Background: Antibacterial, antiviral, anti-infl ammatory and antioxidant effects of gallic acid has been reported in the literature. In order to explore any other effect of gallic acid in living system, the present study aims at exploring its role in the modulation of genotoxicity, induced in a bacterial system by different types of radiation. Materials and Methods: umu-gene induction in saline suspended log phase cells of Salmonella typhimurium containing no or different amounts of gallic acid were assayed by measuring the β-galactosidase produced in the cells after exposure to fi xed doses of ultraviolet, gamma and solar radiation. Results: Gallic acid was found to impart maximum amount of radio-protection to gamma ray exposed cells, intermediate level of radio-protection to sunlight exposed cells and the least amount of radio-protection to UVC exposed cells. Conclusion: Radio-protection imparted by gallic acid against gamma rays is possibly due to its radical scavenging activity and that against UVC is due to its ability to interfere with the formation or reversal of the dimmers formed in the cell's DNA. The radio-protection against solar radiation is presumably due to the effect of both these mechanisms taking place in the cells simultaneously.

Background: Curcumin, believed to be the main bioactive component of turmeric is well-known for its antioxidant, radio-protective, radical-scavenging, and anticancer properties. Commercially available curcumin, found to be composed of at least three different compounds have been employed for their individual biological activity vis-a-vis curcumin as a whole in a bacterial system. Materials and Methods: Commercially available curcumin has been subjected to a round of High performance thin layer chromatography (HPTLC) analysis and their biological activities have been monitored by survival studies in Escherichia coli cells. Results: Curcumin as well as the individual components in it has been found to impart some sort of protection against the toxicity imparted by its delivering solvent namely DMSO. Conclusions: The degree of protection induced by curcumin and all the individual components in it has been discussed in relation to the relative proportions of the individual components present in curcumin.