title: Caffeine metabolites are inhibitors of the nuclear enzyme poly(ADP-ribose)polymerase-1 at physiological concentrations.
abstract: The activity of the nuclear enzyme poly(ADP-ribose)polymerase-1 (E.C.2.4.2.30), which is highly activated by DNA strand breaks, is associated with the pathophysiology of both acute as well as chronic inflammatory diseases. PARP-1 overactivation and the subsequent extensive turnover of its substrate NAD+ put a large demand on mitochondrial ATP-production. Furthermore, due to its reported role in NF-kappaB and AP-1 mediated production of pro-inflammatory cytokines, PARP-1 is considered an interesting target in the treatment of these diseases. In this study the PARP-1 inhibiting capacity of caffeine and several metabolites as well as other (methyl)xanthines was tested using an ELISA-assay with purified human PARP-1. Caffeine itself showed only weak PARP-1 inhibiting activity, whereas the caffeine metabolites 1,7-dimethylxanthine, 3-methylxanthine and 1-methylxanthine, as well as theobromine and theophylline showed significant PARP-1 inhibiting activity. Further evaluation of these compounds in H2O2-treated A549 lung epithelial and RF24 vascular endothelial cells revealed that the decrease in NAD+-levels as well as the formation of the poly(ADP-ribose)polymer was significantly prevented by the major caffeine metabolite 1,7-dimethylxanthine. Furthermore, H2O2-induced necrosis could be prevented by a high dose of 1,7-dimethylxanthine. Finally, antioxidant effects of the methylxanthines could be ruled out with ESR and measurement of the TEAC. Concluding, caffeine metabolites are inhibitors of PARP-1 and the major caffeine metabolite 1,7-dimethylxanthine has significant PARP-1 inhibiting activity in cultured epithelial and endothelial cells at physiological concentrations. This inhibition could have important implications for nutritional treatment of acute and chronic inflammatory pathologies, like prevention of ischemia-reperfusion injury or vascular complications in diabetes.
authors.affiliation: Department of Pharmacology and Toxicology, Faculty of Medicine, University of Maastricht, PO Box 616, 6200 MD Maastricht, The Netherlands. l.geraets@farmaco.unimaas.nl
authors.forename: Liesbeth
authors.initials: L
authors.lastname: Geraets
authors.forename: Harald J J
authors.initials: HJ
authors.lastname: Moonen
authors.forename: Emiel F M
authors.initials: EF
authors.lastname: Wouters
authors.forename: Aalt
authors.initials: A
authors.lastname: Bast
authors.forename: Geja J
authors.initials: GJ
authors.lastname: Hageman
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003497:Cyclic N-Oxides / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D020128:Inhibitory Concentration 50; D015394:Molecular Structure; D009243:NAD / Q000737:chemistry / Q000378:metabolism; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D000071137:Poly (ADP-Ribose) Polymerase-1; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D019097:Spin Trapping / Q000379:methods; D013329:Structure-Activity Relationship; D013806:Theophylline / Q000737:chemistry / Q000494:pharmacology*; D014970:Xanthines / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D003497:Cyclic N-Oxides; D004791:Enzyme Inhibitors; D009687:Nuclear Proteins; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D014970:Xanthines; D009243:NAD; D000244:Adenosine Diphosphate; C017245:5,5-dimethyl-1-pyrroline-1-oxide; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide; D013806:Theophylline; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; C021183:1,7-dimethylxanthine