A new kalihinol diterpene from the Hainan sponge Acanthella sp

A new kalihinol diterpene, 10-epi-kalihinol X (1), together with two known related diterpenes (2 and 3), and two sesquiterpenes (4 and 5) were isolated from the Hainan sponge Acanthella sp. The structure of the new compound was elucidated on the basis of the detailed analysis of its spectroscopic data and by comparison of its NMR data with those of structurally related compounds. Compounds 1 and 3-5 exhibited in vitro moderate cytotoxicities against human lung adenocarcinoma cell line A549, with IC50 values of 9.30, 3.17, 2.44, and 1.98 microg/mL, respectively.