Briaviolides K–N, New Briarane-Type Diterpenoids from Cultured Octocoral Briareum violaceum

Abstract

Four new briarane diterpenoids, briaviolides K-N (<b>1</b>-<b>4</b>), have been obtained from the cultured-type octocoral <i>Briareum violaceum</i>. Using a spectroscopic approach, the structures of briaranes <b>1</b>-<b>4</b> were identified. This study employed an in vitro model of lipopolysaccharide (LPS)-induced inflammation in the murine macrophage RAW 264.7 cell line, and found that among the four briaranes, briarane <b>2</b> possessed anti-inflammatory activity against inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein expressions in cells. In addition, principal component analysis using the chemical global positioning system (ChemGPS) for natural products (ChemGPS-NP) was employed in order to analyze the structure-activity relationship (SAR), and the results indicated that the ring conformation of the compound has a leading role in suppressing the expressions of pro-inflammatory iNOS and COX-2 proteins in macrophages.