Inhibitory effects of Ramulus mori extracts on melanogenesis.
To develop an active agent for skin whitening, the inhibitory effects of 285 plant extracts on tyrosinase activity were examined, and one plant extract having tyrosinase inhibition activity was chosen. Ramulus mori (young twigs of Morus alba L.) extracts showed inhibition activity in tyrosinase and melanin synthesis in B-16 melanoma cells. To clarify the mechanism of its inhibition on melanogenesis, the effect of R. mori extracts on tyrosinase activity, synthesis, and gene expression was evaluated. R. mori extracts showed tyrosinase inhibition activity by competitive method, and there was no suppression of tyrosinase synthesis and gene expression. Further, to evaluate the inhibitory activity of R. mori in vivo, its effect on melanin production in UV-induced brown guinea pigs was examined, where a decrease of melanin production in the guinea pig model was observed. Also, R. mori extracts showed no toxicity in animal tests such as the acute toxicity test, the skin irritation test, the eye irritation test, the skin sensitization test, and the acute oral toxicity test, and no toxicity in the human skin irritation test. A single compound from R. mori extracts was purified using various column chromatography and recrystallization, and its chemical structure was identified using mass chromatography, IR spectroscopy, and NMR analysis. The chemical structure was that of 2,3',4,5'-tetrahydroxystilbene(2-oxyresveratrol) and showed inhibition activity on tyrosinase (IC(50) = 0.23 microg/ml). Also, R. mori extracts inhibited tyrosinase activity in a competitive manner (Ki = 1.5 x 10(-6) M) when L-tyrosine was used as a substrate.
Lee
Kang Tae
KT
Coreana Cosmetics Co., 204-1 JeongchonRi, Senggeoeup, Cheonansi, 330-830, Korea.
Lee
Kwang Sik
KS
Jeong
Ji Hean
JH
Jo
Byoung Kee
BK
Heo
Moon Young
MY
Kim
Hyun Pyo
HP
D000818:Animals; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D008543:Melanins / Q000037:antagonists & inhibitors* / Q000096:biosynthesis; D008546:Melanoma, Experimental / Q000201:enzymology / Q000378:metabolism / Q000473:pathology*; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors / Q000235:genetics; D010936:Plant Extracts / Q000494:pharmacology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
D008543:Melanins; D010936:Plant Extracts; D014442:Monophenol Monooxygenase