Oleanane triterpenoids from Rubia philippinensis and their inhibitory effect on 20-HETE synthesis

A new oleanane triterpenoid (2) was isolated from the roots of Rubia philippinensis. The structure of 2 was determined by analysis of HRMS and NMR data and identified as a rubiprasin analogue, 16 beta-hydroxyrubiprasin B. Four related known compounds were also encountered which include rubiprasin B (1), maslinic acid (3), 4-epi-hederagenin (4) and oleanolic acid (5). The compounds 3-5 displayed moderate inhibitory activity against the synthesis of the eicosanoid 20-HETE. [GRAPHICS] .