Polyoxygenated anti-inflammatory biscembranoids from the soft coral Sarcophyton tortuosum and their stereochemistry

Abstract Five novel biscembranoids, ximaolides H–L (1–5), along with four known related compounds (6–9) were isolated from the Hainan soft coral Sarcophyton tortuosum. The structures of the new compounds were determined by extensive spectroscopic analysis, quantum chemical calculations, and/or by comparing their CD spectra with those of the known compounds. Compounds 1 and 2 are the first examples of biscembranoids bearing a 1, 35-bridged lactone moiety, 4 is the first biscembranoid comprising an uncommon oxetane ring, and 5 represents the first 36-peroxyl biscembranoid. Ximaolides I (2), K (4), and F (9) exhibited interesting anti-inflammatory activity by the inhibition of LPS-induced TNF-α protein release in RAW264.7 macrophages.