Synthesis and evaluation of potent novel inhibitors of human sulfide:quinone oxidoreductase

Here we report the first small-molecule inhibitors of human sulfide:quinone oxidoreductase (SQOR) that decrease the rate of breakdown of hydrogen sulfide (H(2)S), a potent cardioprotective signaling molecule. SQOR is a mitochondrial membrane-bound protein that catalyzes a two-electron oxidation of H(2)S to sulfane sulfur (S(0)), using glutathione (or sulfite) and coenzyme Q (CoQ) as S(0) and electron acceptor, respectively. Inhibition of SQOR may constitute a new approach for the treatment of heart failure with reduced ejection fraction. Starting from top hits identified in a high-throughput screen, we conducted SAR development guided by docking of lead candidates into our crystal structure of SQOR. We identified potent SQOR inhibitors such as 19 which has an IC(50) of 29 nM for SQOR inhibition and favorable pharmacokinetic and ADME properties required for in vivo efficacy testing.