title: Novel isoquinolinone-derived inhibitors of poly(ADP-ribose) polymerase-1: pharmacological characterization and neuroprotective effects in an in vitro model of cerebral ischemia.
abstract: Excessive activation of poly(ADP-ribose) polymerase-1 (PARP-1), a nuclear enzyme catalyzing the transfer of ADP-ribose units from NAD to acceptor proteins, induces cellular energy failure by NAD and ATP depletion and has been proposed to play a causative role in a number of pathological conditions, including ischemia/reperfusion injury. In this study, we used an in vitro enzyme activity assay to characterize a series of newly synthesized isoquinolinone derivatives as potential PARP-1 inhibitors. Several compounds displayed powerful inhibitory activity: thieno[2,3-c]isoquinolin-5-one (TIQ-A) displayed a submicromolar IC50 of 0.45 +/- 0.1 microM, whereas the 5-hydroxy and 5-methoxy TIQ-A derivatives had IC50 values of 0.39 +/- 0.19 and 0.21 +/- 0.12 microM, respectively. We then examined the neuroprotective effects of the newly characterized compounds in cultured mouse cortical cells exposed to 60 min of oxygen and glucose deprivation (OGD). When PARP-1 inhibitors were present in the incubation medium during OGD and the subsequent 24-h recovery period, they significantly attenuated neuronal injury. TIQ-A provided neuroprotection even when added to the culture 30 min after OGD and was able to reduce the early activation of PARP induced by OGD as detected by flow cytometry. When the IC50 values observed in the PARP-1 activity assay for selected compounds were compared with their IC50 values for the neuroprotective activity, a significant correlation (r = 0.93, P < 0.01) was observed. Our results suggest that TIQ-A and its derivatives are a new class of neuroprotectants that may be helpful in studies aimed at understanding the involvement of PARP-1 in physiology and pathology.
authors.affiliation: Dipartimento di Farmacologia Preclinica e Clinica, Università di Firenze, Viale Pieraccini, 6, 50139 Firenze, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Chiarugi
authors.forename: Elena
authors.initials: E
authors.lastname: Meli
authors.forename: Maura
authors.initials: M
authors.lastname: Calvani
authors.forename: Roberta
authors.initials: R
authors.lastname: Picca
authors.forename: Roberto
authors.initials: R
authors.lastname: Baronti
authors.forename: Emidio
authors.initials: E
authors.lastname: Camaioni
authors.forename: Gabriele
authors.initials: G
authors.lastname: Costantino
authors.forename: Maura
authors.initials: M
authors.lastname: Marinozzi
authors.forename: Domenico E
authors.initials: DE
authors.lastname: Pellegrini-Giampietro
authors.forename: Roberto
authors.initials: R
authors.lastname: Pellicciari
authors.forename: Flavio
authors.initials: F
authors.lastname: Moroni
mesh_terms: D000818:Animals; D002545:Brain Ischemia / Q000473:pathology; D002478:Cells, Cultured; D004195:Disease Models, Animal; D007546:Isoquinolines / Q000737:chemistry / Q000494:pharmacology*; D051379:Mice; D018696:Neuroprotective Agents / Q000494:pharmacology*; D010616:Phenanthrenes / Q000737:chemistry / Q000494:pharmacology; D010880:Piperidines / Q000737:chemistry / Q000494:pharmacology*; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D013876:Thiophenes / Q000494:pharmacology*
chemical_list: C475228:3,4-dihydro-5-hydroxy-1(2H)-isoquinolinone; D007546:Isoquinolines; D018696:Neuroprotective Agents; D010616:Phenanthrenes; D010880:Piperidines; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D013876:Thiophenes; C475227:thieno(2,3-c)isoquinolin-5-one; C108729:3,4-dihydro-5-(4-(1-piperidinyl)butoxy)-1(2H)-isoquinolinone; C040601:phenanthridone