus carota; Dehydration; Osmosis

Cryopreservation is known be an effective method for virus elimination in garlic. However, oxidative damage during the cryopreservation seriously affects the survival of garlic after cryopreservation. Ascorbic acid (AsA) can reduce oxidative damage and improve regrowth following cryopreservation, and its effect may be influenced by the step during which it is added. In this study, AsA was added at the osmoprotection (O) and dehydration (DE) steps of cryopreservation. By observing the dynamic changes in cell viability and reactive oxygen species (ROS) components with different AsA treatments, AsA has been linked to the reduced accumulation of ROS in the shoot tips. Increased gene expression levels of antioxidant enzymes also explained the ROS scavenging effect of AsA. The correlation analysis between cell viability, ROS, membrane lipid peroxidation-related indicators and antioxidant-related indicators showed that membrane lipid peroxidation caused by excess ROS was the main factor affecting cell viability. Ascorbic acid added during dehydration minimized the accumulation of ROS from dehydration to dilution and alleviated the oxidative damage during cryopreservation. Thus, the survival and regrowth of the garlic was significantly improved after cryopreservation. Dehydration was found to be the suitable step for the addition of AsA during garlic cryopreservation. We further evaluated the virus elimination effect under optimal AsA treatment. However, there was no significant difference in virus content in regenerated plants when compared with the control.

Topics: Antioxidants; Ascorbic Acid; Cryopreservation; Dehydration; Garlic; Plant Shoots; Reactive Oxygen Species; Viral Load

Thiamin is a crucial vitamin with a vast variety of anti-oxidative and physiological roles in plants subjected to abiotic stresses. We examined the efficiency of foliar-applied thiamin (50 and 100 mM) on growth, yield quality and key-biochemical characteristics of two cultivars (FD1 and FD3) of cauliflower (Brassica oleracea L.) under water-deficit stress. Water stress at the rate of 50% field capacity (F.C.) markedly decreased the plant biomass, leaf total phenolics and ascorbic acid (AsA) contents. In contrast, drought-induced increase was noted in the leaf [hydrogen peroxide (H2O2), AsA, proline, malondialdehyde (MDA), glycinebetaine (GB), total soluble proteins and oxidative defense system in terms of high activities of peroxidase (POD), and catalase (CAT) enzymes] and the inflorescence (total phenolics, proline, GB, MDA, H2O2, and activities of SOD and CAT enzymes) characteristics of cauliflower. However, foliar-applied thiamin significantly improved growth and physio-biochemical attributes except leaf and inflorescence MDA and H2O2 contents of both cauliflower cultivars under water stress. Overall, application of thiamin enhanced the plant growth may be associated with suppressed reactive oxygen species (ROS) and upregulated antioxidants defense system of cauliflower.

Topics: Antioxidants; Ascorbic Acid; Betaine; Biochemical Phenomena; Botrytis; Brassica; Dehydration; Hydrogen Peroxide; Proline; Thiamine

This work evaluated the effect of convective drying of mango impregnated with grape residue flour polyphenols under different vacuum impregnation methods with or without performing osmotic treatment and ultrasound on the global quality of dried mango in relation to chemical, microbiological and sensory aspects. Higher retention of carotenoids, phenolic compounds, and ascorbic acid was obtained with shorter drying times and lower oxygen exposure. Impregnated dried samples submitted to ultrasound-assisted vacuum impregnation showed a higher drying rate, greater retention of carotenoids (6.77 µg/g DM), and softer samples. Greater retention of phenolic compounds (1.84 mg GAE/g DM) was obtained for osmotic dehydration-assisted vacuum impregnation dried mango, while osmosonication-assisted impregnation was able to retain the highest ascorbic acid content (7.05 mg/100 g DM). Sensory evaluation showed that the impregnated samples showed good acceptance. The combination of osmotic dehydration and ultrasound could be a suitable way to produce dried mango impregnated with grape residue polyphenols.

Topics: Ascorbic Acid; Carotenoids; Dehydration; Flour; Fruit; Mangifera; Phenols; Polyphenols; Vitis

Optimum water availability at different growth stages is one the major prerequisites of best growth and yield production of plants. Exogenous application of plant growth regulators considered effective for normal functioning of plants under water-deficit conditions. A study was conducted to examine the influence of exogenously applied L-methionine on sunflower (Helianthus annuus L.) plants grown under water-deficit conditions. Twenty-five-day old seedlings of four sunflower cultivars, FH331, FH572, FH652 and FH623 were exposed to control (100% F.C.) and drought stress (60% F.C.) conditions. After 30-day of drought stress, L-methionine (Met; 20 mg/L) was applied as a foliar spray to control and drought stressed plants. Water deficit stress significantly reduced shoot fresh and dry weights shoot and root lengths, and chlorophyll a content in all four cultivars. While a significant increase was observed due to water deficiency in relative membrane permeability (RMP), malondialdehyde (MDA), total soluble proteins (TSP), total soluble sugars (TSS), ascorbic acid (AsA) and activity of peroxidase (POD). Although, exogenously applied Met was effective in decreasing RMP, MDA and H2O2 contents, it increased the shoot fresh weight, shoot length, chlorophyll a, chlorophyll a/b ratio, proline contents and the activities of SOD, POD and CAT enzymes in all four cultivars under water deficit stress. No change in AsA and total phenolics was observed due to foliar-applied Met under water stress conditions. Of all sunflower cultivars, cv. FH-572 was the highest and cv. FH-652 the lowest of all four cultivars in shoot fresh and dry weights as well as shoot length under drought stress conditions. Overall, foliar applied L-methionine was effective in improving the drought stress tolerance of sunflower plants that was found to be positively associated with Met induced improved growth attributes and reduced RMP, MDA and H2O2 contents under water deficit conditions.

Topics: Ascorbic Acid; Betaine; Chlorophyll A; Dehydration; Gene Expression Regulation, Plant; Helianthus; Hydrogen Peroxide; Malondialdehyde; Methionine; Oxidative Stress; Peroxidase; Plant Shoots; Secondary Metabolism

Individuals of all ages are encouraged to monitor their hydration status daily to prevent clinically severe fluid imbalances such as hyponatremia or dehydration. However, acute oral nutritional supplementation may alter urinary hydration assessments and potentially increase the likelihood of inappropriate clinical decisions or diagnosis. This investigation sought to examine the influence of three common over-the-counter nutritional supplements (beetroot, riboflavin, and Vitamin C) on urinary hydration assessments in physically active young men after a 2% exercise-induced dehydration.. Eight males (Mean ± SD; age: 22 ± 3 yr; body mass index: 27 ± 5.0) consumed either a standard meal with supplementation (intervention) or a standard meal without supplementation (control). Participants performed a variety of aerobic or resistance exercises until reaching ≥2% body mass loss in a counter-balanced, double-blinded design. Following exercise participation, urine samples were collected for an 8 h observational period during which food consumption was replicated. Urine samples were analyzed for urine color, specific gravity, volume, and osmolality. Maintenance of ~2% body mass loss (2.6 ± 0.5%; range: 1.7-4.0%) was confirmed following the 8 h observational period.. Statistically significant (p < 0.05) changes were noted in urine color following Vitamin C supplementation compared to control; however, the difference was not clinically meaningful.. These findings indicate that urine color, specific gravity, and osmolality maintain clinical utility to detect moderate levels of dehydration in physically active men consuming commercially available doses of beetroot, riboflavin, or Vitamin C.

Topics: Adult; Ascorbic Acid; Dehydration; Dietary Supplements; Humans; Male; Riboflavin; Water-Electrolyte Balance; Young Adult

Topics: Ascorbic Acid; Color; Dehydration; Desiccation; Food Packaging; Fruit; Humans; Kinetics; Malus; Osmosis; Phytochemicals; Thermodynamics; Vacuum

Drought stress is the most harmful one among other abiotic stresses with negative impacts on crop growth and development. Drought-hardening is a feasible and widely used method in tobacco seedlings cultivation. It has gained extensive interests due to its role in improving drought tolerance. This research aimed to investigate the role of drought-hardening and to unravel the multiple mechanisms underlying tobacco drought tolerance and adaptation.. This study was designed in which various drought-hardening treatments (CK (no drought-hardening), T1 (drought-hardening for 24 h), T2 (drought-hardening for 48 h), and T3 (drought-hardening for 72 h)) were applied to two tobacco varieties namely HongHuaDaJinYuan (H) and Yun Yan-100 (Y). The findings presented a complete framework of drought-hardening effect at physiological, biochemical, and gene expression levels of the two tobacco varieties under drought stress. The results showed that T2 and T3 significantly reduced the growth of the two varieties under drought stress. Similarly, among the various drought-hardening treatments, T3 improved both the enzymatic (POD, CAT, APX) and non-enzymatic (AsA) defense systems along with the elevated levels of proline and soluble sugar to mitigate the negative effects of oxidative damage and bringing osmoregulation in tobacco plants. Finally, the various drought-hardening treatments (T1, T2, and T3) showed differential regulation of genes expressed in the two varieties, while, particularly T3 drought-hardening treatment-induced drought tolerance via the expression of various stress-responsive genes by triggering the biosynthesis pathways of proline (P5CS1), polyamines (ADC2), ABA-dependent (SnRK2, AREB1), and independent pathways (DREB2B), and antioxidant defense-related genes (CAT, APX1, GR2) in response to drought stress.. Drought-hardening made significant contributions to drought tolerance and adaptation in two tobacco variety seedlings by reducing its growth and, on the other hand, by activating various defense mechanisms at biochemical and molecular levels. The findings of the study pointed out that drought-hardening is a fruitful strategy for conferring drought tolerance and adaptations in tobacco. It will be served as a useful method in the future to understand the drought tolerance and adaptation mechanisms of other plant species. Drought-hardening improved drought tolerance and adaptation of the two tobacco varieties. T1 indicates drought-hardening for 24 h, T2 indicates drought-hardening for 48 h, T3 indicates drought-hardening for 72 h.

Topics: Adaptation, Physiological; Ascorbic Acid; Chlorophyll; Crop Production; Dehydration; Fluorescence; Gene Expression Regulation, Plant; Glutathione; Hydrogen Peroxide; Malondialdehyde; Nicotiana; Oxidation-Reduction; Plant Leaves; Proline

Peach slices were blanched (BL), vacuum infiltrated with D-sodium erythorbate (SE), predehydrated, and then nitrogen packaged (NP) before freezing to improve their quality. Our results showed that the BL, SE, and NP pretreatments remarkably improved the quality of frozen peaches. Frozen peaches pretreated by SE+NP+BL showed the highest total phenolic content (TPC), total antioxidant capacity (TAC), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging capacity after thawing at 20°C for 24 hr. The soluble solids content and firmness of low-maturity peaches dehydrated to 25% dehydration of their weight were 11.1% and 211.2% higher than those of the control samples, respectively, while their drip loss was 71.9% lower than that of the controls. In conclusion, pretreatment by BL, predehydration, SE, and NP before freezing can significantly improve the quality of frozen peaches after thawing. PRACTICAL APPLICATIONS: We believe that our study results have practical applications because the method of vacuum dehydration combined with blanching, nitrogen packaging, and D-sodium erythorbate treatment of peaches maintains their original taste, inhibits color change, and decreases drip loss. This method is suitable for fruit frozen and stored at a commercial freezing temperature of -20°C and does not need advanced equipment or technology. It can be easily carried out during the fruit freezing process and can be applied to other frozen stored fruits besides peaches.

Topics: Ascorbic Acid; Dehydration; Food Packaging; Food Preservation; Food Storage; Freezing; Nitrogen; Prunus persica; Vacuum

Phytoextracts are being widely used these days as a source of bioactive compounds for mitigating the harmful effects of abiotic stresses including drought stress. In this study, it was assessed how far foliar applied pure synthetic ascorbic acid (AsA) or natural sweet orange juice (OJ) enriched with AsA could mitigate the drought stress induced adverse effects on growth and some key metabolic processes in quinoa (Chenopodium quinoa Willd.; cultivar V

Topics: Ascorbic Acid; Chenopodium quinoa; Dehydration; Seedlings

Ascorbate-glutathione (ASA-GSH) cycle is a major pathway of H2O2 scavenging and an effective mechanism of detoxification in plants. The differences in photosynthesis, chlorophyll content (Chl), relative water content (RWC), antioxidants and antioxidative enzyme activities involved in ASA-GSH metabolism were measured between the flag leaves and spike bracts (glumes and lemmas) during grain filling under drought stress. The expression of APX1, GRC1, DHAR, MDHAR, GPX1, and GS3 in ASA-GSH cycle was also measured. Compared with the flag leaves, the spike bracts exhibited stable net photosynthetic rate (PN) and chlorophyll content (Chl), a lower accumulation of reactive oxygen species (ROS), and more enhanced percentages of antioxidant enzyme activities and key enzymes gene transcription levels involved in ASA-GSH metabolism during the grain-filling stage under drought conditions. This could be the reasonable explanation for the more stable photosynthetic capacity in spikes, and the glumes and lemmas senesced later than the flag leaves at the late grain-filling stage. Also, the function of ASA-GSH cycle could not be ignored in alleviating oxidative damage by scavenging more excess ROS in spikes under drought stress.

Topics: Ascorbic Acid; Carbohydrate Metabolism; Chlorophyll; Dehydration; Droughts; Glutathione; Oxidative Stress; Photosynthesis; Plant Leaves; Seasons; Seedlings; Triticum

Endogenous hormones and polyamines (PAs) could interact to regulate growth and tolerance to water stress in white clover. The objective of this study was to investigate whether the alteration of endogenous indole-3-acetic acid (IAA) level affected other hormones level and PAs metabolism contributing to the regulation of tolerance to water stress in white clover. Plants were pretreated with IAA or L-2-aminooxy-3-phenylpropionic acid (L-AOPP, the inhibitor of IAA biosynthesis) for 3 days and then subjected to water-sufficient condition and water stress induced by 15% polyethylene glycol 6000 for 8 days in growth chambers. Exogenous application of IAA significantly increased endogenous IAA, gibberellin (GA), abscisic acid (ABA), and polyamine (PAs) levels, but had no effect on cytokinin content under water stress. The increase in endogenous IAA level enhanced PAs anabolism via the improvement of enzyme activities and transcript level of genes including arginine decarboxylase, ornithine decarboxylase, and S-adenosylmethionine decarboxylase. Exogenous application of IAA also affected PAs catabolism, as manifested by an increase in diamine oxidase and a decrease in polyamine oxidase activities and genes expression. More importantly, the IAA deficiency in white clover decreased endogenous hormone levels (GA, ABA, and PAs) and PAs anabolism along with decline in antioxidant defense and osmotic adjustment (OA). On the contrary, exogenous IAA effectively alleviated stress-induced oxidative damage, growth inhibition, water deficit, and leaf senescence through the maintenance of higher chlorophyll content, OA, and antioxidant defense as well as lower transcript levels of senescence marker genes SAG101 and SAG102 in leaves under water stress. These results indicate that IAA-induced the crosstalk between endogenous hormones and PAs could be involved in the improvement of antioxidant defense and OA conferring tolerance to water stress in white clover.

Topics: Abscisic Acid; Adenosylmethionine Decarboxylase; Ascorbic Acid; Carboxy-Lyases; Dehydration; Gibberellins; Glutathione; Indoleacetic Acids; Malondialdehyde; Ornithine Decarboxylase; Osmotic Pressure; Plant Growth Regulators; Polyamines; Real-Time Polymerase Chain Reaction; Trifolium; Water

Bioactive compounds, vitamins, phenolic acids, flavonoids of A. tricolor are the sources of natural antioxidant that had a great importance for the food industry as these detoxify ROS in the human body. These natural antioxidants protect human from many diseases such as cancer, arthritis, emphysema, retinopathy, neuro-degenerative cardiovascular diseases, atherosclerosis and cataracts. Moreover, previous literature has shown that drought stress elevated bioactive compounds, vitamins, phenolics, flavonoids and antioxidant activity in many leafy vegetables. Hence, we study the nutritional and bioactive compounds, phenolic acids, flavonoids and antioxidant capacity of amaranth under drought stress for evaluation of the significant contribution of these compounds in the human diet.. The genotype VA3 was assessed at four drought stress levels that significantly affected nutritional and bioactive compounds, phenolic acids, flavonoids and antioxidant capacity. Protein, ash, energy, dietary fiber, Ca, K, Cu, S, Mg, Mn, Mo, Na, B content, total carotenoids, TFC, vitamin C, TPC, TAC (DPPH), betacarotene, TAC (ABTS. In A. tricolor, drought stress enhanced the quantitative and qualitative improvement of nutritional and bioactive compounds, phenolic acids, flavonoids and antioxidants. Hence, farmers of semi-arid and dry areas of the world could be able to grow amaranth as a substitute crop.

Topics: Amaranthus; Antioxidants; Ascorbic Acid; Bangladesh; Carotenoids; Chlorophyll; Dehydration; Droughts; Flavonoids; Genotype; Hydroxybenzoates; Minerals; Pigments, Biological; Plant Leaves; Polyphenols

Topics: Ascorbate Peroxidases; Ascorbic Acid; Carotenoids; Catalase; Chlorophyll; Dehydration; Free Radical Scavengers; Glutathione Reductase; Lipid Peroxidation; Monophenol Monooxygenase; Osmoregulation; Osmotic Pressure; Oxidative Stress; Phenylalanine Ammonia-Lyase; Plant Proteins; Potassium; Sodium; Superoxide Dismutase; Triticum

Maintaining a strong antioxidant system is essential for preventing drought-induced oxidative stress. Thus, in the present study we investigated the role of some non-enzymic and enzymic antioxidants in desiccation tolerance of Haberlea rhodopensis. The effects of high light upon desiccation on antioxidant capacity was estimated by comparing the response of shade and sun plants. The significant enhancement of the antioxidant capacity at 8% RWC corresponded to an enormous increase in flavonoid content. The important role of ascorbate-glutathione cycle in overcoming oxidative stress during drying of H. rhodopensis was established. The antioxidant capacity increased upon dehydration of both shade and sun plants but some differences in non-enzymatic and enzymatic antioxidants were observed. Investigations on the role of polyphenols in desiccation tolerance are scarce. In the present study the polyphenol profiles (fingerprints) of the resurrection plant Haberlea rhodopensis, including all components of the complex are obtained for the first time. It was clarified that the polyphenol complex of H. rhodopensis includes only two types of glycosides - phenylethanoid glucosides and hispidulin 8-C-glucosides. Upon desiccation the polyphenol content increase and the main role of phenylethanoid glucosides in the protection of H. rhodopensis was revealed.

Topics: Antioxidants; Ascorbate Peroxidases; Ascorbic Acid; Bulgaria; Dehydration; Droughts; Glutathione; Glutathione Reductase; Glutathione Transferase; Light; Magnoliopsida; Oxidative Stress; Plant Leaves; Plant Proteins; Polyphenols

In this paper, we investigated whether nitric oxide (NO) participated in the regulation of the ascorbate-glutathione (AsA-GSH) cycle by exogenous jasmonic acid (JA) in the leaves of wheat seedlings under drought stress. The findings of our study showed that drought stress significantly enhanced the AsA-GSH cycle by upregulating the activities of ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), and dehydroascorbate reductase (DHAR). Drought stress also markedly increased electrolyte leakage (EL), malondialdehyde (MDA) content, NO content, and significantly reduced the ratios of reduced ascorbate/dehydroascorbic acid (AsA/DHA) and reduced glutathione/oxidized glutathione (GSH/GSSG) compared with control. Exogenous JA significantly increased the above indicators, compared with drought stress alone. All these effects of JA were inhibited by pretreatment with NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO). Meanwhile, exogenous JA markedly decreased MDA content and electrolyte leakage of wheat leaves under drought stress. Pretreatment with cPTIO reversed the above effects of exogenous JA. Our findings indicated that NO induced by exogenous JA upregulated the activity of the AsA-GSH cycle and had important role in drought tolerance.

Topics: Antioxidants; Ascorbic Acid; Cyclopentanes; Dehydration; Droughts; Glutathione; Lipid Peroxidation; Metabolic Networks and Pathways; Nitric Oxide; Oxidative Stress; Oxylipins; Plant Leaves; Reactive Oxygen Species; Seedlings; Signal Transduction; Triticum

Cyclitols were prepared from corresponding allylic hydroperoxides, synthesized by photooxygenation of the appropriate cyclic alkenes. These hydroperoxides were then separately treated with a catalytic amount of OsO4. Synthesized dl-cyclopentane-1,2,3-triol 9 (A), dl-cyclohexane-1,2,3-triol 12 (B), and dl-cycloheptane-1,2,3-triol 15 (C) were used in the investigation of plant stress. Antioxidants, lipid peroxidation, and water status of chickpea species exposed to synthetic cyclitols under water deficit were examined. Cyclitol derivatives significantly decreased leaf water potential, lipid peroxidation and H2O2 levels of wild and cultivated species under water deficit. Cyclitol treatments affected antioxidant enzyme activities differently in both species under water deficit. The highest SOD activity was found in A10-treated Cicer arietinum (cultivar) and C10-treated Cicer reticulatum (wild type) under water deficit. CAT activity increased in C. arietinum exposed to A cyclitols, while it increased slightly and then decreased in cyclitol-treated C. reticulatum under stress conditions. AP and GR activities were significantly increased in C. arietinum under water deficit. AP activity increased in C derivatives-treated C. arietinum, while it remained unchanged in C. reticulatum on day 1 of water deficit. GR activity was increased in A derivaties-treated C. arietinum and C derivatives-treated C. reticulatum on day 1 of water deficit and decreased with severity of stress (except for B10-treated C. arietinum). The level of AsA in C treatments and GSH in A treatments increased in C. arietinum on day 1 of water deficit, while in C. reticulatum, AsA and GSH levels decreased under stress conditions. We conclude that exogenous synthetic cyclitol derivatives are biologically active and noncytotoxic, resulting in higher antioxidant activities and lower water potential, thus increasing the water deficit tolerance of chickpea under water deficit, especially of cultivated chickpea. We also propose that synthetic cyclitol derivatives can reduce reactive oxygen species and membrane damage and are beneficial for stress adaptation.

Topics: Antioxidants; Ascorbate Peroxidases; Ascorbic Acid; Catalase; Cell Survival; Cicer; Cyclitols; Dehydration; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Glutathione; Glutathione Reductase; Hydrogen Peroxide; Lipid Peroxidation; Oxidative Stress; Plant Growth Regulators; Plant Leaves; Reactive Oxygen Species; Superoxide Dismutase; Water

The thermal behavior of dry solid ascorbic acid in nitrogen atmosphere in the temperature range of 25-800°C was investigated by TG-FTIR. During the thermal decomposition process, five evolved gaseous species, including H2O, CO2, CO, CH4 and HCOOH, were identified and monitored, in which HCOOH was detected for the first time. The results indicated that ascorbic acid began to decompose at 191°C. Its decomposition process consisted of three stages, and dehydration and decarboxylation to form furfural were the possible principal mechanism. The kinetic analysis for the first decomposition stage was also carried out by the isoconversional method and the master plots method. The results indicated that this process can be described by the model of 1st order reaction.

Topics: Ascorbic Acid; Decarboxylation; Dehydration; Gases; Kinetics; Nitrogen; Spectroscopy, Fourier Transform Infrared; Temperature; Thermogravimetry

Barley displays a great genetic diversity, constituting a valuable source to delineate the responses of contrasted genotypes to environmental constraints. Here, we investigated the level of oxidative stress and the participation of antioxidant systems in two barley genotypes: Express, a variety known to be sensitive to drought, and Saïda, an Algerian landrace selected for its tolerance to water deficit. Soil-grown 15-day-old plants were subjected to water deficit for 8 days and then rewatered. We observed that upon water stress Express exhibits compared to Saïda accelerated wilting and a higher level of oxidative stress evaluated by HPLC measurements of lipid peroxidation and by imaging techniques. In parallel, Express plants also display lower levels of catalase and superoxide dismutase activity. No great difference was observed regarding peroxiredoxins and methionine sulfoxide reductases, enzymes detoxifying peroxides and repairing oxidized proteins, respectively. In contrast, upon water stress and recovery, much higher contents and oxidation ratios of glutathione and ascorbate were measured in Express compared to Saïda. Express also shows during water deficit greater increases in the pools of lipophilic antioxidants like xantophyll carotenoids and α-tocopherol. Altogether, these data show that the differential behavior of the two genotypes involves distinct responses regarding antioxidant mechanisms. Indeed, the drought sensitivity of Express compared with Saïda is associated with oxidative damage and a lower enzymatic ROS-scavenging capacity, but in parallel with a much stronger enhancement of most mechanisms involving low-molecular weight antioxidant compounds.

Topics: Antioxidants; Ascorbic Acid; Carotenoids; Catalase; Chlorophyll; Dehydration; Droughts; Free Radical Scavengers; Genotype; Glutathione; Hordeum; Hydrogen Peroxide; Lipid Peroxidation; Oxidative Stress; Phenotype; Plant Leaves; Species Specificity; Stress, Physiological; Superoxide Dismutase; Tocopherols; Water

Vitamin C content and sensorial properties have been evaluated in air-dried carrots previously subjected to different ultrasound (US) or conventional blanching pretreatments. In addition, mass spectral fingerprints obtained by the Headspace ChemSensor System have been evaluated for the first time for classification of carrots according to their processing. Conventional blanching treatments at high temperature gave rise to carrots with retention of vitamin C in the range 37.5-85%, whereas carrots blanched conventionally at 60°C and by US-probe at temperatures up to 60 and 70°C showed vitamin C retention values lower than 4%. Regarding sensorial analysis of rehydrated carrots, US-pretreated samples presented acceptable quality, and no statistically significant differences with respect to conventionally blanched carrots, were detected. In spite of this, differentiation of samples processed under comparable intensity conditions and/or with similar composition was possible from their mass spectral fingerprints after chemometric data analysis.

Topics: Ascorbic Acid; Daucus carota; Dehydration; Food Preservation; Hot Temperature; Humans; Taste; Ultrasonics

This study investigated the effects of 12 hr of road transportation during the hot-dry conditions and the modulating role of ascorbic acid (AA) on the hydration state of goats. Twenty goats who served as treatment goats received oral administration of 100 mg/kg body weight of AA, whereas another 20 control goats received sterile water; thereafter, the goats were loaded and transported. The study determined changes in skin thickness; albumin (Alb); total protein (TP); elimination of the gut content; fecal water; urine specific gravity (SG); and pH before, during, and after the transportation. The result obtained in the control goats showed significant (p < .05) increases in the values of TP, Alb, urine SG, and pH; elimination; and drinking behavior, whereas skin thickness decreased over transportation. In the treatment goats who were administered AA, the changes observed in the values were insignificant (p > .05). In conclusion, 12-hr road transportation of goats induced dehydration, which may affect the welfare and health status of the goats. The administration of AA ameliorated the risk of adverse effects of handling, loading, transportation, and hot-dry conditions on hydration state of goats.

Topics: Animals; Ascorbic Acid; Blood Proteins; Dehydration; Feces; Female; Goats; Hot Temperature; Humidity; Hydrogen-Ion Concentration; Male; Serum Albumin; Skinfold Thickness; Specific Gravity; Transportation; Urine

Using Arabidopsis plants transformed with a redox-sensing green fluorescent protein targeted to the cytosol (c-roGFP1), we have demonstrated, in real time, measurements of reversible changes of redox status in the cytosol of plants subjected to a gradual water-stress, followed by re-watering. Plants sensed water stress, and changed the redox potential of their cytosol to a more oxidized value after a gradually-imposed water stress. Small variations in the cytosol redox potential and ascorbate (AA) values suggest that this parameter was tightly regulated. The re-watering was paralleled by a return of water stress, redox potential and ascorbate to initial values, showing the reversibility of water stress and its consequences.

Topics: Arabidopsis; Ascorbic Acid; Cytosol; Dehydration; Dehydroascorbic Acid; Gene Expression Regulation, Plant; Green Fluorescent Proteins; Oxidation-Reduction; Reactive Oxygen Species

Seeds of yellow lupine (Lupinus luteus L. cv. Juno) were collected throughout their development on the mother plant to determine whether the ability to germinate and to tolerate desiccation is related to the level of free radicals and the changes in the redox state of ascorbate and glutathione as well as the activities of antioxidative enzymes. Electron paramagnetic resonance (EPR)-based analyses showed that development of lupine seed was accompanied by generation of free radicals with g(1) and g(2) values of 2.0049+/-0.0004 and 2.0029+/-0.0003, respectively. Free radical level increased significantly 25 DAF and decreased thereafter. The amount of hydrogen peroxide was high in fresh immature seeds and decreased during maturation drying. Ascorbate accumulated in lupine embryos during early seed filling stage whereas glutathione content increased during late seed filling phase. During maturation drying the redox state of both ascorbate and glutathione pools shifted towards the oxidized forms. While superoxide dismutase (SOD, EC 1.15.1.1), and ascorbate peroxidase (APX, EC 1.11.1.11) activities remained high at the early seed filling stage the activities of both dehydroascorbate reductase (DHAR, EC 1.8.5.1) and glutathione reductase (GR, EC 1.6.4.2) and that of catalase (CAT, EC 1.11.1.6) increased before seeds reached physiological maturity and decreased thereafter. The changes of isoform patterns of antioxidative enzymes were observed during seed maturation. Immature lupine seeds tested immediately after harvest acquired the ability to germinate when less than half-filled and reached high tolerance to desiccation just after physiological maturity. The physiological implications of the changes in antioxidative machinery for the acquisition of desiccation tolerance and seeds germinability are discussed.

Topics: Adaptation, Physiological; Antioxidants; Ascorbic Acid; Dehydration; Electron Spin Resonance Spectroscopy; Free Radicals; Germination; Glutathione; Hydrogen Peroxide; Lupinus; Oxidants; Oxidation-Reduction; Seeds

The role of thyroid hormones in the regulation of adrenal function during stress has been documented in mammals, but only limited reports are available in avian species. The present study was undertaken to analyze the effect of hyper- or hypothyroidism on the adrenal activity under control (hydrated) and osmotically stressed (water deprived, WD) conditions, with special emphasis on the expression of arginine vasotocin receptor VT2 (VT2R) in pituitary corticotrophs. Chickens were made hyper- or hypothyroidic by injecting thyroxine (T4) and 2-thiouracil (TU), respectively for 14 days. After 10 days of injections, one sub-group of both, T4- or TU-treated chickens were subjected to osmotic stress by water deprivation. Hyperthyroidism stimulated adrenal steroidogenic activity compared to euthyroid control birds, but no change was observed in the expression of VT2R. On the other hand, TU-induced hypothyroidism however showed no effect on adrenal gland, but a significant increase in the expression of VT2R was observed. Neither hyper- nor hypothyroidism altered pro-opiomelanocortin (POMC) mRNA levels. Following osmotic stress, no effect was observed either on the adrenal gland or on the VT2R expression in hyperthyroidic birds, but in hypothyroidic birds, osmotic stress stimulated adrenal steroidogenic activity and decreased VT2R expression in comparison to its respective controls (T4 or TU). Expression of POMC mRNA was again unaltered following osmotic stress. Although exact mechanism is not clear, the data indicate that high plasma T4 level stimulates adrenal activity and may also modulate function of the pituitary-adrenal axis during dehydration.

Topics: 3-Hydroxysteroid Dehydrogenases; Adrenal Glands; Animals; Ascorbic Acid; Chickens; Cholesterol; Dehydration; Gene Expression Regulation; Hyperthyroidism; Hypothalamo-Hypophyseal System; Hypothyroidism; Immunohistochemistry; In Situ Hybridization; Male; Pituitary Gland; Pituitary-Adrenal System; Pro-Opiomelanocortin; Receptors, Vasopressin; Thyroid Gland; Thyroxine; Triiodothyronine; Water-Electrolyte Balance

Cuttings of Populus przewalskii and P. cathayana, which originated from high and low altitudes in southwest China, were used to examine the effect of water stress on the morphological, physiological and biochemical traits of plants in a greenhouse for one growing season. The dry mass accumulation and allocation, gas exchanges, extent of peroxidation damage, osmotic adjustment and antioxidative defenses, and amounts of pigments were measured to characterize the differences in peroxidation damage and protective mechanisms of two poplar species that contrast in drought tolerance. Under water stress, poplars showed a series of biochemical adjustments and morphological changes as follows: a decrease in leaf relative water content, gas exchanges, plant growth and dry mass accumulation; an increase in relative allocation to roots; an increase in the osmolyte contents (e.g. total amino acids). Additionally, water deficit induced an increase in peroxidation damage [as indicated by an increase in electrolyte leakage, malondialdehyde (MDA), carbonyl (C = O ) and hydrogen peroxide (H(2) O(2) ) content], enhanced activities or contents of antioxidants (e.g. ascorbate peroxidase, guaiacol peroxidase, glutathione redutase and ascorbic acid) and reduced amounts of leaf pigments (e.g. chlorophyll and carotenoid). Furthermore, there were significant differences in the extent of morphological and biochemical changes between the two poplar species. Compared with P. cathayana, P. przewalskii responded to water stress by allocating relatively more to root dry mass, possessing a higher net photosynthesis rate, and having more efficient protective mechanisms, such as more osmolyte accumulation, stronger antioxidant activities and lower chlorophyll/carotenoid ratio. Thus, P. przewalskii suffered less damage as deduced from lower levels of electrolyte leakage, MDA, C=O and H(2) O(2) content. Therefore, P. przewalskii originating from high altitude could possess more efficient protective mechanisms than P. cathayana, which is from low-altitude habitats.

Topics: Altitude; Amino Acids; Ascorbate Peroxidases; Ascorbic Acid; Biomass; Carbohydrates; Carotenoids; China; Chlorophyll; Dehydration; Ecosystem; Electrolytes; Gases; Glutathione Peroxidase; Hydrogen Peroxide; Malondialdehyde; Peroxidase; Plant Leaves; Populus; Solubility; Species Specificity; Water

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

Phenazine-methosulphate (PMS) is a strong oxidant that induces reactive oxygen species (ROS) formation in cells. Though it has been shown that PMS increases the red blood cell (RBC) membrane permeability to K(+), the hypotheses on the mechanism of PMS-induced effects are contradictory and there are no data on volume changes induced by this oxidant. Therefore, the influence of the PMS + ascorbate oxidative system on the volume of normal human RBCs was studied. In a Ca(2 + )-containing medium, PMS + ascorbate caused dehydration (shrinking) of RBCs judged by: (1) changes in the density and osmotic resistance distributions of RBCs, and (2) a decrease in their low-angle scattering assessed by FACS analysis. The dehydration resulted from activation of the Gardos channels, was PMS and ascorbate concentration-dependent, was associated with broadening of the density and osmotic resistance distributions of the RBCs, and decreased in the presence of the taxifolin and rutin antioxidants. These findings contribute to a better understanding of the physiology and pathology of oxidatively-modified RBCs and may be of practical significance in estimating the antioxidant activity of various substances.

Topics: Antioxidants; Ascorbic Acid; Calcium; Dehydration; Erythrocyte Membrane; Erythrocytes; Flow Cytometry; Humans; Methemoglobin; Oxidation-Reduction

A pot culture experiment was conducted to estimate the drought stress mitigating effect of ketoconazole (KCZ), a fungicide cum plant growth regulator, in Catharanthus roseus plants. The plants under pot culture were subjected to drought stress and drought stress with KCZ from 30 days after sowing (DAS) and regular irrigation was kept as control. Antioxidant contents and activities of antioxidant enzymes were estimated from root, stem and leaf of both control and treated plants. The alkaloid ajmalicine was extracted and estimated from the roots of control, drought stressed and KCZ treated plants. Individual and combined drought stress and KCZ treatments increased ascorbic acid, alpha-tocopherol contents, superoxide dismutase, ascorbate peroxidase, catalase and polyphenol oxidase activities when compared to control. There was a significant enhancement in ajmalicine production under KCZ treated plants under drought stress when compared to well watered control as well as drought stressed plants. The KCZ treatment resulted in partial mitigation of drought stress by increasing the antioxidant potentials in C. roseus plants.

Topics: alpha-Tocopherol; Antioxidants; Ascorbate Peroxidases; Ascorbic Acid; Catalase; Catharanthus; Dehydration; Enzyme Activation; Ketoconazole; Peroxidases; Secologanin Tryptamine Alkaloids; Superoxide Dismutase

The influence of water deprivation on potted apple trees (Malus domestica Borkh.) was investigated. Biochemical responses including ascorbic acid, glutathione (GSH), tocopherols, chlorophylls, carotenoids, free amino acids, and soluble carbohydrates were measured in leaves of diploid 'Elstar' and triploid 'Jonagold Wilmuta' subjected to progressive drought. Leaf water potential was chosen to be the primary indicator of water stress in tested plants. Time courses of measured biochemical parameters showed that mild drought did not significantly affect the chosen stress indicators. Moderate drought increased the concentrations of ascorbic acid, total GSH, beta-carotene, zeaxanthin and alpha-tocopherol, indicating the adaptation to oxidative stress in apple trees. Moderate drought also increased concentration of soluble carbohydrates, mostly due to increased sorbitol concentration. Severe drought negatively affected vitality of apple trees, and caused a decrease in sorbitol concentration. Severe drought also caused decreases in ascorbic acid, total GSH, beta-carotene, alpha-tocopherol and chlorophyll concentrations, which, together with the increase in oxidised GSH concentration, indicated severe damage due to oxidative stress. Severe drought increased free amino acid concentration, which was probably the result of increased proteolysis. Zeaxanthin concentration remained high even in leaves of apple trees subjected to severe drought stress. The results were similar for both tested apple cultivars.

Topics: Adaptation, Physiological; Amino Acids; Antioxidants; Ascorbic Acid; Carbohydrate Metabolism; Carotenoids; Chlorophyll; Dehydration; Diploidy; Malus; Plant Leaves; Polyploidy; Tocopherols; Water

Photosynthesis, respiration, and other processes produce reactive oxygen species (ROS) that can cause oxidative modifications to proteins, lipids, and DNA. The production of ROS increases under stress conditions, causing oxidative damage and impairment of normal metabolism. In this work, oxidative damage to various subcellular compartments (i.e. chloroplasts, mitochondria, and peroxisomes) was studied in two cultivars of wheat differing in ascorbic acid content, and growing under good irrigation or drought. In well-watered plants, mitochondria contained 9-28-fold higher concentrations of oxidatively modified proteins than chloroplasts or peroxisomes. In general, oxidative damage to proteins was more intense in the cultivar with the lower content of ascorbic acid, particularly in the chloroplast stroma. Water stress caused a marked increase in oxidative damage to proteins, particularly in mitochondria and peroxisomes. These results indicate that mitochondria are the main target for oxidative damage to proteins under well-irrigated and drought conditions.

Topics: Ascorbic Acid; Chloroplasts; Dehydration; Mitochondria; Oxidation-Reduction; Oxidative Stress; Oxygen Consumption; Peroxisomes; Plant Leaves; Reactive Oxygen Species; Triticum

Adrenocortical responses to diverse stressful situations (dehydration, formaldehyde treatment and salt loading) were studied in the adult female soft-shelled turtle, Lissenmys p. punctata. Dehydration, formaldehyde treatment (formalin, 1%: 0.1 ml/100 g body weight daily) or salt loading (NaCl, 1%: 0.1 ml/100 g body weight daily) treatments consecutively for 7 days caused hypertrophy of the adrenocortical cells with their nuclear diameter increased, and depletions of adrenal cholesterol and ascorbic acid concentrations followed by decreased acid phosphatase and alkaline phosphatase activities in turtles. Corticosterone levels were elevated in both the adrenal gland and serum of turtles after dehydration and formalin stress, but the hormone level remained unaltered after salt loading in turtles. The results suggest active involvement of adrenal cortex in stress for homeostasis in Lissemys turtles.

Topics: Acid Phosphatase; Adrenal Cortex; Alkaline Phosphatase; Animals; Ascorbic Acid; Body Weight; Cholesterol; Corticosterone; Dehydration; Female; Formaldehyde; Homeostasis; Salts; Stress, Physiological; Turtles

Mediterranean plants have evolved a complex antioxidant defense system to cope with summer drought. Flavonoids, and particularly flavanols and flavonols, are potent in vitro antioxidants, but their in vivo significance within the complex network of antioxidant defenses remains unclear, especially in plant responses to stress. To gain insight into the role of flavonoids in the antioxidant defense system of Cistus clusii Dunal, we evaluated drought-induced changes in flavonoids in leaves and compared the response of these compounds with that of other low molecular weight antioxidants (ascorbic acid, tocopherols and carotenoids). Among the antioxidant flavonoids analyzed, epigallocatechin gallate was present in the greatest concentrations (up to about 5 micromol dm(-2)). Other flavanols, such as epicatechin and epicatechin gallate, were found at concentrations below 0.25 and 0.03 micromol dm(-2), respectively. Neither of the antioxidant flavonols analyzed, quercetin and kaempferol, were detected in C. clusii leaves. Epigallocatechin gallate, ascorbic acid and alpha-tocopherol concentrations increased to a similar extent (up to 2.8-, 2.6- and 3.3-fold, respectively) in response to drought, but the kinetics of the drought-induced increases differed. Epigallocatechin gallate, epicatechin and epicatechin gallate concentrations increased progressively during drought, reaching maximum values after 30 days of stress. Ascorbic acid concentrations increased twofold after 15 days of drought, and maximum values were attained after 50 days of drought. In contrast, alpha-tocopherol concentrations remained constant during the first 30 days of drought, but increased sharply by 3.3-fold after 50 days of drought. The maximum efficiency of photosystem II photochemistry and the extent of lipid peroxidation remained constant throughout the drought period, whereas the redox state of ascorbic acid and alpha-tocopherol shifted toward their reduced forms in response to drought, indicating that the concerted action of low molecular weight antioxidants may help prevent oxidative damage in plants.

Topics: Antioxidants; Ascorbic Acid; Cistus; Dehydration; Flavonoids; Lipid Peroxidation; Photosynthesis; Plant Leaves; Tocopherols; Trees

Myrothamnus flabellifolia, a short woody shrub from southern Africa, can survive severe desiccation of its vegetative organs. We studied mechanisms protecting this plant from oxidative damage during desiccation for 2 weeks, 4 and 8 months, and also during subsequent rehydration. This plant retains high concentrations of chlorophyll during desiccation, and these chlorophyll molecules are probably a source for potentially harmful singlet oxygen production. Desiccation triggered substantial increases in zeaxanthin and redox shifts of the antioxidants glutathione and ascorbate towards their oxidised forms. Simultaneously, the concentrations of violaxanthin, beta-carotene, ascorbate, alpha-tocopherol, and glutathione reductase activity progressively decreased. Antheraxanthin, gamma-tocopherol, lutein, neoxanthin and glucose-6-phosphate dehydrogenase displayed less pronounced changes in response to desiccation. Even after 4 months of desiccation, Myrothamnus flabellifolia recovered rapidly upon rehydration. Re-watering induced formation of ascorbate and glutathione, simultaneous reduction of their oxidised forms, and rapid production of alpha-tocopherol and of various carotenoids. Only after 8 months of desiccation did the antioxidant system of M. flabellifolia break down; 3 weeks after the onset of rehydration, these plants abscised their leaves, but even then they were still able to recover and develop new ones. Ascorbate, beta-carotene and alpha-tocopherol were totally depleted after 8 months of desiccation and did not recover upon rehydration; glutathione was partly maintained, but only in the oxidised form. We present a model demonstrating which parts of antioxidant pathways break down as oxidative stress becomes detrimental and we discuss some potential implications of our results for the genetic modification of crop plants to improve their drought tolerance.

Topics: Antioxidants; Ascorbic Acid; beta Carotene; Chlorophyll; Dehydration; Glutathione; Magnoliopsida; Oxidative Stress; Plant Diseases; Tocopherols; Xanthophylls

This study compared mass transfer during osmotic dehydration (OD) and some quality indices of untreated apple slices to those of apple slices pretreated by either blanching, freezing, or applying high-intensity electric field pulses (HELP) or high pressure (HP). HP, HELP, and blanching increased water loss. Untreated and HELP-treated samples had comparable solids gains, which were lower (P < 0.05) than in the other samples. Apple slices turned brown after pretreatment but the L values of these samples increased with OD. The breaking force of dried samples increased with OD time, and pretreated samples had firmer dried texture than the untreated. Vitamin C content decreased with OD time, but HP- and HELP-treated apples had better retention of vitamin C.

Topics: Ascorbic Acid; Color; Dehydration; Diffusion; Electricity; Food Handling; Food Preservation; Kinetics; Osmosis; Pressure; Quality Control; Rosales

Green leafy vegetables are the most underexploited class of vegetables despite high nutritional value. Reports on nutritional composition and storage of some of the fresh leaves are available but the storage behavior of dehydrated leaves apparently has not been studied. Therefore, in the present study, two green leafy vegetables, savoy beets (Beta vulgaris var. bengalensis) and fenugreek (Trigonella foenum graecum) were dehydrated in a low temperature drier and stored for 9 months under ambient and cold stored conditions after packaging in single or double layers of high density polyethylene film (200 gauge). The quality was determined on the basis of retention of beta-carotene, ascorbic acid and chlorophyll, and the extent of browning during storage. Retention of these quality characteristics depended on the crop and storage conditions. Double packed and cold stored samples of fenugreek retained 67% beta-carotene, whereas savoy beet leaves retained only 57% of the initial beta-carotene under similar conditions. Similarly, higher retention of ascorbic acid and chlorophyll, and lower browning was observed in double packed, cold stored samples. Results indicated the efficacy of double packed and cold stored samples over other combinations.

Topics: Ascorbic Acid; beta Carotene; Chlorophyll; Color; Dehydration; Food Handling; Food Packaging; Food Preservation; Humans; Nutritive Value; Plant Leaves; Taste; Temperature; Time Factors; Trigonella; Vegetables

Destruction of Escherichia coli O157:H7 was evaluated on inoculated apple slices dehydrated at two temperatures with and without application of predrying treatments. Half-ring slices (0.6 cm thick) of peeled and cored Gala apples were inoculated by immersion for 30 min in a four-strain composite inoculum of E. coli O157:H7. The inoculated slices (8.7 to 9.4 log CFU/g) either received no predrying treatment (control), were soaked for 15 min in a 3.4% ascorbic acid solution, or were steam blanched for 3 min at 88 degrees C immediately prior to drying at 57.2 or 62.8 degrees C for up to 6 h. Samples were plated on tryptic soy (TSA) and sorbitol MacConkey (SMAC) agar media for direct enumeration of surviving bacterial populations. Steam blanching changed initial inoculation levels by +0.3 to -0.7 log CFU/g, while immersion in the ascorbic acid solution reduced the inoculation levels by 1.4 to 1.6 log CFU/g. Dehydration of control samples for 6 h reduced mean bacterial populations by 2.9 log CFU/g (TSA or SMAC) at 57.2 degrees C and by 3.3 (SMAC) and 3.5 (TSA) log CFU/g at 62.8 degrees C. Mean decreases from initial inoculum levels for steam-blanched slices after 6 h of drying were 2.1 (SMAC) and 2.0 (TSA) log CFU/g at 57.2 degrees C, and 3.6 (TSA or SMAC) log CFU/g at 62.8 degrees C. In contrast, initial bacterial populations on ascorbic acid-pretreated apple slices declined by 5.0 (SMAC) and 5.1 (TSA) log CFU/g after 3 h of dehydration at 57.2 degrees C, and by 7.3 (SMAC) and 6.9 (TSA) log CFU/g after 3 h at 62.8 degrees C. Reductions on slices treated with ascorbic acid were in the range of 8.0 to 8.3 log CFU/g after 6 h of drying, irrespective of drying temperature or agar medium used. The results of immersing apple slices in a 3.4% ascorbic acid solution for 15 min prior to drying indicate that a predrying treatment enhances the destruction of E. coli O157:H7 on home-dried apple products.

Topics: Ascorbic Acid; Colony Count, Microbial; Cooking; Dehydration; Escherichia coli O157; Food Handling; Food Microbiology; Rosales; Time Factors

Topics: 17-Hydroxycorticosteroids; 17-Ketosteroids; Adrenal Glands; Analysis of Variance; Animals; Ascorbic Acid; Body Temperature Regulation; Dehydration; Desert Climate; Drinking; Female; Gerbillinae; Hot Temperature; Male; Potassium; Rodentia; Seasons; Sex Factors; Sodium; Species Specificity

Topics: Ascorbic Acid; Body Weight; Civil Defense; Dehydration; Diet; Electrocardiography; Humans; Hunger; Male; Military Medicine; Nitrogen; Nutritional Physiological Phenomena; Osmolar Concentration; Pantothenic Acid; Pyridoxine; Riboflavin; Sodium; Survival; Thiamine; Thirst; Urine; Water-Electrolyte Balance

Topics: Animals; Ascorbic Acid; Blood Pressure; Brain Diseases; Brain Edema; Dehydration; Glycerol; Hematuria; Injections, Intravenous; Intracranial Pressure; Male; Rabbits

Topics: Animals; Aqueous Humor; Ascorbic Acid; Dehydration; Glycerol; Intraocular Pressure; Rabbits; Vitreous Body

Topics: Ascorbic Acid; Dehydration; Fruit; Plants; Rosa; Seasons; Temperature

Topics: Adrenal Cortex; Adrenalectomy; Ascorbic Acid; Dehydration; Endocrine Glands; Guinea Pigs; Hunger; Vitamins

Topics: Ascorbic Acid; Dehydration; Fruit; Vegetables