Euphopanes A-C, three new diterpenoids from Euphorbia pekinensis.

Three new diterpenoids, euphopanes A-C (1-3), including one ent-isopimarane (1), one ent-abietane (2) and one cembrane (3), along with five known compounds (4-8) were isolated from the roots of Euphorbia pekinensis. Their structures were elucidated by extensive spectroscopic analysis, and the absolute configurations of compounds 1-3 were determined by ECD calculations. All the isolates were screened for the cytotoxicity against three cancer cell lines (C4-2B, C42B/ENZR, and MDA-MB-231), and compounds 1, 2, and 4 showed significant cytotoxicity against human prostate cancer cells C4-2B with IC50 values of 14.3, 16.9, and 15.3 μM, respectively.