Terpenes from Euphorbia antiquorum and Their in Vitro Anti-HIV Activity

Three new compounds (1 - 3), including two euphane type triterpenes, 24,24-dimethoxy-25,26,27-trinoreuphan-3β-ol (1) and (24S)-24-hydroperoxyeupha-8,25-dien-3β-ol (2), and an ent-atisine diterpene, ent-atisane-3α,16α,17-triol (3), were isolated from an acetone extract of the stems of Euphorbia antiquorum, together with eight known diterpenes (4 - 11). The structures of compounds (1 - 11) were elucidated using NMR and MS spectroscopic methods. Compound 7 showed moderate activity against HIV-1 replication in vitro (EC₅₀ = 1.38 μm).