title: Flavonoids as mushroom tyrosinase inhibitors: a fluorescence quenching study.
abstract: Flavonoids, a group of naturally occurring antioxidants and metal chelators, can be used as tyrosinase inhibitors due to their formation of copper-flavonoid complexes. Thus, to investigate the underlying inhibition mechanism, a large group of flavonoids from several major flavones and flavonols were tested using fluorescence quenching spectroscopy. In addition, large differences in the tyrosinase inhibitory activities and chelating capacities according to the location of the hydroxyl group(s) in combination with the A and B rings in the flavonoids were confirmed. Accordingly, the major conclusions from this work are as follows: (i) The tyrosinase inhibitory activity is not only dependent on the number of hydroxyl groups in the flavonoids, (ii) the enzyme is primarily quenched by the hydroxyl group(s) of A and B rings on the ether side of the flavonoids, and (iii) the tyrosinase inhibitory activity of 7,8,3',4'-tetrahydroxyflavone is supported by a virtual model of docking with the mushroom tyrosinase, which depicts the quenching of the enzyme. The results also demonstrated that the dihydroxy substitutions in the A and B rings are crucial for Cu2+-chelate formation, thereby influencing the tyrosinase inhibitory activity.
authors.affiliation: Korea Research Institute of Bioscience and Biotechnology, Yuseong, Daejeon, 305-333, Korea.
authors.forename: Donghyun
authors.initials: D
authors.lastname: Kim
authors.forename: Jiyeoun
authors.initials: J
authors.lastname: Park
authors.forename: Jinhee
authors.initials: J
authors.lastname: Kim
authors.forename: Cheolkyu
authors.initials: C
authors.lastname: Han
authors.forename: Jeonghyeok
authors.initials: J
authors.lastname: Yoon
authors.forename: Namdoo
authors.initials: N
authors.lastname: Kim
authors.forename: Jinho
authors.initials: J
authors.lastname: Seo
authors.forename: Choonghwan
authors.initials: C
authors.lastname: Lee
mesh_terms: D000363:Agaricales / Q000201:enzymology*; D000595:Amino Acid Sequence; D001665:Binding Sites; D003300:Copper / Q000737:chemistry / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005419:Flavonoids / Q000494:pharmacology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors* / Q000737:chemistry; D013050:Spectrometry, Fluorescence
chemical_list: D004791:Enzyme Inhibitors; D005419:Flavonoids; D003300:Copper; D014442:Monophenol Monooxygenase