Radioprotection Imparted by Four Spices in a Bacterial System

Phenolic substances derived from herbs and spices are potent antioxidants and exhibits anti-inflammatory, antimutagenic and anticarcinogenic activities in living systems. [1] These extracts may have the potential to modulate the genotoxic activity caused by harmful radiations and chemicals to which the human population is incessantly exposed to. The study of the modulation of genotoxic activity by some commonly used Indian spices will therefore be meaningful and interesting. As a first step to this, a number of such spices have been employed to study their potential role in the modulation of genotoxic activity induced by a harmful radiation viz. UVC, using Salmonella typhimurium as a model test system. The umu-gene expression assay as devised by Oda et al[2] in Salmonella typhimurium TA 1535/pSK1002 cells have been widely used and accepted as a short term bacterial assay system for the screening of genotoxic agents. In the above noted strain a umuC’-lacZ fusion gene is carried in a multi copy plasmid, thus improving the sensitivity of the system for the detection of umu gene expression (the gene that is believed to be responsible for induced mutagenesis). Measurement of the amount of β-galactosidase produced in these cells under different conditions would therefore reflect the extent of umu gene induction under those conditions. The present study aims at investigating on the modulation of DNA damage in TA 1535/pSK1002 cells induced by a fixed dose of UVC (which produces a significant amount of DNA damage) with varying doses of crude extracts of four commonly used Indian spices viz. Ajwain (Trachyspermum copticum), Black Pepper (Piper nigrum), Clove (Syzyquim aromaticum), and Allspice (Pimenta dioica). A study of the survival of the cells ABSTRACT: Introduction: A wide variety of substances derived from herbs and spices have been shown to possess potent antioxidant, anti-inflammatory, anti-mutagenic and anticarcinogenic activities. The study of the modulation of genotoxicity by the extracts of some such spices would thus be meaningful and interesting. Objective: Aqueous extracts of four extensively used spices viz. Trachyspermum copticum (Ajwain), Piper nigrum (Black pepper), Syzyquim aromaticum (Clove) and Pimenta dioica (Allspice) have been employed to study the modulation of genotoxicity, if any, induced by a potent DNA damaging agent viz. ultraviolet radiation (UV C), in Salmonella typhimurium cells. Methods: Induction of umu-gene was assayed in Salmonella typhimurium cells in presence or absence of varying amounts of the spice extract after a fixed dose of UV C exposure. The percentage survival of the Salmonella typhimurium cells exposed to UV C was computed by the study of the colony forming units on LB-Agar plates. Results: All the aqueous extracts of Ajwain, Black Pepper, Clove and Allspice was found to impart radioprotection to Salmonella typhimurium cells against UV C induced DNA damage in a dose–dependent manner. Clove has been found to impart a very high degree of radioprotection as compared to the other spice extracts and also at a much lower concentration. This has been reflected by both the assay methods mentioned above. Conclusions: Our results indicate that aqueous extracts of all four spices studied, impart radioprotection against UV induced DNA damage in Salmonella typhimurium cells in a dose-dependant manner. All the spice extracts mentioned above, excepting clove, presumably due to its antibacterial activity, were found to support the growth of the Salmonella typhimurium cells. This may be indicative that the extracts are imparting protection by effectively reducing the UV dose upon absorption of a part of UVC by the constituents of the spice extracts excepting clove.