title: Inhibitory effects of 5,6,7-trihydroxyflavones on tyrosinase.
abstract: Baicalein (1), 6-hydroxyapigenin (6), 6-hydroxygalangin (13) and 6-hydroxy-kaempferol (14), which are naturally occurring flavonoids from a set of 14 hydroxy-flavones tested, exhibited high inhibitory effects on tyrosinase with respect to L-DOPA, while each of the 5,6,7-trihydroxyflavones 1, 6, 13 or 14 acted as a cofactor to monophenolase. Moreover, 6-hydroxykaempferol (14) showed the highest activity and was a competitive inhibitor of tyrosinase compared to L-DOPA. 5,6,7-Trihydroxyflavones 1, 6, 13 or 14 showed also high antioxidant activities. Hence, we conclude that the 5,6,7-trihydroxy-flavones are useful as good depigmentation agents with inhibitory effects in addition to their antioxidant properties.
authors: Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Kita-ku, Sapporo, Japan.
authors: Hong
authors: H
authors: Gao
authors: Jun
authors: J
authors: Nishida
authors: Shizuka
authors: S
authors: Saito
authors: Jun
authors: J
authors: Kawabata
mesh_terms: D002384:Catalysis / Q000187:drug effects; D044950:Flavanones / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D007700:Kinetics; D007980:Levodopa / Q000378:metabolism; D015394:Molecular Structure; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D014443:Tyrosine / Q000378:metabolism
chemical_list: D044950:Flavanones; D010455:Peptides; D014443:Tyrosine; D007980:Levodopa; C006680:baicalein; D014442:Monophenol Monooxygenase
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