Species-specific inhibition of human and rat aromatase by mycotoxins: Integrated enzyme assays, docking, and structure-activity relationship analysis.

In placental tissue, human and rat aromatases convert testosterone to estradiol, which was prioritized for investigation over others due to its susceptibility to endocrine disruption by mycotoxins, yet their effects remain unclear. The objective of this study is to investigate the effects of mycotoxins on human and rat aromatase, including inhibition strength, mechanism, and structural-activity relationships (SAR). Screening was conducted to evaluate mycotoxin inhibition using placental microsomes by HPLC-MS/MS. IC50 and Ki values were determined as well as effects on estradiol secretion in human BeWo cells were examined. SAR and 3D quantitative SAR and in silico docking were also performed. The inhibitory strength against human aromatase ranked the order: deoxynivalenol (IC50, 8.78 μM) > patulin (11.66 μM) > β-zearalenol (32.82 μM) > α-zearalenol (34.12 μM) > zearalenone (42.69 μM), and that for rat aromatase ranked deoxynivalenol (IC50, 9.78 μM) > patulin (10.16 μM) > β-zearalenol (16.36 μM) > α-zearalenol (17.14 μM) > β-zearalanol (17.28 μM) > zearalenone (19.31 μM). These mycotoxins exert mixed/noncompetitive inhibition on both enzymes. In BeWo cells, α-zearalenol and β-zearalenol inhibited estradiol output at ≥1 μM, while zearalenone inhibited it at 100 μM. Lipophilicity was negatively correlated with inhibitory potency. A 3D-QSAR pharmacophore showed hydrogen bond features. Docking analyses indicated hydrogen bonds with Met374 and Arg115 of human aromatase. Molecular dynamics simulations investigate the interaction between aromatase and mycotoxins, focusing on the stability and conformational changes within the aromatase -mycotoxins complex. Overall, mycotoxins have selective and varying inhibitory effects on aromatase in humans and rats.