BACKGROUND/AIM:Colorectal cancer is still considered a leading cause of death in the United States and worldwide. One potential way to improve survival besides detection is to look to new therapeutic agents that can be taken prophylactically to reduce the risk of tumor formation. For cancer cells to grow and invade, a higher (more alkaline) intracellular pH must occur. We chose to examine a specific nutraceutical agent, which is Vitamin C. The acute effect of Vitamin C exposure on normal colonic crypts has been studied, providing some insight into how Vitamin C achieve its effect.

METHODS:Distal colon was excised from rats. Following enzymatic digestion single colonic crypts were isolated. Colonic crypts were loaded with pH sensitive dye to measure the intracellular pH changes. Crypts were exposed to solutions +/- Vitamin C.

RESULTS:10 mM Vitamin C decreased Na+-dependent intracellular pH recovery. Vitamin C modulates SVCT leading to changes in proton extrusion. Vitamin C entry occurs via either SVCT2 on the basolateral membrane or by transcellular passive diffusion through tight junctions to the apical membrane and then active transport via SVCT1.

CONCLUSION:Acute addition of Vitamin C to the basolateral membrane maintains low intracellular pH for a longer period which could halt and/or prevent tumor formation.

BACKGROUND/AIMS: To test the impact of vitamin C supplementation on triple therapy for H. pylori eradication. METHODOLOGY: A total of 171 H. pylori-infected patients were randomized to receive different one-week triple therapies, including 20 mg omeprazole, 1 g amoxicillin, plus the following twice daily: (1) 250 mg clarithromycin (C250 group, n=55); (2) 250 mg clarithromycin and 500 mg vitamin C (V-C250 group, n=61); (3) 500 mg clarithromycin (C500 group, n=55). Six weeks after treatment, the success of H. pylori eradication was assessed by a 13C-urea breath test. Each collected H. pylori strain was defined as either clarithromycin susceptible or resistant by E-test. RESULTS: The demographic background, clarithromycin susceptibility of H. pylori, and drug compliance were similar among the three groups (p=NS). For clarithromycin susceptible infection, the V-C250 group had a higher eradication rate than the C250 group (ITT: 85% vs. 68% and PP: 90% vs. 73%, p = 0.03), but had an equivalent rate to the C500 group (p=NS). For clarithromycin resistant infection, all three groups had a similarly poor eradication rate of less than 34%. CONCLUSIONS: Adding vitamin C to one-week triple therapy can reduce the dosage of clarithromycin, but preserve the high eradication efficacy for clarithromycin susceptible H. pylori infection.

The lung cancer incidence in the Xuanwei and neighboring region, Yunnan, China, is among the highest in China and is attributed to severe air pollution with high benzo(a)pyrene levels. We systematically and comparatively analyzed DNA methylation alterations at genome and gene levels in Xuanwei lung cancer tissues and cell lines, as well as benzo(a)pyrene-treated cells and mouse samples. We obtained a comprehensive dataset of genome-wide cytosine-phosphate-guanine island methylation in air pollution-related lung cancer samples. Benzo(a)pyrene exposure induced multiple alterations in DNA methylation and in mRNA expressions of DNA methyltransferases and ten-11 translocation proteins; these alterations partially occurred in Xuanwei lung cancer. Furthermore, benzo(a)pyrene-induced DKK2 and EN1 promoter hypermethylation and LPAR2 promoter hypomethylation led to down-regulation and up-regulation of the genes, respectively; the down-regulation of DKK2 and EN1 promoted the cellular proliferation. Thus, DNA methylation alterations induced by benzo(a)pyrene contribute partially to abnormal DNA methylation in air pollution-related lung cancer, and these DNA methylation alterations may affect the development and progression of lung cancer. Additionally, vitamin C and B6 can reduce benzo(a)pyrene-induced DNA methylation alterations and may be used as chemopreventive agents for air pollution-related lung cancer.

Both alpha-lipoic acid (LA) and ascorbic acid (vitamin C) have been shown to improve endothelial dysfunction, a precursor of atherosclerosis. Since oxidant stress can cause endothelial dysfunction, we tested the interaction and efficacy of these antioxidants in preventing oxidant damage to lipids due to both intra- and extracellular oxidant stresses in EA.hy926 endothelial cells. LA spared intracellular ascorbate in culture and in response to an intracellular oxidant stress induced by the redox cycling agent menadione. Extracellular oxidant stress generated by incubating cells for 2 h in with 0.2 mg/ml LDL and 5 muM Cu2+ caused a time-dependent increase of the lipid peroxidation product malondialdehyde in both cells and LDL, preceded by rapid disappearance of; alpha-tocopherol in LDL. alpha-Lipoic acid at concentrations of 40-80 microM blunted these effects. Similarly, intracellular ascorbate concentrations of 1-2 mM also prevented Cu2+-induced lipid peroxidation in LDL and cells. Cu2+-dependent oxidation of LDL in the presence of ascorbate-loaded cells decreased intracellular ascorbate by 20%, but this decrease was not reversed by LA. Both LA and ascorbate protect endothelial cells and LDL from either intra- or extracellular oxidant stress, but that LA does not spare ascorbate in oxidatively stressed cells.

For a long time, aluminium (Al) has been considered an indifferent element from a toxicological point of view. In recent years, however, Al has been implicated in the pathogenesis of several clinical disorders, such as dialysis dementia, the fulminant neurological disorder that can develop in patients on renal dialysis. Therefore, the present experiment was carried out to determine the effectiveness of l-ascorbic acid (AA) in alleviating the toxicity of aluminium chloride (AlCl3) on certain hemato-biochemical parameters, lipid peroxidation and enzyme activities of male New Zealand white rabbits. Six rabbits per group were assigned to 1 of 4 treatment groups: 0mg AA and 0mg AlCl3/kg body weight (BW) (control); 40 mg AA/kg BW; 34 mg AlCl3/kg BW (1/25 LD50); 34 mg AlCl3 plus 40 mg AA/kg BW. Rabbits were orally administered their respective doses every other day for 16 weeks. Evaluations were made for lipid peroxidation, enzyme activities and hemato-biochemical parameters. Results obtained showed that AlCl3 significantly (P<0.05) induced free radicals and decreased the activity of glutathione S-transferase (GST) and the levels of sulfhydryl groups (SH groups) in rabbit plasma, liver, brain, testes and kidney. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (AlP), acid phosphatase (AcP), and phosphorylase activities were significantly decreased in liver and testes due to AlCl3 administration. While, plasma, liver, testes and brain lactate dehydrogenase (LDH) activities were significantly increased. Contrariwise, the activity of acetylcholinesterase (AChE) was significantly decreased in brain and plasma. Aluminium treatment caused a significant decrease in plasma total lipids (TL), blood haemoglobin (Hb), total erythrocytic count (TEC) and packed cell volume (PCV), and increased total leukocyte count (TLC) and the concentrations of glucose, urea, creatinine, bilirubin and cholesterol. Ascorbic acid alone significantly decreased the levels of free radicals, TL, cholesterol, glucose and creatinine, and increased the activity of GST, SH groups, Hb, TEC and PCV. While, the rest of the tested parameters were not affected. Also, the present study showed that ascorbic acid can be effective in the protection of aluminium-induced toxicity.

Aluminium (Al) has been proposed as an environmental factor that may contribute to some diseases, affect several enzymes and other biomolecules and induced free radical-mediated cytotoxicity. Also, Al induced reproductive toxicity and exerted a significant adverse effect on the steroidogenesis. The antioxidant ascorbic acid (AA) plays an important role in various physiological processes in the body including detoxification of different toxic materials. Therefore, the present investigation aimed to elucidate possible protective effects of AA in alleviating the toxicity of aluminium chloride (AlCl3) on reproductive performance, lipid peroxidation and enzyme activities in seminal plasma of male New Zealand white rabbits. Six rabbits per group were assigned to one of four treatment groups: 0 mg AA and 0 mg AlCl3 /kg body weight (BW) (control); 40 mg AA/kg BW; 34 mg AlCl3 /kg BW; 34 mg AlCl3 plus 40 mg AA/kg BW. Rabbits were orally administered their respective doses every other day for 16 weeks. Results obtained showed that AlCl3 significantly (P<0.05) decreased libido (by increasing the reaction time), ejaculate volume, sperm concentration, total sperm output, sperm motility (%), total motile sperm per ejaculate (TMS), packed sperm volume (PSV), total functional sperm fraction (TFSF), normal and live sperm and semen initial fructose. While initial hydrogen ion concentration (pH) and dead and abnormal sperm were increased (P<0.05). Live body weight (LBW), feed intake (FI) and relative weights of testes (RTW) and epididymis (REW) were significantly (P<0.05) decreased. Concentrations of thiobarbituric acid-reactive substances (TBARS) were significantly (P<0.05) increased in seminal plasma of rabbits treated with AlCl3 compared with control. While, activities of glutathione S-transferase (GST), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and acid phosphatase (AcP) were significantly (P<0.05) decreased. Ascorbic acid alone significantly increased LBW, FI, RTW, REW, semen characteristics and seminal plasma enzymes, and decreased the levels of free radicals. Also, the present study showed that ascorbic acid might be effective in the protection of aluminium-induced reproductive toxicity. It was suggested that AlCl3 exerted a significant adverse effect on reproductive performance of male rabbits. Furthermore, AA could be able to antagonize the toxic effects of AlCl3 and improved semen quality of male rabbit.

The antigenotoxic effect of some phytoproducts like carotenoid (beta-carotene), curcumin, ascorbic acid and flavonoid (genistein)was demonstrated on the genotoxicity induced by hydrocortisone. Human lymphocyte cultures were studied for the induction of chromosomal aberrations, sister chromatid exchanges and effect on cell cycle kinetics with or without the presence of metabolic activation (S9 mix). The phytoproducts were studied in two most effective doses viz. carotenoid (0.5 and 0.7 microM), curcumin (15 and 25 microM), ascorbic acid (60 and 80 microM) and flavonoid (25 and 40 microM) in 24, 48 and 72 h cultures, and they were found to reduce chromosomal aberrations, sister chromatid exchange and increase replication index. The present study showed that the ascorbic acid and curcumin were more effective than carotenoid and flavonoid, though all provide protection against the genotoxicity of hydrocortisone.

The aim of the present study was to investigate the impact of the combined administration of Vitamin C and silymarin on lead toxicity. Male albino rats were subdivided into three groups: the first was a control group, the second received lead acetate in diet as 500 mg/kg diet daily, the third received the same lead acetate dose and supplemented with Vitamin C (1 mg/100g body weight) and silymarin (1 mg/100g body weight) by gastric tube three times per week. Blood samples were taken after 2, 4 and 6 weeks of treatment. Significant lead-induced elevations in serum ALT, AST, GGT and ALP activities were observed after different periods of treatment. However, serum LDLc was decreased. The intensities of RNA and apoptotic fragments of DNA were measured as optical density by Gel-pro program. Lead acetate decreased the intensity of DNA at 6 weeks and induced apoptotic DNA fragments reversibly with time. After 2 weeks of lead administration dilation and congestion of terminal hepatic veins and portal vein branches were observed. Lead also induced hepatocyte proliferation without any localized distribution among zones 1-3. Portal inflammatory infiltrate with disruption of the limiting plates (interface hepatitis), steatosis, apoptosis and mild fibrosis were detected especially by sixth week of lead administration. Combined treatment of lead-exposed animals with Vitamin C and silymarin showed marked improvement of the biochemical, molecular and histopathological findings. These experimental results strongly indicate the protective effect of Vitamin C and silymarin against toxic effects of lead on liver tissue.

The goal of this study was to investigate the effect of resveratrol, an active ingredient found in grapes and other plant products, in ameliorating oxidative stress. Oxidative stress was induced by addition of Fe2+ and t-butyl hydroperoxide to the cultured PC12 cell medium. Resveratrol, vitamins C and/or E, were added to the cell culture medium during oxidative stress. The combination of resveratrol and vitamins C and/or E was more effective in protecting the cell than was any of these three antioxidants alone.

Acute dose of lindane (40 mg/kg body weight, ip) caused significant reduction in butyrylcholinesterase (BChE) activity both in olfactory lobe and cerebrum of mice along with reduction in catalase (CAT), total protein and elevation in superoxide dismutase (SOD) and cholesterol contents. Pretreatment by a combination of antioxidants, vitamin E, vitamin C, a- lipoic acid and stilbene resveratrol (125 mg/kg body weight, ip) significantly augment the altered level of BChE and protect the other parameters in both the brain regions. The results were adequately in agreement with the histochemical findings, suggesting the neuroprotective efficacy of combination of antioxidants studied on the lindane induced neurotoxicity.

1. The present study examined the efficacy of Chlorophytum borivilianum root (powder) in modulating the hyperlipaemic/hypercholesteraemic conditions in male albino rats. 2. Administration of C. borivilianum (0.75 and 1.5 g root powder/rat per day for 4 weeks) to hypercholesteraemic rats significantly increased high-density lipoprotein-cholesterol levels and decreased plasma and hepatic lipid profiles. 3. In addition, there were significant increases in faecal cholesterol, neutral sterol and bile acid excretion with elevated hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase activity and bile acid production. 4. Furthermore, the hypercholesteraemic rats treated with both doses of C. borivilianum also exhibited increases in superoxide dismutase and ascorbic acid levels. 5. Normocholesteraemic animals treated with both doses of C. borivilianum root powder did not show any significant variation in either lipid or anti-oxidant profiles, except for an increase in the hepatic ascorbic acid concentration compared with their untreated counterparts. 6. The hypolipaemic/hypocholesteraemic effect of C. borivilianum root powder appears to be mediated by an increase in cholesterol turnover via increased faecal cholesterol excretion and, second, through an endogenous cholesterol conversion into bile acid. 7. Administration of C. borivilianum root powder also increased the activities of anti-oxidant enzymes and vitamin C levels, which may have enhanced the anti-oxidant capacity of the liver.

The present study evaluated the ameliorative effect of vitamin C on alteration in thyroid hormones induced by low-dose subchronic coadministration of chlorpyrifos (CPF) and lead (Pb). Forty Wistar rats were divided into 4 groups of 10 animals each. Groups I and II were administered soya oil (2 mL/kg) and vitamin C (100 mg/kg), respectively. Group III was coadministered CPF (4.25 mg/kg ~1/20th LD(50)) and Pb (250 mg/kg ~1/20th LD(50)), respectively. Group IV was pretreated with vitamin C (100 mg/kg) and then coadministered with CPF (4.25 mg/kg) and Pb (250 mg/kg), 30 min later. The regimens were administered by gavage for a period of 9 weeks. The marginal decrease in serum triiodothyronine and thyroxine and the significant increase in the concentrations of thyroid stimulating hormone and malonaldehyde in the group coadministered with CPF and Pb were ameliorated by vitamin C partly due to its antioxidant properties.

The present studywas undertaken to assess the bioaccumulation potential of cadmium in liver, kidney, gills and muscles of freshwater fish, Nile tilapia Oreochromis niloticus and the changes in oxidative stress indices in liver and kidney with or without simultaneous treatment with waterborne vitamin C and rosemary leaf extract. Adult tilapia were divided into seven groups. Six groups were exposed to sublethal concentrations of Cd, three groups to 5 ppm, while other three to 10 ppm. Two groups from each of the Cd exposed groups were treated with Vitamin C (5ppm) and rosemary leaf extract (2.5 ppm) for a period of 21 days. Cadmium concentration in liver, kidneys and gills was significantly higher in the cadmium exposed groups being invariably high in the groups exposed to 10 ppm CdCl2.H2O.Treatment with Vitamin C and rosemary leaf extract significantly reduced cadmium concentration in comparison to non-treated Cd exposed groups. Treatment with Vitamin C and rosemary leaf extract significantly reduced oxidative stress in Cd exposed fish as evidenced from lower concentration of lipid peroxides and reduced activity of catalase and higher activity of superoxide dismutase in liver and kidney as compared to control fish. Reduction in Cd induced oxidative stress and bioaccumulation was comparable between the two antioxidant treatments, Vitamin C and rosemary leaf extract. The key findings suggest that both the antioxidants used showed ameliorative potential to reduce tissue accumulation of Cd and associated oxidative stress in fresh water fish, Nile tilapia.

BACKGROUND:Low-grade chronic inflammation in overweight subjects is thought to play an important role in disease development.

OBJECTIVE:It was hypothesized that specific dietary components are able to reduce low-grade inflammation as well as metabolic and oxidative stress.

DESIGN:Dietary products [resveratrol, green tea extract, alpha-tocopherol, vitamin C, n-3 (omega-3) polyunsaturated fatty acids, and tomato extract] selected for their evidence-based antiinflammatory properties were combined and given as supplements to 36 healthy overweight men with mildly elevated plasma C-reactive protein concentrations in a double-blind, placebo-controlled, crossover study with treatment periods of 5 wk. Inflammatory and oxidative stress defense markers were quantified in plasma and urine. Furthermore, 120 plasma proteins, 274 plasma metabolites (lipids, free fatty acids, and polar compounds), and the transcriptomes of peripheral blood mononuclear cells and adipose tissue were quantified.

RESULTS:Plasma adiponectin concentrations increased by 7%, whereas C-reactive protein (principal inflammation marker) was unchanged. However, a multitude of subtle changes were detected by an integrated analysis of the "omics" data, which indicated modulated inflammation of adipose tissue, improved endothelial function, affected oxidative stress, and increased liver fatty acid oxidation.

CONCLUSION:An intervention with selected dietary products affected inflammatory processes, oxidative stress, and metabolism in humans, as shown by large-scale profiling of genes, proteins, and metabolites in plasma, urine, and adipose tissue. This trial was registered at clinical trials.gov as NCT00655798.

PURPOSE:To evaluate the preventive effect of ascorbic acid on sevoflurane-induced acute renal failure in an experimental rat model.

METHODS:Twenty-four adult male Wistar rats were randomly distributed into three groups. Subjects were allocated into 3 groups: Group I received sevoflurane only, whereas Groups II and III had moderate (150 mg/kg) and high (300 mg/kg) doses of AA in addition to sevoflurane, respectively. Rhabdomyolysis and myohemoglobinuric ARF was formed by intramuscular administration of glycerol on the upper hind limb on the 15th minute of inhalation anesthesia. Biochemical parameters consisted of serum levels of blood urea nitrogen, creatinine, neutrophil gelatinase-associated lipocalin (NGAL), total antioxidant capacity (TAC), and protein carbonyl content. Histopathological variables were tubular necrosis, fibrin, and cast formation.

RESULTS:NGAL levels were significantly lower in Group III than Group II and Group I. On the other hand, TAC, PCO, urea and creatinine levels were notably higher in Group I compared with Groups II and III. There was a significant difference between 3 groups on frequencies of acute tubular necrosis (p=0.003), fibrin (p<0.001) and cast (p<0.001). Acute tubular necrosis and fibrin formation were more prominent in Group I. Casts were more common in Groups II and III.

CONCLUSIONS:The ascorbic acid serve as a prophylactic agent against renal damage in patients receiving sevoflurane anesthesia and higher doses were associated with more apparent protective effects.

The alkaline single-cell gel electrophoresis (or Comet) assay was applied to evaluate the eventual DNA damage induced by the triphenolic metabolite of benzene, 1,2,4-benzenetriol (BT), in isolated human lymphocytes. Prior to BT treatment, ranging from 5 to 50 microM, a supplementation with glutathione (GSH, 350 microg/ml) was carried out to assess whether GSH may have a modulating effect on the Comet response. The effect of a fixed dose of BT was also evaluated in the presence of the exogenous antioxidant vitamin C (40 and 200 microM). Additionally, we investigated whether the polymorphism of glutathione S-transferase T1 (GSTT1) gene may affect the individual level of BT-induced DNA damage in vitro. For all donors included in the present study, BT produced a significant dose-response relationship. No clear effect of GSH preincubation was seen on the BT-induced response. On the contrary, a significant reduction of DNA damage was observed in the presence of vitamin C (at least at 200 microM). Although our data suggest some individual differences according to the GSTT1 genotype in the outcome of the Comet assay, a large number of individuals should be studied in further investigations to obtain reliable conclusions.

Full Citation: "Pharmaceutical doses of ascorbic acid (AA, vitamin C, or its salts) have been reported to exert anticancer activity in vitro and in vivo. One proposed mechanism involves direct cytotoxicity mediated by accumulation of ascorbic acid radicals and hydrogen peroxide in the extracellular environment of tumor cells. However, therapeutic effects have been reported at concentrations insufficient to induce direct tumor cell death. We hypothesized that AA may exert anti-angiogenic effects. To test this, we expanded endothelial progenitor cells (EPCs) from peripheral blood and assessed, whether or not high dose AA would inhibit EPC ability to migrate, change energy metabolism, and tube formation ability. We also evaluated the effects of high dose AA on angiogenic activities of HUVECs (human umbilical vein endothelial cells) and HUAECs (human umbilical arterial endothelial cells). According to our data, concentrations of AA higher than 100 mg/dl suppressed capillary-like tube formation on Matrigel for all cells tested and the effect was more pronounced for progenitor cells in comparison with mature cells. Co-culture of differentiated endothelial cells with progenitor cells showed that there was incorporation of EPCs in vessels formed by HUVECs and HUAECs. Cell migration was assessed using an in vitro wound healing model. The results of these experiments showed an inverse correlation between AA concentrations relative to both cell migration and gap filling capacity. Suppression of NO (nitric oxide) generation appeared to be one of the mechanisms by which AA mediated angiostatic effects. This study supports further investigation into non-cytotoxic antitumor activities of AA."

Certain drastic behavioral modifications by arterial wall smooth muscle cells (SMC) have been considered key steps in the formation of atherosclerotic lesions: massive migration of SMC from the media to the intima layer of the vessel, dedifferentiation of SMC to proliferating phenotype, and increased secretion of inflammatory cytokines as a response to inflammatory stimuli. We investigated the anti-atherogenic effects of naturally occurring compounds (ascorbic acid, green tea extract, lysine, proline, arginine, and N-acetyl cysteine) using the model of cultured aortic SMC. Cell growth was measured by DNA synthesis, cell invasiveness was measured through Matrigel, matrix metalloproteinase-2 (MMP-2) secretion was measured by zymography, and SMC secretion of monocyte chemoattractant protein-1 (MCP-1) and interleukin-6 (IL-6) was measured by immunochemistry. Fetal bovine serum-stimulated SMC growth was inhibited by the nutrient mixture (NM) with 85% inhibition at 100 microg/mL. A corresponding concentration of epigallocatechin gallate (EGCG; 15 microM), the most active tea phenolic, produced a significant effect but one lower than NM. NM inhibited aortic SMC Matrigel invasion in a dose-dependent manner and significantly decreased MMP-2 expression. Stimulation of SMC with tumor necrosis factor-alpha significantly increased production and secretion of such mediators of inflammation as IL-6 and MCP-1; addition of 100 microg/mL NM inhibited secretion of MCP-1 and IL-6 by 65% and 47%, respectively. These data suggest that the NM of ascorbic acid, tea phenolics, and selected amino acids has potential in blocking the development of atherosclerotic lesions by inhibiting atherogenic responses of vascular SMC to pathologic stimuli and warrants in vivo studies.

Atherosclerosis is a progressive and multifactorial disease which occurs under the influence of various risk factors including endothelial dysfunction (ED), oxidative stress, and low-density lipoprotein (LDL) oxidation. In contract to the initial hypotheses on the usefulness of vitamin E supplementation for cardiovascular disease prevention, large outcome trials showed consumption of vitamin E has no obvious effect on cardiovascular disease and, in some cases, it may even increase the rate of mortality. This seemingly unexpected finding may be due to the opposite effects of vitamin E compounds. Vitamin E is a group of compounds which have different and even opposing effects, yet in most of the studies, the exact consumed component of vitamin E is not determined. It appears that the combined consumption of gamma-tocopherol, vitamin C, vitamin D, and tetrahydrobiopterin (BH4) may be extremely effective in both preventing atherogenesis and suppressing plaque development. In this regard, one of main issues is effect of vitamin E and D deficiency on microRNAs network in atherosclerosis. Various studies have indicated that miRNAs have key roles in atherosclerosis pathogenesis. The deficiency of vitamin E and D could provide a deregulation for miRNAs network and these events could lead to progression of atherosclerosis. Here, we highlighted a variety of mechanisms involve in the progression of atherosclerosis and effects of vitamin D and E on these mechanisms. Moreover, we summarized miRNAs involve in atherosclerosis and their regulation by vitamin E and D deficiency. This article is protected by copyright. All rights reserved.

To determine the effects of vitamin supplementation on the lipid-peroxidation-mediated toxicity of iron-ions on corneal endothelial cells (CECs) leading to apoptosis, murine CECs were maintained in tissue culture medium supplemented with increasing concentrations of free iron-ions, a treatment known to lead to increased lipid-peroxidation. The concentration of anti-oxidative vitamins (ascorbic acid, tocopherol and retinoic acid) in the cell supernatant and in the cells was determined by high-pressure liquid chromatography. Apoptosis was assessed by quantification of caspase-3-like activity and by using annexin-V/propidium iodide stains for flow cytometry. Lipid-peroxidation was measured by the malondialdehyde method. Supplementation with anti-oxidative vitamins was tested for the ability to counteract the induction of apoptosis. The production of nitric oxide was assessed spectrophotometrically and the expression levels of inducible and endothelial nitric oxide synthase were determined by Western blot. Increasing levels of free iron led to a rapid loss of anti-oxidative vitamins in the supernatant and in the CECs. This was correlated with rising levels of malondialdehyde and increased apoptosis. Supplementation with ascorbic acid or alpha-tocopherol alone did not prevent lipid-peroxidation in the cells. A combination of vitamins C and E (ascorbic acid, tocopherol) or solitary supplementation with vitamin A (retinoic acid) prevented lipid-peroxidation. We thus present a novel in vitro model for testing the direct influence of pro-oxidative species on CECs. We also show that supplementation with anti-oxidative vitamins to CECs significantly prevents the generation of free-radical-induced oxidative injury and apoptosis. These findings may have important implications for the storage of human corneae prior to transplantation and for the prolongation of corneal graft survival.