Inhibition of Genotoxicity by Diallyl Sulfide and Structural Analogues

Higher plants contain an extensive array of biologically active chemicals, some of which are potent modifiers of chemical carcinogenesis (1). Specifically, some of these agents have been shown to be active in inhibiting the initiation stage of the carcinogenesis process (2). Members of the Allium genus, which include onions and garlic, are rich in sulfur-containing compounds. Among the major components of garlic oil are diallyl disulfide (DADS, 66%) and diallyl sulfide (DAS, 14%) (3). It has been previously shown that the latter agent, DAS, can inhibit 1,2-dimethylhydrazine-induced genotoxicity in the murine colonic epithelium (4) and cyclophosphamide-induced genotoxicity in the murine urothelium and hair follicles (5). Recently it has been shown that DAS can inhibit 1,2-dimethylhydrazine-induced colon tumorigenesis (6). The goal of this study was to determine the optimal time for the oral administration of DAS, prior to carcinogen treatment, and to determine the efficacy of other structurally analogous sulfur-containing compounds.