Background: Cancer is the second leading cause of mortality worldwide after heart diseases, and lung
cancer is the topmost cause of all cancer-related deaths in both sexes. Dihydropyrimidinones (DHPMs) are medicinally
important class of molecules with diverse pharmacological activities including anticancer activity. The present
study focuses on the molecular hybridization of novel Benzopyran with Dihydropyrimidinone and evaluation of the
resulting hybrids for cancer cell proliferation, migration and tumor growth.
Methods: We have synthesized a focused library of dihydropyrimidinone benzopyran hybrids (compounds 1 - 11) by
joining the aromatic as well as pyran portions of the benzopyran core with dihydropyrimidinone. All the synthesized
hybrid molecules were evaluated for their cytotoxic activities against a panel of four human cancer cell lines of diverse
tissue origin, viz: A549 (lung carcinoma), MCF7 (mammary gland adenocarcinoma), HCT-116 (colorectal
carcinoma), and PANC-1 (pancreatic duct carcinoma) with the help of MTT cell viability assay. A structure-activity
relationship was made on the basis of IC50 values of different hybrids. Effect on cell proliferation was examined
through colony formation assay, reactive oxygen species generation and mitochondrial membrane potential studies.
Wound healing assays and cell scattering assays were employed to check the effect on cell migration. Western blotting
experiments were performed to find out the molecular mechanism of action and anti-tumor studies were carried
out to evaluate the in vivo efficacy of the selected lead molecule.
Results: Two types of novel hybrids were synthesized efficiently from benzopyran aldehydes, ethylacetoacetate and
urea under heteropolyacid catalysis. Compound 3 was found to be the most potent hybrid among the synthesized
compounds with consistent cytotoxic activities against four human cancer cell lines (IC50 values: 0.139 - 2.32 μM).
Compound 3 strongly inhibited proliferation abilities of A549 cells in colony formation assay. Compound 3 exerted
oxidative stress-mediated mitochondrial dysfunction, in which mitochondrial reactive oxygen species (ROS) generation
as a mechanism of its anti-proliferative effects was analysed. Further, the molecule abrogated migration and cell
scattering properties of aggressive PANC-1 cells. Mechanistic studies revealed that compound 3 modulated NF-kB
expression and its downstream oncogenic proteins involved in cancer cell proliferation and invasion. Finally, compound
3 confirmed its in vivo anti-tumor efficacy; there observed 41.87% tumor growth inhibition at a dose of 30
mg/kg/body weight against a mouse model of Ehrlich solid tumor.
Conclusion: Our study unravels a potential anticancer lead (compound 3) from DHPMs that have opened up new
research avenues for the development of promising anticancer therapeutic agents.