Design, synthesis, and apoptotic antiproliferative activity of novel dihydropyrimidine-5-carbonitrile/1,2,4-oxadiazole hybrids as dual EGFR/VEGFR-2 inhibitors endowed with antioxidant activity

Abstract

A new series of dihydropyrimidine-5-carbonitrile/1,2,4-oxadiazole hybrids (10a–l) was developed as dual inhibitors of EGFR and VEGFR-2. The structures of the newly synthesized compounds were confirmed using ¹H NMR, ¹³C NMR, and elemental analysis. The novel compounds were evaluated for their antioxidant and antiproliferative apoptotic characteristics. Compounds 10e, 10k, and 10l demonstrated the most potent antiproliferative activity and exhibited more efficacy than the reference erlotinib against both Panc-1 (pancreatic) and MCF-7 (breast) cancer cell lines. Compounds 10k and 10l exhibited the highest potency as EGFR and VEGFR-2 inhibitors, with IC₅₀ values of 57 nM and 61 nM against EGFR, respectively, and IC₅₀ values of 21 nM and 26 nM for VEGFR-2, respectively. Moreover, compounds 10k and 10l demonstrated promising apoptotic activity through the overexpression of caspases-3, 8, and 9, as well as Bax and p53, and the downregulation of the anti-apoptotic protein Bcl-2. Additionally, compounds 10k and 10l exhibited notable antioxidant activity at 10 μM, demonstrating DPPH radical scavenging rates of 72.5% and 69.8%, respectively. An integrated computational study was conducted to validate the dual kinase inhibitory potential of compound 10k and 10i against EGFR and VEGFR-2. Compound 10k and 10i established strong hydrogen bonds with Met769 in EGFR and Glu885 in VEGFR-2, achieving interaction energies of −8.21 and −7.42 kcal mol⁻¹, respectively. Molecular dynamics simulations over 100 ns confirmed that the 10k–kinase complexes remained highly stable, showing minimal conformational fluctuations throughout the simulation. Compound 10i also exhibited stable dynamics and favorable interactions; however, 10k consistently maintained stable binding conformations. These results highlight 10k as the most dynamically stable and potent dual EGFR/VEGFR-2 inhibitor in the series. DFT analysis revealed a moderate HOMO–LUMO gap (3.86 eV), chemical hardness (1.93 eV), and a dipole moment of 6.4 debye, which correlates with favorable reactivity and polarity for kinase engagement. ADME profiling highlighted drug-likeness, acceptable bioavailability, and selective CYP inhibition. Altogether, these findings validate 10k as a promising dual EGFR/VEGFR-2 inhibitor with strong structural and pharmacokinetic potential.