The effect of
S-allylcysteine (SAC), a water-soluble garlic constituent, on 7,12-dimethylbenz[a]
anthracene (DMBA)-induced hamster buccal pouch (HBP)
carcinogenesis was investigated in male Syrian hamstes. Forty hamsters were divided into 4 groups of 10 animals. The right buccal pouches of the animals in Group I were painted with a 0.5%
solution of DMBA in
liquid paraffin three times a week. The animals in Group II were painted with DMBA as in Group I and, in addition, received 200 mg/kg body wt p.o. SAC three times a week on days alternate to DMBA application. Group III animals received SAC as in Group II. Group IV animals received neither DMBA nor SAC and served as the control. The hamsters were killed after an experimental period of 14 wk. Measurement of lipid peroxidation, the
antioxidant enzymes superoxide dismutase (SOD) and
catalase, in the buccal pouch mucosa, liver, and circulation was used to monitor the chemopreventive potential of SAC. All hamsters painted with DMBA alone developed
tumors identified histologically as well-differentiated
squamous cell carcinomas. In hamsters bearing DMBA-induced buccal pouch
tumors, diminished lipid peroxidation in the
tumor tissue was accompanied by decreased activities of SOD and
catalase, whereas in the liver and circulation, enhanced lipid peroxidation was associated with compromised
antioxidant defenses. Administration of SAC suppressed the incidence of DMBA-induced HBP
tumors as revealed by the absence of
carcinomas. Histologically, only
keratosis was observed. SAC modulated DMBA-induced decreased susceptibility of the HBP to lipid peroxidation while simultaneously enhancing SOD and
catalase activities, whereas in the liver and circulation, SAC decreased the extent of lipid peroxidation and significantly enhanced
antioxidant activities. We suggest that SAC exerts its chemopreventive effects by modulating lipid peroxidation and enhancing
antioxidant activities in the target organ as well as in the liver and circulation.