Protection against radio-oxidative damage of splenic lymphocytes by ethanolic extract of Nigella Sativa

Cellular membranes are being recognized as a sensitive radiation target and evidence is accumulating in support of membrane oxidative damage playing a central role in the mechanism of radiation induced cell death. Present study was aimed to evaluate radio-oxidative damage in membrane of spleen lymphocytes and its modification by ethanolic extract of herb, Nigella sativa (black cumin), an herbaceous annual plant. Lymphocytes were obtained from swiss mice after cervical dislocation were suspended in culture medium (106 cells/ml) and were exposed to various doses of γ radiation (0.5-5 Gy). Oxidative damage related parameters, such as lipid peroxidation, reactive oxygen species (ROS) and reactive nitrogen species (RNS) were determined by thiobarbituric acid reactive substances (TBARS), H2DCFDA and Greiss reagent methods respectively. It was found that peroxides, ROS and RNS increased with the dose of radiation. When cells were pretreated with N. Sativa extract but present during irradiation, they were found significantly protected against radiation exposure as measured by cellular viability by trypan blue and the protective effect was concentration dependent (1-200 μg/ml). Extract treated cells were found to show reduced ROS, RNS and lipid peroxide formation suggesting that the protective effect was mediated by free radical mechanism. With the increasing dose of radiation, there was decreasing activity of endogenous antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), and glutathioneperoxidase (GPx). Pretreatment of lymphocytes with ethanolic extract was found to prevent radiation induced depletion of the intracellular antioxidant enzymes. It is concluded that radiation exposure of lymphocytes produced free radical induced membrane oxidative damage, which was significantly prevented by the ethanolic extract of N. Sativa. (author)