title: Inhibitory effects of some flavonoids on the activity of mushroom tyrosinase.
abstract: Mushroom tyrosinase (EC 1.14.18.1) is a copper containing oxidase that catalyzes both the hydroxylation of tyrosine into o-diphenols and the oxidation of o-diphenols into o-quinones, and then forms brown or black pigments. In the present study, the effects of some flavonoids on the oxidation of L-3,4-dihydroxyphenylalanine (L-DOPA) have been studied. The results show that flavonoids can lead to reversible inhibition of the enzyme. A kinetic analysis showed that the flavonols are competitive inhibitors, whereas luteolin is an uncompetitive inhibitor. The rank order of inhibition was: quercetin > galangin > morin; fisetin > 3,7,4;-trihydroxyflavone; luteolin > apigenin > chrysin.
authors.affiliation: Department of Biological Science and Biotechnology, Center for Ocean Science and Engineering, Protein Science Laboratory of Ministry of Education, Tsinghua University, Beijing, 100084, P. R. China.
authors.forename: Li-Ping
authors.initials: LP
authors.lastname: Xie
authors.forename: Qing-Xi
authors.initials: QX
authors.lastname: Chen
authors.forename: Huang
authors.initials: H
authors.lastname: Huang
authors.forename: Hong-Zhong
authors.initials: HZ
authors.lastname: Wang
authors.forename: Rong-Qing
authors.initials: RQ
authors.lastname: Zhang
mesh_terms: D000363:Agaricales / Q000201:enzymology*; D047310:Apigenin; D001667:Binding, Competitive; D002384:Catalysis; D003300:Copper / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D005419:Flavonoids / Q000737:chemistry / Q000494:pharmacology*; D044948:Flavonols; D007700:Kinetics; D047311:Luteolin; D008956:Models, Chemical; D015394:Molecular Structure; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011794:Quercetin / Q000737:chemistry / Q000494:pharmacology; D012431:Rutin / Q000737:chemistry / Q000494:pharmacology; D013329:Structure-Activity Relationship; D047309:Flavones
chemical_list: D047310:Apigenin; D003300:Copper; D004791:Enzyme Inhibitors; D005419:Flavonoids; D044948:Flavonols; D047311:Luteolin; D014442:Monophenol Monooxygenase; D011794:Quercetin; D012431:Rutin; C483500:3,7,4'-trihydroxyflavone; C037032:galangin; C043561:chrysin; C008548:morin; D047309:Flavones; C017875:fisetin