Flexibilins A–C, New Cembrane-Type Diterpenoids from the Formosan Soft Coral, Sinularia flexibilis

Abstract

Three new cembrane-type diterpenoids, flexibilins A–C (1–3), along with a known cembrane, (−)-sandensolide (4), were isolated from the soft coral, Sinularia flexibilis. The structures of cembranes 1–4 were elucidated by spectroscopic methods. The structure of 4, including its absolute stereochemistry, was further confirmed by single-crystal X-ray diffraction analysis. Cembrane 2 displayed a moderate inhibitory effect on the release of elastase by human neutrophils.

Keywords

• cembrane
• diterpenoid
• Sinularia flexibilis
• elastase