In vitro and in silico evaluation of 4'-hydroxy-[1,1'-biphenyl]-4-carbohydrazide Schiff base and oxadiazole derivatives targeting EGFR allosteric site

Inhibition of EGFR tyrosine kinase (TK) activity is considered a promising therapeutic strategy for cancer treatment. Type I and II EGFR TK inhibitors bind the ATP-binding site, while type III and IV inhibitors target an allosterically sensitive pocket proximal to the ATP-binding site present in a variety of kinases. The current work aimed to synthesize new biphenyl-containing derivatives that were predicted to act as EGFR tyrosine kinase allosteric site inhibitors based on molecular docking studies. A novel series of 4'-hydroxy-[1,1'-biphenyl]-4-carbohydrazide derivatives (W3–W15) were synthesized and characterized using infrared, ¹HNMR, and ¹³CNMR spectroscopy, and high-resolution mass spectrometry. Compound W4 had a favorable pharmacophore-fit score suggesting that it may have biological activity similar to the reference 6DUK (EGFR with bound allosteric inhibitor). Compound W4 exhibited a favorable ΔG score against EGFR TK allosteric site indicating a high likelihood of compound-receptor complex formation, and it was predicted to be non-carcinogenic and non-irritant. Compounds W3–W7 demonstrated selective cytotoxicity towards the A549 lung cancer cell line as compared to the other two cell lines investigated (HCT-116 colorectal and HeLa cervical cancer cells). Compound W4’s IC₅₀ value against A549 cancer cells (0.4 µM) was 20-fold lower than Erlotinib’s (7.3 µM). Finally, compound W4 targeted EGFR TK in the A549 cell line, causing cell cycle arrest at the G2/M phase and activating the extrinsic apoptotic pathway. In conclusion, compound W4 is a promising EGFR tyrosine kinase allosteric inhibitor that is worthy of further investigation.

Graphical Abstract