Two new lanostane triterpenoids from the branches and leaves of Polyalthia oblique.

Two new lanostane triterpenoids, 20-hydroxyeuphorbol-7-one (1) and 15α-hydroxyeuphorbol-7,11-dione (2), together with four known triterpenoids, euphorbol-7-one (3), friedelin (4), stigmast-4-ene-6α-ol-3-one (5), stigmasta-4-en-3,6-dione (6), were isolated from ethanol extract of the branches and leaves of Polyalthia obliqua. The structures of 1 and 2 were elucidated on the basis of extensive spectroscopic analysis and comparisons with related known compounds. Antibacterial activities of two new compounds and four known compounds were tested.