Triterpenoid alkaloids from Buxus microphylla.

Two new triterpenoid alkaloids, buxmicrophyllines J and K (1 and 2, resp.), together with four analogues, 3-6, were isolated from the leaves and stems of Buxus microphylla. The structures of the new compounds were elucidated by NMR and MS spectroscopic analyses. The partial assignments of the NMR spectra of 3 were also revised. Compounds 1 and 3-6 were evaluated for their growth inhibitory activity against human cell lines HL-60, SMMC-7721, A-549, SK-BR-3, and PANC-1. Compound 6 showed significant cytotoxicity against HL-60, SK-BR-3, and PANC-1 cell lines, with IC(50) values of 6.46, 19.61, and 28.57 microM, respectively.