Abstract

The radiomodulatory effect of guduchi extract (TCE) was studied in HeLa cells incubated with 0, 1, 2, 4, 6 or 8 µg/ml of TCE for 2 or 4 h before exposure to 0, 0.5, 1, 2, 3 or 4 Gy of g-radiation. The molecular DNA damage was assessed using alkaline comet assay, where DNA tail fragmentation olive tail moment (OTM) served as a measure of DNA damage. Exposure of HeLa cells to 0, 0.5, 1, 2, 3 or 4 Gy g-rays caused a dose-dependent rise in the OTM indicating an increase in the DNA damage at all post-irradiation times. Treatment of HeLa cells with different concentrations of TCE before irradiation increased the OTM significantly at different assessment times, when compared with the concurrent non-TCE treated irradiated control. The greatest DNA damage was observed in cells pretreated with 8 µg/ml TCE, which was approximately 10 folds higher at 16 h for all irradiation doses. The cellular DNA did not exhibit repair of lesions as the DNA damage increased constantly up to 16 h post-irradiation and remained unaltered thereafter. TCE increased the cell killing effects of radiation by increasing the DNA damage and could be an alterantive strategy during radiotherapy of tumors.

Key words: HeLa cells, guduchi, DNA damage,radiation, cell survival.