Biol. Pharm. Bull., 26(9),1348-1350, September 2003

Notes

Tyrosinase Inhibitory Prenylated Flavonoids from Sophora flavescens

Soo Jin KIM,^a Kun Ho SON,^b Hyun Wook CHANG,^c Sam Sik KANG,^d and Hyun Pyo KIM^*,a

^a College of Pharmacy, Kangwon National University; Chunchon 200-701, Korea: ^b Department of Food Nutrition, Andong National University; Andong 760-749, Korea: ^c College of Pharmacy, Yeungnam University; Gyongsan 712-749, Korea: and ^d Natural Products Institute, Seoul National University; Seoul 110-460, Korea. * To whom correspondence should be addressed. e-mail: hpkim@kangwon.ac.kr

For the purpose of the development of a skin-whitening agent, Sophora flavescens was evaluated for tyrosinase inhibitory activity and its active principles were identified following activity-guided isolation. The ethanol extract and dichloromethane fraction from S. flavescens showed significant inhibition of mushroom tyrosinase. From the dichloromethane fraction, three known prenylated flavonoids, sophoraflavanone G, kuraridin, and kurarinone, were isolated. Compared with kojic acid (IC₅₀=20.5 μM), these compounds possessed more potent tyrosinase inhibitory activity. The IC₅₀ values were 6.6, 0.6, and 6.2 μM for sophoraflavanone G, kuraridin, and kurarinone, respectively.

Key words tyrosinase; skin whitening; Sophora flavescens; sophoraflavanone; kuraridin; kurarinone