Five new furanobutenolide-derived C 19 -norcembranoid diterpenes, sinudenoids A−E (1−5, respectively), were isolated from the soft coral Sinularia densa. Sinudenoid A (1) possesses an uncommon 5/5/11-fused tricyclic ring system. Sinudenoids B−D (2−4, respectively) share the same tetracyclic 5/5/6/6 ring system but represent two kinds of new skeletons. Sinudenoid E ( 5) is the second compound with the rare 8/8 bicyclic carbon core. A plausible biosynthesis pathway for compounds 1−6 is proposed. Compound 5 exhibits strong antiinflammatory activity in the zebrafish model.

Five new cembranes, named sarcoeleganolides C–G (1–5), along with three known analogs (6–8) were isolated from soft coral Sarcophyton elegans collected from the Yagong Island, South China Sea. Their structures and absolute configurations were determined by extensive spectroscopic analysis, QM-NMR, and TDDFT-ECD calculations. In addition, compound 3 exhibited better anti-inflammation activity compared to the indomethacin as a positive control in zebrafish at 20 μM.

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