title: Effects of reactive oxygen and nitrogen species on cyclooxygenase-1 and -2 activities.
abstract: The effects of reactive oxygen species (superoxide anion radical--O(2)*-, hydrogen peroxide--H(2)O(2) and hydroxyl radical--*OH; the reaction products of xanthine plus xanthine oxidase system) and reactive nitrogen species [nitric oxide--NO*; from 1-hydroxyl-2-oxo-3-(N-methyl-3-aminopropyl)-3-methyl-1-triazene--NOC7 and peroxynitrite--ONOO(-)] on the activities of purified cyclooxygenase (COX)-1 and -2 were studied. Xanthine plus xanthine oxidase suppressed the COX-1 and -2 activities in a xanthine oxidase concentration-dependent fashion. This effect was reversed by addition of catalase to the reactive oxygen species-generating system but not by superoxide dismutase or mannitol, indicating that H(2)O(2) is the responsible metabolite. NOC7 activated the COX-1 activity but inhibited the COX-2 activity at concentrations ranging from 1 to 50 microM. Experiments utilizing a NO* antidote, carboxy-2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide revealed that the observed effects of NOC7 are caused by NO*.ONOO(-), a product of NO* and O(2)*-, both activated and inhibited the COX-1 and -2 activities, depending on ONOO(-) concentration. At a low concentration of ONOO(-) (5 microM) there was enhancement of the COX-1 and -2 activities, but with higher concentrations there was suppression of these two enzyme activities (COX-1, at 200 microM; COX-2, >50 microM). These results suggest that H(2)O(2), NO* and ONOO(-) can have different modulatory effects on the COX-1 and -2 activities.
authors.affiliation: Department of Hygienic Chemistry, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan. fujimoto@gly.oups.ac.jp
authors.forename: Yohko
authors.initials: Y
authors.lastname: Fujimoto
authors.forename: Eriko
authors.initials: E
authors.lastname: Uno
authors.forename: Satoru
authors.initials: S
authors.lastname: Sakuma
mesh_terms: D000818:Animals; D002374:Catalase / Q000494:pharmacology; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D005260:Female; D006861:Hydrogen Peroxide / Q000494:pharmacology; D017665:Hydroxyl Radical / Q000494:pharmacology; D008297:Male; D009569:Nitric Oxide / Q000494:pharmacology; D030421:Peroxynitrous Acid / Q000494:pharmacology; D010920:Placenta / Q000201:enzymology; D011247:Pregnancy; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D026361:Reactive Nitrogen Species / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000494:pharmacology*; D012669:Seminal Vesicles / Q000201:enzymology; D012756:Sheep; D013481:Superoxides / Q000494:pharmacology; D014226:Triazenes / Q000494:pharmacology; D019820:Xanthine / Q000378:metabolism; D014969:Xanthine Oxidase / Q000378:metabolism
chemical_list: C100973:(1-hydroxy-2-oxo-3-(N-methyl-3-aminopropyl)-3-methyl-3-aminopropyl)-3-methyl-1-triazene; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species; D014226:Triazenes; D013481:Superoxides; D030421:Peroxynitrous Acid; D019820:Xanthine; D009569:Nitric Oxide; D017665:Hydroxyl Radical; D006861:Hydrogen Peroxide; D002374:Catalase; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D014969:Xanthine Oxidase