Briarellins J−P and Polyanthellin A: New Eunicellin-Based Diterpenes from the Gorgonian Coral <i>Briareum polyanthes</i> and Their Antimalarial Activity

Abstract

A new chemical study of the hexane extract of the gorgonian Briareum polyanthes collected in Puerto Rico afforded 10 new diterpenes of the eunicellin class, briarellins 1−9 and polyanthellin A (10), along with the known diterpene briarellin D (11). The structures and relative stereochemistry of metabolites 1−10 were assigned on the basis of NMR studies, chemical methods, and comparisons to the spectral properties of 11. A reassessment of prior structural assignment for briarellin A and two known sclerophytin-type diterpenes, 13 and 14, is proposed. Antimalarial tests on 1−6 and 8−12 indicated that they were active against Plasmodium falciparum.