Bioactive Diterpenoid Containing a Reversible “Spring-Loaded” (E,Z)-dieneone Michael Acceptor

Three new briarane diterpenoids, briareolate esters L – N (1 – 3) have been isolated from a gorgonian Briareum asbestinum. Briareolate esters L (1) and M (2) are the first natural products possessing a 10-membered macrocyclic ring with a (E,Z)-dieneone and exhibit growth inhibition activity against both human embryonic stem cells (BG02) and a pancreatic cancer cell line (BxPC-3). Briareolate ester L (1), was found to contain a “spring-loaded” (E,Z)-dieneone Michael acceptor group that can form a reversible covalent bond to model sulfur-based nucleophiles.