Diterpenes from the stem bark of Euphorbia neriifolia and their in vitro anti-HIV activity

Abstract Six previously undescribed diterpenoids, named euphorantins S–T and euphorneroids A–D, including ingol and ent -atisane types, along with eleven known diterpenoids, were isolated from Euphorbia neriifolia . Their structures were elucidated on the basis of extensive NMR analysis and high resolution mass spectrometry. Euphorneroid D and ent -3-oxoatisan-16 α ,17-acetonide exhibited moderate anti-HIV-1 activities, with EC 50 values of 34  μ M (SI = 2.3) and 24  μ M (SI = 1.9), respectively.