Chemical constituents from the aerial parts of Euphorbia sikkimensis and their bioactivities

Phytochemical investigation of the aerial parts of Euphorbia sikkimensis led to the isolation of one new diterpenoids, named sikkimenoid E ( 1 ), together with thirteen other known compounds ( 2–14 ). Their structures were established by means of spectroscopic methods. Compound 2 was identified to be a trinortriterpenoid, and derived for the first time from a natural source. In this paper we reveal for the first time its comprehensive spectral data and NMR spectral assignment. Compound 4 showed antiangiogenic activity with an IC 50 value of 5.66 µM in a zebrafish model, and compounds 5 and 6 exhibited cytotoxicity toward A549 cell line with IC 50 values of 12.12 and 6.45 µM, respectively.