Dichloromethane Extract of Giloe (Tinospora Cordifolia, Wild) Increases the Radiosensitivity of Cultured Hela Cells Exposed to Different Doses of Γ-Radiation

Ionizing radiations are in frequent clinical use to treat cancer either alone or in combination with surgery or chemotherapy. The radioresistance of tumors is a stumbling block to realize the full potential of radiotherapy. Therefore, pharmacophores that reduce the radioresistance of tumors may be of great importance during tumor therapy. In the present study an attempt has been made to evaluate the potential of dichloromethane extract of giloe i.e. Tinospora cordifolia (TCE) in cultured HeLa cells. Exposure of HeLa cells to TCE for 4 h before exposure to 2 Gy γ-radiation led to a significant decrease in the cell viability (approximately 50 %) accompanied by a reduction in the surviving fraction (SF) up to 0.52 after 4 h of TCE treatment. Thereafter, clonogenecity of HeLa cells declined negligibly with increase in treatment duration up to 6 h post- treatment. There has been a dose dependent attrition in the cell viability of HeLa cells exposed to 1-4 Gy γ-irradiation, whereas treatment of HeLa cells with various doses of TCE further decreased the cell viability depending not only on the irradiation dose but also on the concentration of TCE. The irradiation of HeLa cells resulted in a radiation dose dependent decline in the SF and increasing TCE concentration before irradiation caused a further TCE concentration dependent reduction in SF, and a lowest SF was observed for 4 µg/ml TCE for all irradiation doses. Treatment of HeLa cells with different concentrations of TCE before 3 Gy irradiation resulted in a concentration dependent depletion in glutathione-S-transferase activity until 12 h post-irradiation, whereas lactate dehydrogenase and lipid peroxidation increased up to 4 h post-irradiation and declined gradually thereafter up to 12 h post-irradiation. The TCE treatment increased the radiosensitivity of HeLa cells by reducing glutathione-S-transferase activity and increasing the activity of lactate dehydrogenase and lipid peroxidation.