allicins

Allicin is an organosulfur compound produced in Allium plants, most notably garlic, when tissue is damaged. It is formed from the precursor alliin by the plant enzyme alliinase during crushing or chopping. Allicin is often described as diallyl thiosulfinate and has the chemical formula C6H10OS2. The compound is highly reactive and unstable in air and at room temperature, rapidly rearranging and decomposing into a range of sulfur-containing products such as diallyl disulfide, diallyl trisulfide, and ajoene, which also contribute to flavor and aroma.

In biology and nutrition, allicin is credited with much of garlic’s antimicrobial activity. Laboratory studies show broad-spectrum effects against bacteria, fungi, and some parasites, largely through reactions with thiol groups in proteins and enzymes, which can disrupt cellular function. However, the clinical relevance of allicin in humans is uncertain because it is poorly absorbed in its intact form and rapidly metabolized; in vivo effects may arise from a combination of allicin and its degradation products rather than allicin alone.

In culinary contexts, allicin formation explains garlic’s characteristic odor and many of its flavor properties. Cooking, processing, or heat inactivates alliinase, reducing allicin production and altering the profile of sulfur-containing compounds that develop.

Research and regulation: allicin is not approved as a medical treatment. It has been studied for potential antimicrobial, cardiovascular, anti-inflammatory, and anticancer effects, but robust clinical evidence is lacking, and commercial products vary in content and stability.