Identification of xenobiotics interfering with 5α-reductase (SRD5A2) activity.

5α-Dihydroxytestosterone (DHT) is essential for male sexual development, and its synthesis from testosterone is mediated by the steroid 5α-reductase (SRD5A) isoenzymes, SRD5A1 and SRD5A2. SRD5A2 is the predominant isoform expressed in reproductive organs. Disruption of SRD5A2 activity can significantly lower the available DHT concentration in human reproductive organs and cause complications during development. Hence, unintentional inhibition of this enzyme should be avoided. This study aimed to establish an in silico/in vitro approach to identify potential inhibitors of SRD5A2 through virtual screening. Therefore, we generated an ensemble of minimized SRD5A2 receptor conformational states using molecular dynamics simulations, and applied consensus docking with a validation set to select the most representative structure. Next, compounds from various databases were docked to the selected protein structure and their binding poses were evaluated through an automated protocol. The selected potential inhibitors were then tested in an enzyme activity assay, revealing that the androgen receptor modulator MK-0773 is a moderate SRD5A2 inhibitor with an IC value of 1.70 ±0.54μM. Quantum-mechanical calculations suggested, however, that MK-0773 does not act as a covalent inhibitor, as observed for the structurally similar known inhibitor finasteride. These findings improve our understanding of the SRD5A2-ligand interactions. Lastly, our in silico/in vitro approach can be used to identify new SRD5A2 inhibitors.