ascorbic-acid and purine

Drug-induced urinary calculi, although they account for only 1-2% of urinary calculi, deserve consideration because most of them are preventable. In the drug-containing calculi resulting from the crystallization of a certain drug and its metabolites in the urine, stone analysis can identify the responsible drug. While, in the drug-induced metabolic calculi caused by interference with calcium, oxalate and purine metabolism, careful clinical inquiry is necessary to reveal involvement of a certain drug in stone formation. Better awareness of the possible drugs with lithogenic potential and close surveillance of patients on long-term treatment with these drugs are necessary. Especially, in patients with a history of urolithiaisis, prescription of lithogenic drugs deserve careful consideration.

Topics: Allopurinol; Anti-Bacterial Agents; Ascorbic Acid; Benzbromarone; Calcium; Calcium Compounds; Carbonic Anhydrase Inhibitors; Crystallization; Diuretics; Drug Combinations; Furosemide; Glucocorticoids; Humans; Magnesium Silicates; Oxalates; Protease Inhibitors; Purines; Time Factors; Triamterene; Urinary Calculi; Vitamin D

The health positive effects of diets high in fruits and vegetables are generally not replicated in supplementation trials with isolated antioxidants and vitamins, and as a consequence the emphasis of chronic disease prevention has shifted to whole foods and whole food products.. We carried out a human intervention trial with the golden kiwifruit, Actinidia chinensis, measuring markers of antioxidant status, DNA stability, plasma lipids, and platelet aggregation. Our hypothesis was that supplementation of a normal diet with kiwifruits would have an effect on biomarkers of oxidative status. Healthy volunteers supplemented a normal diet with either one or two golden kiwifruits per day in a cross-over study lasting 2 × 4 weeks. Plasma levels of vitamin C, and carotenoids, and the ferric reducing activity of plasma (FRAP) were measured. Malondialdehyde was assessed as a biomarker of lipid oxidation. Effects on DNA damage in circulating lymphocytes were estimated using the comet assay with enzyme modification to measure specific lesions; another modification allowed estimation of DNA repair.. Plasma vitamin C increased after supplementation as did resistance towards H₂O₂-induced DNA damage. Purine oxidation in lymphocyte DNA decreased significantly after one kiwifruit per day, pyrimidine oxidation decreased after two fruits per day. Neither DNA base excision nor nucleotide excision repair was influenced by kiwifruit consumption. Malondialdehyde was not affected, but plasma triglycerides decreased. Whole blood platelet aggregation was decreased by kiwifruit supplementation.. Golden kiwifruit consumption strengthens resistance towards endogenous oxidative damage.

Topics: Actinidia; Adult; Antioxidants; Ascorbic Acid; Biomarkers; Carotenoids; Comet Assay; Cross-Over Studies; Diet; Dietary Supplements; DNA Damage; DNA Repair; Female; Fruit; Humans; Hydrogen Peroxide; Lipid Metabolism; Lymphocytes; Male; Malondialdehyde; Middle Aged; Oxidative Stress; Platelet Aggregation; Purines; Pyrimidines; Triglycerides; Young Adult

The aim of this study was to evaluate the effects of organosulfurs, isothiocyanates and vitamin C towards hydrogen peroxide-induced DNA damage (DNA strand breaks and oxidized purines/pyrimidines) in human hepatoma cells (HepG2), using the Comet assay. Treatment with hydrogen peroxide (H(2)O(2)) increased the levels of DNA strand breaks and oxidized purine and pyrimidine bases, in a concentration and time dependent manner. Organosulfur compounds (OSCs) reduced DNA strand breaks induced by H(2)O(2). In addition, OSCs also decreased the levels of oxidized pyrimidines. However, none of the OSCs tested reduced the levels of oxidized purines. Isothiocyanates compounds (ITCs) and vitamin C showed protective effects towards H(2)O(2)-induced DNA strand breaks and oxidized purine and pyrimidine bases. The results indicate that removal of oxidized purine and pyrimidine bases by ITCs was more efficient than by OSCs and vitamin C. Our findings suggest that OSCs, ITCs and vitamin C could exert their protective effects towards H(2)O(2)-induced DNA strand breaks and oxidative DNA damage by the free radical-scavenging efficiency of these compounds.

Topics: Ascorbic Acid; Carcinoma, Hepatocellular; Cell Line, Tumor; Comet Assay; Cytoprotection; DNA Damage; Humans; Hydrogen Peroxide; Isothiocyanates; Organic Chemicals; Oxidation-Reduction; Purines; Pyrimidines; Sulfur

The syntheses of the novel C-5 substituted pyrimidine derivatives of l-ascorbic acid containing free hydroxy groups at C-2' (6-10) or C-2' and C-3' (11-15) positions of the lactone ring are described. Debenzylation of the 6-chloro- and 6-(N-pyrrolyl)purine derivatives of 2,3-O,O-dibenzyl-l-ascorbic acid (16 and 17) gave the new compounds containing hydroxy groups at C-2' (18) and C-2' and C-3' (19 and 20). Z- and E-configuration of the C4'C5' double bond and position of the lactone ring of the compounds 6-9 were deduced from their one- and two-dimensional (1)H and (13)C NMR spectra and connectivities in NOESY and HMBC spectra. Compounds 15 and 18 showed the best inhibitory activities of all evaluated compounds in the series. The compound 15 containing 5-(trifluoromethyl)uracil showed marked inhibitory activity against all human malignant cell lines (IC(50): 5.6-12.8 microM) except on human T-lymphocytes. Besides, this compound influenced the cell cycle by increasing the cell population in G2/M phase and induced apoptosis in SW 620 and MiaPaCa-2 cells. The compound 18 containing 6-chloropurine ring expressed the most pronounced inhibitory activities against HeLa (IC(50): 6.8 microM) and MiaPaCa-2 cells (IC(50): 6.5 microM). The compound 20 with 6-(N-pyrrolyl)purine moiety showed the best differential inhibitory effect against MCF-7 cells (IC(50): 35.9 microM).

Topics: Antineoplastic Agents; Antiviral Agents; Ascorbic Acid; Carbon Isotopes; Cell Line, Tumor; Drug Evaluation, Preclinical; Humans; Magnetic Resonance Spectroscopy; Protons; Purines; Pyrimidines; Spectrophotometry, Ultraviolet

Topics: Ascorbic Acid; Blood; Body Fluids; Humans; Liver; Oxidoreductases; Purines; Uric Acid; Urine; Vitamins