Cytotoxicity based screening for radioprotective properties of methanolic extract of Tragia involucrata L. on cultured human peripheral lymphocytes exposed to gamma radiation

Radioprotective drugs of plant origin with bioactives are a boon against ionizing radiation injuries. Tragia involucrata L. (Indian stinging nettle), has medicinal properties and is traditionally used to treat various ailments. Here, we evaluated the radioprotective efficacy of the methanolic whole plant extract of T. involucrata against the damaging effects of gamma radiation. Cultured lymphocytes were treated with methanolic extract for one hour and irradiated with (1-4 Gy) gamma radiation. This pretreatment of lymphocytes with methanolic extract significantly increased the cell viability at 10 mu g/mL and reduced the damage to the treated cells compared to the radiation control. In addition, a significant decrease in comet parameters (Comet length and percent DNA in tail and olive moment) and formation of micronuclei (P < 0.001) were observed. It also decreased the levels of malondialdehyde, while regulating the status of the total antioxidant capacity, superoxide dismutase, catalase, reduced glutathione, and glutathione transferase (P < 0.05)-when compared to the radiation control, Similarly, a decrease in caspase 3 cellular activity compared to the radiation control was observed. The results indicated the methanolic extract to be an effective radioprotector up to 4 Gy, by enhancing the antioxidant enzyme levels, scavenging the production of reactive oxygen species, reducing the damaging effects of radiation by increasing the DNA repair mechanism, and by inhibiting the mitochondrial apoptotic pathway. Therefore, methanolic extract of the Indian stinging nettle, Tragia involucrata L. has been proposed as a candidate with a radioprotective property, and further study on animal models would strengthen this claim.