A novel class of pyrazole analogues as aurora kinase A inhibitor: design, synthesis, and anticancer evaluation.

Pyrazole, as a small molecule, was discovered for higher cytotoxicity and affinity towards Aurora-A kinase. Based on these facts, a novel pyrazole substituted at the 4 position was designed, synthesized, and evaluated against MCF-7, MDA-MB-23, and Vero (non-cancerous kidney cell) cell lines. Compounds5hand5eexhibited greater cytotoxicity in the series against MCF-7 and MDA-MB-231, with GI values of 0.12 µM and 0.63 µM, respectively, as compared to Imatinib (GI values of 16.08 µM and 10.36 µM). All of the compounds displayed selective cytotoxicity against cancer cells but not on normal Vero cells, supporting the design strategy to be a selective anticancer agent. Furthermore, compounds 5h and 5e inhibited Aurora-A kinase with IC values of 0.78 µM (4.70-fold) and 1.12 µM (2.84-fold), respectively, as compared to alisertib (IC = 3.36 µM). In addition, compound 5h significantly arrested the cell cycle at G2/M (34.89 %, 5.56-fold) and the apoptotic phase (25.04 %, 11.81-fold) compared to the control. It also triggered an increase in early (7.43 %) and late (14.89 %) phase apoptosis compared to vehicle (0.235 and 0.36 %, respectively), causing 37.89-fold higher total apoptosis in the annexin-V assay. These data imply that Aurora-A kinase inhibition may be linked to apoptosis induction and cell cycle arrest. Furthermore, their higher docking score in the study confirmed evidence of Aurora-kinase suppression. It was observed that fluorine and imidazole increased the H-bond and lipophilic interactions with the binding residue. Also, the substitution of electron-rich and lipophilic groups increased hydrophobic interactions. Moreover, the three-atom linkage (CHNHCH) expanded compound 5h to fill the cavity. Based on current findings, it is concluded that compounds 5h and 5e with strong Aurora-A kinase suppression may be promising anticancer agents.