Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:EXPT00568 (ascorbate)
 23,072 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Antioxidants such as vitamins C and E have been reported to inhibit the progression of ultraviolet (UV) radiation-induced pigmentation in the skin of hairless mice. However, little is known of the lightening effect of proanthocyanidin, a powerful polyphenolic antioxidant, on UV-induced pigmentation of the skin. We investigated the lightening effect of oral administration of a proanthocyanidin-rich grape seed extract (GSE) using guinea pigs with UV-induced pigmentation. These pigmented guinea pigs were fed diets containing 1% GSE or 1% vitamin C (w/w) for 8 weeks. GSE-feeding had an apparent lightening effect on the guinea pigs' pigmented skin. Histologic evaluation demonstrated a decrease in the number of 3,4-dihydroxyphenylalanine (DOPA)-positive melanocytes as well as 8-hydroxy-2'-deoxyguanosine (8-OHdG)-positive, Ki-67-positive, proliferating cell nuclear antigen (PCNA)-positive melanin-containing cells in the basal epidermal layer of the UV-irradiated skin in GSE-fed guinea pigs. In contrast, these parameters did not change in the skin of vitamin C-fed or control guinea pigs. GSE inhibited the activity of mushroom tyrosinase and also inhibited melanogenesis without inhibiting the growth of cultured B16 mouse melanoma cells. In conclusion, we demonstrated that oral administration of GSE is effective in lightening the UV-induced pigmentation of guinea pig skin. This effect may be related to the inhibition of melanin synthesis by tyrosinase in melanocytes and the reactive oxygen species (ROS)-related proliferation of melanocytes.
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PMID:Lightening effect on ultraviolet-induced pigmentation of guinea pig skin by oral administration of a proanthocyanidin-rich extract from grape seeds. 1462 20

Some selected oxidative stress parameters were measured in 56 Fanconi anaemia (FA) patients (42 untransplanted and 14 transplanted), 54 FA heterozygotes (parents) and 173 controls. Untransplanted FA patients showed a highly significant increase in leukocyte 8-hydroxy-2'-deoxyguanosine (8-OHdG) (P = 0.00003) and a borderline increase (P = 0.076) in urinary levels of 8-OHdG versus child controls. These increases were more pronounced in female FA patients (P = 0.00005 for leukocyte 8-OHdG and P = 0.021 for urinary 8-OHdG). Female FA patients also displayed a highly significant excess of spontaneous chromosomal breaks versus male patients (P = 0.00026), in the same female:male ratio ( approximately 1.4) as detected for both leukocyte and urine 8-OHdG levels. Plasma methylglyoxal (MGlx) levels were increased in untransplanted FA patients versus child controls (P = 0.032). The increases in leukocyte and urinary 8-OHdG and in MGlx levels were detected in young FA patients (< or =15 years), whereas patients aged 16-29 years failed to display any differences versus controls in the same age group. A significant increase in oxidized:reduced glutathione (GSSG:GSH) ratio was observed (P = 0.046) in the FA patients aged < or =15 years, whereas those aged 16-29 years, both untransplanted and transplanted, displayed a decrease (P = 0.06) in the GSSG:GSH ratio versus the controls of the respective age groups. No significant changes were detected in plasma levels of vitamin C, vitamin E or uric acid. Transplanted FA patients showed lesser alterations in leukocyte 8-OHdG and in GSSG:GSH ratio versus untransplanted patients. The parents of FA patients displayed a significant increase in plasma MGlx levels (P = 0.0014) versus adult controls. The results suggest a gender- and age-related modulation of oxidative stress in FA patients. The observed increase in urinary 8-OHdG in untransplanted FA patients suggests a proficient removal of oxidized DNA bases.
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PMID:Gender- and age-related distinctions for the in vivo prooxidant state in Fanconi anaemia patients. 1519 13

A great deal of effort has been made on the effect of oxidative stress for smokers. What seems to be lacking, however, is its evidence. Analyzing 1076 participants (age 35.9 +/- 12.9, urinary8-OHdG Mean +/- S.D., 11.4 +/- 6.7, n = 1076), our study found the significant increase in a biomarker of DNA damage urinary 8-OHdG/creatinine among smokers (7.75 +/- 2.8 ng/ml x CRE (n = 154) and 7.36 +/- 2.5 ng/ml x CRE (n = 627) (p < 0.05), Relative Risk = 2.9 (1.4-6.2) sex and age +/- 2 matching 105 male smokers and non-smokers. There was no significance on the comparison between female smokers and non-smokers. Smokers have significantly decreased serum alpha-tocopherol (1012 +/- 455, 1152 +/- 857, p < 0.03). The amount of serum ascorbate did not change. Smokers lowered serum HDL-cholesterol compared to non-smokers (59.3 +/- 11.8, 63.9 +/- 13.3, p < 0.05). The result of oxidative stress profile (OSP) also indicated that the increase of oxidative stress to smokers (p < 0.05). The calculated value of oxygen radical absorbance capacity (ORAC) of the meal for subjects was 1600 ORAC units.
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PMID:Comparison of an oxidative stress biomarker "urinary8-hydroxy-2'-deoxyguanosine," between smokers and non-smokers. 1563 Feb 93

Although vitamin C is considered to act both as pro-oxidant and antioxidant, the mechanisms underlying these actions are still unclear. Using the oxygen-sensitive system of a strict anaerobe, Prevotella melaninogenica, we investigated both the pro-oxidant and antioxidant mechanisms of vitamin C. In the presence of vitamin C, the 8-hydroxydeoxyguanosine (8OHdG) formation induced by oxygen exposure was enhanced, probably due to the action of vitamin C on hydrogen peroxide generated during oxygen exposure: while catalase almost completely suppressed the enhancing effect of vitamin C, 8OHdG formation induced by hydrogen peroxide was enhanced by vitamin C. By contrast, the presence of vitamin C inhibited bacterial cell death, membrane damage, and lipid peroxidation induced by oxygen exposure. Sodium azide showed similar effects to vitamin C, thus the antioxidant action of vitamin C may be due to its quenching of the singlet oxygen generated in this system. Both the pro-oxidant and antioxidant effects of vitamin C were observed only in acidic conditions.
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PMID:Dual role of vitamin C in an oxygen-sensitive system: discrepancy between DNA damage and cell death. 1576 69

Hydroxyl radical, ascorbate free radical, superoxide dismutase (SOD) activities, Cu,Zn-SOD protein, Mn-SOD protein, 8-hydroxy-2' -deoxyguanosine (8-OHdG) and metals were compared in red blood cells (RBC), plasma and/or cerebrospinal fluid (CSF) between patients with sporadic amyotrophic lateral sclerosis (SALS), familial ALS (FALS) showing the Leu126Ser mutation in the Cu, Zn-SOD gene and controls. In patients with FALS or SALS, concentrations of hydroxyl radical in blood and ascorbate free radical and 8-OHdG in CSF were higher than control group values, while SOD activities in RBC and CSF were lower. In contrast, Cu, Zn-SOD protein concentrations in RBC were low only in FALS patients. Concentrations of Cu in CSF of SALS patients were higher than in controls. Thus, the pathogenesis of increased oxidative stress differs between SALS patients and FALS patients with a mutant Leu126Ser SOD1 gene.
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PMID:Oxidative stress and metal content in blood and cerebrospinal fluid of amyotrophic lateral sclerosis patients with and without a Cu, Zn-superoxide dismutase mutation. 1582 69

Ataxia severity, cerebellar hemispheric blood flow (CHBF), ascorbate free radical (AFR), superoxide dismutase protein, superoxide scavenging activity, and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in cerebrospinal fluid (CSF) were compared before and after an 8-week course of repetitive transcranial magnetic stimulation (rTMS) in 20 patients with spinocerebellar degenerations (SCD). SCD patients showed higher AFR, 8-OHdG, and superoxide scavenging activity than 19 controls. In SCD patients, AFR and ataxia severity declined, and CHBF increased after rTMS. As the SCD patients showed negative correlations between ataxia severity and CHBF or superoxide scavenging activity, the therapeutic mechanism of rTMS may involve decreased oxidative stress and increased CHBF.
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PMID:Influence of repetitive transcranial magnetic stimulation on disease severity and oxidative stress markers in the cerebrospinal fluid of patients with spinocerebellar degeneration. 1584 14

The effect of antioxidant ascorbic acid (vitamin C) pretreatment on chromium(VI)-induced damage was investigated using the yeast Saccharomyces cerevisiae as a model organism. The objective of this study was to pretreat yeast cells with the antioxidant ascorbic acid in an effort to increase cell tolerance against reactive chromium intermediates and reactive oxygen species formed during chromium(VI) reduction. Intracellular oxidation was estimated using the fluorescence indicators dihidro-2,7-dichlorofluorescein, dihydroethidium and dihydrorhodamine 123. The role of ascorbic acid pretreatment on chromium(VI) toxicity was determined by measuring mitotic gene conversion, reverse mutations, 8-OHdG, hydroxyl radical, superoxide anion and chromium(V) formation. The chromium content in the biomass was determined by flame atomic absorption spectrometry. In the absence of chromium, ascorbic acid effectively protected the cells against endogenous reactive oxygen species formed during normal cellular metabolism. In vitro measurements employing EPR and the results of supercoiled DNA cleavage revealed that the pro-oxidative action of ascorbic acid during Cr(VI) reduction was concentration-dependent and that harmful hydroxyl radical and Cr(V) had formed following Cr(VI) reduction. However, the in vivo results highlighted the important role of increased cytosol reduction capacity related to modification of Cr(V) formation, increased chromium accumulation, better scavenging ability of superoxide anions and hydrogen peroxide, and consequently decreased cytotoxicity and genotoxicity in ascorbic acid pretreated cells. Ascorbic acid influenced Cr(VI) toxicity both as a reducing agent, by decreasing Cr(V) persistence, and as an antioxidant, by decreasing intracellular superoxide anion and hydrogen peroxide formation and by quenching free radicals formed during Cr(VI) to Cr(III) reduction. Increased 8-OHdG and decreased reduced glutathione in ascorbic acid-treated cells might induce an endogenous antioxidant defense system and thus increase cell tolerance against subsequent Cr-induced stress.
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PMID:Pro-oxidative vs antioxidative properties of ascorbic acid in chromium(VI)-induced damage: an in vivo and in vitro approach. 1609 82

Microcystin LR (MC-LR), a liver-specific toxin synthesized by Microcystis aeruginosa, was investigated. MC-LR initiated reactive oxygen species formation followed by damaging DNA and some other cellular components. We investigated the ability of MC-LR to induce oxidative DNA damage by examining the formation of 8-hydroxydeoxyguanosine (8-OH-dG) using HPLC with electrochemical detection. Melatonin, vitamin C (ascorbate), and vitamin E (as Trolox), all of which are free radical scavengers, markedly inhibited the formation of 8-OH-dG in a concentration-dependent manner. The concentration that reduced DNA damage by 50% (IC(50)) was 0.55, 31.4, and 36.8 microM for melatonin, ascorbate, and Trolox, respectively. The results show that melatonin is 60- and 70-fold more effective than vitamin C or vitamin E, respectively, in reducing oxidative DNA damage. These findings are consistent with the conclusion that melatonin's highly protective effect against microcystin toxicity relates, at least in part, to its direct hydroxyl radical scavenging ability.
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PMID:Microcystin-induced 8-hydroxydeoxyguanosine in DNA and its reduction by melatonin, vitamin C, and vitamin E in mice. 1712 60

The product of oxidative damage to DNA, 8-hydroxy-2'-deoxyguanosine (8-OHdG), when detected in urine, is considered to be a global, noninvasive biomarker of in vivo oxidative DNA damage. In this paper we describe a novel approach to confirm the presence of oligonucleotides containing 8-OHdG in human urine. Fractions of urine were prepared by gel-filtration chromatography, and the presence of oligonucleotides was confirmed by ELISA using a monoclonal anti-(single-stranded DNA) antibody. Pools of urine fractions were subsequently prepared according to ELISA reactivity, each containing oligonucleotides with a known range of base numbers. The level of 8-OHdG in each pool was subsequently determined using a commercial ELISA kit. Results confirmed that oligonucleotides containing 8-OHdG are present in urine and, most significantly, oligomers of <30-55 bases were found to be associated with 8-OHdG. This finding strongly supports the involvement of nucleotide excision repair (NER) in the removal of 8-OHdG from the cell. The novel approach adopted in this study was validated using cell culture supernatant obtained from an in vitro model comprising CCRF cells exposed to vitamin C; this model has previously been shown to stimulate removal of 8-OHdG from the cell by an NER-dependent process.
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PMID:Evidence of oligonucleotides containing 8-hydroxy-2'-deoxyguanosine in human urine. 1727 87

Arterial dysfunction is a hallmark of early atherosclerosis; however, its behavior in patients with metabolic syndrome (MS) is still unclear. We investigated the role of oxidative stress on ischemia-induced flow-mediated dilatation (FMD) in patients with MS. FMD and oxidative stress, as assessed by serum levels of 8-hydroxy-2-deoxy-2-deoxyguanosine (8-OHdG), were studied in 18 MS and 30 control subjects. Thereafter, in the 18 MS patients, FMD was assessed after iv infusion of 1 g vitamin C or placebo in a randomized, double-blind, crossover design; serial blood samples were taken in peripheral circulation before and after FMD to analyze 8-OHdG. Compared to controls, MS patients had higher 8-OHdG (p<0.001) and lower FMD (p<0.001); 8-OHdG and FMD were inversely correlated (R=-0.74; p<0.01). In MS patients, placebo administration did not change FMD, whereas vitamin C significantly enhanced it (p<0.001). After placebo, ischemia-induced FMD was associated with a significant increase in 8-OHdG (p<0.001), an effect that was counteracted by vitamin C. Vitamin C infusion was associated with an inverse correlation between the changes in FMD and oxidative stress (R=-0.67; p<0.01). The present study shows that arterial dilatation is impaired and that enhanced oxidative stress may play a key role in patients with MS.
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PMID:Oxidative stress-mediated arterial dysfunction in patients with metabolic syndrome: Effect of ascorbic acid. 1766 49


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