Protective effect of boric acid on lead- and cadmium-induced genotoxicity in V79 cells

The toxic heavy metals cadmium (Cd) and lead (Pb) are important environmental pollutants which can cause serious damage to human health. As the metal ions (Cd2+ and Pb2+) accumulate in the organism, there is special concern regarding chronic toxicity and damage to the genetic material. Metal-induced genotoxicity has been attributed to indirect mechanisms, such as induction of oxidative stress and interference with DNA repair. Boron is a naturally occurring element and considered to be an essential micronutrient, although the cellular activities of boron compounds remain largely unexplored. The present study has been conducted to evaluate potential protective effects of boric acid (BA) against genotoxicity induced by cadmium chloride (CdCl2) and lead chloride (PbCl2) in V79 cell cultures. Cytotoxicity assays (neutral red uptake and cell titer blue assay) served to determine suitable concentrations for subsequent genotoxicity assays. Chromosomal damage and DNA strand breaks were assessed by micronucleus tests and comet assays. Both PbCl2 and CdCl2 (at 3, 5 and 10 A mu M) were shown to induce concentration-dependent increases in micronucleus frequencies and DNA strand breaks in V79 cells. BA itself was not cytotoxic (up to 300 A mu M) and showed no genotoxic effects. Pretreatment of cells with low levels of BA (2.5 and 10 A mu M) was found to strongly reduce the genotoxic effects of the tested metals. Based on the findings of this in vitro study, it can be suggested that boron provides an efficient protection against the induction of DNA strand breaks and micronuclei by lead and cadmium. Further studies on the underlying mechanisms for the protective effect of boron are needed.