title: Humic acid induced genotoxicity in human peripheral blood lymphocytes using comet and sister chromatid exchange assay.
abstract: Humic acid (HA) in well water used by the inhabitants for drinking is one of the possible etiological factors for blackfoot disease (BFD). Moreover, within BFD endemic areas cancers occur at significantly higher rates than in areas free of BFD. In this study, the genotoxic potential of HA is assessed using human peripheral blood lymphocytes. The cells were exposed to HA (0-200 microg/mL for 2 h), and the induction of DNA primary damage in cellular DNA was evaluated by single-cell gel electrophoresis (comet assay). HA-induced DNA damage was decreased by superoxide (O(2)(-)), hydrogen peroxide (H(2)O(2)), and reactive oxygen species (ROS) scavengers (superoxide dismutase, catalase, and Trolox), and nitric oxide (NO) synthase inhibitors (N(G)-nitro-l-arginine methyl ester and N(G)-methyl-l-arginine). Moreover, formamidopyrimidine-DNA glycosylase (Fpg) and endonuclease III (Endo III), known to catalyze the excision of oxidized bases, increase the amount of DNA migration in HA-treated cells. Pretreatment of the cells with both the Ca(2+)-chelator BAPTA and EGTA completely inhibited HA-induced DNA damage, indicating that HA-induced changes in Ca(2+)-homeostasis are the predominant pathways for the HA induction of genotoxicity. Furthermore, sister chromatid exchange was found in the HA-treated lymphocytes. Our findings suggest that HA can induce oxidative DNA damage and genotoxicity in human lymphocytes.
authors.affiliation: Department of Cosmeceutics, China Medical University, Taichung, Taiwan.
authors.forename: You-Cheng
authors.initials: YC
authors.lastname: Hseu
authors.forename: Ssu-Ching
authors.initials: SC
authors.lastname: Chen
authors.forename: Ya-Lai
authors.initials: YL
authors.lastname: Chen
authors.forename: Jing-Yi
authors.initials: JY
authors.lastname: Chen
authors.forename: Mei-Ling
authors.initials: ML
authors.lastname: Lee
authors.forename: Fung-Jou
authors.initials: FJ
authors.lastname: Lu
authors.forename: Fang-Yang
authors.initials: FY
authors.lastname: Wu
authors.forename: Jim-Shoung
authors.initials: JS
authors.lastname: Lai
authors.forename: Hsin-Ling
authors.initials: HL
authors.lastname: Yang
mesh_terms: D002374:Catalase / Q000494:pharmacology; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D002839:Chromans / Q000494:pharmacology; D020552:Comet Assay; D004249:DNA Damage / Q000187:drug effects; D043382:DNA-Formamidopyrimidine Glycosylase / Q000494:pharmacology; D043224:Deoxyribonuclease (Pyrimidine Dimer) / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D029968:Escherichia coli Proteins / Q000494:pharmacology; D006801:Humans; D006812:Humic Substances / Q000633:toxicity*; D008214:Lymphocytes / Q000187:drug effects; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D010618:Phenanthrolines / Q000494:pharmacology; D012854:Sister Chromatid Exchange; D013482:Superoxide Dismutase / Q000494:pharmacology; D014873:Water Pollutants / Q000633:toxicity*; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D002614:Chelating Agents; D002839:Chromans; D029968:Escherichia coli Proteins; D006812:Humic Substances; D010618:Phenanthrolines; D014873:Water Pollutants; D019323:omega-N-Methylarginine; D004533:Egtazic Acid; D002374:Catalase; D013482:Superoxide Dismutase; D043224:Deoxyribonuclease (Pyrimidine Dimer); C106403:NTH protein, E coli; D043382:DNA-Formamidopyrimidine Glycosylase; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid; D019331:NG-Nitroarginine Methyl Ester; C025205:1,10-phenanthroline