Pseudoceranoids A-J, Sesquiterpene-Based Meroterpenoids with Cytotoxicity from the Sponge Pseudoceratina purpurea .

Pseudoceranoid A ( 1 ), a rare merosesquiterpene featuring a rearranged 4,9-friedodrimane-type core with a crotonolactone moiety, two new rearranged 4,9-friedodrimane-type sesquiterpene cyclopentanones ( 2 and 3 ), and three new rearranged 4,9-friedodrimane-type sesquiterpene hydroquinones ( 4 - 6 ), along with two new drimane-type sesquiterpene derivatives ( 7 and 8 ), as well as two new 4,9-friedodrimane-type sesquiterpene quinones ( 9 and 10 ), were isolated from the South China Sea sponge Pseudoceratina purpurea . The structures of compounds were established by analysis of spectroscopic data, as well as by single-crystal X-ray diffraction, DP4+ probability analyses, and calculated electronic circular dichroism. Compound 4 showed weak cytotoxicity against K562, H69AR, and MDAMB-231 cell lines with IC 50 values of 3.01, 7.74, and 9.82 μM, respectively. Compound 5 exhibited cytotoxicity against the H69AR cell line with an IC 50 value of 2.85 μM.