A series of novel 2-substituted indoline imidazolium salt derivatives has been prepared and evaluated in vitro against a panel of human tumor cell lines. The results suggest that the existence of a substituted benzimidazole ring and substitution of the imidazolyl-3-position with a naphthylacyl or 2-naphthylmethyl group were vital for modulating the cytotoxic activity. Compound 25 was found to be the most potent derivative with IC50 values of 0.24-1.18 mu M, and exhibited cytotoxic activity selectively against MCF-7, SW480, SMMC-7721 and HL-60 cell lines, while compound 26 showed powerful inhibitory activities selectively against SMMC-7721 and A549 cell lines. Compound 25 can induce G2/M phase cell cycle arrest and apoptosis in SMMC-7721 cells.
