title: The effects of organic solvents on poly(ADP-ribose) polymerase-1 activity: implications for neurotoxicity.
abstract: Poly(ADP-ribose) polymerase-1 (PARP-1; EC 2.4.2.30), also termed as poly(ADP-ribose) synthetase, is a key enzyme in the recognition and repair of damaged DNA. Several conditions (e.g., ischemia-reperfusion or chemical-induced injury) have been shown to overactivate PARP-1, causing neurodegeneration and necrotic or apoptotic cell death from NAD+ and ATP depletion. In contrast, inhibitors of PARP-1 have been shown to have a neuroprotective effect by ameliorating this response. The purpose of this study was to determine the effects of three routinely used organic solvents (ethanol, methanol, and dimethyl sulfoxide (DMSO)) on the activity of purified PARP-1. A dose-response was examined with each of these solvents. A 112% and 82% increase in PARP-1 activity was observed with 15% ethanol and 20% methanol, respectively. In contrast, a near 20% decrease in the activity was observed with 4% DMSO. Kinetic analysis revealed that the maximal velocity remained unchanged with increasing concentrations of DMSO up to 20%, indicating that DMSO is a competitive inhibitor of PARP-1. Thus, PARP-1 inhibition by DMSO depends on NAD+ concentration and in some pathological processes might be significant even at low DMSO concentrations. Our findings suggest that the interpretation of data from dose-response studies obtained when using common organic solvents may be dramatically skewed, either exaggerating the inherent toxicity of the compound or masking its potential for damage.
authors.affiliation: Laboratory of Toxicology and Risk Assessment, Institute of Coal Chemistry, Polish Academy of Sciences, 5 Sowińtskiego St., 44-121 Gliwice, Poland. mbanasik@karboch.gliwice.pl.
authors.forename: Marek
authors.initials: M
authors.lastname: Banasik
authors.forename: Todd
authors.initials: T
authors.lastname: Stedeford
authors.forename: Robert P
authors.initials: RP
authors.lastname: Strosznajder
authors.forename: Amanda S
authors.initials: AS
authors.lastname: Persad
authors.forename: Seigo
authors.initials: S
authors.lastname: Tanaka
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Ueda
mesh_terms: D000818:Animals; D002247:Carbon Isotopes / Q000493:pharmacokinetics; D002417:Cattle; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000494:pharmacology; D020128:Inhibitory Concentration 50; D007700:Kinetics; D000432:Methanol / Q000494:pharmacology; D009243:NAD / Q000493:pharmacokinetics; D020258:Neurotoxicity Syndromes / Q000209:etiology; D011065:Poly(ADP-ribose) Polymerases / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D012995:Solubility; D012997:Solvents / Q000494:pharmacology* / Q000633:toxicity
chemical_list: D002247:Carbon Isotopes; D012997:Solvents; D009243:NAD; D000431:Ethanol; D011065:Poly(ADP-ribose) Polymerases; D000432:Methanol; D004121:Dimethyl Sulfoxide