The NOX1/4 Inhibitor GKT136901 as Selective and Direct Scavenger of Peroxynitrite

S. Schildknecht, A. Weber, H. Gerding, R. Pape, M. Robotta, M. Drescher, A. Marquardt, A. Daiber, B. Ferger, M. Leist
2013 Current Medicinal Chemistry  
NADPH oxidases (NOX), catalyzing the reduction of molecular oxygen to form the superoxide radical anion ( • O 2 -) and hydrogen peroxide (H 2 O 2 ), are involved in several pathological conditions, such as stroke, diabetes, atheroscle rosis, but also in chronic neurodegenerative diseases such as Parkinson's disease, Alzheimer's disease, or multiple sclero sis. GKT136901 is a novel NOX 1/4 inhibitor with potential application in the areas of diabetic nephropathy, stroke, or neurodegeneration. In
more » ... urodegeneration. In the present study, we investigated additional pharmacological activities of the compound with re spect to direct free radical scavenging. GKT136901 did not interact with nitric oxide ( • NO), • O 2 -, or hydroxyl radicals ( • OH), but it acted as selective scavenger of peroxynitrite (PON) already in the submicromolar concentration range. Alpha synuclein (ASYN) is a protein involved in the pathogenesis of Parkinson's disease and a known target for PON dependent tyrosine nitration. Submicromolar concentrations of GKT136901 prevented tyrosine nitration and di tyrosine dependent dimer formation of ASYN by PON as indicated by Western blot and mass spectrometric analysis. GKT136901 itself was degraded when exposed to PON. In a human neuronal cell model, GKT136901 prevented both the depletion of reduced intracellular glutathione, and the degeneration of neurites when present during PON treatment of the cells. When GKT136901 was applied after PON treatment, no protective effect was observed, thus excluding an impact of GKT136901 on cellular death/survival pathways. In summary, selective scavenging of PON is an additional pharmacol ogical property of the NOX 1/4 inhibitor GKT136901, and this may add to the efficiency of the drug in several disease models. NO alone, • OH and • NO 2 represent highly reactive free radical species, capable of attacking proteins, lipids, and DNA. Nitration of tyrosine residues in proteins is predominantly mediated by the • NO 2 radical. Selective inhibitors for the different NOS and NOX isoforms are expected to prevent oxidative damage under pathological conditions. While selective NOS-2 inhibitors such as AMT (2-Amino-5,6-dihydro-6-methyl-4H-1,3-thiazine) are
doi:10.2174/09298673113209990179 pmid:23848532 fatcat:l22uyrwwyvcupnu5sjuimjow3q