Tyrosinase Inhibitory Xanthones from Cudrania tricuspidata

The methanolic roots bark extract of Cudrania tricuspidata (Carr.) Bureau was chromatographed, which yielded three xanthones 1-3 by tyrosinase inhibitory activity-guided fractionation. The structures were fully characterized by analysis of physical and spectral data. Among them, furano prenylxanthone 3, never reported as tyrosinase inhibitor, showed potent activity with $IC_{50}$ value of $16.5{\mu}M$, and appeared to inhibit the polyphenol oxidase activity of tyrosinase in an uncompetitive inhibitor($K_i=1.6{\mu}m$) when L-tyrosine was used as a substrate. Moreover, potent inhibitor furano prenylxanthone 3 had an extended lag time of 310 sec at $20{\mu}M$, while lag time of kojic acid as positive control was prolonged with 350 sec at the same concentration.

꾸지뽕나무에서 분리한 xanthones의 tyrosinase 저해제 연구

꾸지뽕나무(Cudrania tricuspidata(Carr.) Bureau) 뿌리껍질에서 3종의 xanthones 화합물을 분리하였으며, 분광학적인 자료를 바탕으로 cudraxanthone L (1), cudraxanthone D (2), 그리고 cudraxanthone M (3)으로 구조동정되었다. 분리된 화합물을 L-tyrosine이 기질로 작용할 때 tyrosinase 저해 활성을 측정한 결과 cudraxanthone M (3)의 $IC_{50}$ 값이 $16.5{\mu}M$로 가장 높은 저해 효능을 보였으며, kinetic type은 uncompetitive inhibition로 저해 상수($K_i$)는 $1.6{\mu}M$로 측정되었다. 또한 이 화합물은 $20{\mu}M$의 농도에서 lag time이 310초로 측정 되어 대조화합물인 kojic acid와 유사한 저해능을 나타내었다.