Mechanistic Insights into Polyphenols-mediated Squalene Epoxidase Inhibition: Computational Models and Experimental Validation for Targeting Cholesterol Biosynthesis.

Abstract

Squalene epoxidase is a key enzyme in sterol biosynthesis, particularly in cholesterol metabolism. Its inhibition has emerged as a promising therapeutic strategy for metabolic disorders, hypercholesterolemia, and certain infections. Herein, we investigated the SQLE inhibitory potential of six polyphenolic compounds, identified through in silico virtual screening of a large natural phenolic library and selected for high predicted binding affinity and structural diversity. Molecular docking demonstrated strong interactions between these candidates and SQLE, with curcumin exhibiting the highest binding affinity (-10.1 kcal/mol). Molecular dynamics simulations confirmed stable interactions for all compounds, highlighting curcumin, piceatannol, and pterostilbene as particularly favorable. Their strong binding free energies were further supported by MM/PBSA calculations (-36.62 ± 4.17, -31.32 ± 3.77, and -32.01 ± 1.34 kcal/mol, respectively), corroborated by free energy landscape analysis. ADMET profiling revealed diverse pharmacokinetic properties among the six polyphenolics. In vitro testing confirmed curcumin as the most potent inhibitor (IC₅₀ = 1.88 ± 0.21 µM), with piceatannol (2.55 ± 0.30 µM) and pterostilbene (2.69 ± 0.11 µM) following closely. Enzyme kinetics demonstrated that these three compounds act as competitive inhibitors targeting the enzyme's active site. Collectively, these findings highlight the combined power of computational and experimental approaches for identifying novel SQLE inhibitors.