Synthesis of novel pyridine and pyrazolyl pyridine conjugates with potent cytotoxicity against HepG2 cancer cells as PIM-1 kinase inhibitors and caspase activators

Abstract

A novel series of nicotinonitrile and pyrazolyl nicotinonitrile were synthesized, and their PIM-1 kinase inhibitors and caspase activators were investigated. New Manich bases 6-8 were synthesized <i>via</i> reaction of pyridine 4 with piperidine, dimethyl amine, and morpholine in the presence of formalin. On the other hand, the pyrazolyl analogues 10-12 were synthesized <i>via</i> heterocyclization of acetohydrazide derivative 9 with acetylacetone, malononitrile, and ethyl cyanoacetate, respectively, in ethanol. The cytotoxic activity of compound 9 against MCF-7 and HepG2 cells was particularly noteworthy, with IC₅₀ values of 0.34 μM and 0.18 μM, respectively, among these derivatives. Compared to staurosporine with potent PIM-1 kinase inhibition, which had an IC₅₀ value of 16.7 nM and an inhibition of 95.6%, compound 9 had a strong inhibitory effect, with IC₅₀ values of 20.4 nM and 93.8%. It induced apoptosis activity in HepG2 cancer cells. Accordingly, compound 9 was proven to be an effective chemotherapeutic drug that targets PIM-1 in treating liver cancer.