New oxadiazoles with selective-COX-2 and EGFR dual inhibitory activity: Design, synthesis, cytotoxicity evaluation and in silico studies.

Novel heterocyclic oxadiazoles viz. 2-subsituted-5-(4-pyridyl)-1,3,4-oxadiazoles, 2-subsituted-5-(3-pyridyl)-1,3,4-oxadiazoles and 2-subsituted-5-(phenyl or 4-chlorophenyl-1,3,4-oxadiazoles) were designed and synthesized as potential anticancer agents. In this investigation, all compounds were evaluated for their COX-1 and COX-2 inhibitory activity in vitro as new therapeutic approaches assumed cytotoxic effect associated with selective COX-2 inhibition. Results showed that most of the derivatives demonstrated inhibition towards both isoforms of COX comparable to the standard reference drugs indomethacin, diclofenac sodium and celecoxib. Then, nine selected compounds (IIId, VIb, VIIc, IX, XI, XIIa, XIVa, XVIb and XVIIIb) were subjected to cytotoxic screening against UO-31 renal cancer cell line using MTT assay. Compounds IIId, IX and XIIa displayed promising behavior by showing good anticancer activity. Moreover, kinase inhibitory assay against the tyrosine kinase EGFR was performed for the three compounds showing the highest cytotoxic activity. The tested compounds were potent against EGFR with the highest activity being observed for compound IX showing nearly double the potency of the reference drug Erlotinib. Moreover, molecular docking and molecular dynamics were performed for IIId, IX and XIIa against EGFR, in an attempt to elucidate a model for their binding at the molecular level, simulate and understand the possible binding interactions underlying the association between these small molecules and the kinase enzyme ATP binding pocket essential amino acids. Finally, in silico pharmacokinetic profile predication was investigated for IIId, IX and XIIIa using SWISS/ADME to identify the most promising small-molecule cytotoxic agent on the basis of displaying the best drug-like properties. Results indicated that compound IX has a potential to serve as a lead compound for developing novel anticancer therapeutic agents.