S2propenylLcysteine

S-2-propenyl-L-cysteine, also known as S-allyl-L-cysteine (SAC), is a thioether derivative of the amino acid L-cysteine in which the sulfur atom is bonded to an allyl group (prop-2-en-1-yl). Its chemical formula is C6H11NO2S and its molecular weight is about 161.23 g/mol; the compound exists in the L-configuration corresponding to natural amino acids.

SAC occurs naturally in Allium vegetables such as garlic and related products, including aged garlic extracts. It is one of several sulfur-containing amino acid derivatives present in garlic and has attracted interest for its potential biological activities. The compound is typically studied for its antioxidant properties, and research has explored possible anti-inflammatory and neuroprotective effects in cellular and animal models. Human evidence remains limited and inconclusive, and SAC is not approved as a treatment for any medical condition.

Chemically, SAC is a stable thioether under neutral conditions, but sulfur-containing compounds can undergo oxidation to sulfoxide or sulfone forms under appropriate conditions. In the laboratory, SAC can be prepared by alkylating the thiol group of L-cysteine with an allylating agent or isolated from garlic-derived materials through purification processes.

Applications and safety considerations: SAC is primarily discussed in the context of dietary supplements and nutraceuticals due to its presence in garlic and its proposed health-related activities. As with garlic-derived constituents, typical dietary exposure from food is considered safe for most people, but the safety and efficacy of high-dose SAC supplements have not been established.

See also: S-allyl-L-cysteine sulfoxide (alliin) and allicin.