Cyclomyrsinane and premyrsinane diterpenes from Euphorbia sogdiana Popov

Three new (1-3) cyclomyrsinane diterpenes and three new (7-9) premyrsinane diterpenes were isolated from the aerial parts of Euphorbia sogdiana Popov. Their chemical structures and relative configurations were elucidated by spectroscopic analysis, including HRESIMS and 1D and 2D NMR techniques. The compounds are hexa- and penta-esters of two diterpene polyol skeletons, esterified with aliphatic (acetic, propanoic, isobutanoic, tiglic and methyltiglic) and aromatic (benzoic and nicotinic) acids. Three known cyclomyrsinane diterpenes (4-6), previously reported from Euphorbia tehranica (4 and 6) and Euphorbia aellenii (5), were also isolated. These structures, based on cyclomyrsinane and premyrsinane skeleta, are very rare and could be considered as taxonomic marker of the Euphorbia genus. The isolated compounds together with myrsinane (10) and tigliane (11), first reported from E. aellenii and isolated previously from this plant, were subjected to preliminary tests to evaluate cytotoxic activity against EJ-138 bladder carcinoma and Jurkat T-leukemia cells. (C) 2016 Published by Elsevier Ltd.