Chalcone analog-based 5-reductase 1 inhibition in neurosteroidogenesis: Mechanistic insights from integrated SPR binding, enzyme kinetics, 3D-QSAR, and docking.

This study systematically evaluates the inhibitory effects and mechanistic actions of chalcone and 10 chalcone analogs from herbs against human and rat 5α-reductase type 1 (5α-R1), a key enzyme in dihydrotestosterone biosynthesis (for neurosteroid and androgen biosynthesis). Screening of these chemicals identified licochalcone A as the most potent inhibitor (human IC50 = 4.08 μM; rat IC50 = 4.55 μM), displaying 5.15-fold higher binding affinity than the weakest analog (4-hydroxychalcone) via surface plasmon resonance. Michaelis-Menten kinetics revealed mixed inhibition, corroborated by intersecting Lineweaver-Burk plots. SPR competitive assay showed that 4-hydroxychalcone and licochalcone A competed with NADPH in cofactor binding site of human 5α-R1. Cellular assays confirmed licochalcone A's efficacy in suppressing dihydrotestosterone production (≥1 μM in SF-126 cells). Structure-activity relationship (SAR) analysis highlighted lipophilicity (logP), steric bulk (Vol, Sterimol B5), and heteroatom count as critical determinants of potency, validated by a 3D-QSAR pharmacophore model. Molecular docking localized chalcone binding to NADPH/testosterone interfacial sites, with licochalcone A forming hydrogen bonds (Asp169, Arg232) and hydrophobic interactions. ADMET profiling indicated favorable blood-brain barrier penetration but flagged hepatotoxicity for licochalcone A. These findings position licochalcone A as a lead compound for targeting 5α-R1 in neurosteroid/androgen-related disorders.