Almost half of all medicines approved by the U.S. Food and Drug Administration have been found to be developed based on inspiration from natural products (NPs). Here, we report a novel strategy of scaffold overlaying of scaffold-hopped analogs of bioactive flavones and isoflavones and installation of drug-privileged motifs, which has led to discovery of anticancer agents that surpass the functional efficiency of the original NPs. The analogs, 2,3-diaryl-pyridopyrimidin-4-imine/ones were efficiently synthesized by an approach of a nitrile-stabilized quaternary ammonium ylide as masked synthon and Pd-catalyzed activation–arylation methods. Compared to the NPs, these NP-analogs exhibited differentiated functions; dual inhibition of human topoisomerase-II (hTopo-II) enzyme and tubulin polymerization, and pronounced antiproliferative effect against various cancer cell lines, including numerous drug-resistant cancer cells. The most active compound 5l displayed significant inhibition of migration ability of cancer cells and blocked G1/S phase transition in cell cycle. Compound 5l caused pronounced effect in expression patterns of various key cell cycle regulatory proteins; up-regulation of apoptotic proteins, Bax, Caspase 3 and p53, and down-regulation of apoptosis-inhibiting proteins, BcL-xL, Cyclin D1, Cyclin E1 and NF-κB, which indicates high efficiency of the molecule 5l in apoptosis-signal axis interfering potential. Cheminformatics analysis revealed that 2,3-diaryl-pyridopyrimidin-4-imine/ones occupy a distinctive drug-relevant chemical space that is seldom represented by natural products and good physicochemical, ADMET and pharmacokinetic-relevant profile. Together, the anticancer potential of the investigated analogs was found to be much more efficient compared to the original natural products and two anticancer drugs, Etoposide (hTopo-II inhibitor) and 5-Flurouracile (5-FU).
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