Cepathiolactols and Cepathiolactones─Two Newly Discovered Families of Organosulfur Compounds Formed in Cut Onion.

Isolation and structural characterization of two large families of organosulfur compounds spontaneously formed upon cutting of onion () were carried out. The structures of these hitherto unknown species, trivially named cepathiolactols and cepathiolactones, were established based on NMR, MS, and IR data. It was found that cepathiolactols (CHOS and CHOS; = 7-12, = 14-24) are 3,4-dimethyl-γ-thiolactols bearing various side chains linked via a disulfanyl moiety at position C-5.

Organosulfur Compounds of Subgenus Species.

Organosulfur compounds formed upon comminuting the bulbs of two subgenus species ( and ) were analyzed by HPLC-PDA-MS/MS. The major organosulfur components were isolated and structurally characterized (MS, NMR), including several previously unknown compounds. It was found that the organosulfur chemistry occurring when these plants are cut is very similar to that observed in onion ().