title: Inhibition of myeloperoxidase-catalyzed tyrosylation by phenolic antioxidants in vitro.
abstract: We have developed an in vitro assay system for the evaluation of the inhibitory effects of phenolic antioxidants on myeloperoxidase (MPO) activity. The formation of dityrosine from the MPO/H2O2/L-tyrosine system was used as an indicator of the MPO activity. Because the buffer system used does not include chloride ion, this assay has the advantage of exclusion of direct reaction between an antioxidant and HOCl. In this assay, ferulic acid, gallic acid, and quercetin strongly inhibited the dityrosine formation, and curcumin and caffeic acid were also effective.
authors.affiliation: School of Humanities for Environmental Policy and Technology, Himeji Institute of Technology, 1-1-12 Shinzaike-honcho, Himeji, Hyogo 670-0092, Japan. yojikato@hept.himeji-tech.ac.jp
authors.forename: Yoji
authors.initials: Y
authors.lastname: Kato
authors.forename: Akihiko
authors.initials: A
authors.lastname: Nagao
authors.forename: Junji
authors.initials: J
authors.lastname: Terao
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Osawa
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D002021:Buffers; D002851:Chromatography, High Pressure Liquid; D003373:Coumaric Acids / Q000494:pharmacology; D003474:Curcumin / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005707:Gallic Acid / Q000494:pharmacology; D009195:Peroxidase / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D010636:Phenols / Q000494:pharmacology*; D011794:Quercetin / Q000494:pharmacology; D013050:Spectrometry, Fluorescence; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D002021:Buffers; D003373:Coumaric Acids; D004791:Enzyme Inhibitors; D010636:Phenols; D014443:Tyrosine; D005707:Gallic Acid; D011794:Quercetin; C004999:ferulic acid; C007543:dityrosine; D009195:Peroxidase; D003474:Curcumin