Lee Kang Tae, Lee Kwang Sik, Jeong Ji Hean, Jo Byoung Kee, Heo Moon Young, Kim Hyun Pyo
Coreana Cosmetics Co., 204-1 JeongchonRi, Senggeoeup, Cheonansi, 330-830, Korea.
J Cosmet Sci. 2003 Mar-Apr;54(2):133-42.
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.
为开发一种用于皮肤美白的活性剂，检测了285种植物提取物对酪氨酸酶活性的抑制作用，并选择了一种具有酪氨酸酶抑制活性的植物提取物。桑枝（桑科植物桑的嫩枝）提取物对B - 16黑色素瘤细胞中的酪氨酸酶和黑色素合成具有抑制活性。为阐明其对黑色素生成的抑制机制，评估了桑枝提取物对酪氨酸酶活性、合成及基因表达的影响。桑枝提取物通过竞争法显示出酪氨酸酶抑制活性，且对酪氨酸酶的合成和基因表达无抑制作用。此外，为评估桑枝在体内的抑制活性，检测了其对紫外线诱导的棕色豚鼠黑色素生成的影响，观察到豚鼠模型中黑色素生成减少。而且，桑枝提取物在急性毒性试验、皮肤刺激性试验、眼刺激性试验、皮肤致敏试验和急性经口毒性试验等动物试验中均未显示毒性，在人体皮肤刺激性试验中也无毒性。采用各种柱色谱和重结晶方法从桑枝提取物中纯化出一种单一化合物，并通过质谱、红外光谱和核磁共振分析鉴定了其化学结构。该化学结构为2,3',4,5'-四羟基茋（2 - 氧白藜芦醇），对酪氨酸酶显示出抑制活性（IC(50) = 0.23微克/毫升）。此外，当以L - 酪氨酸为底物时，桑枝提取物以竞争方式抑制酪氨酸酶活性（Ki = 1.5 x 10(-6) M）。
