Cembrane-type diterpenoids from the South China Sea soft coral Sarcophyton mililatensis

摘要

Eight cembrane-type diterpenoids, namely,(t)-(6 R)-6-hydroxyisosarcophytoxide(1),(t)-(6 R)-6-acetoxyisosarcophytoxide(2),(t)-17-hydroxyisosarcophytoxide(3), sarcomililatins A–D(4–7), and sarcomililatol(8), were isolated from the soft coral Sarcophyton mililatensis collected from Weizhou Island, Guangxi Autonomous Region, together with 2 known related analogues,(t)-isosarcophytoxide(9) and(t)-isosarcophine(10). The structures of these compounds were elucidated by a combination of detailed spectroscopic analyses, chemical methods, and comparison with reported data.The absolute configuration of compound 1 was established by the modified Mosher's method, while the absolute configurations of compounds 4 and 5 were assigned by electronic circular dichroism(ECD)spectroscopy and that of compound 8 was established by time-dependent density functional theory electronic circular dichroism(TD-DFT ECD) calculation. In in vitro bioassays, compound 9 displayed significant cytotoxicity against the human cancer cell lines human promyelocytic leukemia cells(HL-60)and human lung adenocarcinoma cells(A-549) with IC_(50) values of 0.7870.21 and 1.2670.80 μmol/L,respectively. Compounds 4 and 9 also showed moderate inhibitory effects on the TNFα-induced Nuclear factor kappa B(NF-κB, a therapeutical target in cancer) activation, showing IC_(50) values of 35.23712.42 and 22.5274.44 μmol/L, respectively.