Structure and bioactivities of a thiosulfinate derived by preventing onion lachrymatory factor synthesis.

摘要

In normal onion (Allium cepa), trans-S-1-propenyl-L-cysteine sulfoxide (PRENCSO) is transformed via 1-propenesulfenic acid into propanethial S-oxide, a lachrymatory factor (LF), through successive reactions catalyzed by alliinase and lachrymatory factor synthase (LFS). A recent report showed that suppression of the LFS activity caused a dramatic increase in thiosulfinates previously reported as "zwiebelane isomers". After purification by recycle-HPLC and subsequent analyses, we established the planar structure of the putative "zwiebelane isomers" as S-3,4-dimethyl-5-hydroxythiolane-2-yl 1-propenethiosulfinate, in which two of the three molecules of 1-propenesulfenic acid involved in the formation gave the thiolane backbone, and the third molecule gave the thiosulfinate structure. Of at least three stereoisomers observed, one in (2'R,3'R,4'R,5'R)-configuration was collected as an isolated fraction, and the other isomers were collected as a combined fraction because spontaneous tautomerization prevented further purification. Both fractions showed inhibitory activities against cyclooxygenase-1 (COX-1) and alpha -glucosidase in vitro.