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.