Caffeine metabolites are inhibitors of the nuclear enzyme poly(ADP-ribose)polymerase-1 at physiological concentrations.

L. Geraets, H.J. Moonen, E.F. Wouters, A. Bast, G.J. Hageman

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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 H(2)O(2)-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, H(2)O(2)-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
Original languageEnglish
Pages (from-to)902-910
JournalBiochemical Pharmacology
Volume72
Issue number7
DOIs
Publication statusPublished - 1 Jan 2006

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