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 <100 μg/ml did not demonstrate any significant cytotoxic effects. On the other hand, ethanol PM extract was about 3-4 folds more cytotoxic. / Tyrosinase is the rate-limiting enzyme for melanogenesis. In a cell-free kinetic analysis, THSG inhibited tyrosinase activity in a reversible and non-competitive manner. At the cellular level, this inhibition is mediated through a PKA-dependent melanogenic pathway, as well as in a dose-dependent manner, with IC₅₀ = 123.0 μM and 61.5 μM for murine and human melanocytes, respectively. Tyrosinase was much more sensitive to the inhibitory effect of THSG in the melanocytelkeratinocyte co-culture system than in the melanocyte mono-culture system. / Functional tyrosinase is regulated at both transcriptional and post-translational modification levels. At the transcription level, THSG reduced expression of microphthalmia-associated transcription factor (MITF) esulted in a down-regulation of tyrosinase expression. At the post-translational modification level, THSG inhibited expression of PKC-β which is responsible for tyrosinase phosphorylation, and enhanced tyrosinase/TRP-1 complex formation. On the hand, THSG did not affect glycosylation of tyrosinase nor its trafficking from ER/Golgi to endosomal/ lysosomal compartments. / Taken our results together, the anti-melanogenic property of PM extracts and THSG were firstly demonstrated in both mono- and co-culture system using murine or human melanocytes and keratinocytes. THSG is a reversible and competitive inhibitor, which lowered the tyrosinase activity at both transcription and post-translational modification levels via PKA-mediated melanogenesis. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Cheung, Wing Ki. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 160-174). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Chapter 1 / General introduction / Chapter 1.1 --- Anatomy and Physiology of the Skin --- p.5 / Chapter 1.1.1 --- Epidermis --- p.5 / Chapter 1.1.1.1 --- Stratum basale --- p.6 / Chapter 1.1.1.2 --- Stratum spinosum --- p.6 / Chapter 1.1.1.3 --- stratum granulosum --- p.7 / Chapter 1.1.1.4 --- Stratum corneum --- p.7 / Chapter 1.1.2 --- Dermis --- p.8 / Chapter 1.2 --- Melanogenesis of the Skin --- p.9 / Chapter 1.2.1 --- History of melanogenesis study --- p.9 / Chapter 1.2.2 --- Today's melanogenesis study --- p.10 / Chapter 1.3 --- Hyperpigmentary Disorders --- p.14 / Chapter 1.3.1 --- Malasma --- p.14 / Chapter 1.3.2 --- Lentigines --- p.15 / Chapter 1.3.2.1 --- Lentigo simplex --- p.16 / Chapter 1.3.2.2 --- Lentigo senilis etActinicus --- p.16 / Chapter 1.3.3 --- Post-inflammatory hyperpigmentation --- p.17 / Chapter 1.4 --- Current Available Treatment for Hyperpigmentation --- p.18 / Chapter 1.4.1 --- Topical treatment and their strategies --- p.18 / Chapter 1.4.1.1 --- Inhibition of tyrosinase activity --- p.18 / Chapter 1.4.1.2 --- Antioxidation --- p.21 / Chapter 1.4.1.3 --- Melanosome transfer inhibition --- p.22 / Chapter 1.4.1.4 --- Stimulation of desquamation --- p.22 / Chapter 1.4.2 --- Laser treatment and their strategies --- p.23 / Chapter 1.4.3 --- Sunscreen --- p.24 / Chapter 1.5 --- Theories and the Treatment of Hyperpigmentation with Chinese Herbal Medicine --- p.25 / Chapter 1.6 --- Testing Systems --- p.26 / Chapter 1.7 --- Aims and Objectives of Study --- p.27 / Chapter 2 / Chemical Properties of THSG / Chapter 2.1 --- Introduction --- p.30 / Chapter 2.1.1 --- Radix Polygoni multiflori --- p.30 / Chapter 2.1.2 --- 2,3,5,4'-tetrahydroxystilbene glucoside (THSG) --- p.31 / Chapter 2.1.2.1 --- Stilbene --- p.32 / Chapter 2.1.2.2 --- Chemical properties of THSG --- p.34 / Chapter 2.1.3 --- Objectives --- p.35 / Chapter 2.2 --- Materials and Methods --- p.36 / Chapter 2.2.1 --- Plant materials --- p.36 / Chapter 2.2.2 --- Extraction --- p.36 / Chapter 2.2.3 --- High performance liquid chromatography (HPLC) analysis --- p.36 / Chapter 2.2.4 --- Enzymatic hydrolysis of THSG and salicin --- p.37 / Chapter 2.2.5 --- HPLC/MS analysis --- p.38 / Chapter 2.2.6 --- Benedict's test --- p.38 / Chapter 2.2.7 --- Enzymatic oxidation --- p.38 / Chapter 2.2.8 --- Thin layer chromatography (TLC) analysis --- p.39 / Chapter 2.3 --- Results / Chapter 2.3.1 --- The THSG content in water and alcohol extracts of PM --- p.40 / Chapter 2.3.2 --- The stability of THSG against oxidation --- p.41 / Chapter 2.3.3 --- Enzymatic hydrolysis ofTHSG --- p.42 / Chapter 2.4 --- Discussion --- p.46 / Chapter 3 / The Melanogenic inhibitory mechanisms of Radix Polygonum multiflorum (PM) extracts and THSG in murine melanocyte / Chapter 3.1 --- Introduction --- p.47 / Chapter 3.1.1 --- Murine melanocyte --- p.47 / Chapter 3.1.2 --- Melanogenesis --- p.48 / Chapter 3.1.2.1 --- Factors affecting Melanogenesis --- Oxidation --- p.49 / Chapter 3.1.2.2 --- Factors affecting Melanogenesis --- UV radiation --- p.50 / Chapter 3.1.2.3 --- Factors affecting melanogenesis---- Cellular regulation --- p.51 / Chapter 3.1.2.3.1 --- The regulation of transcription, translation, and post-translational modification of tyrosianse --- p.51 / Chapter 3.1.2.3.2 --- PKA-, PKC-, and PKG- melangenic pathways --- p.56 / Chapter 3.1.3 --- Kinetic analysis of tyrosinase --- p.57 / Chapter 3.1.4 --- Objectives --- p.58 / Chapter 3.2 --- Materials and Methods --- p.59 / Chapter 3.2.1 --- Cell culture --- p.59 / Chapter 3.2.2 --- Kinetic analysis of tyrosinase activity inhibition --- p.60 / Chapter 3.2.3 --- SRB assay --- p.61 / Chapter 3.2.4 --- L -DOPA conversion assay --- p.62 / Chapter 3.2.5 --- Melanin production measurement --- p.62 / Chapter 3.2.6 --- ROS detection by flow cytometer --- p.63 / Chapter 3.2.7 --- In-situ tyrosinase activity assay --- p.63 / Chapter 3.2.8 --- Western blotting (WB) analysis --- p.64 / Chapter 3.2.9 --- Immunofluorescence microscopy --- p.66 / Chapter 3.2.10 --- Glycosylation analysis --- p.67 / Chapter 3.2.11 --- Co-Immunoprecipitation --- p.68 / Chapter 3.2.12 --- Radix Polygonum Multiflorum and THSG metabolite collection from rat serum --- p.69 / Chapter 3.3 --- Results --- p.71 / Chapter 3.3.1 --- Enzyme kinetic study of the catalysis of L-DOPA by murine melanocyte lysate --- p.71 / Chapter 3.3.2 --- Inhibitory effect of crude PM preparations and THSG on tyrosinase activity and melanin synthesis in murine melan-a melanocytes --- p.74 / Chapter 3.3.3 --- Effect of THSG on H₂0₂- induced oxidation --- p.77 / Chapter 3.3.4 --- THSG inhibits PKA-induced melanogenesis --- p.78 / Chapter 3.3.5 --- Reduction of in situ tyrosinase activity in PKA-induced melanogenesis --- p.82 / Chapter 3.3.6 --- Alternation of melanogenic proteins --- p.85 / Chapter 3.3.7 --- THSG does not alter the tyrosinase trafficking in ER and Golgi --- p.89 / Chapter 3.3.8 --- THSG does not alter the tyrosinase trafficking in endosomal lysosomal compartments --- p.93 / Chapter 3.3.9 --- Glycosylation analysis --- p.95 / Chapter 3.3.10 --- Reduction of interaction between tyrosinase and TRP-1 to form heterodimeric complexes --- p.97 / Chapter 3.3.11 --- The metabolite of PM water extract and THSG maintained the in vitro tyrosinase activity --- p.101 / Chapter 3.4 --- Discussion --- p.103 / Chapter 4 / The Inhibitory Effect of THSG on Melanogenesis in Monolayer Culture of Human Melanocytes and in Co-culture of Melanocyte-Keratinocyte / Chapter 4.1 --- Introduction --- p.110 / Chapter 4.1.1 --- Human melanocyte --- p.110 / Chapter 4.1.1.1 --- The origin and the development of melanocyte --- p.110 / Chapter 4.1.1.2 --- Morphology, body site distribution and histological location --- p.111 / Chapter 4.1.1.3 --- In vitro growth of human melanocyte --- p.112 / Chapter 4.1.1.3.1 --- Lifespan vs. culture conditions --- p.113 / Chapter 4.1.1.3.2 --- Lifespan vs. donor age and skin type --- p.114 / Chapter 4.1.1.4 --- Modulation of pigmentation in response to stress --- p.114 / Chapter 4.1.1.5 --- Difference between human and murine TRPs --- p.115 / Chapter 4.1.2 --- Keratinocyte-Melanocyte interaction --- p.117 / Chapter 4.1.2.1 --- Release of melanogenic factors --- p.117 / Chapter 4.1.2.2 --- Release of survival and proliferating factors --- p.118 / Chapter 4.1.2.3 --- Melanosome transfer determines the cutaneous pigmentation --- p.118 / Chapter 4.1.2.3.1 --- Molecular events during melanosome transfer --- p.119 / Chapter 4.1.2.4 --- Others --- p.121 / Chapter 4.1.3 --- Objectives --- p.121 / Chapter 4.2 --- Materials and Methods --- p.122 / Chapter 4.2.1 --- Cell Culture --- p.122 / Chapter 4.2.1.1 --- Human melanocytes isolation and cultivation --- p.122 / Chapter 4.2.1.2 --- Immortalized keratinocytes - HaCaT cells --- p.123 / Chapter 4.2.1.3 --- Co-culture of melanocytes and HaCaT cells --- p.124 / Chapter 4.2.1.3.1 --- Monolayer co-culture --- p.124 / Chapter 4.2.1.3.2 --- Two-layer co-culture --- p.124 / Chapter 4.2.2 --- SRB assay --- p.125 / Chapter 4.2.3 --- L-DOPA conversion assay --- p.125 / Chapter 4.2.4 --- Western blotting (WB) analysis --- p.125 / Chapter 4.2.5 --- Light microscopy and immunofluorescent microscopy --- p.126 / Chapter 4.2.6 --- cAMP immunoassay --- p.126 / Chapter 4.3 --- Results --- p.128 / Chapter 4.3.1 --- The isolation and purification of human melanocytes --- p.128 / Chapter 4.3.2 --- Aging vs. Tyrosinase activity and melanin content --- p.131 / Chapter 4.3.3 --- Inhibitory effect of THSG in tyrosinase activity in human melanocyte --- p.133 / Chapter 4.3.4 --- Alternation of melanogenic proteins --- p.135 / Chapter 4.3.5 --- Sensitization of melanocytes to THSG treatment in co-culture system --- p.138 / Chapter 4.3.6 --- Induction of melanocyte dendricity in co-culture system --- p.140 / Chapter 4.3.7 --- THSG inhibited cAMP induction by forskolin and paracrine factors from keratinocytes --- p.141 / Chapter 4.4 --- Discussion --- p.143 / Discussion / Chapter 5.1 --- Discussion --- p.149 / References --- p.160
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_328203 |
| Date | January 2011 |
| Contributors | Cheung, Wing Ki., Chinese University of Hong Kong Graduate School. Division of Chinese Medicine. |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, bibliography |
| Format | electronic resource, electronic resource, remote, 1 online resource (ix, 174 leaves) : ill. (some col.) |
| Coverage | China, China |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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