Gossypetin, a naturally occurring hexahydroxy flavone, ameliorates gamma radiation-mediated DNA damage

Purpose: To evaluate the protective effect of gossypetin (GTIN) against gamma (gamma)-radiation-mediated DNA damage. Materials and methods: Increasing concentrations (10-150 mu M) of GTIN were incubated with supercoiled DNA 1 h prior exposure to gamma-radiation in the range of 5-Gy absorbed dose from Co-60 gamma source. To establish the effective protective concentration of GTIN, supercoiled DNA was pre-incubated with 50 mu M of GTIN for 1 h followed by exposure of 5, 10 and 20 Gy doses of gamma-radiation. Moreover, 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical, hydroxyl radical, nitric oxide (NO) scavenging, metal chelating activity and ferric reducing antioxidant power (FRAP) of GTIN were measured and compared with standards. The flowcytometric analysis and radiation-induced genomic DNA damage by comet assay were employed to estimate the level of intracellular reactive oxygen species (ROS) using isolated murine hepatocytes. Results: GTIN was able to effectively scavenge different free radicals in in vitro situations. It could significantly prevent radiation induced supercoiled and genomic DNA damage with reduced comet parameters. It also acted as a potent scavenger of the radiation induced ROS. Conclusions: GTIN ameliorated radiation-induced oxidative stress and DNA damage by its free-radical scavenging activity.