Three new diterpenoids from the roots of Euphorbia fischeriana and their cytotoxicity

Euphorbiabietane F (1), a novel abietane diterpenoid with the unprecedented 6/6/5/6/5 carbon skeleton, one new strobane diterpenoid (2), together with one new pimarane diterpenoid (3) were isolated from the roots of Euphorbia fischeriana. The structures were elucidated by the extensive spectroscopic data, gauge-independent atomic orbital (GIAO) NMR calculations, the comparison of experimental and calculated ECD spectra, as well as single crystal X-ray diffraction. The cytotoxicity result suggested the moderate inhibition rate of 1 on the cell lines of HepG2 and A549.