title: An oxidative coupling product of luteolin with cysteine ester and its enhanced inhibitory activity for xanthine oxidase.
abstract: Oxidative coupling reactions of several flavonoids with a cysteine ester (a radicalic and nucleophilic biochemical) were carried out and the abilities of the coupling products against xanthine oxidase (XO) were screened. One of the products, derived from luteolin, showed a notable inhibitory effect. A potent XO inhibitory compound was isolated from the complex mixture of the product of the coupling of luteolin and cysteine ethyl ester, and its structure was determined by NMR and MS analysis. The compound has a unique 1,4-thiazine ring unit on the luteolin B-ring and is inhibited XO 4.5 times more strongly than it did luteolin.
authors.affiliation: Graduate School of Human Life Science, Osaka City University, Osaka 558-8585, Japan. Electronic address: masuda_t@life.osaka-cu.ac.jp.
authors.forename: Toshiya
authors.initials: T
authors.lastname: Masuda
authors.affiliation: Graduate School of Human Life Science, Osaka City University, Osaka 558-8585, Japan.
authors.forename: Shoko
authors.initials: S
authors.lastname: Nojima
authors.affiliation: Graduate School of Integrated Arts and Sciences, University of Tokushima, Tokushima 770-8502, Japan.
authors.forename: Yukari
authors.initials: Y
authors.lastname: Miura
authors.affiliation: Graduate School of Human Life Science, Osaka City University, Osaka 558-8585, Japan; Graduate School of Integrated Arts and Sciences, University of Tokushima, Tokushima 770-8502, Japan.
authors.forename: Sari
authors.initials: S
authors.lastname: Honda
authors.affiliation: Faculty of Human Life Science, Shikoku University, Tokushima 770-1192, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Masuda
mesh_terms: D003545:Cysteine / Q000031:analogs & derivatives* / Q000737:chemistry; D004791:Enzyme Inhibitors / Q000138:chemical synthesis / Q000737:chemistry*; D047311:Luteolin / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008968:Molecular Conformation; D058451:Oxidative Coupling; D014969:Xanthine Oxidase / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; C031752:ethyl cysteine; D014969:Xanthine Oxidase; D003545:Cysteine; D047311:Luteolin
keywords: Cysteine; Flavonoid; Oxidative coupling; Structure determination; Xanthine oxidase inhibition