Unraveling the interaction of pyranocoumarins with P-glycoprotein: Implications for overcoming multidrug resistance in cancer therapy

This study aimed to investigate the antiproliferative activity and P-glycoprotein (P-gp) inhibitory potential of a series of novel pyranocoumarin derivatives. Compounds 4a-c and 4f-i showed the most potent activity against MCF-7 (breast cancer), MCF-7/ADR (human breast cancer cell) resistant to Adriamycin (ADR), and Caco-2 (colon carcinoma) cell lines compared to Sorafenib and Doxorubicin, while all the compounds 4a-i demonstrated week growth inhibitory impact toward two normal cell lines, HFL-1 and WI-38 with IC₅₀ values between 56.5 and 81.8 μM. Compounds 4b, 4g, and 4h, featuring trifluoromethyl, ethoxy, and benzyloxy substituents, demonstrated significant efficacy against P-glycoprotein-mediated multidrug resistance in MCF-7/ADR cells, with IC₅₀ values between 15.88 and 21.96 μM, outperforming Doxorubicin (IC₅₀ = 50.9 μM). Flow cytometric efflux assays confirmed increased intracellular accumulation of Rho123 in MCF-7/ADR cells treated with pyranocoumarin derivatives (4g, 4h). Mechanistic studies, including molecular docking and molecular dynamic (MD), leading to inhibition of P-glycoprotein (P-gp) function. Compound 4h exhibited the strongest binding affinity, and molecular dynamics simulations of the 4h-4ASD complex indicated a stable association with the binding site. These findings enhance our understanding of the binding mechanisms and potential functional implications of compound 4h's inhibition of P-glycoprotein.