Thesis (M.Sc.)--Chulalongkorn University, 2008

The objectives of this study were to investigate the direct mutagenicity of fresh, pasteurized and sterilized pomegranate juices and their effects on mutagenesis induced by nitrite treated 1-aminopyrene and nitrite treated chicken extract in the absence of metabolic activation on Salmonella typhimurium strains TA98 and TA100. It was found that fresh juice was not mutagenic on both strains either with or without nitrite treatment. The pasteurized and sterilized juices exhibited slight mutagenicity on TA98, but on TA100, only day90 sterilized juice exhibited slightly mutagenic at 24.67 mg/plate. Fresh juice, pasteurized juices kept for 0 and 7 days and sterilized juices kept for 0, 30 and 90 days were evaluated for their antimutagenicity against nitrite treated 1-aminopyrene and nitrite treated chicken extract. Fresh pomegranate juice did not show antimutagenic activity but it presented co-mutagenic effect. It might be due to unknown natural compounds from arils and/or seeds. Pasteurized juices presented negligible effect (0-20%). On the other hand, sterilized juice kept for 90 days exhibited weak antimutagenic activity (31-34% inhibition) against nitrite treated 1- aminopyrene, but exhibited moderate co-mutagenic activity (46–57% enhancement) with nitrite treated 1- aminopyrene. This was possibly due to some flavonoids and tannins that could enhance activating enzymes of mutagens (nitroreductase and O-acetyltransferase) in Salmonella cell or induce the bacterial membrane permeability.