A novel series of 3-alkyl-substituted 7-phenyl-3H-pyrrolo[3,2-f]quinolin-9-ones (7-PPyQs) was synthesized with the aim to optimize the cytotoxic activity of recently identified PPyQs, promising inhibitors of tubulin polymerization. All compounds inhibited the growth of 11 human tumor cell lines at submicromolar concentrations as well as two human resistant cancer sublines, A549-T12 and A549-T24. FACS analysis indicated that all compounds caused significant arrest of the A549 cell cycle in G2/M phase at 0.1 and 1 muM and a good correlation between the cytotoxicity IC50 and their ability to block the cell cycle was observed.