New diterpenoids from the stems of Euphorbia antiquorum growing in Vietnam

Phytochemical analysis of Euphorbia antiquorum stem extracts afforded two new ent-atisane compounds, ent-3a-acetoxy16b,17,18-trihydroxyatisane (1) and ent-3a,14,16b,17-tetrahydroxyatisane (2) together with three known compounds, 20-deoxy-16- hydroxyingenol (3), ent-14[S],16a,17-trihydroxyatisan-3-one (4), and agallochaol C (5). Their structures were elucidated by spectroscopic data analysis and comparison with published NMR data. Compounds 1–5 were evaluated for a-glucosidase inhibition and cytotoxicity. Compounds 1, 4, and 5 revealed significant inhibitory activity against a-glucosidase with the IC50 values of 119.9, 135.5, and 134.3 mM, respectively. None showed activity in cytotoxicity assay