# A novel inhibitor of soluble epoxide hydrolase that adducts C521 is cardioprotective

## TL;DR

A new compound called RLC14 protects the heart from injury during blood flow restoration by inhibiting a specific enzyme through a key cysteine residue.

## Contribution

RLC14 is a novel, potent inhibitor of sEH that adducts to C521 and provides cardioprotection during ischemia-reperfusion.

## Key findings

- RLC14 reduced infarction in wild-type hearts but not in C521S knock-in mice.
- RLC14 increased the EET/DHET ratio in plasma, indicating sEH inhibition.
- Mass spectrometry confirmed RLC14 adducts to C521 in sEH.

## Abstract

The lipid electrophile nitro-oleic acid (NO2-OA) and inhibitors of soluble epoxide hydrolase (sEH) limit injury during myocardial ischemia and reperfusion (IR). We investigated if cardioprotection by NO2-OA was mediated by inhibitory adduction of this electrophile to C521 of the hydrolase. Indeed, administering NO2-OA to wild type (WT) isolated perfused hearts prior to IR limited infarction, but this protection was absent in C521S sEH knock-in (KI) mice - demonstrating the critical importance of this cysteine. To identify more potent and selective inhibitors, we screened a library of electrophiles for their ability to inhibit sEH. A compound, we termed RLC14, had an IC50 of 6.8x10−9 M and protected WT, but not KI, isolated hearts from infarction during IR. Systemic administration of RLC14 decreased myocardial sEH activity and increased plasma EET/DHET ratio selectively in WT mice, consistent with inhibition of the hydrolase. In line with these findings, RLC14 protected WT, but not KI, mice from in vivo coronary artery ligation IR-induced infarction. Mass spectrometry analyses showed the novel electrophilic inhibitor, RLC14, which contains a disulfide, adducts to C521 in sEH to mediate its effects. This study identifies RLC14 as a potent cardioprotective agent that limits IR injury through C521-dependent hydrolase inhibition.