Synthesis and biological evaluation of N(9)-substituted harmine derivatives as potential anticancer agents.

A series of N(9)-substituted harmine derivatives were synthesized and evaluated for their anticancer activity on a panel of cancer cell lines, their apoptosis induction and their cell cycle effects. The results showed that N(9)-substituted harmine derivatives had anticancer effects. In particular, N(9)-haloalkyl derivatives 9a-9c and N(9)-acyl harmine derivatives 11c and 11d, with IC50 values less than 1μM, were more potent than doxorubicin against A-549 and/or MCF-7 cell lines. Moreover, structure-activity relationships (SARs) indicated that introducing a haloalkyl or benzenesulfonyl group in the N(9)-position of harmine could significantly increase the anticancer activity. The most active compound (11d) caused cell cycle arrest in the G2/M phase, and induced cell apoptosis in a dose-dependent manner.