A novel series of 2-(benzimidazol-2-yl)quinoxalines with
three
types of pharmacophore groups, namely, piperazine, piperidine, and
morpholine moieties, which are part of known antitumor drugs, was
designed and synthesized. The compounds have been characterized by
NMR and IR spectroscopy, high- and low-resolution mass spectrometry,
and X-ray crystallography. 2-(Benzimidazol-2-yl)quinoxalines with N-methylpiperazine substituents showed promising activity
against a wide range of cancer lines, without causing hemolysis and
showing little cytotoxicity against normal human Wi-38 cells (human
fetal lung). A mixture of regioisomers 2-(benzimidazol-2-yl)-3-(4-fluorophenyl)-6(and
7)-(4-methylpiperazin-1-yl)quinoxalines (mri
BIQ 13da/14da) showed a highly selective cytotoxic
effect against human lung adenocarcinoma (cell line A549) with a half-maximal
inhibitory concentration at the level of doxorubicin with a selectivity
index of 12. The data obtained by flow cytometry, fluorescence microscopy,
and multiparametric fluorescence analysis suggested that the mechanism
of the cytotoxic effect of the mri
BIQ 13da/14da on A549 cells may be associated with the stopping
of the cell cycle in phase S and inhibition of DNA synthesis as well
as with the induction of mithochondrial apoptosis. Thus, mri
BIQ 13da/14da can be considered as a leading
compound deserving further study, optimization, and development as
a new anticancer agent.