Knema is a genus of tropical evergreen trees of the family Myristicaceae found in South East Asian countries such as Vietnam, Thailand, and Malaysia. In this paper, four lignans, (+)-pinoresinol (1),(+) epi-pinoresinol (2), piperitol (3), and pluviatilol (4), were isolated from the ethyl acetate extract of the fruit of Knema pachycarpa, an indigenus tree in Vietnam. The chemical structures were determined by spectroscopic data and comparison with the reported literature. These compounds were isolated from Knema genus for the first time.

A new azaoxoaporphine alkaloid, 8,9-dimethoxysampangine (1), and a new naphthyridine alkaloid, 7-methoxy-8-hydroxyeupolauridine (2), along with two known azaoxoaporphine alkaloids, sampangine (3) and 9-methoxysampangine (4), were isolated from the EtOAc extract of the barks of Polyalthia nemoralis. Their structures were established on the basis of spectral evidences. Compound 1 exhibited significant cytotoxicity against KB, MCF7, LU-1, HepG2, LNCap, SW626 and SW480 cancer cell lines with IC 50 values in the range of 5.060.04-7.610.06 M.