Although garlic has been traditionally used for over 5,000 years, most scientific significance has just been developed in the past 50 years. The key compounds in garlic and its preparations include the following phytochemicals.
Recently, researchers have been focusing on the benefits of a variety of sulfur-containing compounds in garlic instead of allicin. These are classified as oil- and water-soluble compounds. Oil-soluble compounds include sulfides, such as diallyl sulfide (DAS), diallyl disulfide (DADS), diallyl trisulfide and allyl methyl trisulfide, dithiins, and ajoene. Water-soluble compounds include cysteine derivatives, such as S-allyl cysteine (SAC), S-allyl mercaptocysteine (SAMC) and S-methyl cysteine, and gamma-glutamyl cysteine derivatives. Oil-soluble sulfur compounds are odorous, whereas water-soluble compounds are odorless. Moreover, water-soluble compounds are more stable and safer than oil-soluble compounds (1).
Garlic was also found to contain unique non-sulfur compounds, such as allixin and saponins and recent studies have revealed the important contribution of these compounds to garlic’s health benefits (2-4).