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

The chemical study of the bryozoan has led to the isolation of six new 5-alkylresorcinol derivatives, schizols A-F (-), whose structures were established by spectrocospic means. Schizol A () exhibits a ()-6-phenylnon-5-enyl moiety linked to the C-5 of a resorcinol ring, while in schizol B () the substituent at C-5 contains an unusual 1,2-dihydrocyclobutabenzene moiety. Schizols C () and D () have been characterized as the 1-sulfate derivatives of and , respectively, and schizols E () and F () are the corresponding 1,3-disulfates. Schizol A () 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 () and schizol B () showed higher radical scavenging activity than the Trolox standard.