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′,C-2′ bond and a Julia–Kocienski olefination for the synthesis of the C-5′,C-6′ double bond. In the ABTS (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.