Alteration in the radiosensitivity of HeLa cells by dichloromethane extract of guduchi (Tinospora cordifolia).

Exposure of HeLa cells to TCE (dichloromethane extract of Tinospora cordifolia) for 4 hours before exposure to 2-Gy γ-radiation caused a significant decrease in the cell viability (approximately 50%). The surviving fraction (SF) was reduced to 0.52 after 4 hours of TCE treatment; thereafter, clonogenecity of HeLa cells declined negligibly with treatment duration up to 6 hours posttreatment. Exposure of HeLa cells to different doses of γ-radiation resulted in a dose-dependent decline in the viability of HeLa cells, 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. Treatment of HeLa cells with various doses of TCE caused a significant decline in cell viability after exposure to 1 to 4 Gy γ-radiation. The increase in TCE concentration before irradiation caused a concentration-dependent reduction in the SF, and a lowest SF was observed for 4 μg/mL TCE for all exposure doses. HeLa cells treated with TCE showed an increase in lactate dehydrogenase and decrease in glutathioneS-transferase activity at all postirradiation times. Lipid peroxidation increased up to 4 hours postirradiation and declined gradually up to 12 hours postirradiation.