Isogosterones A−D, Antifouling 13,17-<i>Seco</i>steroids from an Octocoral <i>Dendronephthya</i> sp.

Abstract

Four antifouling secosteroids named isogosterones A−D (1−4) have been isolated from a Japanese octocoral Dendronephthya sp. Their structures were elucidated on the basis of spectroscopic data as 12α-acetoxy-13,17-seco-cholesta-1,4-dien-3-ones possessing a hemiacetal or acetal functionality. Isogosterones inhibited larval settlement of the barnacle Balanus amphitrite with an EC50 value of 2.2 μg/mL.