5-Alkylresorcinol Derivatives from the Bryozoan Schizomavella mamillata : Isolation, Synthesis, and Antioxidant Activity

摘要

The chemical study of the bryozoan Schizomavella mamillata has led to the isolation of six new 5-alkylresorcinol derivatives, schizols A?￠????F ( 1 ?￠???? 6 ), whose structures were established by spectrocospic means. Schizol A ( 1 ) exhibits a ( E )-6-phenylnon-5-enyl moiety linked to the C-5 of a resorcinol ring, while in schizol B ( 2 ) the substituent at C-5 contains an unusual 1,2-dihydrocyclobutabenzene moiety. Schizols C ( 3 ) and D ( 4 ) have been characterized as the 1-sulfate derivatives of 1 and 2 , respectively, and schizols E ( 5 ) and F ( 6 ) are the corresponding 1,3-disulfates. Schizol A ( 1 ) has been synthetized from 3,5-dimethoxybenzaldehyde through a sequence involving a Wittig reaction for the construction of the C-1?￠???2,C-2?￠???2 bond and a Julia?￠????Kocienski olefination for the synthesis of the C-5?￠???2,C-6?￠???2 double bond. In the ABTS (2,2?￠???2-azinobis(3-ethylbenzothiazoline-6-sulphonic acid)) antioxidant assay, the natural compounds schizol A ( 1 ) and schizol B ( 2 ) showed higher radical scavenging activity than the Trolox standard.