Design, synthesis and biological evaluation of novel thieno[3,2-d] pyrimidine and quinazoline derivatives as potent antitumor agents

Four series of novel thieno[3,2-d] pyrimidine and quinazoline derivatives containing N-acylhydrazone or semi-carbazone were designed, synthesized, and evaluated for their biological activity. Of which compound 14 showed the most potent antitumor activities with IC50 values of 1.78 mu M, 1.02 mu M, 1.98 mu M, 0.41 mu M and 0.22 mu M against HT-29, MDA-MB-231, U87MG, PC-3 and HCT-116 cell lines respectively. Inhibition of enzymatic assays showed that PI3K alpha was very likely to be one of the drug targets of 14 with the IC50 value of 0.20 mu M. According to the results of antitumor activity, the SARs were summarized, which indicated that thieno [3,2-d] pyrimidine and semicarbazone are optimal fragments. In addition, compounds with hydroxyl group at the 4-position on the terminal phenyl ring were more active. Annexin-V and propidium iodide (PI) double staining confirmed that the most active cytotoxic compound 14 can induce cell apoptosis in HCT-116 cells. Moreover, the influence of 14 on the cell cycle distribution was assessed on the HCT-116 cell line, exhibiting a cell cycle arrest at the G2/M phase. Furthermore, molecular docking analysis was also performed to determine possible binding modes between PI3K alpha and the target compound. These results will guide us to further refine the structure of the thieno[3,2-d] pyrimidine and quinazoline derivatives to achieve optimal antitumor activity.