KLYP956 is a non-imidazole-based orally active inhibitor of nitric-oxide synthase dimerization.
Nitric-oxide synthases (NOS) generate nitric oxide (NO) through the oxidation of l-arginine. Inappropriate or excessive production of NO by NOS is associated with the pathophysiology of various disease states. Efforts to treat these disorders by developing arginine mimetic, substrate-competitive NOS inhibitors as drugs have met with little success. Small-molecule-mediated inhibition of NOS dimerization represents an intriguing alternative to substrate-competitive inhibition. An ultra-high-throughput cell-based screen of 880,000 small molecules identified a novel quinolinone with inducible NOS (iNOS) inhibitory activity. Exploratory chemistry based on this initial screening hit resulted in the synthesis of KLYP956, which inhibits iNOS at low nanomolar concentrations. The iNOS inhibitory potency of KLYP956 is insensitive to changes in concentrations of the substrate arginine, or the cofactor tetrahydrobiopterin. Mechanistic analysis suggests that KLYP956 binds the oxygenase domain in the vicinity of the active site heme and inhibits iNOS and neuronal NOS (nNOS) by preventing the formation of enzymatically active dimers. Oral administration of KLYP956 [N-(3-chlorophenyl)-N-((8-fluoro-2-oxo-1,2-dihydroquinolin-4-yl)methyl)-4-methylthiazole-5-carboxamide] inhibits iNOS activity in a murine model of endotoxemia and blocks pain behaviors in a formalin model of nociception. KLYP956 thus represents the first nonimidazole-based inhibitor of iNOS and nNOS dimerization and provides a novel pharmaceutical alternative to previously described substrate competitive inhibitors.
Department of Biology, Kalypsys Inc, San Diego, CA, USA.
Kent T
KT
Symons
Mark E
ME
Massari
Phan M
PM
Nguyen
Tom T
TT
Lee
Jeffrey
J
Roppe
Céline
C
Bonnefous
Joseph E
JE
Payne
Nicholas D
ND
Smith
Stewart A
SA
Noble
Marciano
M
Sablad
Natasha
N
Rozenkrants
Yan
Y
Zhang
Tadimeti S
TS
Rao
Andrew K
AK
Shiau
Christian A
CA
Hassig
D000284:Administration, Oral; D000818:Animals; D002478:Cells, Cultured; D019281:Dimerization; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D024841:Fluoroquinolones / Q000494:pharmacology*; D006801:Humans; D051379:Mice; D009569:Nitric Oxide / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000737:chemistry; D052248:Nitric Oxide Synthase Type I / Q000737:chemistry; D052247:Nitric Oxide Synthase Type II / Q000737:chemistry; D010146:Pain / Q000188:drug therapy; D013045:Species Specificity; D013844:Thiazoles / Q000494:pharmacology*
D004791:Enzyme Inhibitors; D024841:Fluoroquinolones; C542108:N-(3-chlorophenyl)-N-((8-fluoro-2-oxo-1,2-dihydroquinolin-4-yl)methyl)-4-methylthiazole-5-carboxamide; D013844:Thiazoles; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II