Title:The NOX1/4 Inhibitor GKT136901 as Selective and Direct Scavenger of Peroxynitrite
VOLUME: 21 ISSUE: 3
Author(s):S. Schildknecht, A. Weber, H. R. Gerding, R. Pape, M. Robotta, M. Drescher, A. Marquardt, A. Daiber, B. Ferger and M. Leist
Affiliation:University of Konstanz; PO Box M657; 78457 Konstanz, Germany.
Keywords:Alpha synuclein, GKT136901, LUHMES, NADPH oxidase, NOX, peroxynitrite.
Abstract:NADPH oxidases (NOX), catalyzing the reduction of molecular oxygen to form the superoxide radical anion
(•O2
-) and hydrogen peroxide (H2O2), are involved in several pathological conditions, such as stroke, diabetes, atherosclerosis,
but also in chronic neurodegenerative diseases such as Parkinson’s disease, Alzheimer’s disease, or multiple sclerosis.
GKT136901 is a novel NOX-1/4 inhibitor with potential application in the areas of diabetic nephropathy, stroke, or
neurodegeneration. In the present study, we investigated additional pharmacological activities of the compound with respect
to direct free radical scavenging. GKT136901 did not interact with nitric oxide (•NO), •O2
-, 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 pharmacological
property of the NOX-1/4 inhibitor GKT136901, and this may add to the efficiency of the drug in several disease
models.
