Cyclozonarone, a sesquiterpene-substituted benzoquinone derivative from the brown alga Dictyopteris undulata

Abstract A new sesquiterpene-substituted benzoquinone derivative, which we have named cyclozonarone, has been isolated from the brown alga Dictyopteris undulata collected in ‘Isoyake areas’. Its structure was determined on the basis of spectroscopic evidence. Cyclozonarone showed potent feeding-deterrent activity toward young abalones.