Elucidating the novel mechanism of organochlorine fungicides in inhibiting human and rat gonadal 3β-hydroxysteroid dehydrogenase via molecular docking and 3D-QSAR analysis

Organochlorine fungicides are widely used in agriculture and personal care products for their antimicrobial properties, but growing evidence suggests they may act as endocrine disruptors. This study investigated the inhibitory effects of seven organochlorine fungicides on 3β-hydroxysteroid dehydrogenase (3β-HSD) using in vitro assays, molecular docking, and 3D-QSAR analysis. Five fungicides significantly inhibited human 3β-HSD2 in KGN cells, with dichlone (DCN) being the most potent (IC 50 = 1.97 µM). In contrast, only four fungicides affected rat 3β-HSD1, with triclosan (TCS) exhibiting the strongest inhibition (IC 50 = 19.5 µM). Both human 3β-HSD2 and rat 3β-HSD1 were inhibited in a mixed manner, leading to reduced progesterone production in KGN cells. Molecular docking revealed interactions with the enzyme's steroid-active site. Inhibitory strength correlated with lipophilicity (LogP), topological polar surface area (tPSA), and binding energy (ΔG). Pharmacophore analysis identified hydrogen bond acceptor-lipid (HBA-lipid) and hydrophobic (HY) features as critical. These findings demonstrate that organochlorine fungicides disrupt gonadal steroidogenesis by inhibiting 3β-HSD, raising concerns about their potential adverse effects on reproductive health.