Benzene ring bisphenol A substitutes potently inhibit human, rat, and mouse gonadal 3ß-hydroxysteroid dehydrogenases: Structure-activity relationship and in silico docking analysis.

Bisphenol A (BPA) is a chemical used in the production of certain plastics and resins. Recent research has found that BPA can inhibit the activity of 3ß-hydroxysteroid dehydrogenase/Δ5,4-isomerases (3ß-HSDs). Whether benzene ring BPA substitutes can inhibit human, rat, and mouse gonadal 3ß-HSDs, the structure-activity relationship and the underlying mechanism remain unclear. In this study, we compared 6 benzene ring BPA substitutes to BPA in the inhibition of human, rat, and mouse gonadal 3ß-HSDs and conducted structure-activity relationship and in silico docking analysis. The inhibitory activity (IC50) of human 3ß-HSD2 in KGN cells ranged from about 0.02 µM for bisphenol H to 8.75 µM for BPA, that of rat 3ß-HSD1 in testicular microsomes ranged from 0.099 µM for bisphenol H to 31.32 µM for BPA, and that of mouse 3ß-HSD6 ranged from 0.021 µM for BPH to ineffectiveness for 100 µM BPA. These compounds acted as mixed inhibitors with LogP inversely correlated with IC50 and ΔG positively correlated with IC50 value. Docking analysis showed that these compounds bind to the steroid active site of the 3ß-HSD enzymes. In conclusion, some benzene ring BPA substitutes potently inhibit gonadal 3ß-HSD in various species, and lipophilicity and binding affinity determine their inhibitory strength.

Structure-activity relationship and docking analysis of nature flavonoids as inhibitors of human and rat gonadal 3ß-hydroxysteroid dehydrogenases for therapeutic purposes.

The potential inhibitory effects of flavonoids on gonadal steroid biosynthesis have gained attention due to their widespread presence in natural plant sources. Specifically, our study focused on evaluating the inhibitory efficacy of these compounds on human 3ß-hydroxysteroid dehydrogenase 2 (h3ß-HSD2) and rat homolog r3ß-HSD1, enzymes responsible for the conversion of pregnenolone to progesterone. Through our investigations, we observed that the potency of flavonoids was silymarin (IC50, 1.31 µM) > luteolin (4.63 µM) > tectorigenin > (5.86 µM), and rutin (44.12 µM) in inhibiting human KGN cell microsomal h3ß-HSD2. Similarly, the potency of flavonoids was silymarin (9.50 µM) > luteolin (11.49 µM) > tectorigenin (14.06 µM), and rutin (145.71 µM) in inhibiting rat testicular r3ß-HSD1. Silymarin, luteolin, and tectorigenin acted as mixed inhibitors of both human and rat 3ß-HSDs. Luteolin and tectorigenin were able to penetrate human KGN cells to inhibit progesterone secretion. Furthermore, docking analysis and structure-activity relationship analysis highlighted the importance of hydrogen bond formation for the inhibitory efficacy of these compounds against h3ß-HSD2 and r3ß-HSD1. Overall, this study demonstrates that silymarin exhibits the most potent inhibition of human and rat gonadal 3ß-HSDs, and significant SAR differences exist among the tested compounds.