Chemical examination of the Taiwanese soft coral Sinularia flexibilis led to the
isolation of five cembrane-based diterpenoids 1–5, including two new metabolites,
11-acetylsinuflexolide (1) and 11-acetyldihydrosinuflexolide (2). The structures of the new
metabolites were determined based on extensive spectroscopic analysis, particularly mass
spectrometry and 2D NMR (1H–1H COSY, HMQC, HMBC, and NOESY) spectroscopy.
Metabolites 1, 3 and 4 exhibited moderate to weak cytotoxicity to human tumor cell lines,
HeLa, HEp-2, MCF-7 and MDA-MB-231.
