ascorbic-acid and ferric-chloride

The aim of the current study was to compare the bond strength of an experimental bonding system with commercial bonding systems.. An aqueous solution of 10% ascorbic acid and 5% ferric chloride was prepared as an experimental conditioner (Exp). The flattened human dentin surfaces were conditioned with phosphoric acid, NaOCl, and Exp. They were bonded to a stainless steel rod with 4-META/MMA-TBB resin. Super-Bond C&B (10-3), Panavia Fluoro Cement (Panavia), Panavia Fluoro Cement with AD gel (AD/Panavia), and All-Bond 2 system (All-Bond 2) were also used. After immersion in water for 24 h, half of the specimens of each group were tested for tensile bond strength, and the remaining specimen groups were subjected to 10,000 cycles of thermo-cycling prior to tensile testing. All of the data were analysed by ANOVA and a post hoc test. In addition, two thermo-cycled specimens (10-3/10,000, Exp/10,000) were prepared for photomicrography.. The bond strengths of Exp and AD/Panavia groups showed no decrease after 10,000 thermo-cycles, although those of 10-3, Panavia, and All-Bond groups decreased significantly after thermo-cycling. SEM micrographs exhibited that cracks and voids can be observed in the 10-3/10,000 specimen at the interface of the adhesive resin and the hybrid layer, although neither a hybrid layer nor cracks can be seen in the Exp/10,000 specimen.. Comparison of the tensile bond strengths for all adhesive resins revealed that the novel dentin bond system with experimental conditioner and Panavia Fluoro Cement with AD gel exhibited the most durable bonding after thermo-cycling.

Topics: Acid Etching, Dental; Analysis of Variance; Ascorbic Acid; Boron Compounds; Chlorides; Dental Bonding; Dentin; Dentin-Bonding Agents; Ferric Compounds; Humans; Materials Testing; Methacrylates; Methylmethacrylates; Phosphoric Acids; Resin Cements; Sodium Hypochlorite; Stainless Steel; Surface Properties; Tensile Strength

Topics: Ascorbic Acid; beta-Cyclodextrins; Chlorides; Dendrimers; Drug Carriers; Drug Liberation; Ferric Compounds; Ferrous Compounds; Fluorescent Dyes; Micelles; Oxidation-Reduction; Rhodamines

The low operating temperatures employed in atmospheric freeze-drying permits an effective drying of heat sensitive products, without any impairment of their quality attributes. When using power ultrasound, the drying rate can be increased, thus reducing the process duration. However, ultrasound can also affect the product quality. The aim of this study was to evaluate the effect of various drying process variables, namely air temperature and velocity, ultrasound power and sample size, on the antioxidant properties of eggplant (Solanum melongena L.) samples. For this reason, drying experiments were carried out at different drying temperatures (-5, -7.5, -10 °C), power ultrasound levels (0, 25, 50 W; 21.9 kHz) and air velocities (2, 5 m s

Topics: Antioxidants; Ascorbic Acid; Chlorides; Ferric Compounds; Food Handling; Freeze Drying; Fruit; Motion; Nutritive Value; Oxidation-Reduction; Phenols; Solanum melongena; Temperature; Time Factors; Ultrasonic Waves; Ultrasonics

Microorganisms produce siderophores to facilitate iron uptake and even though this trait has been extensively studied, there is growing evidence suggesting that siderophores may have other physiological roles aside from iron acquisition. In support of this notion, we previously linked the archetypal siderophore enterobactin with oxidative stress alleviation. To further characterize this association, we studied the sensitivity of Escherichia coli strains lacking different components of the enterobactin system to the classical oxidative stressors hydrogen peroxide and paraquat. We observed that strains impaired in enterobactin production, uptake and hydrolysis were more susceptible to the oxidative damage caused by both compounds than the wild-type strain. In addition, meanwhile iron supplementation had little impact on the sensitivity, the reducing agent ascorbic acid alleviated the oxidative stress and therefore significantly decreased the sensitivity to the stressors. This indicated that the enterobactin-mediated protection is independent of its ability to scavenge iron. Furthermore, enterobactin supplementation conferred resistance to the entE mutant but did not have any protective effect on the fepG and fes mutants. Thus, we inferred that only after enterobactin is hydrolysed by Fes in the cell cytoplasm and iron is released, the free hydroxyl groups are available for radical stabilization. This hypothesis was validated testing the ability of enterobactin to scavenge radicals in vitro. Given the strong connection between enterobactin and oxidative stress, we studied the transcription of the entE gene and the concomitant production of the siderophore in response to such kind of stress. Interestingly, we observed that meanwhile iron represses the expression and production of the siderophore, hydrogen peroxide and paraquat favour these events even if iron is present. Our results support the involvement of enterobactin as part of the oxidative stress response and highlight the existence of a novel regulation mechanism for enterobactin biosynthesis.

Topics: Antioxidants; Ascorbic Acid; Carboxylic Ester Hydrolases; Chlorides; Enterobactin; Escherichia coli; Escherichia coli Proteins; Ferric Compounds; Gene Expression Regulation; Hydrogen Peroxide; Hydrolysis; Iron; Ligases; Mutation; Oxidants; Oxidation-Reduction; Oxidative Stress; Paraquat; Siderophores; Stress, Physiological; Transcription, Genetic

Neurodegerative diseases have been linked to oxidative stress arising from peroxidation of membrane biomolecules and high levels of Fe have been reported to play an important role in neurodegenerative diseases and other brain disorder. Malondialdehyde (MDA) is the end-product of lipid peroxidation and the production of this aldehyde is used as a biomarker to measure the level of oxidative stress in an organism. The present study compares the protective properties of two varieties of ginger [red ginger (Zingiber officinale var. Rubra) and white ginger (Zingiber officinale Roscoe)] on Fe(2+) induced lipid peroxidation in rat brain in vitro. Incubation of the brain tissue homogenate in the presence of Fe caused a significant increase in the malondialdehyde (MDA) contents of the brain. However, the aqueous extract from both varieties of ginger caused a significant decrease in the MDA contents of the brain in a dose-dependent manner. However, the aqueous extract of red ginger had a significantly higher inhibitory effect on both Fe(2+)-induced lipid peroxidation in the rat brain homogenates than that of white ginger. This higher inhibitory effect of red ginger could be attributed to its significantly higher phytochemical content, Fe(2+) chelating ability, OH scavenging ability and reducing power. However, part of the mechanisms through which the extractable phytochemicals in ginger (red and white) protect the brain may be through their antioxidant activity, Fe(2+) chelating and OH scavenging ability. Therefore, oxidative stress in the brain could be potentially managed/prevented by dietary intake of ginger varieties (red ginger and white ginger rhizomes).

Topics: Animals; Antioxidants; Ascorbic Acid; Brain; Chlorides; Ferric Compounds; Ferrous Compounds; Flavonoids; In Vitro Techniques; Iron Chelating Agents; Lipid Peroxidation; Male; Oxidation-Reduction; Phenol; Plant Extracts; Rats; Rats, Wistar; Rhizome; Zingiber officinale

An experimental conditioner (Exp), which was an aqueous solution of 10% ascorbic acid and 5% ferric chloride, was prepared in this study. This study evaluated the effect of Exp on the microtensile bond strength between a self-curing resin and dentin after long-term water immersion. Flat human dentin surfaces were sequentially pretreated with 40% phosphoric acid, 10% sodium hypochlorite, and Exp. Surface pretreatment with an aqueous solution of 10% citric and 3% ferric chloride (10-3) was used as a control. Composite resin rods were bonded to pretreated dentin surfaces using 4-META/MMA-TBB resin. Microtensile bond strengths were evaluated after water immersion at 24 h, 12 months, 24 months, and 36 months. At each immersion period, the bond strength of Exp was significantly higher than that of 10-3. After 36 months, Exp showed no significant decrease in microtensile bond strength, but 10-3 showed significant reductions. Pretreatment with experimental acid/base conditioner markedly improved the bonding durability of 4-META/MMA-TBB resin to human dentin when compared against the conventional 10-3 treatment.

Topics: Acid Etching, Dental; Ascorbic Acid; Boron Compounds; Chlorides; Citric Acid; Composite Resins; Dental Bonding; Dental Materials; Dentin; Ferric Compounds; Humans; Hydrogen-Ion Concentration; Immersion; Materials Testing; Methacrylates; Methylmethacrylates; Microscopy, Electron, Scanning; Phosphoric Acids; Resin Cements; Sodium Hypochlorite; Stress, Mechanical; Tensile Strength; Time Factors; Water

Flavonoids are ubiquitous phenolic plant metabolites. Many of them are well known for their pro- and antioxidant properties. Myricetin has been reported to be either a potent antioxidant or a pro-oxidant depending on the conditions. The reaction conditions for the pro- and antioxidant activities were therefore investigated using variations of the deoxyribose degradation assay systems.. The deoxyribose degradation assay systems were conducted as follows; H(2)O(2)/Fe(III)/ascorbic acid, H(2)O(2)/Fe(III), Fe(III)/ascorbic acid, and Fe(III). Each system was carried out in two variants, FeCl(3) (iron ions added as FeCl(3)) and FeEDTA (iron added in complex with ethylenediaminetetraacetic acid).. When ascorbic acid was present, myricetin showed antioxidant properties, especially when it occurred in complex with iron. In ascorbic acid-free systems, pro-oxidant activities prevailed, which where enhanced if iron was in complex with EDTA.. Myricetin's antioxidant activity depends on both the reactive oxygen species (ROS) scavenging and iron ions chelation properties. The pro-oxidative properties are caused by reduction of molecular oxygen to ROS and iron(III) to iron(II). Myricetin is able to substitute for ascorbic acid albeit less efficiently.

Topics: Antioxidants; Ascorbic Acid; Chlorides; Deoxyribose; Dose-Response Relationship, Drug; Edetic Acid; Ferric Compounds; Ferrous Compounds; Flavonoids; Hydrogen Peroxide; Molecular Structure; Oxidation-Reduction; Reactive Oxygen Species

Cholestasis, encountered in a variety of clinical disorders, is characterized by intracellular accumulation of toxic bile acids in the liver. Furthermore, oxidative stress plays an important role in the pathogenesis of bile acids. Taurolithocholic acid (TLC) was revealed in previous studies as the most pro-oxidative bile acid. Melatonin, a well-known antioxidant, is a safe and widely used therapeutic agent. Herein, we investigated the hepatoprotective role of melatonin on lipid and protein oxidation induced by TLC alone and in combination with FeCl(3) and ascorbic acid in rat liver homogenates and hepatic membranes. The lipid peroxidation products, malondialdehyde and 4-hydroxyalkenals (MDA + 4-HDA), and carbonyl levels were quantified as indices of oxidative damage to hepatic lipids and proteins, respectively. In the current study, the rise in MDA + 4-HDA levels induced by TLC was inhibited by melatonin in a concentration-dependent manner in both liver homogenates and in hepatic membranes. Melatonin also had protective effects against structural damage to proteins induced by TLC in membranes. These results suggest that the indoleamine melatonin may potentially act as a protective agent in the therapy of those diseases that involve bile acid toxicity.

Topics: Aldehydes; Animals; Antioxidants; Ascorbic Acid; Chlorides; Cholagogues and Choleretics; Dose-Response Relationship, Drug; Ferric Compounds; Lipid Peroxidation; Liver; Malondialdehyde; Melatonin; Oxidation-Reduction; Oxidative Stress; Protein Carbonylation; Rats; Rats, Sprague-Dawley; Taurolithocholic Acid

Cocultures of two human cell lines, Caco-2 and HT29-MTX mucus-producing cells, have been incorporated into an in vitro digestion/cell culture model used to predict iron bioavailability. A range of different foods were subjected to in vitro digestion, and iron bioavailability from digests was assessed with Caco-2, Caco-2 overlaid with porcine mucin, HT29-MTX or cocultures of Caco-2 and HT29-MTX at varying ratios. It was found that increasing the ratio of HT29-MTX cells decreased the amount of ferritin formed and resulted in an overall decline in the ability of the model to detect differences in iron bioavailability. At the physiologically relevant ratios of 90% Caco-2/10% HT29-MTX and 75% Caco-2/25% HT29-MTX, however, a mucus layer completely covered the cell monolayer and the in vitro digestion model was nearly as responsive to changes in sample iron bioavailability as pure Caco-2 cultures. The in vitro digestion/Caco-2 cell culture model correlates well with human iron bioavailability studies, but, as mucus appears to play a role in iron absorption, the addition of a physiologically realistic mucus layer and goblet-type cells to this model may give more accurate iron bioavailability predictions.

Topics: Animals; Ascorbic Acid; Caco-2 Cells; Chlorides; Coculture Techniques; Digestion; Ferric Compounds; Ferritins; HT29 Cells; Humans; Iron; Models, Biological; Mucus

Polyphenol oxidases (PPOs) were isolated from cell suspensions of two cultivars of cotton (Gossypium hirsutum L.), and their biochemical characteristics were studied. PPO from Coker 312, an embryogenic cultivar, showed a highest affinity to catechol 20 mM, and PPO from R405-2000, a nonembryogenic cultivar, showed a highest affinity to 4-methylcatechol 20 mM. The optimal pH for PPO activity was 7.0 and 6.0 for Coker 312 and R405-2000, respectively. The enzyme had an optimal temperature of 25 degrees C and was relatively stable at 20-30 degrees C. Reducing sodium metabisulfite, ascorbic acid, dithiothreitol, SnCl(2), and FeCl(3) markedly inhibited PPO activity, whereas its activity was highly enhanced by Mg(2+), Ca(2+), and Mn(2+) and was moderately inhibited by Ba(2+), Cu(2+), and Zn(2+). The analysis revealed a single band on the sodium dodecyl sulfate polyacrylamide gel electrophoresis which corresponded to a molecular weight of 55 kDa for Coker 312 and 42 kDa for R405-2000.

Topics: Ascorbic Acid; Barium; Calcium; Catechol Oxidase; Catechols; Chlorides; Copper; Dithiothreitol; Electrophoresis, Polyacrylamide Gel; Enzyme Activation; Enzyme Inhibitors; Ferric Compounds; Gossypium; Hydrogen-Ion Concentration; Magnesium; Manganese; Sulfites; Temperature; Tin Compounds; Zinc

This study aims to understand the enhancing effect of glycosaminoglycans (GAGs), such as chondroitin/dermatan structures, on Fe uptake to Caco-2 cells. High-sulfated GAGs were selectively purified from cooked haddock. An in vitro digestion/Caco-2 cell culture model was used to evaluate Fe uptake (cell ferritin formation) from a Fe(+3)-containing solution, and Fe(+3)/ascorbic acid (AA) and Fe(+3)/GAGs mixtures. Mitochondria (MTT test) and endosomal/lysosomal activities (neutral red uptake, NR), intracellular accumulation of reactive oxygen species, and GSH concentration were monitored as biomarkers of the changes of cellular metabolism. Changes in mRNA expression of Fe transporters, divalent metal transporter-1 (DMT1), and duodenal cytochrome-b (DcytB) were also evaluated. The Fe uptake from Fe(+3)/GAGs mixture was up to 1.8-fold higher than from Fe(+3) alone. Both Fe(+3) alone and Fe(+3)/AA mixture produced highest increase in MTT conversion. In contrast, cell cultures exposed to the Fe(+3)/GAGs mixture exhibited highest NR uptake values. All Fe-containing solutions tested caused a sharp intramitochondrial accumulation of reactive oxygen species. Cell cultures exposed to the Fe(+3)/GAGs mixture exhibited a more preserved (by 8%) intracellular GSH concentration compared to cultures exposed to Fe(+3) or Fe(+3)/AA mixture. In addition to cell responses, the mRNA expression of Fe transporters may suggest that Fe could also be internalized into cells by endocytosis in addition to via DMT1 in Fe(+3)/GAGs mixtures. These aspects need to be confirmed in in vivo experiments to better establish nutritional interventional strategies.

Topics: Animals; Ascorbic Acid; Caco-2 Cells; Cation Transport Proteins; Chlorides; Cytochrome b Group; Digestion; Endocytosis; Ferric Compounds; Ferritins; Fishes; Glutathione; Glycosaminoglycans; Hot Temperature; Humans; Hydrolysis; Iron; Lysosomes; Microwaves; Mitochondria; Oxidative Stress; Oxidoreductases; Reactive Oxygen Species; RNA, Messenger; Seafood

The purpose of this study was to investigate the efficacy of an experimental dentin conditioner consisting of ascorbic acid (AA) and ferric chloride (Fe), in terms of micro-tensile bond strength (microTBS).. Five experimental solutions were prepared and evaluated: 10% AA and 5% Fe (10AA-5Fe); 10% AA and 0% Fe (10AA-0Fe); 0% AA and 5% Fe (0AA-5Fe); 10% citric acid and 3% ferric chloride (10-3); and, 0% AA and 0% Fe (0AA-0Fe). Flattened dentin surfaces were treated with each of the experimental solutions. A composite material rod was bonded to the dentin surface with a self curing luting agent (4-META/MMA-TBB resin). The specimens were stressed to failure under tension after 24h of immersion in water.. The 10AA-5Fe group showed significantly higher bond strength than the 10AA-0Fe, 0AA-5Fe, 10-3 and AA-0Fe groups.. It was found that an experimental conditioner consisting of 10% ascorbic acid and 5% ferric chloride significantly improved the micro-tensile bond strength between 4-META/MMA-TBB resin and dentin.

Topics: Acid Etching, Dental; Analysis of Variance; Ascorbic Acid; Boron Compounds; Chlorides; Dental Bonding; Dental Stress Analysis; Dentin; Dentin Permeability; Dentin-Bonding Agents; Drug Combinations; Ferric Compounds; Humans; Methacrylates; Methylmethacrylates; Molar, Third; Resin Cements; Surface Properties; Tensile Strength

The purpose of this study was to investigate the protective effects of the saponins isolated from the root of Platycodi Radix (Changkil saponins: CKS) on carbon tetrachloride (CCl(4))-induced hepatotoxicities in mice. Pretreatment with CKS prior to the administration of CCl(4) significantly prevented the increase in serum alanine aminotransferase and aspartate aminotransferase activities and hepatic lipid peroxidation formation. In addition, CKS prevented CCl(4)-induced apoptosis and necrosis, as indicated by a liver histopathologic study and DNA laddering. To determine whether Fas/Fas ligand (FasL) pathway involved in CCl(4)-induced acute liver injury, Fas and FasL proteins and caspase-3, -8 activities were tested by western blotting and ELISA. CKS markedly decreased CCl(4)-induced Fas/FasL protein expression levels and in turn attenuated CCl(4)-induced caspase-3, -8 activities in mouse livers. Additionally, CKS protected the CCl(4)-induced depletion of hepatic glutathione levels. The effect of CKS on CYP2E1, the major isozyme involved in CCl(4) bioactivation, was investigated. Treatment with CKS resulted in a significant decrease in the CYP2E1-dependent hydroxylation of aniline. In addition, CKS exhibited antioxidant effects on FeCl(2)-ascorbate induced lipid peroxidation in liver homogenates, and on superoxide radical scavenging activity. These findings suggest that the protective effects of CKS against CCl(4)-induced acute liver injury possibly involve mechanisms related to its ability to block CYP2El-mediated CCl(4) bioactivation and its free radical scavenging effects, and that is also protects against Fas/FasL pathway mediated apoptosis.

Topics: Animals; Ascorbic Acid; Blotting, Western; Campanulaceae; Carbon Tetrachloride Poisoning; Caspase 3; Caspase 8; Chemical and Drug Induced Liver Injury; Chlorides; Cytochrome P-450 CYP2E1; DNA; Dose-Response Relationship, Drug; Fas Ligand Protein; Ferric Compounds; Free Radical Scavengers; Glutathione; Glutathione Transferase; Lipid Peroxidation; Liver; Liver Function Tests; Male; Mice; Mice, Inbred ICR; Saponins

As superoxide (.O2-) and hydroxyl radical (.OH) have been implicated in the pathogenesis of Parkinson disease, free radical scavenging and antioxidants have attracted attention as way to prevent progression of this disease. We examined the effects of eugenol, an essential oil extracted from cloves, on 6-hydroxydopamine (6-OHDA)-induced dopamine (DA) reduction in the mouse striatum. Eugenol administration 3 d before and 7 more days following one intracerebroventricular 6-OHDA injection prevented the reduction of striatal DA and its metabolites. Eugenol administration for 3 d reduced the increase of thiobarbituric acid-reactive substances (an indicator of lipid peroxidation) induced by ferric ion and increased glutathione (GSH) and L-ascorbate (Asc) in the striatum. Eugenol did not change the levels of catalase, glutathione peroxidase, or superoxide dismutase-like activities. Eugenol is known to have .O2- and .OH scavenging activities in vitro. These results suggest that eugenol prevents 6-OHDA-induced DA depression by preventing lipid peroxidation directly and indirectly (via stimulation of GSH and Asc generating systems). Furthermore, increased GSH may protect cell death by conjugating with p-quinone produced in 6-OHDA auto-oxidation. The effects of eugenol treatment in this model suggest its possible usefulness for the treatment of Parkinson disease.

Topics: Animals; Ascorbic Acid; Catalase; Chlorides; Corpus Striatum; Dopamine; Eugenol; Ferric Compounds; Free Radical Scavengers; Glutathione; Glutathione Peroxidase; Injections, Subcutaneous; Lipid Peroxidation; Male; Mice; Mice, Inbred ICR; Oxidopamine; Superoxides; Thiobarbituric Acid Reactive Substances

It has been reported that the tensile bond strength between the 4-META/MMA-TBB resin and dentin pretreated with 10% citric/3% ferric chloride solution decreased after immersion in water for 2 years. The current study investigated the effect of an experimental dentin conditioner on the bonding of 4-META/MMA-TBB resin to dentin after thermocycling. The experimental conditioner was an aqueous solution of 10% ascorbic acid and 5% ferric chloride (Exp). Human teeth were prepared to expose flat dentin surfaces. These were treated sequentially with 40% phosphoric acid, 10% sodium hypochlorite, and the experimental conditioner. A commercially available dentin conditioner, an aqueous solution of 10% citric/3% ferric chloride (10-3) was used for a control group. Stainless steel rods were bonded to the pretreated dentin surfaces with the use of the 4-META/MMA-TBB resin. Tensile bond strengths were determined after 0, 5,000, 10,000, 20,000 themocycles. All data were analyzed by ANOVA, and differences among groups were analyzed by Duncan's new multiple range test (n = 10, p < 0.05). The experimental group showed no significant decrease in bond strength through 20,000 thermocycles, while the control group exhibited significant decrease after 10,000 thermocycles. Mean bond strength of the experimental groups were significantly higher than those of the control group at both 10,000 and 20,000 thermocycles. A hybrid layer could not be identified in SEM micrographs of the experimental groups. 10-3-conditioned specimen SEMs displayed crack formation between the adhesive resin and a hybrid layer. The experimental dentin pretreatment improved the bond strength of a 4-META/MMA-TBB resin to human dentin compared to 10-3 treatment after thermocycling.

Topics: Acid Etching, Dental; Analysis of Variance; Ascorbic Acid; Biocompatible Materials; Chlorides; Dental Bonding; Dentin; Dentin-Bonding Agents; Ferric Compounds; Hot Temperature; Humans; Materials Testing; Methacrylates; Microscopy, Electron, Scanning; Phosphoric Acids; Resin Cements; Sodium Hypochlorite; Surface Properties; Tensile Strength; Time Factors; Tooth; Water

Carnosine has antioxidant properties and is efficient in the treatment of chemically-induced inflammatory lesions in animals. However, some studies question its biological significance as antioxidant and show lack of protection and even pro-oxidant effect of carnosine in systems containing nickel and iron ions. The ability of carnosine to: (1) reduce Fe(3+) into Fe(2+) ions; (2) protect deoxyribose from oxidation by Fe(2+)-, Fe(3+)-, and Cu(2+)-H(2)O(2)-EDTA systems; (3) protect DNA from damage caused by Cu(2+)-, and Fe(2+)-H(2)O(2)-ascorbate systems; (4) inhibit HClO- and H(2)O(2)-peroxidase-induced luminol dependent chemiluminescence was tested in vitro. At concentration 10 mM carnosine reduced 16.6+/-0.5 nmoles of Fe(3+) into Fe(2+) ions during 20 min. incubation and added to plasma significantly increased its ferric reducing ability. Inhibition of deoxyribose oxidation by 10 mM carnosine reached 56+/-5, 40+/-11 and 30+/-11% for systems containing Fe(2+), Fe(3+) and Cu(2+) ions, respectively. The damage to DNA was decreased by 84+/-9 and 61+/-14% when Cu(2+)-, and Fe(2+)-H(2)O(2)-ascorbate systems were applied. Combination of 10 mM histidine with alanine or histidine alone (but not alanine) enhanced 1.3 and 2.3 times (P<0.05) the DNA damage induced by Fe(2+)-H(2)O(2)-ascorbate. These amino acids added to 10 mM carnosine decreased 3.1-fold (P<0.05) its protective effect on DNA. Carnosine at 10 and 20 mM decreased by more than 90% light emission from both chemiluminescent systems. It is concluded that carnosine has significant antioxidant activity especially in the presence of transition metal ions. However, hydrolysis of carnosine with subsequent histidine release may be responsible for some pro-oxidant effects.

Topics: Animals; Antioxidants; Ascorbic Acid; Carnosine; Cattle; Chlorides; Copper Sulfate; DNA; DNA Damage; Ferric Compounds; Ferrous Compounds; Humans; Hydrogen Peroxide; Hydrolysis; In Vitro Techniques; Iron Compounds; Male; Oxidation-Reduction; Oxidative Stress; Plasma

The purpose of this study was to investigate the efficacy of an experimental dentin primer consisting of ascorbic acid (AA) and ferric chloride (Fe). Three exprimental primers - 10 wt%AA and 0.075 wt%Fe (i.e., 10AA-0.075Fe), 10AA-0Fe, and 0AA-0.075Fe - were prepared. Flattened dentin surfaces were first treated with phosphoric acid and NaClO, and subsequently primed using each experimental solution. Besides the experimental solutions, 10 wt% citric acid and 3 wt% ferric chroride (10CA-3Fe) was also used. A stainless steel rod was bonded to the dentin surface with Super-Bond C&B. 10CA-3Fe/Super-Bond C&B was then used as a control. Tensile bond strengths were evaluated after 24-hour immersion in water. 10AA-0.075Fe showed significantly high bond strength compared to 10AA-0Fe, 0AA-0.075Fe, 0AA-0Fe, and 10CA-3Fe. No significant differences were found between 10AA-0.075Fe and Super-Bond C&B system. The experimental primer consisting of 10 wt% ascorbic acid and 0.075 wt% ferric chloride improved the bonding between Super-Bond C&B and dentin conditioned with phosphoric acid and NaClO.

Topics: Acid Etching, Dental; Acrylic Resins; Analysis of Variance; Ascorbic Acid; Boron Compounds; Chlorides; Dental Bonding; Dental Stress Analysis; Dentin; Dentin-Bonding Agents; Ferric Compounds; Humans; Materials Testing; Methacrylates; Methylmethacrylates; Molar; Phosphoric Acids; Resin Cements; Sodium Hypochlorite; Tensile Strength

Off-flavor and discoloration of meat products result from lipid oxidation and myoglobin (Mb) oxidation, respectively, and these two processes appear to be interrelated. The objective of this study was to investigate their potential interaction in mitochondria and the effects of mitochondrial alpha-tocopherol concentrations on lipid oxidation and metmyoglobin (MetMb) formation in vitro. The addition of ascorbic acid and ferric chloride (AA-Fe(3+)) increased ovine and bovine mitochondrial lipid oxidation when compared with their controls (p < 0.05); MetMb formation also increased with increased lipid oxidation relative to controls (p < 0.05). Reactions containing Mb and mitochondria with greater alpha-tocopherol concentrations demonstrated less lipid oxidation and MetMb formation than mitochondria with lower alpha-tocopherol concentrations. Greater mitochondrial alpha-tocopherol concentration was also correlated with increased mitochondrial oxygen consumption in vitro and with a more pronounced effect at pH 7.2 than at pH 5.6. Relative to controls, succinate addition to bovine mitochondria resulted in increased concentrations of ubiquinol 10 and alpha-tocopherol and decreased lipid and Mb oxidation (p < 0.05). Mitochondrial lipid oxidation was closely related to MetMb formation; both processes were inhibited by alpha-tocopherol in a concentration-dependent manner.

Topics: alpha-Tocopherol; Animals; Ascorbic Acid; Cattle; Chlorides; Ferric Compounds; Hydrogen-Ion Concentration; Lipid Peroxidation; Meat; Mitochondria, Heart; Myoglobin; Oxidation-Reduction; Oxygen Consumption; Sheep

Insulysin (IDE) and neprilysin (NEP) were found to be inactivated by oxidation with hydrogen peroxide, an iron-ascorbate oxidation system, and by treatment with 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH). In each case reaction led to the introduction of protein carbonyl groups as judged by reaction with 2,4-dintrophenylhydrazine. IDE was inactivated by reaction with 4-hydroxy-2-nonenal (HNE) with the concomitant formation of protein adducts. NEP was not inactivated to a significant extent by HNE, but some HNE-adduct formation did occur. Prior reaction with hydrogen peroxide or AAPH led to enhanced formation of HNE adducts. Treatment of IDE with AAHP or hydrogen peroxide increased its susceptibility to proteolysis, while treatment of NEP with iron/ascorbate or hydrogen peroxide increased its susceptibility to proteolysis. Since IDE and NEP play a prominent role in the clearance of amyloid beta peptides, their oxidative inactivation and enhanced proteolysis can contribute to the onset and/or progression of Alzheimer's disease.

Topics: Aldehydes; Alzheimer Disease; Amidines; Amyloid beta-Peptides; Ascorbic Acid; Chlorides; Chymotrypsin; Ferric Compounds; Hydrogen Peroxide; Insulysin; Neprilysin; Oxidation-Reduction; Trypsin

This study investigated the protective effects of acteoside, a phenylethanoid glycoside, on the carbon tetrachloride-induced hepatotoxicity as well as the possible mechanisms involved in this protection in mice. Pretreatment with acteoside prior to the administration of carbon tetrachloride significantly prevented the increased serum enzymatic activities of alanine and aspartate aminotransferase in a dose-dependent manner. In addition, pretreatment with acteoside significantly prevented the increase in hepatic malondialdehyde formation and the depletion of the reduced glutathione content in the liver of carbon tetrachloride-intoxicated mice. Carbon tetrachloride-induced hepatotoxicity was also essentially prevented, as indicated by a liver histopathologic study. The effects of acteoside on cytochrome P450 (P450) 2E1, the major isozyme involved in carbon tetrachloride bioactivation were also investigated. Treatment of the mice with acteoside resulted in a significant decrease in the P450 2E1-dependent pnitrophenol and aniline hydroxylation in a dose-dependent manner. Consistent with these observations, the P450 2El protein levels were also lower. Acteoside exhibited anti-oxidant effects on FeCl2-ascorbate induced lipid peroxidation in a mouse liver homogenate, and on superoxide radical scavenging activity. These results suggest that the protective effects of acteoside against the carbon tetrachloride-induced hepatotoxicity possibly involve mechanisms related to its ability to block the P450-mediated carbon tetrachloride bioactivation and free radical scavenging effects.

Topics: Alanine Transaminase; Animals; Antioxidants; Ascorbic Acid; Aspartate Aminotransferases; Carbon Tetrachloride Poisoning; Chemical and Drug Induced Liver Injury; Chlorides; Cytochrome P-450 CYP2E1; Dose-Response Relationship, Drug; Ferric Compounds; Free Radical Scavengers; Glucosides; Glutathione; Immunoblotting; Lipid Peroxidation; Liver; Liver Function Tests; Male; Mice; Mice, Inbred ICR; Microsomes, Liver; Mixed Function Oxygenases; Phenols; Superoxides

The purpose of this study was to evaluate ascorbic acid (AS) and ferric chloride (FE) for bonding 4-META/MMA-TBB resin to dentin that had been treated with NaClO. An experimental dentin conditioner consisting of 10%AS and 5%Fe (10AS-5FE) and three controls (10AS-0FE, 0AS-5FE, and 0AS-0FE) were prepared. Ascorcic acid neutralizes NaClO. The flattened dentin surfaces were modified sequentially with phosphoric acid etchant, NaClO agent, and the experimental conditioner, then each surface was bonded to a stainless steel rod with 4-META/MMA-TBB resin. The Super-Bond C&B (10-3/SB) system was also used. 24-hour tensile bond strengths were determined. The bonding system using 10AS-5FE conditioner showed significantly high bond strength compared to 10AS-0FE, 0AS-5FE, and 0AS-0FE. No significant differences were observed between 10AS-5FE and 10-3/SB. Microphotographs suggested that no hybrid layer formed in the 10AS-5FE group. Although the use of phosphoric acid and NaClO resulted in decreased bond strength between 4-META/MMA-TBB resin and dentin, additional conditioning with ascorbic acid and ferric chloride improved the bond strength.

Topics: Adhesiveness; Analysis of Variance; Animals; Ascorbic Acid; Boron Compounds; Cattle; Chlorides; Collagen; Dental Bonding; Dental Stress Analysis; Dentin; Dentin-Bonding Agents; Ferric Compounds; Materials Testing; Methylmethacrylates; Resin Cements; Sodium Hypochlorite; Tensile Strength

Peptides with two or more acidic amino acids are damaged to a greater extent than other peptides under Fenton conditions as revealed by treating a 29791 membered one-bead-one-compound peptide library with FeCl(3), sodium ascorbate and hydrogen peroxide.

Topics: Amino Acid Sequence; Amino Acids, Acidic; Ascorbic Acid; Chlorides; Ferric Compounds; Hydrogen Peroxide; Peptide Fragments; Peptide Library; Spectrometry, Fluorescence

The protective effects of 18beta-glycyrrhetinic acid (GA), the aglycone of glycyrrhizin (GL) derived from licorice, on carbon tetrachloride-induced hepatotoxicity and the possible mechanisms involved in this protection were investigated in mice. Pretreatment with GA prior to the administration of carbon tetrachloride significantly prevented an increase in serum alanine, aspartate aminotransferase activity and hepatic lipid peroxidation in a dose-dependent manner. In addition, pretreatment with GA also significantly prevented the depletion of glutathione (GSH) content in the livers of carbon tetrachloride-intoxicated mice. However, reduced hepatic GSH levels and glutathione-S-transferase activities were unaffected by treatment with GA alone. Carbon tetrachloride-induced hepatotoxicity was also prevented, as indicated by a liver histopathologic study. The effects of GA on the cytochrome P450 (P450) 2E1, the major isozyme involved in carbon tetrachloride bioactivation, were also investigated. Treatment of mice with GA resulted in a significant decrease of the P450 2E1-dependent hydroxylation of p-nitrophenol and aniline in a dose-dependent manner. Consistent with these observations, the P450 2E1 expressions were also decreased, as determined by immunoblot analysis. GA also showed antioxidant effects upon FeCl(2)-ascorbate-induced lipid peroxidation in mice liver homogenate and upon superoxide radical scavenging activity. These results show that protective effects of GA against the carbon tetrachloride-induced hepatotoxicity may be due to its ability to block the bioactivation of carbon tetrachloride, primarily by inhibiting the expression and activity of P450 2E1, and its free radical scavenging effects.

Topics: Administration, Topical; Alanine; Animals; Anti-Inflammatory Agents; Ascorbic Acid; Aspartate Aminotransferases; Carbon Tetrachloride; Chlorides; Cytochrome P-450 CYP2E1; Cytochrome P-450 CYP2E1 Inhibitors; Ferric Compounds; Free Radical Scavengers; Glutathione; Glycyrrhetinic Acid; Glycyrrhiza; Glycyrrhizic Acid; Lipid Peroxidation; Liver Failure, Acute; Male; Mice; Mice, Inbred ICR; Phytotherapy; Plant Extracts; Superoxides

The purpose of this study was to identify the cis-acting elements and the trans-acting factors involved in the iron-induced expression of the collagen alpha1(I) (COL1aI) gene. Rat hepatic stellate cells were cultured in the presence of 50 microM ferric chloride, 50 microM ascorbic acid, and 250 microM citric acid (Fe/AA/CA), and the effects on collagen gene expression and the binding of nuclear proteins to the COL1aI promoter were measured. The Fe/AA/CA treatment induced a time- and dose-dependent increase in the cellular levels of COL1aI mRNA that was abrogate by pretreating cells with cycloheximide, antioxidants, and inhibitors of aldehyde-protein adduct formation. Transient transfection experiments showed that Fe/AA/CA exerted its effect through regulatory elements located between -220 and -110 bp of the COL1aI promoter. Gel retardation assays showed that Fe/AA/CA increased the binding of nuclear proteins to two elements located between -161 and -110 bp of the COL1aI promoter. These bindings were blocked by unlabeled consensus Sp1 oligonucleotide and supershifted with Sp1 and Sp3 antibodies. Finally, Fe/AA/CA increased cellular levels of the Sp1 and Sp3 proteins and Sp1 mRNA. Treatment with Fe/AA/CA stimulates COL1aI gene expression by inducing the synthesis of Sp1 and Sp3 and their binding to two regulatory elements located between -161 and -110 bp of the COL1aI promoter.

Topics: Animals; Antioxidants; Ascorbic Acid; Cell Line; Chlorides; Citric Acid; Collagen; Cycloheximide; DNA-Binding Proteins; Ferric Compounds; Gene Expression Regulation; Nuclear Proteins; Proline; Promoter Regions, Genetic; Rats; Recombinant Proteins; RNA, Messenger; Sp1 Transcription Factor; Sp3 Transcription Factor; Thiobarbituric Acid Reactive Substances; Transcription Factors; Transcription, Genetic; Transfection

An attempt was made to study the effect of histidine on reactive oxygen species in a rodent model of hypoxic stress and in Fe(3+)-ascorbic acid-induced lipid peroxidation in mouse brain homogenates. The latency for onset of hypoxic stress-induced convulsions was decreased in histidine-treated animals with a concomitant rise in brain lipid peroxidation levels. In vitro, histidine potentiated Fe(3+)-ascorbic acid-induced lipid peroxidation in mouse brain homogenates while other antioxidants like B-HT and U-74500A inhibited the same. Moreover, Fe(3+)-histidine-induced lipid peroxidation could not be inhibited by preincubation of the system with high concentrations of ascorbic acid. Thus, it is concluded that histidine acts as a strong prooxidant potentiating the genesis of reactive oxygen species during hypoxic stress as well as during Fe(3+)-ascorbic acid-induced lipid peroxidation.

Topics: Animals; Antioxidants; Ascorbic Acid; Chlorides; Ferric Compounds; Histidine; Hypoxia, Brain; Lipid Peroxidation; Male; Malondialdehyde; Mice; Reactive Oxygen Species; Stress, Physiological

Neurofilament proteins are highly phosphorylated molecules in the axonal compartment of the adult nervous system. We report the structural analysis of neurofilament proteins after oxidative damage. SDS-PAGE, immunoblotting, circular dichroism, and Fourier transform infrared spectroscopy were used to investigate the relative sensitivity of neurofilaments to oxidative stress and to identify changes in their molecular organization. An ascorbate-Fe+3-O2 buffer system as well as catechols were used to generate free radicals on a substrate of phosphorylated and dephosphorylated neurofilaments. By Fourier Transform Infrared spectroscopy and circular dichroism, we established that the neurofilament secondary structure is mainly composed of alpha-helices and that after free radical damage of the peptide backbone of neurofilaments, those helices are partly modified into beta-sheet and random coil structures. These characteristic reorganizations of the neurofilament structure after oxidative exposure suggest that free radical activity might play an important role in the biogenesis of the cytoplasmic inclusions found in several neurodegenerative diseases.

Topics: 3,4-Dihydroxyphenylacetic Acid; Animals; Ascorbic Acid; Chlorides; Circular Dichroism; Dopamine; Electrophoresis, Polyacrylamide Gel; Ferric Compounds; Free Radicals; Levodopa; Molecular Weight; Neurofilament Proteins; Oxidation-Reduction; Oxidative Stress; Phosphorylation; Protein Structure, Secondary; Spectroscopy, Fourier Transform Infrared; Swine

Ascorbate and dehydroascorbate transport was investigated in rat liver microsomal vesicles using radiolabeled compounds and a rapid filtration method. The uptake of both compounds was time- and temperature-dependent, and saturable. Ascorbate uptake did not reach complete equilibrium, it had low affinity and high capacity. Ascorbate influx could not be inhibited by glucose, dehydroascorbate, or glucose transport inhibitors (phloretin, cytochalasin B) but it was reduced by the anion transport inhibitor 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid and by the alkylating agent N-ethylmaleimide. Ascorbate uptake could be stimulated by ferric iron and could be diminished by reducing agents (dithiothreitol, reduced glutathione). In contrast, dehydroascorbate uptake exceeded the level of passive equilibrium, it had high affinity and low capacity. Glucose cis inhibited and trans stimulated the uptake. Glucose transport inhibitors were also effective. The presence of intravesicular reducing compounds increased, while extravesicular reducing environment decreased dehydroascorbate influx. Our results suggest that dehydroascorbate transport is preferred in hepatic endoplasmic reticulum and it is mediated by a GLUT-type transporter. The intravesicular reduction of dehydroascorbate leads to the accumulation of ascorbate and contributes to the low intraluminal reduced/oxidized glutathione ratio.

Topics: 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; Animals; Ascorbic Acid; Biological Transport; Chlorides; Dehydroascorbic Acid; Endoplasmic Reticulum; Ethylmaleimide; Ferric Compounds; Glucose; Male; Microsomes, Liver; Monosaccharide Transport Proteins; Rats; Rats, Sprague-Dawley; Subcellular Fractions

The mechanism of captopril, an angiotensin converting enzyme (ACE) inhibitor with sulfhydryl group (SH) in its structure, to produce an endothelium-dependent vasorelaxation was studied. In rabbit aorta with intact endothelium and precontracted with phenylephrine, captopril and superoxide dismutase (SOD) produced dose-dependent relaxation. Lisinopril, an ACE inhibitor without a -SH group in its structure, did not produce endothelium-dependent relaxation. It was observed that captopril, like SOD, produced the relaxation by protecting the EDRF from getting inactivated by superoxide anions as pyrogallol and methylene blue inhibited both the captopril and SOD-mediated relaxation. The free radical scavenging action of captopril is further substantiated by the observation that captopril, but not lisinopril, inhibited FeCl3/ascorbic acid-induced lipid peroxidation in whole tissue homogenates of rabbit aorta to a level comparable to that of SOD. These results suggest that endothelium-dependent vasodilation produced by captopril may be due to its ability to scavenge superoxide anion and this property may be ascribed to the -SH group present in its structure.

Topics: Angiotensin-Converting Enzyme Inhibitors; Animals; Aorta; Ascorbic Acid; Captopril; Chlorides; Dose-Response Relationship, Drug; Endothelium, Vascular; Female; Ferric Compounds; In Vitro Techniques; Lipid Peroxidation; Male; Muscle Relaxation; Phenylephrine; Rabbits; Reactive Oxygen Species; Sulfhydryl Compounds; Superoxide Dismutase

Ferritin is the major intracellular iron storage protein which has been shown to protect cells against oxidative damage. Recent reports that an inherited abnormality in human ferritin synthesis is associated with early bilateral cataracts underscore the importance of understanding ferritin synthesis and iron storage in lens epithelial cells. We previously demonstrated that ascorbic acid greatly increases de novo synthesis of ferritin in lens epithelial cells. The objectives of the present study were to determine: (1) the effects of ascorbic acid and ferric ammonium citrate on iron uptake by canine lens epithelial cells from iron bound to transferrin and from ferric chloride and (2) the incorporation of this element into ferritin. Iron uptake by lens epithelial cells from 59ferric chloride was 20 times higher than from 59iron-transferrin and iron deposition into ferritin was 8-fold higher when 59ferric chloride was the source. Ascorbic acid had a stimulatory effect on iron uptake from transferrin and on incorporation of this element into ferritin. The ascorbic acid-induced increase of iron uptake required de novo protein synthesis but not specifically de novo ferritin biosynthesis. Although ferritin is not directly involved in iron uptake, the level of ferritin protein could control the pool of intracellular iron. The present results indicate that iron homeostasis in lens epithelial cells is affected mainly by changes in apoferritin synthesis, which is greatly stimulated by ascorbic acid, rather than by altering the rate of protein degradation, which is very slow in these cells under all circumstances. Ferric ammonium citrate activates iron uptake from transferrin in a wide range of cell lines by generation of free radicals. Ferric ammonium citrate also increased iron uptake from Tf in lens epithelial cells. Ferric ammonium citrate treated cells incorporated 5 times more iron and deposited 2 times more iron into ferritin than control cells. Increased incorporation of iron into ferritin was due to ferric ammonium citrate-induced stimulation of de novo ferritin synthesis rather than an increased rate of iron deposition into pre-existing ferritin. Ferric ammonium citrate had a different effect on iron uptake from ferric chloride; total iron uptake was not significantly increased while deposition into ferritin was significantly decreased. These results demonstrate that iron homeostasis in lens epithelial cells is regulated by ascorbic acid and by changes in th

Topics: Animals; Apoferritins; Ascorbic Acid; Cells, Cultured; Chlorides; Dogs; Epithelial Cells; Ferric Compounds; Homeostasis; Humans; Infant, Newborn; Iron Radioisotopes; Lens, Crystalline; Quaternary Ammonium Compounds; Transferrin

Exposure of intact rabbit erythrocytes or erythrocyte lysates to ascorbic acid/FeCl3 in a glucose-free saline promoted a rapid decline in reduced glutathione and this response was paralleled by inactivation of hexokinase. Under the same conditions, the activity of the enzymes glyceraldehyde-3-phosphate dehydrogenase and glucose-6-phosphate dehydrogenase did not show appreciablevariations in intact cells, but was severely inhibited in the cell-free system. Similar results were obtained by replacing ascorbic acid/FeCl3 with dehydroascorbic acid. In addition, both treatments effectively inhibited the activity of purified hexokinase as well as those of glucose-6-phosphate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase. Further studies using the cell-free system indicated that the inhibition of enzyme activities elicited by either of the two treatments was effectively counteracted by the specific substrates of these enzymes. The fact that the hexokinase substrate glucose freely permeates the plasma membrane, unlike the substrates of glucose-6-phosphate dehydrogenase and glyceraldehyde-3-phosphatedehydrogenase, explains the selective inhibition of hexokinase observed in intact cells. The above results also indicate that dehydroascorbic acid is an inhibitor of these enzymes and strongly suggest that it is at least in part responsible for the effects mediated by the cocktail ascorbic acid/FeCl3.

Topics: Animals; Ascorbic Acid; Chlorides; Dehydroascorbic Acid; Enzyme Activation; Erythrocytes; Ferric Compounds; Glucosephosphate Dehydrogenase; Glutathione; Glyceraldehyde-3-Phosphate Dehydrogenases; Hemolysis; Hexokinase; Rabbits; Substrate Specificity

The ability of Cu(II) and Fe(III) to promote site-specific DNA damage in the presence of endogenous reductants was investigated by using 32P-5'-end-labeled DNA fragments obtained from the human p53 tumor suppressor gene and the c-Ha-ras-1 protooncogene. Ascorbate induced metal-dependent DNA damage most efficiently (ascorbate > GSH > NADH). Cu(II) induced endogenous reductants-dependent DNA damage more efficiently than Fe(III). Endogenous reductants plus Fe(III) caused DNA cleavage at every nucleotide, without marked site preference. DNA damage by Fe(III) was inhibited by hydroxyl free radical (.OH) scavengers and catalase. These results suggest that endogenous reductants plus Fe(III) generate free or extremely near free .OH via H2O2 formation, and that .OH causes DNA damage. In the presence of 50 microM Cu(II) in bicarbonate buffer, ascorbate caused DNA cleavage frequently at sites of two or more adjacent guanine residues. In contrast, in the presence of 20 microM Cu(II), ascorbate caused DNA cleavage frequently at thymine residues. Catalase and a Cu(I)-specific chelator inhibited DNA damage by Cu(II), whereas .OH scavengers did not. Fe(III)-dependent 8-oxo-7,8-dihydro-2'-deoxyguanosine formation was inhibited by .OH scavengers, whereas no inhibition by .OH scavengers was observed with Cu(II). These results suggest that .OH is the main active species formed with Fe(III), whereas copper-peroxide complexes with a reactivity similar to .OH participate in Cu(II)-dependent DNA damage. The polyguanosine sequence specificity of DNA damage in the presence of high concentrations of Cu(II) can be explained by the preferential binding of Cu(II) to guanine residues.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Ascorbic Acid; Cattle; Chlorides; Copper; Deoxyguanosine; DNA Damage; DNA Fragmentation; Ferric Compounds; Free Radical Scavengers; Hydrogen Peroxide; Hydroxyl Radical; NAD; Oxidation-Reduction

Enhanced oxidative stress is a feature of inflammatory and infectious conditions. Proteins may be important targets of oxidation and this may alter their function. We evaluated whether metal-catalyzed oxidation of IgG could alter its ability to bind to Fc receptors on macrophages. Human IgG incubated with an FeCl3/EDTA/ascorbate metal-catalyzed oxidation system resulted in a significant increase in carbonyl content, a measure of protein oxidation, compared to IgG treated with EDTA alone (control). Western blot analysis using an antibody to oxidized protein revealed an increase in antibody binding to both the heavy (Fc portion-containing) and light chains of IgG treated with the oxidizing system. Western blot analysis of papain-digested IgG confirmed oxidative modification of the Fc portion. Binding studies carried out with J774.16 macrophages demonstrated significantly diminished ability of the oxidized IgG to bind to macrophage Fc receptors compared to control IgG. These data demonstrate that IgG is susceptible to metal-catalyzed oxidation and that this impairs its ability to bind to macrophage Fc receptors. Oxidation of IgG might play a role in modulating immune function in infection and disorders associated with immune complex formation by diminishing IgG binding to phagocytic cells.

Topics: Ascorbic Acid; Blotting, Western; Chlorides; Edetic Acid; Ferric Compounds; Humans; Immunoglobulin Fc Fragments; Immunoglobulin G; Macrophages; Oxidation-Reduction; Papain; Receptors, Fc

Topics: Animals; Antioxidants; Ascorbic Acid; Brain; Cardiotonic Agents; Cattle; Chlorides; Estradiol; Estrogens, Non-Steroidal; Ferric Compounds; Isoflavones; Kinetics; Lipid Peroxidation; Liposomes; Male; Microsomes, Liver; Phytoestrogens; Plant Preparations; Rats; Thiobarbituric Acid Reactive Substances

Potential antioxidant properties of therapeutically achievable concentrations of the protonated, active form of omeprazole (OM) were investigated in vitro at specific acidic pH values to mimic intragastric conditions in the clinical setting. We found that OM is a powerful scavenger of hypochlorous acid (HOCl) even at a drug concentration of 10 microM at pH 5.3 or 3.5. This effect is also evident in the presence of the physiological HOCl scavenger ascorbate. Moreover, 10 and 50 microM OM inhibit significantly both iron- and copper-driven oxidant damage at pH 5.3 and 3.5, respectively. Since oxidative stress is involved the gastric injury of peptic ulcer and gastritis, it may be hypothesized that some therapeutical effects of OM could also be related to its antioxidant properties.

Topics: Anti-Ulcer Agents; Antioxidants; Ascorbic Acid; beta Carotene; Carotenoids; Chlorides; Copper; Deoxyribose; Ferric Compounds; Hydrogen-Ion Concentration; Hypochlorous Acid; Omeprazole; Oxidation-Reduction

Neurofilaments (NF) are important determinants of the shape and size of nerve cells. The oxidation of NF, relevant to aging, neurodegenerative disorders, and axonal (Wallerian) degeneration, has not been studied. In this investigation, we have combined biochemical and ultrastructural methods to study the metal-catalyzed oxidation (MCO) of bovine NF using an ascorbate/Fe+3/O2 system. The oxidation of NF proteins was documented by increases in carbonyl content, which were time- and concentration-dependent. Polyacrylamide gel electrophoresis (PAGE) and immunoblot analyses revealed the fragmentation of oxidized NF proteins, predominantly NF-H and NF-M. Electron microscopy (EM) showed that oxidized NF formed dense aggregates and bundles of laterally aggregated filaments. Finally, we also demonstrated that oxidized NF proteins were more susceptible to calpain proteolysis. In view of the growing evidence supporting increased oxidative stress on the nervous system in aging and the report of Cu/Zn superoxide dismutase mutation in familial motor neuron disease, oxidative injury of NF may be relevant to cell atrophy and degeneration of nerve cells and to the formation of abnormal cytoskeletal structures.

Topics: Animals; Ascorbic Acid; Calpain; Cattle; Cell Fractionation; Chlorides; Electrophoresis, Polyacrylamide Gel; Ferric Compounds; Guanidine; Guanidines; Intermediate Filaments; Microscopy, Electron; Molecular Weight; Neurofilament Proteins; Oxidation-Reduction; Solubility; Spinal Cord; Ultracentrifugation

Oxidative stress and adenine nucleotide catabolism occur concomitantly in several disease states, such as cardiac ischaemia-reperfusion, and may act as synergistic determinants of tissue injury. However, the mechanisms underlying this potential interaction remain ill-defined. We examined the influence of oxidative stress on the molecular, kinetic and regulatory properties of a ubiquitous AMP-catabolizing enzyme, adenylate deaminase (AMPD) (EC 3.5.4.6). To this intent, rabbit heart AMPD and an H2O2/ascorbate/iron oxidation system were employed. Enzyme exposure to the complete oxidation system acutely impaired its catalytic activity, lowered the Vmax. by 7-fold within 5 min, and rendered the enzyme unresponsive to nucleotide effectors. Irreversible AMPD inactivation resulted within about 15 min of oxidative insult and was not prevented by free-radical scavengers. Oxidative stress did not affect the molecular mass, tetrameric nature, Km, immunoreactivity or trypsinolytic pattern of the enzyme; nor did it induce carbonyl formation, Zn2+ release from the holoenzyme or net AMPD S-thiolation. This injury pattern is inconsistent with a radical-fragmentation mechanism as the basis for the oxidative AMPD inactivation observed. Rather, the sensitivity of the enzyme to both S-thiolation and thiol alkylation and the significant (3 of 9/mol of denatured enzyme) net loss of DTNB-reactive thiols on exposure to oxidant strongly implicate the conversion of essential thiol moieties into stable higher-oxidation states in the oxidative inactivation of cardiac AMPD. The altered thiol status of the enzyme on oxidative insult may prohibit a catalytically permissible conformation and, in so doing, increase AMP availability to 5'-nucleotidase in vivo.

Topics: 5'-Nucleotidase; Alkylation; AMP Deaminase; Animals; Ascorbic Acid; Catalysis; Chlorides; Dithionitrobenzoic Acid; Ferric Compounds; Ferrous Compounds; Hydrogen Peroxide; Kinetics; Macromolecular Substances; Molecular Weight; Myocardium; Oxidative Stress; Rabbits; Sulfhydryl Compounds; Trypsin; Zinc

The effect of primary structure and external conditions on the oxidation of methionine to methionine sulfoxide by the ascorbate/Fe3+ system was studied in small model peptides. Degradation kinetics and yield of sulfoxide formation were dependent on the concentration of ascorbate and H+, with a maximum rate observed at pH 6-7. Phosphate buffer significantly accelerated the peptide degradation compared to Tris, HEPES, and MOPS buffers; however, the formation of sulfoxide was low. The oxidation could not be inhibited by the addition of EDTA. Other side products besides sulfoxide were observed, indicating the existence of various other pathways. The influence of methionine location at the C terminus, at the N terminus, and in the middle of the sequence was investigated. The presence of histidine in the sequence markedly increased the degradation rate as well as the sulfoxide production. The histidine catalysis of methionine oxidation occurred intramolecularly with a maximum enhancement of the oxidation rate and sulfoxide production when one residue was placed between the histidine and the methionine residue.

Topics: Amino Acid Sequence; Ascorbic Acid; Buffers; Chlorides; Edetic Acid; Ferric Compounds; Histidine; Hydrogen-Ion Concentration; Methionine; Molecular Sequence Data; Oxidation-Reduction; Peptides; Temperature

Iron-ascorbate stimulated lipid peroxidation in rat liver microsomes can be inhibited by glutathione (GSH). The role of protein thiols and vitamin E in this process was studied in liver microsomes isolated from rats fed diets either sufficient or deficient in vitamin E and incubated at 37 degrees C under 100% O2. Lipid peroxidation was induced by adding 400 microM adenosine 5'-triphosphate, 2.5 to 20 microM FeCl3, and 450 microM ascorbic acid. One mL of the incubation mixture was removed at defined intervals for the measurement of thiobarbituric acid reactive substances (TBARS), protein thiols and vitamin E. In vitamin E sufficient microsomes, the addition of GSH enhanced the lag time prior to the onset of maximal TBARS accumulation and inhibited the loss of vitamin E. Treatment of these microsomes with the protein thiol oxidant diamide resulted in a 56% loss of protein thiols, but did not significantly change vitamin E levels. However, diamide treatment abolished the GSH-mediated protection against TBARS formation and loss of vitamin E during ascorbate-induced peroxidation. Liver microsomes isolated from rats fed a vitamin E deficient diet contained 40-fold less vitamin E and generated levels of TBARS similar to vitamin E sufficient microsomes at a 4-fold lower concentration of iron. GSH did not affect the lag time prior to the onset of maximal TBARS formation in vitamin E deficient microsomes although total TBARS accumulation was inhibited. Similar to what was previously found in vitamin E sufficient microsomes [Palamanda and Kehrer, (1992) Arch. Biochem. Biophys. 293, 103-109], GSH prevented the loss of protein thiols in vitamin E deficient microsomes.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adenosine Triphosphate; Animals; Ascorbic Acid; Chlorides; Ferric Compounds; Glutathione; Kinetics; Lipid Peroxidation; Microsomes, Liver; Rats; Sulfhydryl Compounds; Thiobarbiturates; Vitamin E

The present study was carried out to determine if iron chloride (FeCl3) injections into the substantia nigra of guinea-pigs produced changes in nigro-striatal uric acid levels. Two-weeks following unilateral injection of FeCl3 (185 nmol Fe3+), ipsilateral uric acid levels were increased 176% over contralateral levels in the substantia nigra. No effect on striatal uric acid levels was observed. Iron chloride injection produced a 74% depletion of dopamine levels in the ipsilateral striatum. Ipsilateral/contralateral ratios were significantly decreased for striatal dopamine and significantly increased for nigral uric acid when compared with saline-injected controls. The results of this work indicate that FeCl3 injections into the substantia nigra of guinea-pigs produce a significant, localized increase in tissue uric acid levels two weeks after treatment.

Topics: Animals; Ascorbic Acid; Cell Death; Chlorides; Dopamine; Ferric Compounds; Guinea Pigs; Injections; Male; Mesencephalon; Substantia Nigra; Uric Acid

The rate of photohaemolysis of human red blood cells sensitized by chloroaluminium phthalocyanine sulphonate is increased by ascorbate, with or without added FeCl3. Stimulation of haemolysis by ascorbate without addition of metal salt, and in the presence of a strong chelator such as desferrioxamine, is an unexpected phenomenon. Lysis rate and ascorbate concentration were directly related, suggesting that ascorbate acts as a reactant and not as a catalyst. The process also requires oxygen; azide and D2O tests indicate some participation of singlet oxygen, although to a lesser extent than in the photosensitized haemolysis in the absence of ascorbate. Kinetic considerations suggest a reaction path initiated by excited sensitizer and ascorbate, parallel to the singlet oxygen-mediated process. Because of the ubiquitous presence of ascorbate in human tissues in concentrations comparable to those of dissolved oxygen, it is quite possible that in photodynamic therapy a fraction of the photodynamic damage proceeds via a Type I, ascorbate-assisted, mechanism.

Topics: Ascorbic Acid; Chlorides; Drug Synergism; Erythrocytes; Ferric Compounds; Hemolysis; Humans; Indoles; Organometallic Compounds; Radiation-Sensitizing Agents

12-(1-pyrene)dodecanoic fatty acid (P12) uptake by Spiroplasma floricola BNR-1 cells was characterized with regard to its kinetics, specificity, metabolism and susceptibility to protein and lipid inhibitors. The uptake process depended on temperature and pH, and exhibited biphasic saturation kinetics with a very low (2.7 microM) and a high (37 microM) apparent Km value. Lauric, myristic, palmitic, stearic and oleic fatty acids did not compete with P12 for transport. The fluorescence of P12 was exclusively recovered in the neutral lipid fraction, suggesting that this fatty acid is not further utilized for phospholipid biosynthesis. Valinomycin, carbonylcyanide m-chlorophenyldrazone (CCCP), dicyclohexylcarbodiimide (DCCD), and pronase strongly reduced P12 uptake by cells, but not by membrane vesicles, affecting the high affinity (low Km) component of the uptake system. Uptake of P12 by cells, as well as by membrane vesicles, was very sensitive to glutaraldehyde, chlorpromazine, phospholipase A21 and ascorbate with FeCl3, which affected the low affinity (high Km) component of a transport system. Digitonin stimulated P12 uptake. We suggest that the incorporation of P12 into spiroplasma cell membrane is a two-step process: a high specificity energy-dependent and protease-sensitive binding to the outer surface of membrane, and a low specificity and energy-independent diffusion and partition into the membrane lipid environment.

Topics: Ascorbic Acid; Biological Transport; Carbonyl Cyanide m-Chlorophenyl Hydrazone; Chlorides; Chlorpromazine; Dicyclohexylcarbodiimide; Ferric Compounds; Fluorescent Dyes; Glutaral; Kinetics; Lauric Acids; Membrane Lipids; Membranes; Phospholipases A; Pronase; Spiroplasma; Subcellular Fractions; Valinomycin

The hyperthermic exposure (39-49 degrees C) of human erythrocyte membranes augmented their lipid peroxidation stimulated by 0.1 mM FeCl3 + 1.5 mM ascorbate while having no significant influence on the non-stimulated lipid peroxidation. No effect of hyperthermia and lipid peroxidation on the post-exposure fluidity of the erythrocyte membrane lipids was found by the fluorescence anisotropy of hexatriene and trimethylaminophenylhexatriene, and excimerization efficiency of pyrene. Exposure to iron/ascorbate increased the accessibility of membrane protein tryptophan residues to acrylamide as judged by fluorescence quenching. These results suggest a higher sensitivity of membrane protein organization than of membrane lipid fluidity to the effect of the system inducing lipid peroxidation.

Topics: Ascorbic Acid; Chlorides; Erythrocyte Membrane; Ferric Compounds; Hot Temperature; Humans; In Vitro Techniques; Lipid Peroxidation; Membrane Fluidity; Stimulation, Chemical

The occurrence of age-related modifications in enzymes is a well-established symptom of aging that has been explained by several possible mechanisms including the oxidation of amino acid residues by mixed-function oxidation (MFO) systems. In the present study native old phosphoglycerate kinase was compared with young enzyme which had been modified by oxidation with ascorbate: FeCl3 followed by reduction. The comparison was done by monitoring the rates of heat denaturation of these enzyme forms, as well as their inactivation by trypsin. A remarkable similarity between the old and treated young enzyme was revealed, while native young phosphoglycerate kinase was inactivated with a different rate. Extensive unfolding followed by refolding converted both old and MFO-treated young phosphoglycerate kinase to species which greatly resemble the native young enzyme in their heat inactivation kinetics. These results demonstrate that the exposure of phosphoglycerate kinase to the mixed-function oxidation system introduces some modifications which are not reversed by subsequent enzyme reduction and which resemble those found in the native old enzyme. This mechanism, therefore, may account for the aging of phosphoglycerate kinase in vivo.

Topics: Aging; Animals; Ascorbic Acid; Chlorides; Cysteine; Enzyme Activation; Female; Ferric Compounds; Hot Temperature; Mercaptoethanol; Muscles; Oxidation-Reduction; Phosphoglycerate Kinase; Protein Conformation; Rats; Rats, Inbred Strains; Trypsin

Current evidence suggests that products of activated inflammatory cells cause or contribute to the acute lung injury of the adult respiratory distress syndrome (ARDS). To assess the possibility that these products may impair surfactant function during ARDS, we exposed surfactant in vitro to polymorphonuclear leukocytes (PMN) activated by phorbol myristate acetate and to the oxidant-producing pair ferric chloride/ascorbate (FeCl3/ASC). After incubation of surfactant with 8 to 32 x 10(6) activated PMN for 1 to 4 h or with FeCl3/ASC for 16 h, its isopycnic density (d), minimum surface tension (gamma min), time course of adsorption, compressibility (SC), and stability index (SI) were determined. We found progressive decreases of d, adsorption, and SI and progressive increases of gamma min and SC after exposure to activated PMN in increasing numbers or for longer time periods. Superoxide dismutase completely inhibited all of these effects except the decreased adsorption, which it did not significantly inhibit. Similar changes in all of these parameters occurred after exposure of surfactant to FeCl3/ASC. Polyacrylamide gel electrophoresis of surfactant after exposure to activated PMN showed a decrease of the major apoprotein that progressed with exposure time and was associated with the appearance of several bands with both lower and higher molecular weights than that of the apoprotein. The data show that activated PMN are capable of impairing surfactant function in vitro and of degrading the major apoprotein. They suggest that the effects upon d, gamma min, SC, and SI are mediated largely if not exclusively by oxidant radicals. While oxidants may contribute to delayed adsorption, proteolysis appears to play the principal role in this effect.

Topics: Adsorption; Animals; Ascorbic Acid; Centrifugation, Isopycnic; Chlorides; Dogs; Electrophoresis, Polyacrylamide Gel; Ferric Compounds; Humans; Kinetics; Lymphocyte Activation; Male; Neutrophils; Pulmonary Surfactants; Superoxide Dismutase; Surface Tension; Tetradecanoylphorbol Acetate

Topics: 3,4-Dihydroxyphenylacetic Acid; Animals; Ascorbic Acid; Chlorides; Chromatography, High Pressure Liquid; Corpus Striatum; Dopamine; Ferric Compounds; Free Radical Scavengers; Homovanillic Acid; Hydroxyindoleacetic Acid; Lipid Peroxidation; Male; Rats; Rats, Inbred Strains; Serotonin; Vitamin E

Incubation of rat-liver microsomes, previously azide-treated to inhibit catalase, with H2O2 caused a loss of cytochrome P-450 but not of cytochrome b5. This loss of P-450 was not prevented by scavengers of hydroxyl radical, chain-breaking antioxidants or metal ion-chelating agents. Application of the thiobarbituric acid (TBA) assay to the reaction mixture suggested that H2O2 induces lipid peroxidation, but this was found to be due largely or completely to an effect of H2O2 on the TBA assay. By contrast, addition of ascorbic acid and Fe(III) to the microsomes led to lipid peroxidation and P-450 degradation: both processes were inhibited by chelating agents and chain-breaking antioxidants, but not by hydroxyl radical scavengers. H2O2 inhibited ascorbate/Fe(III)-induced microsomal lipid peroxidation, but part of this effect was dues to an action of H2O2 in the TBA test itself. H2O2 also decreased the colour measured after carrying out the TBA test upon authentic malondialdehyde, tetraethoxypropane, a DNA-Cu2+/o-phenanthroline system in the presence of a reducing agent, ox-brain phospholipid liposomes in the presence of Fe(III) and ascorbate, or a bleomycin-ion iron/DNA/ascorbate system. Caution must be used in interpreting the results of TBA tests upon systems containing H2O2.

Topics: Animals; Ascorbic Acid; Bleomycin; Chlorides; Cytochrome P-450 Enzyme Inhibitors; Deferoxamine; DNA; DNA Damage; Edetic Acid; Ferric Compounds; Hydrogen Peroxide; Lipid Peroxidation; Liposomes; Male; Microsomes, Liver; Phenanthrolines; Rats; Thiobarbiturates

The anti-oestrogen drug tamoxifen is an inhibitor of lipid peroxidation in rat liver microsomes and in phospholipid liposomes. Its cis isomer and N-desmethyl form are weaker inhibitors, but 4-hydroxytamoxifen is much more powerful. It is possible that the antioxidant property of tamoxifen might contribute to its biological actions.

Topics: Animals; Antioxidants; Ascorbic Acid; Chlorides; Ferric Compounds; In Vitro Techniques; Lipid Peroxidation; Male; Microsomes, Liver; Rats; Tamoxifen

Non-enzymatic and enzymatically-driven lipid peroxidation processes were studied in rat liver nuclei and isolated nuclear membranes, by evaluating the formation of thiobarbituric acid-chromophore, free malondialdehyde, lipofuscin-like pigments, and the degradation of polyunsaturated fatty acids of the nuclear membrane lipids. The results obtained show that: (1) both non-enzymatic and enzymatically driven lipid peroxidation processes are operative in cell nuclei and isolated nuclear membranes; (2) only for isolated nuclear membranes, a good qualitative and up to a great extent quantitative correlation between malondialdehyde and lipofuscin-like pigment formation was obtained; (3) there is a qualitative but not quantitative correlation between malondialdehyde formation and polyunsaturated fatty acid degradation; (4) lipid peroxidation processes in isolated nuclear membranes and intact nuclei have an essentially identical kinetic behaviour. No statistical differences in the relative increases in the concentrations of malondialdehyde and lipofuscin-like pigments or in the degradation of polyunsaturated fatty acids were obtained, when the two systems were compared, except in the presence of NADPH-ADP-Fe3+, which induced a significantly larger degradation of polyunsaturated fatty acids in isolated nuclear membranes than in intact nuclei, and (5) no malondialdehyde-DNA fluorescent adduct formation was observed in any of the experimental groups studied, as inferred from the characteristics of the fluorescent spectra of lipofuscin-like pigments extracted from incubated nuclear preparations.

Topics: Adenosine Diphosphate; Animals; Ascorbic Acid; Cell Nucleus; Chlorides; Chromatography, High Pressure Liquid; Fatty Acids; Fatty Acids, Unsaturated; Ferric Compounds; Ferrous Compounds; Kinetics; Lipid Peroxides; Lipids; Lipofuscin; Liver; Male; Malondialdehyde; NADP; Nuclear Envelope; Rats; Rats, Inbred Strains; Thiobarbiturates

The purified human placental insulin-receptor beta-subunit autophosphorylating activity was found to be inhibited, in a time- and concentration-dependent manner, by the specific thiol-alkylating agents N-ethylmaleimide and 5,5'-dithiobis-(2-nitrobenzoic acid). The insulin-receptor kinase was observed to be more sensitive to inhibition by N-ethylmaleimide in the presence [IC50 (concn, giving 50% inhibition) = 25 +/- 3 microM] than in the absence (IC50 = 73 +/- 6 microM) of insulin. Similarly, inhibition by 5,5'-dithiobis-(2-nitrobenzoic acid) occurred with IC50 = 30 +/- 6 microM in the presence and 155 +/- 35 microM in the absence of insulin. Examination of the exogenous-substrate protein kinase activity demonstrated that the differential sensitivity to N-ethylmaleimide was due to direct inhibition of protein kinase activity, as opposed to blockade of the phospho-acceptor properties of the insulin receptor. In contrast, iodoacetamide had essentially no effect on the insulin-receptor beta-subunit autophosphorylating activity and was able to protect partially against the N-ethylmaleimide inhibition in both the presence and the absence of insulin. Consistent with these findings, none of the thiol-specific agents were able to alter significantly insulin binding at concentrations which maximally inhibited the beta-subunit autophosphorylation. Further, in the presence of insulin, the insulin-receptor kinase activity was also observed to be more sensitive to oxidation by H2O2 and FeCl3/ascorbate compared with insulin receptors in the absence of insulin. These results indicate that there is a critical thiol group(s) necessary for the beta-subunit autophosphorylating activity of the insulin-receptor kinase and that in the presence of insulin is more susceptible to exogenously added thiol and oxidizing agents.

Topics: Adenosine Triphosphate; Ascorbic Acid; Chlorides; Dithionitrobenzoic Acid; Ethylmaleimide; Ferric Compounds; Humans; Hydrogen Peroxide; Insulin; Iodoacetamide; Oxidation-Reduction; Phosphorylation; Protein-Tyrosine Kinases; Receptor, Insulin; Sulfhydryl Compounds

Our earlier studies showed that rabbit muscle phosphoglucomutase was irreversibly inactivated by exposure to a mixture of vitamin C, FeCl3 and O2. The enzyme lost about 70% of its phosphate (V.V. Desphande and J.G. Joshi, J. Biol. Chem. 260, 754-764, 1985). The present report shows that several other iron proteins can substitute for FeCl3 to a varying degree. The rate of inactivation by FeCl3 greater than ferritin greater than hemoglobin = hemerythrin greater than transferrin = ferridoxin = vitamin C. These iron compounds also produced dephosphoenzyme but did not dephosphorylate ATP, ADP, AMP or phospholipids.

Topics: Animals; Apoproteins; Ascorbic Acid; Chlorides; Ferredoxins; Ferric Compounds; Ferritins; Hemerythrin; Hemoglobins; Humans; Iron; Kinetics; Metalloproteins; Muscles; Phosphoglucomutase; Phospholipids; Rabbits; Transferrin

The effects of ascorbic acid, iron and ADP on hyaluronic acid, a compound present in inflamed joints, were investigated in an in vitro system. Ascorbic acid induces degradation of hyaluronic acid which increased in the presence of FeCl3 and which is additionally stimulated by ADP chelated ferric ions. The hyaluronic acid degrading reactions induced by the Fe-III/ADP/ascorbic acid system were inhibited by catalase and formate to various extents whereas the presence of superoxide dismutase did not exert any inhibitory effect. Desferrioxamine, a specific iron chelator, completely inhibited hyaluronic acid depolymerisation by ascorbic acid as well as in combination with FeCl3 or FeCl3/ADP, respectively. We suggest that the ultimate hyaluronic acid degrading species is OH, generated via the Fe-III/ADP catalysed Haber Weiss reaction. There is also an indication for the involvement of perferryl or/and ferryl species in the degradation process.

Topics: Adenosine Diphosphate; Ascorbic Acid; Chlorides; Ferric Compounds; Hyaluronic Acid

To clarify the mechanism of fluorescence formation between DNA and lipid degradation products in the presence of ferric chloride and ascorbic acid, a number of carbonyl compounds and decomposition products of pure methyl linolenate hydroperoxides were examined. Keto derivatives of methyl ricinoleate, linoleate, and oleate, alkanals and 2-alkenals produced little or no fluorescence with DNA in the presence of ferric chloride-ascorbic acid. 2,4-Alkadienals were more active and 2,4,7-decatrienal was the most active. Mixtures of volatile aldehydes prepared from linolenate hydroperoxide decomposed either thermally or with iron and ascorbate had the same activity as 2,4,7-decatrienal. Higher molecular-weight products from the decomposition of methyl linolenate hydroperoxides showed relatively low activity. beta-Carotene, alpha-tocopherol and other antioxidants effectively reduced the amount of fluorescence formed by linolenate hydroperoxides. The results suggest that, in addition to hydroperoxide decomposition products, singlet oxygen and/or free radical species contribute significantly to the fluorescence formed from the interaction of methyl linolenate hydroperoxides with DNA in the presence of ferric chloride and ascorbic acid.

Topics: Aldehydes; Antioxidants; Ascorbic Acid; beta Carotene; Carotenoids; Chemical Phenomena; Chemistry; Chlorides; DNA; Ferric Compounds; Free Radicals; Gases; Lipid Peroxides; Oxygen; Spectrometry, Fluorescence; Vitamin E

Topics: Adult; Ascorbic Acid; Chlorides; Ferric Compounds; Humans; Oxalates; Oxalic Acid; Reagent Kits, Diagnostic; Sodium Nitrite

Iron ascorbate chelate was prepared and purified with iron and ascorbate combined in a 1:1 molar ratio. Some iron dissociated from the chelate and bound to raw wheat bran and alfalfa meal, indicating something in these fiber sources produced the dissociation. The chelate bound intact to alpha-cellulose in bicarbonate and phosphate buffer. More iron as ferric chloride bound to the three fiber sources than did iron as chelate. Iron became more soluble in bicarbonate buffer in the presence of raw wheat bran and alfalfa meal, but became less soluble in phosphate buffer in the presence of these fiber sources.

Topics: Ascorbic Acid; Bicarbonates; Buffers; Cellulose; Chlorides; Dietary Fiber; Edetic Acid; Ferric Compounds; Flour; Iron; Iron Chelating Agents; Medicago sativa; Nutritive Value; Solutions

Topics: Acid Etching, Dental; Adhesiveness; Ascorbic Acid; Chlorides; Citrates; Citric Acid; Dental Bonding; Dental Cements; Dentin; Edetic Acid; Ferric Compounds; Glass Ionomer Cements

Protoporphyrinogen oxidase activity and ferrochelatase activity were measured in leucocytes from patients with porphyria variegata. The mean activity of protoporphyrinogen oxidase (PPO) in porphyria variegata (PV) was about 50% of normal (P less than 0.05). The mean activity of ferrochelatase with 59Fe2+ sulphate and protoporphyrin as substrates (in the presence of ascorbic acid) was reduced by 40% (P less than 0.009). The mean activity of ferrochelatase with 59Fe3+ chloride and protoporphyrin as substrates (in the presence of reduced glutathione) was increased by 65% (P less than 0.005). Both are statistically highly significant. The findings are interpreted as follows: (a) The occurrence of a low level of protoporphyrinogen oxidase in PV is confirmed. (b) The findings indicate a concurrent structural change in ferrochelatase (this may be structurally related to (a) but no evidence of this is at present available).

Topics: Adult; Ascorbic Acid; Chlorides; Female; Ferric Compounds; Ferrochelatase; Ferrous Compounds; Flavoproteins; Glutathione; Heme; Humans; Leukocytes; Lyases; Male; Middle Aged; Mitochondrial Proteins; Oxidoreductases; Oxidoreductases Acting on CH-CH Group Donors; Porphyrias; Protoporphyrinogen Oxidase; Protoporphyrins

Topics: Ascorbate Oxidase; Ascorbic Acid; Ascorbic Acid Deficiency; Blood Chemical Analysis; Chlorides; Colorimetry; Ferric Compounds; Humans; Hydrogen-Ion Concentration; Oxidation-Reduction; Time Factors; Triazines

Iron absorption is frequently studied experimentally in animals by placing iron directly into tied-off intestinal segments in vivo, usually in acid solutions. We have monitored the changes in pH that occur in the intestinal lumen when acid iron solutions are administered and have related this to the time course of iron absorption in iron-deficient rats. Within 5 minutes of giving of 5.6 micrograms Fe (FeCl3), in 0.50 ml 0.01 M HCl, 0.9% NaCl, the pH of the lumen had climbed above pH 4, where Fe3+ is insoluble; reached 6.8 by 10-15 minutes. In parallel with rising pH, mucosal Fe uptake ceased by 5 minutes after its administration. Addition of 2 mM ascorbate to the same solution prevented the cessation of iron uptake despite the usual pH rise. Intestinal fluid of fasted rats had a limited buffering capacity from pH 7 to 3. When added to this fluid, 59FeCl3 largely precipitated, but microgram quantities bound to components with apparent molecular weights greater than 25,000. This iron was available to desferrioxamine B. The results demonstrate the dramatic effects of pH on iron bioavailability, in the absence of chelators such as ascorbate, and the importance of considering iron solubility in measurements of iron absorption.

Topics: Animals; Ascorbic Acid; Buffers; Chlorides; Fasting; Female; Ferric Compounds; Hydrogen-Ion Concentration; Intestinal Absorption; Intestine, Small; Iron; Rats; Time Factors

The effects of ferric chloride mordant solution, two cleansing solutions, and three chemical adhesion promoters were examined on resin-dentin adhesion. Adhesion was increased with the use of ferric chloride solution. An NPG-GMA or butyl acrylate-acrylic acid copolymer type of adhesion promoter also increased resistance to shear separation.

Topics: Acrylic Resins; Ascorbic Acid; Chlorides; Composite Resins; Dental Bonding; Dentin; Edetic Acid; Ferric Compounds; Glycine; Iron; Methacrylates; Silanes

Application ot the alpha,alpha'- dipyridyl method for determination of ascorbic acid in urine is described. The urine sample was acidified with trichloracetic acid and shaken with activated carbon to remove interfering substances. The acid filtrate was first neutralized (pH 7.0) by adding Na2HPO4. The dehydroascorbic acid was then reduced back to ascorbic acid by incubation with dithiothreitol. After removal of the excess dithiothreitol with N-ethylmaleimide, ascorbic acid was determined by measuring the reduction of ferric ion. The ferrous ion produced was coupled to alpha,alpha'-dipyridyl in the presence of H3PO4. Ferrous ion in urine samples, which theoretically interferes with the method, was removed by a combination of Na2HPO4 and H3PO4.

Topics: 2,2'-Dipyridyl; Ascorbic Acid; Chlorides; Dehydroascorbic Acid; Ferric Compounds; Oxidation-Reduction; Phenylhydrazines; Pyridines; Specific Gravity; Spectrophotometry; Urine