S-propyl-L-cysteine sulfoxide (Propiin)

S-propyl-L-cysteine sulfoxide, commonly known as propiin, is a naturally occurring organosulfur compound and secondary metabolite found in plants of the genus Allium, such as onions (Allium cepa) and leeks [1, 16]. It is a sulfur-containing amino acid derivative that serves as a precursor to bioactive thiosulfinates, which are released when plant tissue is damaged and the molecule is exposed to the enzyme alliinase [8, 13]. Although propiin is not a therapeutic target such as a receptor or enzyme, it has gained attention in medicinal chemistry as a prodrug substrate in enzyme-prodrug therapy [3]. In this context, it is paired with enzymes like methionine γ-lyase (MGL) to generate cytotoxic propyl-propane thiosulfinate (PTS) specifically at tumor sites, demonstrating potential in treating various solid tumors [4, 10]. Beyond its role in experimental oncology, propiin and its derivatives exhibit antioxidant, antimicrobial, and cardioprotective properties [2, 8]. It is also utilized as a urinary biomarker to monitor the dietary intake and metabolism of Allium-derived compounds in humans [9].

Other names

Propiin(+)-S-propyl-L-cysteine sulfoxide3-(Propylsulfinyl)-L-alanineS-propylcysteine sulfoxide

Acts as a prodrug substrate for enzymes such as alliinase or methionine γ-lyase, which catalyze its conversion into bioactive thiosulfinates with cytotoxic and antimicrobial properties.