Cepathiolactols\nand CepathiolactonesTwo Newly\nDiscovered Families of Organosulfur Compounds Formed in Cut Onion

Isolation\nand structural characterization of two large\nfamilies\nof organosulfur compounds spontaneously formed upon cutting of onion\n(Allium cepa) were carried out. The\nstructures of these hitherto unknown species, trivially named cepathiolactols\nand cepathiolactones, were established based on NMR, MS, and IR data.\nIt was found that cepathiolactols (C<sub><i>x</i></sub>H<sub><i>y</i></sub>OS<sub>3</sub> and C<sub><i>x</i></sub>H<sub><i>y</i></sub>O<sub>2</sub>S<sub>4</sub>; <i>x</i> = 7–12, <i>y</i> = 14–24) are\n3,4-dimethyl-γ-thiolactols bearing various side chains linked\nvia a disulfanyl moiety at position C-5. On the other hand, cepathiolactones\nwere shown to be 3,4-dimethyl-γ-thiolactones structurally analogous\nto cepathiolactols. Sensory properties of cepathiolactols were also\nevaluated, along with testing their ability to participate in the\nformation of pink discoloration of processed onion.