In vitro genotoxicity assays to evaluate the role of vitamin A on arsenic in human lymphocytes

Shielding effect of anethole against arsenic induced genotoxicity in cultured human peripheral blood lymphocytes and effect of GSTO1 polymorphism

Chronic exposure of inorganic arsenic compounds is responsible for the manifestation of various tumours as well as other diseases. The principal mechanism behind arsenic toxicity is the induction of a strong oxidative stress with production of free radicals in cells. The present study was aimed to explore the shielding effect of anethole against oxidative damage induced by arsenic in cultured human peripheral blood lymphocytes and the effect of GSTO1 polymorphism. Sister chromatid exchange (SCE) frequency, comet tail moment and lipid peroxidation levels were used as biomarkers to assess the oxidative damage. Heparinised venous blood was collected from healthy individuals and treated with sodium arsenite (50 µM) in the presence of anethole (25 and 50 µM) for the analysis of shielding effect of anethole. For the genotyping of GSTO1, PCR RFLP method was adopted. A significant dose-dependent increase in the frequency of SCEs, tail moment and lipid peroxidation levels, was observed when lymphocytes were treated with sodium arsenite. Anethole in combination with sodium arsenite has shown a dose-dependent significant decrease in the frequency of SCEs, tail moment and lipid peroxidation levels. Genetic polymorphism of GSTO1 was found to effect individual susceptibility towards arsenic-mediated genotoxicity and was found insignificant when antigenotoxic effect of anethole was considered. GSTO1 mutant genotypes were found to have significant higher genotoxicity of sodium arsenite as compared to wild-type genotype. The results of the present study suggest ameliorative effects of anethole against arsenic-mediated genotoxic damage in cultured human peripheral blood lymphocytes. A significant effect of GSTO1 polymorphism was observed on genotoxicity of sodium arsenite.

Evaluation of in vitro anti-genotoxic potential of melatonin against arsenic and fluoride in human blood cultures

Melatonin has been known for its anti-oxidant potential but not much studied for the anti-genotoxic potential. The current study elucidate the role of melatonin against in vitro genotoxicity by arsenic (As) and fluoride (F). Human peripheral blood cultures were exposed to As (1.4 microM) and F (34 microM), alone and in combination, with and without melatonin (0.2 mM). Ethyl methane sulphonate (EMS; 1.9 mM) was selected as the positive control to analyze the genotoxic parameters like sister chromatid exchanges (SCEs), cell cycle proliferative index (CCPI) and primary DNA damage. The frequency of SCE/cell, SCE/chromosome and primary DNA damage reduced significantly (p<0.001) accompanied with a marked increase in CCPI upon addition of melatonin. Similarly marked recovery was attained by melatonin from As and F induced primary DNA damage as studied using comet assay. The results clearly indicate towards the protection of lymphocytes from toxic effects af As and F by melatonin in vitro.

Curcumin supplementation protects from genotoxic effects of arsenic and fluoride

The present study was aimed to evaluate curcumin as a potential natural antioxidant to mitigate the genotoxic effects of arsenic (As) and fluoride (F) in human peripheral blood lymphocytes. The study was divided into nine groups consisting of negative control, positive control treated with ethyl methane sulphonate (EMS; 1.93 mM) and curcumin control with only curcumin (1.7 microM) in blood culture. As (1.4 microM) and F (34 microM) were added alone as well as in combination, to the cultures, with and without curcumin. Cultures were analysed for chromosomal aberrations (both structural and numerical) and primary DNA damage via comet assay as the genotoxic parameters after an exposure duration of 24h. Results revealed that curcumin efficiently ameliorates the toxic effect of As and F by reducing the frequency of structural aberrations (>60%), hypoploidy (>50%) and primary DNA damage. In conclusion, curcumin mitigates the genotoxic effects of the two well known water contaminants (As and F) effectively and efficiently at the given concentration in vitro.