alliinlike

Alliin-like refers to a class of sulfur-containing amino acid sulfoxides that resemble alliin in structure and function. These compounds are found primarily in Allium vegetables such as garlic, onions, leeks, and chives, where they serve as precursors to a family of reactive sulfur species. Chemically, alliin-like molecules are S-alk(en)yl-L-cysteine sulfoxides, featuring a cysteine backbone with a sulfoxide group and an alk(en)yl side chain. The main members reported in Allium species include alliin (S-allyl-L-cysteine sulfoxide), isoalliin (S-2-propenyl-L-cysteine sulfoxide), and methiin (S-methyl-L-cysteine sulfoxide).

Distribution and biosynthesis: Alliin-like compounds are produced in plant tissues and stored in cellular compartments, often in vacuoles, to minimize spontaneous reactions. Upon tissue disruption, they come into contact with specific enzymes and undergo rapid transformation, enabling the plant to generate defense-related sulfur compounds.

Enzymatic transformation: The key enzyme is alliinase, which cleaves alliin-like substrates to produce sulfenic acids that quickly condense to form thiosulfinates and related volatile sulfur compounds. For example, alliin yields allyl sulfenic acid that combines to form allicin, the characteristic antimicrobial and strongly fragrant compound. Substrate structure influences the exact sulfenic acids and thiosulfinates formed, leading to a variety of odorants and bioactive products.

Relevance: Alliin-like compounds are of interest in plant biochemistry, food science, and nutrition due to their roles as aroma-active precursors and potential health-related effects. Cooking, processing, and storage can affect their stability and the profile of resulting sulfur compounds.