title: Identifying 6,7,4'-trihydroxyisoflavone as a potent tyrosinase inhibitor.
abstract: A known biotransformed compound, 6,7,4'-trihydroxyisoflavone, was identified as a potent tyrosinase inhibitor. It inhibited mushroom tyrosinase with an IC50 value of 9.2 microM, which is six times the anti-tyrosinase activity of kojic acid (IC50 = 54.4 microM). The inhibition kinetics, analyzed by Lineweaver-Burk plots, indicated 6,7,4'-trihydroxyisoflavone to be a competitive inhibitor of tyrosinase when L-tyrosine was used as a substrate. Its biosynthesis precursors and analogs, including glycitein, daidzein, and genistein, showed little anti-tyrosinase activity. The results suggest that hydroxyl groups at the C-6 and C-7 positions of the isoflavone skeleton might play an important role in the expression of tyrosinase inhibitory activity.
authors.affiliation: Department of Biological Science and Technology, National University of Tainan, Taiwan. mozyme2001@yahoo.com.tw
authors.forename: Te-Sheng
authors.initials: TS
authors.lastname: Chang
authors.forename: Hsiou-Yu
authors.initials: HY
authors.lastname: Ding
authors.forename: Hang-Ching
authors.initials: HC
authors.lastname: Lin
mesh_terms: D000363:Agaricales; D001667:Binding, Competitive; D004791:Enzyme Inhibitors; D005656:Fungal Proteins / Q000037:antagonists & inhibitors; D020128:Inhibitory Concentration 50; D007529:Isoflavones / Q000494:pharmacology*; D007700:Kinetics; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors*; D013329:Structure-Activity Relationship; D014443:Tyrosine / Q000378:metabolism
chemical_list: C502164:6,7,4'-trihydroxyisoflavone; D004791:Enzyme Inhibitors; D005656:Fungal Proteins; D007529:Isoflavones; D014443:Tyrosine; D014442:Monophenol Monooxygenase