Chemoprevention of 1,2-Dimethylhydrazine-induced Colon Cancer in Mice by Naturally Occurring Organosulfur Compounds1

Organosulfur compounds (OSCs) present in garlic and onion oil have been shown to inhibit chemical carcinogenesis. In this study, we compared the chemopreventive efficacy of five lipidand four water-soluble OSCs using the murine nuclear aberration assay. Administration of diallyl sulfide and 5-allyl cysteine p.o. at a dose of 200 mg/kg 3 h prior to i.p. 1,2-dimethylhydrazine (DMII) injection (20 mg/kg) significantly inhib ited colonie nuclear damage in female C57B1/6J mice by 47% and 36%, respectively. The inhibitory effect of .S'-allyl cysteine was found to be dose dependent. The other OSCs did not affect the level of DMH-induced nuclear toxicity. Furthermore, the incidence and frequency of colonie tumors induced by DMI I (20 mg/kg, 10 weekly i.p. injections) in female CF-1 mice were significantly inhibited by 5-allyl cysteine pretreatment, given 3 h prior to each carcinogen injection. These data indicate that the ally! group coupled to a single sulfur atom might play an important structural role in inhibition of DMH-induced colonie nuclear toxicity and carcinogenesis. OSCs containing allyl groups stimulated glutathione Stransferase activity in both the liver and colon. However, their saturated analogues stimulated little or no hepatic and colonie glutathione .Vtransferase activity. Induction of hepatic and colonie glutathione Stransferase might assist in detoxification of carcinogens and could be necessary for some aspects of chemoprevention.