In this study, the chemopreventive efficacy of Nigella sativa seed powder as an important chemopreventive herb on the formation of colon tumor has been examined through measuring the levels of hepatic oxidative stress and metabolizing enzymes in 1,2-dimethylhydrazine (DMH)-induced colon cancer in rats. Male Wistar rats were divided into 6 groups as untreated control, Sham, DMH (30mg/kg b.w) received carcinogen via subcutaneously (s.c) injection once a week for 18 weeks and treatment groups received diet containing Nigella sativa (2 and 4%) until the end of whole experimental period of 6 months. It is indicated that Nigella sativa seed powder could prevent colon tumor formation by modulating the activities of hepatic detoxification enzymes, GST and CYP450 whereas antioxidant statues are not affected. The data was confirmed by histopathological findings It is obvious that one of the mechanisms of chemoprevention of colon tumorigenesis by Nigella sativa seed powder may be the enhancement of carcinogen detoxification but not antioxidant system in the liver.
Key words: Nigella sativa, Colon tumor, DMH, Antioxidant parameters, Xenobiotic metabolizing enzymes.