New molecular hybrids integrated with quinoxaline and pyrazole structural motifs: VGFR2 inhibitors and apoptosis inducers.

The vascular endothelial growth factor receptor is essential for the angiogenesis of cancer. Tumor propagation was effectively suppressed by inhibiting VEGFR-2 activity. As a result, the target quinoxaline-pyrazole hybrids were created in a way that closely resembled the structural characteristics of VEGFR-2 inhibitors. The synthesized compounds were assessed in vitro using the MTT assay with doxorubicin serving as a reference standard for their cytotoxic properties against the HCT-116 and MCF-7 cell lines. Additionally, when tested on human normal fibroblasts (WI38), the promising cytotoxic compounds 8, 11, 13, and 15 were shown to be selective to cancer cells. Using ELISA, they showed mechanistically inhibitory activities against VEGFR-2; compound 13 was the most effective inhibitor, with an IC50 of 0.045 ± 6.24 uM, surpassing sorafenib (IC50 of 0.049 ± 5.24 μM). Notably, it was discovered that our target compound, 13, was 1.1 times more potent than sorafenib and 3.19 times more potent than sunitinib as a VGFRA2 inhibitor. Furthermore, Western blot analysis revealed that its VEGFR2 protein levels were noticeably higher than the control. Compound 13's selectivity towards VEGFR2 was further confirmed by testing it against other kinases, such as PDGFRA (IC50 0.329 ± 0.014 μM) and EGFR (IC50 0.6 ± 0.019 μM). Furthermore, 13 demonstrated a 50 % decrease in VEGF-A secretion in comparison to the control group, demonstrating its anti-angiogenic quality. A scratch closure percentage of 57.78 %, which was much lower than the 97.04 percent of untreated control cells, showed 13's anti-migratory capability. According to the cell cycle study, compound 13 induces apoptosis at the sub-G1 phase and terminates the cell cycle at the G1 phase. Consequently,flow cytometric analysis revealed that it caused apoptosis; compound 13 increases the BAX/Bcl-2 ratio from control to 13.66, and it also activates caspase 3 to 422.48 ± 43.82 and induces p53 to 366.79 ± 40.21. Docking simulations revealed potential binding modes and crucial structural elements of active drugs, and they were almost in agreement with enzymatic examination. For every hybrid, in silico physicochemical attributes, drug likeness metrics, and ligand efficiency were plausible. It's interesting to note that 13 and 15 are plausible medication candidates.