Secondary metabolites and cytotoxic activities from the stem bark of Zanthoxylum nitidum.

A dihydrobenzo[c]phenanthridine alkaloid, epizanthocadinanine A (1), together with 27 known compounds, including eight benzo[c]phenanthridines, i.e., oxynitidine (2), oxyavicine (3), oxychelerythrine (4), dihydrochelerythrine (5), 6-acetonyldihydrochelerythrine (6), norchelerythrine (7), decarine (8), and arnottianamide (9); two 2-quinolones, i.e., flindersine (10) and 4-methoxy-1-methyl-2-quinolone (11); two furoquinolines, i.e., skimmianine (12) and gamma-fagarine (13); three aporphines, i.e., liriodenine (14), N-acetyldehydroanonaine (15), and N-acetylanonaine (16); six lignans, i.e., sesamin (17), episesamin (18), piperitol-3,3-dimethylallyl ether (19), xanthoxylol-3,3-dimethylallyl ether (20), savinin (21), and 2,3-bis(3,4-methylenedioxybenzyl)but-2-en-4-olide (22); three terpenoids, i.e., alpha-cadinol (23), anticopalol (24), and spathulenol (25); one coumarin, i.e., aesculetin dimethyl ether (26); and two steroids, i.e., beta-sitosterol (27) and beta-sitostenone (28) were isolated from the stem bark of Zanthoxylum nitidum. Their structures were elucidated on the basis of extensive 1D- and 2D-NMR as well as MS analyses. Moreover, the recently reported structures 2'-4' of rhoifolines B and A, and '8-methoxynorchelerythrine', resp., isolated as new compounds from Z. rhoifolium and Z. nitidum, resp., could be assigned the revised structures 2-4 by reinvestigation of the spectroscopic data. In addition, the cytotoxicity of the isolates was evaluated on the MCF-7, NCI-H460, and SF-268 cell lines. Among these isolates, liriodenine (14) was the most active compound against the MCF-7, NCI-H460, and SF-268 cell lines with IC(50) values of 2.19, 2.38, and 3.19 microg/ml, resp.