He shou wu zhong you xiao cheng fen 2,3,5,4'-si qian ji er ben yi xi-2-O-β-D-pu tao tang gan de yi zhi hei se su sheng cheng huo xing yan jiu

何首烏為寥科多年生藤本植物，而中藥何首烏則為該植物的乾燥塊根。常用於治療白髮及與老年化相關的疾病。然而，何首烏的治療機理卻少有報導。本文對何首烏的粗提物及其主要生物活性成份2,3,5,4' -四羥基二萃乙烯-2-0-ß-D-葡萄糖苷(THSG) 在老鼠及人類的黑色素細胞中影響黑色素生成機理及細胞毒性進行了深入研究。利用高效液相層析連接質譜儀的測定， THSG 在水及乙醇粗提物中含量分別為0.064 及0.75 的百分比。由於THSG 在水及乙醇粗提物中佔有一定份量，所以它對粗提物所產生的生物及生化反應有著重要的影響。在低於細胞毒範圍的劑量內，何首烏粗提物及THSG 能降低老鼠黑色素細胞株melan-a 的左旋多巴(L-DOPA)的轉化反應。在細胞毒性檢測中，水粗提物及THSG 在<100 μg/ml的劑量下均未有對至少5 種黑色素細胞株及黑色素瘤細胞造成傷害。然而，乙醇粗提物的細胞毒卻是水粗提物或THSG 的3-4 倍。在無細胞系統中， THSG 在可逆轉的情況下抑制酪氨酸酶將左旋多巴轉化成黑色素。在細胞系統中，它也能阻止由蛋白激醋A (PKA)引發的黑色素生成反應。THSG 在老鼠及人類黑色素細胞中的中位值抑制率(lC₅₀)分別為123.0 μM及61.5 μM。 THSG 抑制酪氮酸醋的能力展現在黑色素細胞/角質細胞的共培養比在單黑色素細胞培養中更明顯。調控酪氯酸臨可以在脫氧核糖核酸(DNA)轉錄及翻譯後修飾兩方面達成。在DNA 轉錄中，小眼球相關轉錄因數(MITF)的減少導致酪氨酸酶的表達隨著THSG 濃度而減少。翻譯後酪氮酸臨主要依靠蛋白激臨C-ß (PKC-ß)使其磷酸化，從而增加酪氯酸酶/酪氯酸酶相關蛋白-1(TRP-1 )組成複合蛋白。然而THSG 均減少蛋白激酶 C-ß的表達及酪氮酸酪/酪氮酸醋相關蛋白-1 所組成的複合蛋白。 另一方面， THSG 卻沒有影響酪氯酸酶蛋白在內質網/高爾基氏複合體內的糖基化及內涵體與溶酶體間的運輸。總而言之，本文首次展示何首烏粗提物及THSG 在單細胞培養及共培養細胞的系統下抑制黑色素生成。THSG 能在可逆轉的抑制機制下阻止酪氯酸酶作出反應。而在PKA 引發的黑色素生成反應中， THSG 也能在DNA 轉錄及翻譯後修飾等過程中減低酪氯酸酶的活性。Radix Polygoni Multiflori, the dried root of Polygonum multiflorum (PM), is well documented for its clinical effects in treating various diseases associated with aging and hair graying, but the evidence based-mechanisms remain largely unknown. In this study, PM was extracted with water and 70% ethanol and a major constituent, 2,3,5,4'-tetrahydroxystilbene-2-0-I3-D-glucoside (THSG) of about 0.064% and 0.75%, respectively, were found in these extracts as analyzed by high-performance liquid chromatography (HPLC) coupled to mass spectrometry. The melanogenic properties and cytotoxicity of the two extracts and THSG were evaluated using murine and human melanocytes.Both water and ethanol extracts of PM and THSG showed a dose-dependent anti-melanogenic activity in an in vitro murine melan-a melanocyte assay for reduction of L-DOPA conversion by tyrosinase. Of at least 5 melanoma and melanocyte cell lines tested, both water PM extract and THSG were relatively safe, which at doses