Sartrolides A–G and bissartrolide, new cembranolides from the South China Sea soft coral Sarcophyton trocheliophorum Marenzeller

The cembranolides sartrolides A–G (1–7) and the dimer bissartrolide (8) were isolated from Sarcophyton trocheliophorum Marenzeller, along with three known analogues (9–11). Their stereochemistry was elucidated by spectroscopic analysis (IR, UV, NMR) and Flack single crystal X-ray diffraction analysis (for sarcrassin D and emblide), applied for the first time to this class of compounds. Sartrolides A–G (1–7) include an α,β-unsaturated ɛ-lactone and differ for the pattern of functionalization at C-1/C-8 moiety, including the rare 1Z,3E-diene system in sartrolide G. Bissartrolide (8) is only the third example of cembrane dimer found as a natural product. The known cembranolide 11 showed significant antibacterial activity against Staphylococcus aureus Newman strain.