Design, synthesis, molecular simulation, and biological activities of novel quinazolinone-pyrimidine hybrid derivatives as dipeptidyl peptidase-4 inhibitors and anticancer agents

Two novel series of quinazolinone–pyrimidine (series a: 9a–9i) and benzyl-pyrimidine hybrids (series b: 12a–12c) were designed, synthesized and characterized by spectroscopic methods. The dipeptidyl peptidase-4 inhibition potencies of these compounds were assessed through a MAK 203 kit. Compound 9e was found to be the most potent agent with an IC50 value of 34.3 ± 3.3 μM. A kinetic study revealed that it acted as a competitive inhibitor. Molecular modeling of these compounds was in agreement with the in vitro results. Due to the crucial role of dipeptidyl peptidase-4 in cancer therapy, the cytotoxic activities of the compounds were also evaluated against three cancerous cell lines (HT-29, SW1116 and A549). Almost all the compounds displayed better antiproliferative activity on colon cancer cell lines (HT-29 and SW1116) compared to a lung cancer cell line (A549). Compounds 9e and 12c exhibited significant activity toward the HT-29 cell line with an IC50 of 10.67 ± 0.3 μM and 27.9 ± 6.5 μM in comparison to sitagliptin and cisplatin as a positive control, respectively. Among the different cells, the compounds showed the best inhibitory effects on HT-29, which was compatible with the greater expression of the dipeptidyl peptidase-4 marker detected by flow cytometry in this cell line. Further studies on the hit compounds (9e and 12c) through cell cycle and apoptosis assays also showed that these compounds could induce cell death by apoptosis or arrest cells in the G2/M phase. Accordingly, the results imply that 9e is a potent inhibitor of dipeptidyl peptidase-4 with efficient anti-cancer activity and could play a role as a cytotoxic agent in colorectal cancer.