抄録
Larvae of the wild bruchid seed beetle Bruchidius dorsalis infest dry mature seeds of the Japanese honey locust Gleditsia japonica. In the course of our continuing search for biologically active compounds from natural sources, we found that the CHCl_3 extract of the larvae of B. dorsalis exhibited radical scavenging activity. The CHC13 extract was subjected to silica gel column chromatography and ODS HPLC to afford six active compounds designated dorsamin-A761 (1), -A763 (2), -A737 (3), -A765 (4), -A739 (5), and -A767 (6). The structures of dorsamin-As (1-6) were determined to be new glycerol derivatives by interpretation of ELMS, (+)APCIMS, IR, UV, and NMR spectral data. Absolute configuration of dorsamin-As were determined as follows: the 1,2-diacylglycerols obtained after hydrolysis of dorsamin-As were converted into 1,2-diacylglycerol-3-0-TBDMS derivatives. The CD spectrum of the derivatives consisted with that of the authentic sample derived from 1,2-dioleyl-sn-glycerol, revealing the absolute configuration of dorsamin-As. Consequently, the structures of dorsamin-As were elucidated to be 1,2-dioleyl-sn-glycero-3- dehydrophenylalanine esters. The fatty acid composition of dorsamin-As was also determined by the analysis of the fragment ions observed in the EIMS. Although several naturally occurring compounds with dehydroamino acids have been reported, most of them are peptides. There are very few, if any, glycerol derivatives having a dehydroamino acid ester. Dorsamin-As exhibited ABTS radical scavenging activity.
