OBJECTIVETo explore arsenic-induced oxidative stress and the protective efficacy of α-lipoic acid and vitamin c.

METHODS50 male SD rats were randomly divided into 5 groups. Ten rats (the control group) were exposed to deionized water for 6 weeks, and the others were alone exposed to sodium arsenite (50 mg/L water) for 6 weeks, at the same time, three group rats were administered intragastrically (i.g.) with α-lipoic acid 10 mg×kg(-1)×d(-1) and vitamin C 25 mg×kg(-1)×d(-1) either alone or in combination. At the end of experiment, blood was drawn from abdominal aorta, and then the blood, brain and liver of rats were used for biochemical assays, including blood glutathione (GSH), δ-aminolevulinic acid dehydratase (δ-ALAD ), reactive oxygen species (ROS) and oxidized glutathione (GSSG) level. At the same time, the super oxide dismutase (SOD) activity, glutathione peroxidase (GSH-Px) activity, catalase (CAT) activity, ATPase activity of brain and liver were determined. The caspase activity of brain were also determined.

RESULTSThere were a significant increase in ROS level (P < 0.05), but a significant decrease in δ-ALAD activity (P < 0.01) in the chronic arsenic toxicity model group compared with the control group. These alterations were marginally restored by co-administration of vitamin C and α-lipoic acid individually, while significant recovery was observed in the animals supplemented with both the antioxidants together with arsenite in rat (P < 0.05). At the same time, there was a significant increase in the ROS and TBARS level of the brain and liver (P < 0.05), and caspase activity of the brain (P < 0.05), while there was a significant decrease in antioxidant enzymes and ATPase activity on arsenite exposure in rats (P < 0.05). These alterations were also marginally restored by co-administration of vitamin C and α-lipoic acid individually, while significant recovery was observed in the animals supplemented with both the antioxidants together with arsenite in rat (P < 0.05).

CONCLUSIONSArsenite-induced oxidative stress can be significantly protected by co-administration of α-lipoic acid and vitamin C individually, but the best effects could be observed with combined administration of two antioxidants during arsenite exposure in animals. The dietary intervention of or supplementation with natural dietary nutrients is possible to prevent the effects of arsenic in populations of risk.

Animals ; Arsenic Poisoning ; metabolism ; Ascorbic Acid ; pharmacology ; Male ; Oxidative Stress ; drug effects ; Rats ; Rats, Sprague-Dawley ; Thioctic Acid ; pharmacology

OBJECTIVETo explore the putative effects of Vitamin C (Vit C) on inhibition of human leucocyte antigen class I (HLA-I) expression of human peripheral blood mononuclear cells (HPBMCs) induced by deoxynivalenol (DON) in vitro.

METHODSThe effects of Vit C on the changes of HLA-I expression of HPBMCs induced by DON in vitro were evaluated with cell culture, flow cytometry (FCM), Western blotting and immunocytochemical methods.

RESULTSFCM analysis showed that HLA-I expression of HPBMCs in DON treated cells was significantly lower than that in controls (FI 0.88 +/- 0.02 vs 1.00 +/- 0.03, P < 0.05). As compared with DON group, the HLA-I expressions of HPBMCs in the two Vit C (25 micromol/L and 100 micromol/L) pretreatment groups were all significantly increased (1.15 +/- 0.06 and 1.10 +/- 0.02 vs 0.88 +/- 0.02, P < 0.05). Exposure to different dosage of Vit C alone could dramatically increase the expression of HLA-I of HPBMCs in vitro as compared with that in the normal control (FI for 25 micromol/L and 100 micromol/L Vit C treatment group was 1.28 +/- 0.03 and 1.25 +/- 0.05 respectively, P < 0.05). Immunocytochemical results showed that the percentages of HLA-I positive expression of HPBMCs in Vit C pretreatment groups at different dosages were significantly higher than those in DON group (70.10 +/- 6.90)%, (64.50 +/- 5.50)% vs (42.20 +/- 4.30)%, P < 0.05. Western blotting confirmed the results of FCM and immunocytochemistry.

CONCLUSIONSVitamin C pretreatment at different dosages could reverse at some extent the inhibitive effects of DON on HLA-I expression of HPBMCs.

Ascorbic Acid ; pharmacology ; Cells, Cultured ; Flow Cytometry ; Histocompatibility Antigens Class I ; metabolism ; Humans ; Monocytes ; drug effects ; metabolism ; Trichothecenes ; pharmacology

Phytoremediation plays an important role in the treatment of heavy metal pollution in soil. In order to elucidate the mechanism of salicylic acid (SA) on copper absorption, seedlings from Xuzhou (with strong Cu-tolerance) and Weifang Helianthus tuberosus cultivars (with weak Cu-tolerance) were selected for pot culture experiments. 1 mmol/L SA was sprayed upon 300 mg/kg soil copper stress, and the photosynthesis, leaf antioxidant system, several essential mineral nutrients and the changes of root upon copper stress were analyzed to explore the mechanism of copper resistance. The results showed that Pn, Tr, Gs and Ci upon copper stress decreased significantly compared to the control group. Meanwhile, chlorophyll a, chlorophyll b and carotenoid decreased with significant increase in initial fluorescence (F₀), maximum photochemical quantum yield of PSⅡ (Fv/Fm), electron transfer rate (ETR) and photochemical quenching coefficient (qP) content all decreased. The ascorbic acid (AsA) content was decreased, the glutathione (GSH) value was increased, the superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) activity in the leaves were decreased, and the peroxidase (POD) activity was significantly increased. SA increased the Cu content in the ground and root system, and weakened the nutrient uptake capacity of K, Ca, Mg, and Zn in the root stem and leaves. Spray of exogenous SA can maintain the opening of leaf stomata, improve the adverse effect of copper on photosynthetic pigment and PSⅡ reaction center. Mediating the SOD and APX activity started the AsA-GSH cycle process, effectively regulated the antioxidant enzyme system in chrysanthemum taro, significantly reduced the copper content of all parts of the plant, and improved the ion exchange capacity in the body. External SA increased the content of the negative electric group on the root by changing the proportion of components in the root, promoted the absorption of mineral nutrient elements and the accumulation of osmoregulatory substances, strengthened the fixation effect of the root on metal copper, and avoided its massive accumulation in the H. tuberosus body, so as to alleviate the inhibitory effect of copper on plant growth. The study revealed the physiological regulation of SA upon copper stress, and provided a theoretical basis for planting H. tuberosus to repair soil copper pollution.
Antioxidants ; Copper ; Helianthus/metabolism* ; Salicylic Acid/pharmacology* ; Chlorophyll A/pharmacology* ; Spectroscopy, Fourier Transform Infrared ; Chlorophyll/pharmacology* ; Ascorbic Acid ; Superoxide Dismutase/metabolism* ; Photosynthesis ; Glutathione ; Plant Leaves ; Stress, Physiological ; Seedlings

Animals ; Ascorbic Acid ; metabolism ; Brain Ischemia ; metabolism ; Glutamic Acid ; metabolism ; Hippocampus ; drug effects ; metabolism ; Male ; Propofol ; pharmacology ; Rats ; Rats, Wistar ; Reperfusion Injury ; metabolism

The observation that ascorbate known to retain pro-oxidant properties induces cell death in a number of immortal cell lines, led us to examine its mechanism and whether it is involved in oxidative stress injury in such asocorbate-enriched tissue cells as hepatocytes. In rat liver homogenates, higher concentrations (1 and 3 mM) of ascorbate suppressed lipid peroxide productions but lower concentrations (0.1 and 0.3 mM) did not. In contrast to the homogenate, ascorbate increased lipid peroxide production in liver slices in a concentration dependant manner. Iso-ascorbate, the epimer of ascorbate did not cause an increase the oxidative stress in liver slices. This differential effect between homogenates and liver slices implies that cellular integrity is required for ascorbate to induce oxidative stress. Wortmannin, an inhibitor of the GLUT (glucose transporter) thought to transport dehydroascorbate into cells, inhibited [14C]- ascorbate uptake and suppressed oxidative stress in liver slices. Wortmannin suppressed that [14C]- ascorbate uptake by GLUT following oxidation to [14C]dehydroascorbate. Taken together, these observations support our hypothesis that ascorbate is oxidized to dehydroascorbate by molecular oxygen in solution (i.e., plasma and culture medium) which is then carried into hepatocytes (via a GLUT) where it is reduced back to ascorbate causing oxidative stress.
Androstadienes/pharmacology ; Animals ; Ascorbic Acid/*metabolism/*pharmacology ; Biological Transport ; Edetic Acid/pharmacology ; Glutathione/*metabolism ; In Vitro ; Liver/*drug effects/*metabolism ; Male ; Oxidation-Reduction/drug effects ; Oxidative Stress/*drug effects ; Rats ; Rats, Sprague-Dawley ; Thiobarbituric Acid Reactive Substances/metabolism ; Time Factors

This study investigated the effects of N-acetylcysteine (NAC) and ascorbic acid (AA) on hemin-induced K562 cell erythroid differentiation and the role of reactive oxygen species (ROS) in this process. Hemin increased ROS levels in a concentration-dependent manner, whereas NAC and AA had opposite effects. Both NAC and AA eliminated transient increased ROS levels after hemin treatment, inhibited hemin-induced hemoglobin synthesis, and decreased mRNA expression levels of β-globin, γ-globin, and GATA-1 genes significantly. Pretreatment with 5,000 μmol/L AA for 2 h resulted in a considerably lower inhibition ratio of hemoglobin synthesis than that when pretreated for 24 h, whereas the ROS levels were the lowest when treated with 5,000 μmol/L AA for 2 h. These results show that NAC and AA might inhibit hemin-induced K562 cell erythroid differentiation by downregulating ROS levels.
Acetylcysteine ; pharmacology ; Antioxidants ; pharmacology ; Ascorbic Acid ; pharmacology ; Cell Differentiation ; drug effects ; Down-Regulation ; Erythroid Cells ; drug effects ; Hemin ; pharmacology ; Humans ; K562 Cells ; Reactive Oxygen Species ; metabolism

OBJECTIVETo study the effects of ascorbic acid and citric acid on iron bioavailability using an in vitro digestion/Caco-2 cell culture model and evaluate the validity of this cell model.

METHODSThis model combined in vitro digestion technique with Fe uptake by Caco-2 cells by utilizing an inserted ring attached to a dialysis membrane to simulate the gastrointestinal environment to allow simultaneous food digestion and uptake processes. Ferritin formation in the Caco-2 cells was measured as the indicator of Fe uptake by exposing Caco-2 cells to the digests containing Fe plus ascorbic acid or citric acid.

RESULTSWhen Fe concentration in the digest was below 100 micromol/L, ferritin formation increased with the Fe concentration in the digest. The iron digest containing ascorbic acid exhibited a significant increase in ferritin formation relative to the iron digest containing citric acid. The model was more sensitive to lower iron concentrations when ascorbic acid was present in the digest, while wider range of iron concentration could be assessed by addition of citric acid.

CONCLUSIONSThe in vitro digestion/ Caco-2 cell culture model is a valuable tool for iron bioavailability assessment. Ascorbic acid has a stronger effect than citric acid in promoting iron bioavailability.

Ascorbic Acid ; pharmacology ; Biological Availability ; Caco-2 Cells ; metabolism ; Citric Acid ; pharmacology ; Ferritins ; biosynthesis ; Ferrous Compounds ; pharmacokinetics ; Humans ; Iron ; pharmacokinetics ; Models, Biological

In peripheral blood hematopoietic stem cell transplantation (PBHSCT) , the mobilization and circulating of bone marrow hematopoietic stem cells in blood with higher oxygen concentration all increase reactive oxygen species(ROS) production, which has negative effect on the biological function of BMHSC. In order to investigate the protective effect of antioxidant on hematopoietic stem cells (HSC), the ascorbic acid 2-phosphate (AA2P), an ascorbic acid derivative of vitamin C, was added in HSC culturing by imitating oxygen conditions which BMHSC experienced in peripheral blood stem cell transplantation. The protective effect of above-mentioned culture methods on the biologic functions of BMHSC was evaluated by vitro amplification assay, committed division assay, reactive oxygen species (ROS) measurement, CD34(+) HSC engraftment. The results showed that the ROS level in HSC from in vitro cultures was much higher than that freshly separated BMHSC, and the amplified AC133(+)CD34(+) HSC, BFU-E, CFU-GM, CFU-GEMM colonies, migration rate and severe combined immunodeficiency (SCID)-repopulating cells (SRC) were all much more than HSC cultured without AA2P. It is concluded that antioxidant intervention may be an effective methods for protecting the biological function of PBHSC and improving the therapeutic effect of PBHSCT.
Antigens, CD34 ; metabolism ; Antioxidants ; pharmacology ; Ascorbic Acid ; analogs & derivatives ; pharmacology ; Cells, Cultured ; Hematopoietic Stem Cells ; cytology ; drug effects ; Humans ; Reactive Oxygen Species ; metabolism

OBJECTIVE3-Bromobenzanthrone (3-BBA), an anthraquinone intermediate dye, is extensively used in textile industry. Since, our prior studies have shown that 3-BBA caused significant depletion of ascorbic acid (AsA) levels, the effect of exogenous supplementation of AsA on the urinary elimination of 3-BBA metabolites was investigated.

METHODGuinea pigs were treated with single oral dose of 3-BBA (50 mg/kg b. wt.) in groundnut oil while another group was treated with single oral dose of 3-BBA (50 mg/kg b. wt.) along with 3 day prior and post oral supplementation of AsA. Control groups were either treated with groundnut oil or AsA alone. Urine from individual animals was collected, extracted and analysed on HPTLC.

RESULTSThe highest elimination of 3-BBA (75 microg) was found to be in 0-24 h urine fraction which decreased to 18 microg and 5 microg in the two subsequent 24 hourly fractions of urine. Exogenous supplementation of AsA increased the total urinary elimination of 3-BBA by almost 77%. A total of 10 fluorescent metabolites excluding the parent compound were eliminated in the urine of guinea pigs treated with 3-BBA. Densitometric scanning of chromatogram showed different peaks at Rf 0.18, 0.22, 0.27, 0.34, 0.40, 0.48, 0.56, 0.66, 0.72, 0.80, and 0.95 which were eliminated and marked as urinary metabolite 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, and 11 respectively. AsA not only significantly enhanced the elimination of 3-BBA metabolites but also modified the pattern of metabolites drastically in 0-6 h, 6-24 h and 24-48 h urine fractions.

CONCLUSIONThese results indicate that AsA may be useful in protecting the toxicity of 3-BBA by fascilitating the urinary metabolite(s) excretion of 3-BBA.

Administration, Oral ; Animals ; Antioxidants ; pharmacology ; Ascorbic Acid ; pharmacology ; urine ; Benz(a)Anthracenes ; analysis ; metabolism ; Chromatography, High Pressure Liquid ; Guinea Pigs ; Lipid Peroxidation ; drug effects ; Plant Oils ; metabolism ; Time Factors

OBJECTIVETo find out the mechanisms of redifferentiation and reversion of malignant human gastric cancer cells induced by ascorbic acid.

METHODSHuman gastric cancer cells grown in the laboratory were used. The Trypan blue dye exclusion method was used to determine the cell doubling time. The electrophoresis rate and colonogenic potential were the indices used to measure the rate of redifferentiation. The content of malondialdehyde (MDA) was measured using the thiobarbituric acid (TBA) method. The activities of superoxide dismutase (SOD), catalase (CAT) and the content of H202 were evaluated by spectrophotography.

RESULTSSix mmol/L ascorbic acid was used as a positive control. Human gastric cancer cells were treated with 75 microm hydrogen peroxide, which alleviated many of the malignant characteristics. For example, the cell surface charge obviously decreased and the electrophoresis rate dropped from 2.21 to 1.10 microm x s(-1) x V(-1) x cm(-1). The colonogenic potential, a measure of cell differentiation, decreased 90.2%. After treatment with ascorbic acid, there was a concentration- and time-dependent increase in hydrogen peroxide (H202) and the activity of superoxide dismutase (SOD). However, the activity of catalase (CAT) resulted in a concentration- and time-dependent decrease. SOD and 3-amino-1,2,4-triazole (AT) exhibited some effects, but there were statistically significant differences between the SOD and AT group and the H202 group.

CONCLUSIONSAscorbic acid induces growth inhibition and redifferentiation of human gastric cancer cells through the production of hydrogen peroxide.

Antioxidants ; pharmacology ; Ascorbic Acid ; pharmacology ; Cell Differentiation ; drug effects ; Humans ; Hydrogen Peroxide ; metabolism ; Stomach Neoplasms ; drug therapy ; metabolism ; pathology ; Tumor Cells, Cultured