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Tyrosinase inhibitory constituents from the stems of Maackia fauriei
Author(s) -
Kim Jeong Mi,
Ko Ryeo Kyeong,
Jung Duk Sang,
Kim Sang Suk,
Lee Nam Ho
Publication year - 2010
Publication title -
phytotherapy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.019
H-Index - 129
eISSN - 1099-1573
pISSN - 0951-418X
DOI - 10.1002/ptr.2870
Subject(s) - tyrosinase , kojic acid , chemistry , arbutin , skin whitening , formononetin , flavonoid , daidzein , stereochemistry , non competitive inhibition , biochemistry , genistein , enzyme , pharmacology , antioxidant , biology , active ingredient , endocrinology
Bioassay‐guided investigation of the stems of Maackia fauriei led to the isolation of seven flavonoid constituents, formononetin (1), genistein (2), daidzein (3), texasin (4), tectorigenin (5), odoratin (6) and mirkoin (7). Their structures were elucidated on the basis of spectral studies as well as by comparison with literature data. Tyrosinase inhibition activities were carried out on the isolated compounds. Among these, mirkoin (7) was identified as a potent tyrosinase inhibitor. It inhibited mushroom tyrosinase with an IC 50 value of 0.005 m m , which is ten times more active than kojic acid (IC 50 = 0.045 m m ). The inhibition kinetics, analysed by Lineweaver‐Burk plots, indicated mirkoin (7) to be a competitive inhibitor of tyrosinase when l ‐tyrosinase was used as a substrate. The results suggest that hydroxyl groups at C‐4′ in the B ring of flavonoids play an important role in the tyrosinase inhibition activities. Interestingly, compounds 4–7 were isolated for the first time from this plant. Copyright © 2009 John Wiley & Sons, Ltd.