Two new ent-abietane diterpenoids from Euphorbia helioscopia

Two new ent-abietane diterpenoids, euphcopenoids A (1) and B (2), along with six known analogues (3 - 8), were isolated from the whole plants of Euphorbia helioscopia. Their structures were determined by various spectroscopic methods (MS, UV, IR, and NMR), and the absolute configurations of compounds 1 and 2 were determined by quantum chemical ECD calculations. All compounds were screened for the cytotoxicity against A549 and HEPG2 cancer cell lines, but were inactive.[Formula: see text].