Targeted suppression of oral squamous cell carcinoma by pyrimidine-tethered quinoxaline derivatives†

Oral cancer (OC) stands as a prominent cause of global mortality. Despite numerous efforts in recent decades, the efficacy of novel therapies to extend the lifespan of OC patients remains disappointingly low. Consequently, the demand for innovative therapeutic agents has become all the more pressing. In this context, we present our work on the design and synthesis of twenty-five novel quinoxaline-tethered imidazopyri(mi)dine derivatives. This was followed by comprehensive investigations into the impact of these molecules on the OC cell line. The in vitro cytotoxicity studies performed in CAL-27 and normal oral epithelial (NOE) cell lines revealed that some of the synthesized molecules like 12d have potent antiproliferative activity specifically towards OC cells with an IC₅₀ of 0.79 μM and show negligible cytotoxicity over NOE cells. Further, 12d arrested cell growth in the S phase of the cell cycle and induced cell death by early apoptosis. The in silico studies validated that 12d binds to the activator binding site on pyruvate kinase M2 (PKM2) overexpressed in OC while the lactate dehydrogenase (LDH)-coupled enzyme assay established 12d as a potent PKM2 activator with an AC₅₀ of 0.6 nM. Hence, this study provides fruitful evidence for the designed compounds as anticancer agents against OC.