Mechanisms of the preventive properties of some garlic components in the carbon tetrachloride promoted oxidative stress. Diallyl sulfide, diallyl disulfide, allyl mercaptan and allyl methyl sulfide

Previous studies evidenced that garlic extracts and/or garlic components we re able to prevent against chemically induced tumors or acute toxic effects of chemicals (e.g. CCl4 induced liver injury). The chemopreventive potenti al of garlic has been attributed to the presence in it of several bioactive organosulfur compounds. Those components might act as antioxidants able to scavenge free radicals. In the present work we describe initial studies on the antioxidative-stress properties of some garlic components such as: dia llyl disulfide (DDS), diallyl sulfide (DAS), allyl mercaptan (AMT) and ally l methyl sulfide (AMS). We found that DAS, DDS and AMT but not AMS were abl e to trap trichloromethyl and trichloromethylperoxyl free radicals. Further , DDS but not DAS or AMT also inhibited CCl4 promoted liver microsomal lipi d peroxidation. DAS, but not DDS, AMT or AMS was able to react with free ra dicals arised during UVC activation of hydrogen peroxide or terbutyl hydrop eroxide but not with those produced during WC activation of terbutyl peroxi de. However, all garlic components tested absorbed energy from UVC and beca me partially destroyed in the process. AMY, but not DDS, AMS or DAS was abl e to destroy 4-hydroxynonenal, a key reactive aldehyde produced during lipi d peroxidation. AMT and DDS were also able to prevent UVC plus CCl4 promote d oxidation of albumin in vitro, but DAS and AMS failed to do so. Results s uggest that the antioxidative stress properties of garlic might result from the contributions of its sulfur component in different steps and not neces sarily from the contribution of only one of them.