Design, synthesis, and antitumor evaluation of quinoline-imidazole derivatives.

A series of compounds bearing quinoline-imidazole (8a-e, 9a-e, 10a-e, 11a-e, and 12a-e) not reported previously were designed and synthesized. The target compounds were evaluated for antitumor activity against A549, PC-3, HepG2, and MCF-7 cells by the MTT method, with NVP-BEZ235 being the positive control. Most compounds showed moderate activity and compound 12a showed the best activity against HepG2, A549, and PC-3 cells, with half-maximal inhibitory concentration (IC50 ) values of 2.42 ± 1.02 µM, 6.29 ± 0.99 µM, and 5.11 ± 1.00 µM, respectively, which was equal to NVP-BEZ235 (0.54 ± 0.13 µM, 0.36 ± 0.06 µM, 0.20 ± 0.01 µM). Besides, the IC50 value of 12a against the cell line WI-38 (human fetal lung fibroblasts) was 32.8 ± 1.23 µM, indicating that the target compounds were selective for cancer cells. So, 11a and 12a were evaluated against PI3Kα and mTOR to find out if the compounds acted through the PI3K-Akt-mTOR signal transduction pathway. The inhibition ratios to PI3Kα and mTOR were slightly lower than that of NVP-BEZ235, suggesting there may be some other mechanisms of action. The structure-activity relationships and docking study of 11a and 12a revealed that the latter was superior. Moreover, the target compounds showed better in vitro anticancer activity when the C-6 of the quinoline ring was replaced by a bromine atom.