Abstract

The term thiol refers to compounds containing sulfur. Thiol-containing compounds are found in all body cells and are indispensable for life. Some of these include cysteine, methionine, taurine, glutathione, lipoic acid, mercaptopropionylglycine, N-acetylcysteine, and the three major organosulfur compounds of garlic oil, namely, diallylsulfide, diallyldisulfide, and diallyltrisulfide. With respect to structure-function relationship, dihydrolipoic acid is the most effective antioxidant. Dihydrolipoic acid has two sulfhydryl groups and it can undergo further oxidation reaction forming lipoic acid. The more highly reduced form a thiol-containing compound has, the more stronger antioxidative activity it exerts. The number of sulfur atoms determines, at least in part, the modulatory activity on the glutathione-related antioxidant enzymes. In this article, antioxidant and antioxidative effects of garlic and some thiol-containing compounds are reviewed.