Rationale, in silico docking, ADMET profile, design, synthesis and cytotoxicity evaluations of phthalazine derivatives as VEGFR-2 inhibitors and apoptosis inducers

New phthalazine derivatives as vascular endothelial growth factor receptor-2 (VEGFR-2) inhibitors were synthesized joined to different spacers including pyrazole, α,β-unsaturated ketonic fragment, pyrimidinone and/or pyrimidinthione. A docking study was carried out to explore the suggested binding orientations of the novel derivatives inside the active site of VEGFR-2. The obtained biological data were extremely interrelated to that of the docking study. In particular, compounds 4b and 3e showed the highest activities against Michigan Cancer Foundation-7 (MCF-7) and Hepatocellular carcinoma G2 (HepG2) with half maximal inhibitory concentration (IC ) = 0.06, 0.06 μM and 0.08, 0.19 μM respectively. Our derivatives 3a-e, 4a,b and 5a,b were evaluated for their cytotoxicity against normal VERO cells. Our compounds exhibited low toxicity concerning normal VERO cells with IC = 3.00-4.75 μM. In addition, our final derivatives 3a-e, 4a, 4b, 5a and 5b were investigated for their VEGFR-2 inhibitory activities. Derivative 4b exhibited the highest VEGFR-2 inhibitory activities at an IC value of 0.09 ± 0.02 μM. Derivatives 3e, 4a and 5b demonstrated good activities with IC values = 0.12 ± 0.02, 0.15 ± 0.03 and 0.13 ± 0.03 μM respectively. Furthermore, the activities of 4b were assessed against MCF-7 cancer cells for apoptosis induction, cell cycle distribution and growth inhibition. Compound 4b caused cell growth arrest in growth 2-mitosis (G2-M) phase; accumulation of cells at that phase became 6.92% after being 13.2 in control cells. Moreover, our derivatives 3e, 4b and 5b revealed a good considered absorption, distribution, metabolism, excretion, and toxicity (ADMET) profile in comparison to sorafenib.