Jatropholane-Type Diterpenes from Euphorbia sikkimensis

Four new jatropholane-type diterpenes (1–4), named sikkimenoids A–D, were isolated from the aerial parts of Euphorbia sikkimensis. The structural elucidations of 1–4 were accomplished by extensive NMR analyses, and their absolute configurations were established by ECD calculations. Compound 2 exhibited weak antiangiogenic activity with an IC50 value of 43.0 μM when evaluated using a zebrafish model.