Isothiocyanates as H2S Donors Triggered by Cysteine: Reaction Mechanism and Structure and Activity Relationship.

Isothiocyanates are reported as H2S donors, yet the mechanisms are not clear. Herein, we reported that isothiocyanates (ITCs, R-NCS) rapidly formed adducts with cysteine. These adducts underwent intramolecular cyclization followed by releasing organic amine R-NH2 and raphanusamic acid (RA) as major products with formation of H2S and 2-carbylamino-4,5-dihydrothiazole-4-carboxylic acids as minor products. The ratios of the two groups of products are dependent on the R groups which have strong impact on H2S releasing rates.