Inhibition of soluble epoxide hydrolase by steroidal metabolites from the starfish Patiria pectinifera: Integrated enzyme kinetic and computational studies.

Soluble epoxide hydrolase (sEH) is a promising therapeutic target for inflammation-related disorders; however, current synthetic inhibitors are limited due to pharmacokinetic constraints. Marine steroidal metabolites offer a potential source of natural sEH inhibitors. Therefore, this study aims to investigate the sEH inhibitory activity of compounds isolated from the starfish Patiria pectinifera. Six steroidal compounds (1-6) were isolated and evaluated using enzymatic assays, kinetic analysis, molecular docking, and molecular dynamics simulations. Compounds 1 and 2 demonstrated potent sEH inhibition (IC50 = 16.10 ± 2.43 μM and 4.13 ± 1.24 μM, respectively), while compounds 3-6 were inactive. Kinetic studies showed mixed-type inhibition, with lower Kis than Ki values, indicating preferential binding to the enzyme-substrate complex. Computational analyses revealed that compounds 1 and 2 bind to distinct sites within the C-terminal domain with higher affinity than that of the native substrate, inducing conformational changes consistent with allosteric modulation. These findings indicate compounds 1 and 2 as promising allosteric sEH inhibitors, highlighting the potential of P. pectinifera steroids as anti-inflammatory agents.