Field bean protease inhibitor mitigates the sister-chromatid exchanges induced by bromoform and depresses the spontaneous sister-chromatid exchange frequency of human lymphocytes in vitro

Black bean (Phaseolus vulgaris L.) as a protective agent against DNA damage in mice

This study was designed to evaluate the toxicogenetic or protective effect of cooked and dehydrated black beans (Phaseolus vulgaris L.) in bone marrow and peripheral blood cells of exposed mice. The frequency of micronuclei detected using the bone marrow erythrocyte micronucleus test and level of DNA lesions detected by the comet assay were chosen as end-points reflecting mutagenic and genotoxic damage, respectively. Initially, Swiss male mice were fed with a 20% black bean diet in order to detect mutagenic and genotoxic activity. However, no increase in the frequency of bone marrow micronucleated polychromatic erythrocytes (MN PCEs) or DNA lesion in leukocytes was observed. In contrast, received diets containing 1, 10 or 20% of black beans, a clear, but not dose-dependent reduction in the frequency of MN PCEs were observed in animals simultaneously treated with cyclophosphamide, an indirect acting mutagen. Similar results were observed in leukocytes by the comet assay. Commercial anthocyanin was also tested in an attempt to identify the bean components responsible for this protective effect. However, instead of being protective, the flavonoid, at the highest dose administered (50 mg/kg bw), induced primary DNA lesion, as detected by the comet assay. These data indicate the importance of food components in preventing genetic damage induced by chemical mutagens, and also reinforce the role of toxicogenetic techniques in protecting human health.

Induction of sister chromatid exchanges in human peripheral blood lymphocytes by bromoform: investigation of the role of GSTT1-1 polymorphism

Brominated trihalomethanes (THMs) are disinfection by-products present frequently in chlorinated drinking water. Brominated THMs are mutagenic in a variety of systems and are carcinogenic in rodents. The metabolism of brominated THMs is thought to involve a GSH conjugation reaction leading either to formaldehyde or DNA-reactive intermediates via glutathione S-transferase-theta (GSTT1-1), which is polymorphic in humans. In the present study, we have determined the genotoxicity of one of the brominated THMs, bromoform (BF), by measuring its ability to induce sister chromatid exchanges (SCEs) in whole-blood (WB) cultures of human peripheral blood lymphocytes from GSTT1-1+ and GSTT1-1- donors. The results showed no differences in SCEs per cell by BF between GSTT1-1+ and GSTT1-1- individuals when the cells were exposed to 5 x 10(-3) M BF at the beginning of cell culturing (10.8+/-0.85 vs. 10.57+/-0.47, respectively), at the 16th (9.66+/-0.91 vs. 9.57+/-0.07), or the 24th h (8.21+/-0.61 vs. 8.29+/-0.24) of cell growth. Although GSTT1-1 is expressed in the erythrocytes, the lack of expression of the GSTT1-1 gene in the target cells (lymphocytes) may account for this observation.