Two New Isonakafurans from the Great Barrier Reef Sponge Dysidea sp. nov.

Abstract

Two new sesquiterpenes, the furan Δ^7,14-isonakafuran-9 (11) and the autoxidized derivative (12), were isolated from the sponge Dysidea sp. nov. collected from One Tree Island on the Great Barrier Reef. The structures of the two new sesquiterpenes, which both contain a bicyclo[4.3.1]decane skeleton, were deduced by use of one- and two-dimensional n.m.r. spectroscopy, in particular by n.O.e. and HMBC experiments. Compound (11) is isomeric with nakafuran-9 (6) while the hydroperoxide derivative (12) was subjected to X-ray crystallographic analysis to confirm its relative stereochemistry at C1 and C11. Both metabolites have growth inhibitory activity against the P₃₈₈ cell line, while the hydroperoxide derivative (12) is also inhibitory to the marine fungus Trichophyton mentagrophytes.