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Six 6-chlorine-containing briarane analogues, including two new compounds, briarenols U (1) and V (2), as well as four known metabolites, solenolides B (3) and E (4); briaexcavatolide E (5); and brianolide (6) were isolated from an octocoral identified as Briareum stechei. The structures of compounds 1–6 were elucidated by using spectroscopic methods, and the stereochemistry of solenolide B (3) was revised. The absolute configuration of 6 was further determined by a single-crystal X-ray diffraction analysis. Briarane 1 was found to induce significant in vitro inflammatory activity in LPS-induced RAW264.7 macrophage cells by enhancing the expression of iNOS and COX-2 protein.

Chemical examination of Briareum excavatum, collected in the waters of Taiwan, led to the isolation of four briarane diterpenoids, including three known compounds, briarenol G (1), briaviolides Y (2), and Z (3), as well as a new metabolite, briarenol L (4). The absolute configuration of 1 was determined by a single-crystal X-ray diffraction analysis for the first time in this study and the structure of 4 was established on the basis of spectroscopic analysis. Briaranes 2 and 3 exerted inhibition effects on COX-2 and iNOS, respectively, release from RAW 264.7 macrophages.

Two known briarane diterpenoids, excavatolide C (1) and briacavatolide C (5), along with three new polyoxygenated analogues, briarenols F–H (2–4), have been isolated from the supercritical CO2 extraction of an octocoral identified as Briareum excavatum. The absolute configuration of 1 was determined by a single-crystal X-ray diffraction analysis for the first time and the structures of 2–5 were established by spectroscopic methods. Bioactivity study showed that briaranes 1, 4 and 5 showed inhibition effects on iNOS release from RAW264.7.