Keywords: human lymphocytes, micronucleus, thiol antioxidants, free radicals, radioprotection, ionising radiation, low radiation, chromosome damage, blood pretreatment
Thiol antioxidants protect against ionising radiation-induced micronuclei formation in cultured human lymphocytes
The major biological consequences of ionising radiation are generally attributed to the generated free radicals and their reactions with vital cellular components. The level of antioxidants in irradiated cells and animals is generally considered an important determinant of radiobiological damage. The present study aimed to investigate the effect of antioxidants of the thiol family, namely, N-acetyl cysteine (NAC), glutathione (GSH) and thioproline (TP) on the radiation-induced chromosomal damage in human lymphocytes in vitro. The incidence of micronucleus (MN) formation, as measured by the cytochalasin B method, was found to be dependent on low to moderate radiation doses (0-200 cGy). The frequency of MN formation in lymphocytes pretreated with antioxidants was found to decrease with their concentration (100-300 μM). The results show that GSH was a more effective protector than NAC or TP, possibly due to relative radical scavenging efficiency. It was further found that treatment with equimolar concentrations of combined NAC and GSH yielded the most effective reduction in MN frequency compared to other combinations of NAC-TP and GSH-TP. The results suggest that the pretreatment of blood with thiol antioxidants significantly prevented MN formation in the isolated lymphocytes. These results may help in developing protocols for effective protectors against radiation exposure for practical applications.