Mechanism of Inhibition for N6022, a First-in-Class Drug Targeting S-Nitrosoglutathione Reductase

Abstract

N6022 is a novel, first-in-class drug with potent inhibitory activity against S-nitrosoglutathione reductase (GSNOR), an enzyme important in the metabolism of S-nitrosoglutathione (GSNO) and in the maintenance of nitric oxide (NO) homeostasis. Inhibition of GSNOR by N6022 and related compounds has shown safety and efficacy in animal models of asthma, chronic obstructive pulmonary disease, and inflammatory bowel disease [Sun, X., et al. (2011) ACS Med. Chem. Lett. 2, 402-406]. N6022 is currently in early phase clinical studies in humans. We show here that N6022 is a tight-binding, specific, and fully reversible inhibitor of GSNOR with an IC(50) of 8 nM and a K(i) of 2.5 nM. We accounted for the fact that the NAD(+)- and NADH-dependent oxidation and reduction reactions, catalyzed by GSNOR are bisubstrate in nature in our calculations. N6022 binds in the GSNO substrate binding pocket like a competitive inhibitor, although in kinetic assays it behaves with a mixed uncompetitive mode of inhibition (MOI) toward the GSNO substrate and a mixed competitive MOI toward the formaldehyde adduct, S-hydroxymethylglutathione (HMGSH). N6022 is uncompetitive with cofactors NAD(+) and NADH. The potency, specificity, and MOI of related GSNOR inhibitor compounds are also reported.

S-nitrosoglutathione reductase (GSNOR) inhibitor as an immune modulator in experimental autoimmune encephalomyelitis

“…In this study, we assessed the role of exogenous vs. endogenous GSNO in modulation of pro-inflammatory (T H 1 and T H 17) and anti-inflammatory (T H 2 and Treg) CD4 + T cells by treating EAE mice with exogenous GSNO as compared to inhibitor of GSNOR (N6022) for endogenous GSNO under EAE conditions. N6022 is a first-in-class very potent, specific, and reversible inhibitor of GSNOR [50]. N6022 has been found to be beneficial in animal models of experimental asthma [51], allergic airway inflammation [52] and endothelial vasodilatory dysfunction [53].…”

“…N6022 has been found to be beneficial in animal models of experimental asthma [51], allergic airway inflammation [52] and endothelial vasodilatory dysfunction [53]. In addition, safety of N6022 for human use is proven by Phase I and II studies for asthma and cystic fibrosis (ClinicalTrials.gov) [50]. In this study, we observed that overall effects of exogenously supplemented GSNO vs. endogenous generated GSNO by N6022-mediated inhibition of its degradation were similar in terms of attenuation of EAE disease with greater efficacy with N6022 than GSNO treatment.…”

S-Nitrosoglutathione Reductase: A Key Regulator of S-Nitrosylation in Plant Development and Stress Responses

“…100-times higher as compared to GSNO. The catalytic constant is about 10-times higher for GSNO reduction, but the catalytic efficiency is about 2 times higher for HMGSH (Hedberg et al 2003;Sanghani et al 2000;Green et al 2012).…”

“…Several new potent pyrrole-based GSNOR inhibitors including the compound N6022 have been described for the human enzyme (Sun et al 2011). The binding of N6022 includes an interaction of the propionic acid side chain of the inhibitor with all three residues forming the GSNOR anionic pocket (Green et al 2012). N6022 was found to inhibit tomato GSNOR at concentrations of 10 À7 M and thus represents an attractive tool for GSNOR inhibition studies in plants (Kubienová et al 2013).…”

Novel N‐(2,2′‐disubstituted‐2H‐cromenyl)‐N′,N″‐disubstituted Guanidine Derivatives as an S‐Nitrosoglutathion Reductase Inhibitor

“…A small-molecule inhibitor of GSNO reductase, N6022, has been developed and is now under clinical trials in patients with asthma. 9 Although N6022 demonstrated potent activity against GSNO reductase and acceptable safety profile in vivo, its oral bioavailability was very low, possibly due to the high polarity of the compound. 10 To address this deficiency, we ventured to discover distinct scaffolds that can be further elaborated to obtain inhibitors with the desired spectrum of inhibitory activities.…”