Synthesis of novel bioactive pyrido[2,3- <i>d</i> ]pyrimidine derivatives with potent cytotoxicity through apoptosis as PIM-1 kinase inhibitors

Abstract

Direct synthesis and cytotoxicity activity of new series of pyrido[2,3-<i>d</i>]pyrimidine was described. Nicotinamide 2 was synthesized <i>via</i> cyclization of <i>N</i>-cyclohexyl derivative with cyanoacetamide. The <i>o</i>-aminonicotinonitrile 2 was subjected to acylation or thio acylation process followed by intramolecular heterocyclization to afford the desired pyrido[2,3-<i>d</i>]pyrimidine (3-10) and pyrido triazine 11. Compounds 4 and 11 exhibited remarkable cytotoxicity against MCF-7 cells with IC₅₀ values of 0.57 μM and 1.31 μM and IC₅₀ values of 1.13 μM and 0.99 μM against HepG2 cells. Interestingly, compounds 4 and 10 had potent PIM-1 kinase inhibition with IC₅₀ values of 11.4 and 17.2 nM, respectively, with inhibition of 97.8% and 94.6% compared to staurosporine (IC₅₀ = 16.7 nM, with 95.6% inhibition). Moreover, compound 4 significantly activated apoptosis in MCF-7 cells, increasing the cell apoptosis by 58.29-fold by having 36.14% total apoptosis in treated cells compared to 0.62% for control. Moreover, it arrested the cell cycle at the G1 phase. PIM-1 kinase inhibition was virtually elucidated by the molecular docking study, highlighting binding interactions of the lead compound 4 towards the PIM-1 protein. Accordingly, compound 4 was validated as a promising PIM-1 targeted chemotherapeutic agent to treat breast cancer.