ABSTRACT
We disclose herein our efforts aimed at discovery of selective PARP-1 and PARP-2 inhibitors. We have recently discovered several novel classes of quinazolinones, quinazolidinones, and quinoxalines as potent PARP-1 inhibitors, which may represent attractive therapeutic candidates. In PARP enzyme assays using recombinant PARP-1 and PARP-2, the quinazolinone derivatives displayed relatively high selectivity for PARP-1 and quinoxaline derivatives showed superior selectivity for PARP-2, and the quinazolidinone derivatives did not have selectivity for PARP-1/2. Structure-based drug design analysis via a combination of X-ray structural study utilizing the complexes of inhibitors and human PARP-1 catalytic domain, and homology modeling using murine PARP-2 suggested distinct interactions of inhibitors with PARP-1 and PARP-2. These findings provide a new structural framework for the design of selective inhibitors for PARP-1 and PARP-2.
Subject(s)
Enzyme Inhibitors/chemical synthesis , Poly(ADP-ribose) Polymerase Inhibitors , Quinazolines/chemical synthesis , Quinoxalines/chemical synthesis , Binding Sites , Catalytic Domain , Enzyme Inhibitors/pharmacology , Humans , Models, Chemical , Models, Molecular , Poly (ADP-Ribose) Polymerase-1 , Poly(ADP-ribose) Polymerases , Quinazolines/pharmacology , Quinoxalines/pharmacology , Structure-Activity RelationshipABSTRACT
Two classes of quinazolinone derivatives and quinoxaline derivatives were identified as potent and selective poly(ADP-ribose) polymerase-1 and 2 (PARP-1) and (PARP-2) inhibitors, respectively. In PARP enzyme assays using recombinant PARP-1 and PARP-2, quinazolinone derivatives displayed relatively high selectivity for PARP-1 and quinoxaline derivatives showed superior selectivity for PARP-2. SBDD analysis via a combination of X-ray structural study and homology modeling suggested distinct interactions of inhibitors with PARP-1 and PARP-2. These findings provide a new structural framework for the design of selective inhibitors for PARP-1 and PARP-2.
Subject(s)
Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Poly(ADP-ribose) Polymerase Inhibitors , Quinazolines/chemistry , Quinazolines/pharmacology , Quinoxalines/chemistry , Quinoxalines/pharmacology , Crystallography, X-Ray , Humans , Models, Molecular , Molecular Structure , Poly(ADP-ribose) Polymerases/chemistry , Poly(ADP-ribose) Polymerases/metabolism , Protein Conformation , Structure-Activity RelationshipABSTRACT
A novel class of quinazolinone derivatives as potent poly(ADP-ribose)polymerase-1 (PARP-1) inhibitors has been discovered. Key to success was application of a rational discovery strategy involving structure-based design, combinatorial chemistry, and classical SAR for improvement of potency and bioavailability. The new inhibitors were shown to bind to the nicotinamide-ribose binding site (NI site) and the adenosine-ribose binding site (AD site) of NAD+.
Subject(s)
Blood-Brain Barrier/metabolism , Poly(ADP-ribose) Polymerase Inhibitors , Quinazolines/chemical synthesis , Administration, Oral , Animals , Biological Availability , Brain/metabolism , Catalytic Domain , Combinatorial Chemistry Techniques , Dogs , Humans , In Vitro Techniques , Mice , Mice, Inbred C57BL , Microsomes, Liver/metabolism , Models, Molecular , Parkinsonian Disorders/drug therapy , Parkinsonian Disorders/pathology , Poly(ADP-ribose) Polymerases/chemistry , Quinazolines/chemistry , Quinazolines/pharmacokinetics , Rats , Structure-Activity RelationshipABSTRACT
The activation of poly(ADP-ribose) polymerase-1 (PARP-1) after exposure to nitric oxide or oxygen-free radicals can lead to cell injury via severe, irreversible depletion of NAD. Genetic deletion or pharmacological inhibition of PARP-1 attenuates brain injury after focal ischemia and neurotoxicity in several neurodegenerative models in animals. FR247304 (5-chloro-2-[3-(4-phenyl-3,6-dihydro-1(2H)-pyridinyl)propyl]-4(3H)-quinazolinone) is a novel PARP-1 inhibitor that has recently been identified through structure-based drug design. In an enzyme kinetic analysis, FR247304 exhibits potent and competitive inhibition of PARP-1 activity, with a K(i) value of 35 nM. Here, we show that prevention of PARP activation by FR247304 treatment protects against both reactive oxygen species-induced PC12 cell injury in vitro and ischemic brain injury in vivo. In cell death model, treatment with FR247304 (10(-8)-10(-5) M) significantly reduced NAD depletion by PARP-1 inhibition and attenuated cell death after hydrogen peroxide (100 microM) exposure. After 90 min of middle cerebral artery occlusion in rats, poly(ADP-ribosy)lation and NAD depletion were markedly increased in the cortex and striatum from 1 h after reperfusion. The increased poly(ADP-ribose) immunoreactivity and NAD depletion were attenuated by FR247304 (32 mg/kg i.p.) treatment, and FR247304 significantly decreased ischemic brain damage measured at 24 h after reperfusion. Whereas other PARP inhibitors such as 3-aminobenzamide and PJ34 [N-(6-oxo-5,6-dihydro-phenanthridin-2-yl)-N,N-dimethylactamide] showed similar neuroprotective actions, they were less potent in in vitro assays and less efficacious in an in vivo model compared with FR247304. These results indicate that the novel PARP-1 inhibitor FR247304 exerts its neuroprotective efficacy in in vitro and in vivo experimental models of cerebral ischemia via potent PARP-1 inhibition and also suggest that FR247304 or its derivatives could be attractive therapeutic candidates for stroke and neurodegenerative disease.
