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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Phytochemical study on sabina przewalskii, a Tibetan medicinal plant. / CUHK electronic theses & dissertations collection / Digital dissertation consortium

January 2003 (has links)
Woo Ka-yan. / "September 2003." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web.
2

Phytochemical characterization and supercritical fluid extraction of bioactive triterpenes from ganoderma lucidum. / CUHK electronic theses & dissertations collection

January 2006 (has links)
Aims. The objectives of this study were (i) to isolate and characterize by conventional column chromatography, structurally diverse triterpenes from G. lucidum to serve as chemical markers; (ii) to develop a high performance liquid chromatography (HPLC) method for the quality control and/or standardization of Lingzhi-containing products; (iii) to utilize and optimize operating conditions for the newer extraction technology: supercritical fluid extraction (SFE), in order to maximize yields of bioactive triterpenes, and to reduce time and costs. / Background. The dried fruiting body of Ganoderma lucidum, commonly known as Lingzhi, has been used extensively as a traditional Chinese medicine (TCM) for many centuries not only in China, but also in other countries such as Japan and Korea. In recent years, Lingzhi has also become a popular health supplement in many Western countries. The chemical composition of Lingzhi is complex, but it has been well documented that the lipophilic triterpenoid class of compounds possess a range of biological effects that include antitumor, immunomodulatory, cardiovascular, respiratory and antihepatotoxic activity. A major drawback in TCM research has been the lack of authentic chemical standards, and efficient methods for the extraction and analysis of bioactive fractions and/or single components. Conventional extraction methods for G. lucidum are time-consuming and laborious, and often result in low yields of useful chemical constituents. / Conclusion. This study enabled the development of a method for the simultaneous analysis of structurally diverse triterpenes with remarkably different chromatographic profiles. The isolated triterpenes, as chemical markers, and the HPLC method can readily be used for quality control and/or standardization purposes in evaluating Lingzhi-containing products. Optimization of operating conditions for SFE facilitated the rapid and selective extraction of acidic triterpenes from raw G. lucidum in significantly higher yields. / Methods. Raw material of G. lucidum was extracted with 80% ethanol; subjected to repeated column chromatography to purify triterpenes; and characterized by NMR (1H and 13C) and mass spectroscopy. Isolated lipophilic triterpenes were qualitatively and quantitatively analyzed by reversed-phase HPLC using an ODS column (150 x 4.6 mm) and PDA detection at 256 nm. The assay was validated over appropriate concentration ranges and benzophenone was used as an internal standard. Supercritical fluid extraction of G. lucidum was carried out using a commercial supercritical fluid extractor system Thar, SFE-1000M. Briefly, the raw powder of G. lucidum was soaked in ethanol containing 10% aqueous ammonia for 30 minutes prior to extraction. Extractions were performed at temperatures of 40, 50 and 60°C; and pressures of 200, 250, 300 and 350 bar; 5% ethanol was used as the co-solvent; and the flow rate of CO 2 was set at 20 g/min. / Results. Eight compounds were isolated and identified from G. lucidum: four triterpenes; namely, lucidenic acid N, ganoderic acid B, ganodermanontriol, and ganodermadiol; two steroids; ergosterol-7, 22-dien-3beta-ol and ergosterol peroxide; and two fatty acids, oleic acid and tetracosanoic acid. The four triterpenes were utilized as chemical markers, and the developed HPLC method was able to simultaneously analyze the structurally diverse components with good resolution. The total analysis run time was 110 min, and retention times (tR) were 14.88, 18.96, 63.88 and 90.73 min respectively, and the eluting system was a mixture of three solvents, methanol (A), acetonitrile (B) and 2% acetic acid solution (C): 0-22 min, 5% A, 25% B and 70% C; 22-85 min, gradient elution, the ratio changed gradually to 5% A, 80% B and 15% C; 85-110 min, gradient elution, the ratio changed gradually to 5% A, 85% B and 10% C. The validated HPLC method and the isolated chemical markers were effectively applied to determine the triterpenoid contents in a variety of commercial Lingzhi products. Supercritical fluid extraction conditions of: pressure 300 bar and temperature 50°C, gave the highest yields of triterpene-containing extracts. HPLC analysis of the SFE extracts showed predominantly acidic triterpenes such as lucidenic acid N and ganoderic acid B. / Hong Xin. / "December 2006." / Advisers: Ho Yee Ping; Albert H. L. Chow. / Source: Dissertation Abstracts International, Volume: 68-09, Section: B, page: 5968. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 149-175). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.
3

Identification, purification and biological studies of the lead compound from Chinese herbs for the reactivation of fetal hemoglobin expression. / CUHK electronic theses & dissertations collection / Digital dissertation consortium

January 2003 (has links)
Xing Hongtao. / "February 2003." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (p. 149-176). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.
4

Studies on metabolism and pharmacological effect of active constituents of a Tibetan herbal medicine, halenia elliptica /cWong, Yan. / CUHK electronic theses & dissertations collection

January 2007 (has links)
Halenia elliptica D. Don belongs to Gentianaceae family. It is often used as part of a traditional Tibetan medicine to treat hepatitis. In the present investigation, six major xanthone components were isolated and identified from Halenia elliptica. An HPLC/DAD/APCI/MS method was developed and validated for the quantitative analysis of these xanthones, including 1-hydroxy-2,3,5-trimethoxy-xanthone (HM-1), 1-hydroxy-2,3,4,7-tetramethoxy- xanthone (HM-2), 1-hydroxy-2,3,4,5-tetramethoxy-xanthone (HM-3), 1,7- dihydroxy-2,3,4,5-tetramethoxy-xanthone (HM-4), 1,5-dihydroxy-2,3-dimethoxy-xanthone (HM-5) and 1-0-[beta-D-xylopyranosyl-(1-6)-beta-D-glucopyranosyl]-2,3,5-trimethoxy-xanthone (HM-2-10). All the xanthones aglycons caused vasodilation in the coronary artery pre-contracted with 1 muM 5-HT, but the xanthone glycoside had no effect. HM-1 was one of the most abundant xanthones with the most potent vasorelaxant activity. / Mechanisms of the vasorelaxant effect of HM-1 were investigated. HM-1 showed a potent vasorelaxant activity on rat coronary artery involved both an endothelium-dependent mechanism involving NO and an endothelium-independent mechanism by inhibiting Ca2+ influx through L-type voltage-operated Ca2+ channels. / Taken together, in spite of the pharmacokinetics results showed that HM-1 was rapidly and widely distributed to tissues after intravenous administration in rats, with conjugation to being the major metabolic pathway in vivo, both HM-1 and its active metabolite (HM-5) show that they are important pharmacological agents with potentially useful therapeutic indications. / The metabolism and pharmacokinetics of HM-1 displayed biphasic elimination kinetics, with an elimination half-life of 60.4 +/- 4.2 min. Four other Phase I metabolites were isolated and identified as demethylated products in vitro. HM-1 was metabolised to HM-5 in the liver. Biliary excretion studies showed that both HM-1 and the metabolite (HM-5) underwent extensive phase II conjugation to form glucuronides and sulfates. Tissue distribution studies showed that HM-1 was widely distributed to different organs. Collection of urine and faeces over 24 h showed that 10.88% of dose was excreted from urine and 1.91% of dose via faeces. / With HM-5 being one of the major in vivo metabolites of HM-1, the effect of HM-5 has been studied on rat coronary artery and compared to HM-1. HM-5-mediated vasorelaxant effect was mediated through opening of potassium channel (TEA, 4-AP) and altering intracellular calcium by partial inhibition of Ca2+ influx through L-type voltage-operated Ca 2+ channels and intracellular Ca2+ stores. / "September 2007." / Source: Dissertation Abstracts International, Volume: 69-08, Section: B, page: 4699. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 195-218). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.
5

HPLC-MS analysis of radix astragali, cortex phellodendri, rhizoma coptidis and sanhuang xiexin decoction /cTsai, Sam Hip. / CUHK electronic theses & dissertations collection

January 2007 (has links)
A method is presented for the simultaneous identification of nine compounds in samples of A. membranaceus and A. membranaceus var. mongholicus. Compounds identified in the extracts of the two plants included glycosides, saponins and flavonoids. They are identified as Calycosin-7-O-beta-D-glucoside (C1), Ononin (C2), (6aR,11aR)-3-hydroxy- 9,10-dimethoxypterocarpan-3-O-beta-D-glucoside (C3), (3R)-7,2'-dihydr- oxy-3',4'-dimethoxyisoflavan-7-O-beta-D-glucoside (C4), Calycosin (C6), Astragaloside IV (C5 ), Formononetin (C7), (6aR,11a R)-3-hydroxy-9,10-di-methoxypterocarpan (C8), and Isomucronulatol (C9). / An HPLC-DAD-MS method is proposed for the differentiation of Rhizoma Coptidis and Cortex Phellodendri samples. This method can also be used to identify two common species of Rhizome Coptidis, i.e., C. chinensis and C. deltoidea, and two species of Cortex Phellodendri, i.e., P. chinensis and P. amurense. From the experiment results, there are thirteen, twelve and seven common components found in samples Rhizoma Coptidis, P. amurense and P. chinensis, respectively. Nine compounds in Rhizoma Coptidis were identified to be alkaloids. The common components in Cortex Phellodendri included four alkaloids and two lactones, i.e., obaculacotone and obacunone, present in all samples of P. amurense. / High Performance Liquid Chromatography-Atmospheric Pressure Chemical Ionization Mass-Spectrometry has been applied to the analysis and standardization of Chinese Herbal Medicines. The applications included quantitative study of Astragaloside in Radix Astragali, investigation on the chromatographic fingerprint of Radix Astragali, differentiation of Cortex Phellodendri and Rhizoma Coptidis, and identification of constituents in Sanhuang Xiexin Decoction. / In the quantitative study of Astragaloside, an Multiple Reaction Monitoring scan mode was used. The linearity between 2 and 500 mg/L is 0.9996. The precision of injection and reproducibility of method is 1.72% and 3.27% respectively. A total of 20 samples from local market and mainland China were analyzed and the results are comparable to those obtained from HPLC-ELSD analysis. / The present study also proposed a HPLC separation and online identification for the 15 constituents in a composite Chinese herbal formula, the Sanhuang Xiexin Decoction. It provided a possible starting point to evaluate related herbal preparations containing Rhizoma Coptidis, Radix Scutellariae and Rhizoma Rhei. Thirteen constituents in the decoction were identified, including five major alkaloids from Rhizoma Coptidis, five anthraquinones from Rhizoma Rhei and two favonoids and one glycoside from Radix Scutellariae. / "November 2007." / Adviser: Chi Chun Tao. / Source: Dissertation Abstracts International, Volume: 69-08, Section: B, page: 4726. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 177-200). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.
6

Authentication of traditional Chinese medicines Radix Aconiti and Radix Aucklandiae by DNA and chemical technologies.

January 2006 (has links)
Shum Ka Chiu. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 174-182). / Abstracts in English and Chinese. / Acknowledgement --- p.ii / Abstract --- p.iii / 摘要 --- p.vi / Table of content --- p.viii / List of figures --- p.xvi / List of tables --- p.xxii / Abbreviations --- p.xxv / Chapter Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Importance of authentication of Traditional Chinese Medicines --- p.1 / Chapter 1.1.1 --- Confusing nomenclatures --- p.1 / Chapter 1.1.2 --- Similar morphologies of different medicinal materials --- p.2 / Chapter 1.1.3 --- Toxicities of medicinal materials --- p.2 / Chapter 1.1.4 --- Conservation of natural products --- p.2 / Chapter 1.2 --- TCM listed in the Pharmacopoeia of People's Republic of China --- p.3 / Chapter 1.3 --- Overview of mis-use and intoxication of TCM --- p.4 / Chapter 1.4 --- Ordinances regulating Chinese medicines as natural products --- p.7 / Chapter 1.4.1 --- Laws governing Chinese medicine --- p.7 / Chapter 1.4.2 --- Laws governing endangered species --- p.8 / Chapter 1.5 --- Current technologies in the authentication of Traditional Chinese Medicines and their limitations --- p.9 / Chapter 1.6 --- Historical applications of Radix Aconiti --- p.12 / Chapter 1.7 --- Modern applications of Radix Aconiti --- p.16 / Chapter 1.8 --- Research on Radix Aconiti and its chemical components --- p.17 / Chapter 1.8.1 --- Chemistry --- p.17 / Chapter 1.8.2 --- Pharmacology --- p.19 / Chapter 1.8.3 --- Molecular interaction --- p.22 / Chapter 1.9 --- Brief review on the systematics and phylogeny of Aconitum --- p.23 / Chapter 1.10 --- Historical applications of Radix Aucklandiae and related materials --- p.25 / Chapter 1.11 --- Modern applications of Radix Aucklandiae and related material --- p.27 / Chapter 1.12 --- Research on Aucklandiae and related material and their chemical components --- p.28 / Chapter 1.12.1 --- Chemistry --- p.28 / Chapter 1.12.2 --- Pharmacology --- p.29 / Chapter 1.13 --- Brief review on the systematics and phylogeny of Aucklandia and related medicinal species --- p.31 / Chapter 1.14 --- Authentication by DNA sequencing --- p.33 / Chapter 1.14.1 --- Introduction --- p.33 / Chapter 1.14.2 --- Criteria of sequence markers --- p.36 / Chapter 1.14.3 --- Model used to process polymorphism in DNA sequences --- p.37 / Chapter 1.15 --- Screening for novel markers --- p.38 / Chapter 1.15.1 --- Reason for screening novel markers --- p.38 / Chapter 1.15.2 --- Basic principle --- p.39 / Chapter 1.16 --- Introduction to gas chromatography- mass spectrometry --- p.40 / Chapter 1.16.1 --- Basic principles and components of GC-MS --- p.41 / Chapter 1.16.2 --- Advantages and limitations of GC-MS --- p.42 / Chapter 1.16.3 --- Usage of GC-MS on natural product analysis --- p.43 / Chapter 1.16.4 --- Chemometric analysis --- p.44 / Chapter 1.17 --- Objectives --- p.46 / Chapter Chapter 2. --- Materials and Methods --- p.47 / Chapter 2.1 --- Plant samples --- p.47 / Chapter 2.1.1 --- Samples of Aconitum --- p.47 / Chapter 2.1.2 --- Samples of Aucklandia and related species --- p.51 / Chapter 2.2 --- DNA extraction method --- p.58 / Chapter 2.2.1 --- Reagents --- p.58 / Chapter 2.2.2 --- Methods --- p.59 / Chapter 2.3 --- Chemical extraction methods --- p.61 / Chapter 2.4 --- Chemical standard extraction and purification method --- p.62 / Chapter 2.5 --- DNA sequencing --- p.63 / Chapter 2.5.1 --- Reagents --- p.63 / Chapter 2.5.2 --- Methods --- p.65 / Chapter 2.6 --- Genomic subtraction --- p.70 / Chapter 2.7 --- Search for species-specific markers from the subtraction library --- p.74 / Chapter 2.8 --- Gas chromatography- mass spectrometry --- p.74 / Chapter 2.9 --- GC-MS chemometric analysis --- p.75 / Chapter Chapter 3. --- Authentication of Aconitum by DNA Sequencing --- p.76 / Chapter 3.1 --- Introduction --- p.76 / Chapter 3.2 --- Methods --- p.77 / Chapter 3.3 --- Results - 5S spacer --- p.77 / Chapter 3.3.1 --- Sequence information --- p.77 / Chapter 3.3.2 --- Sequence similarity --- p.78 / Chapter 3.3.3 --- Phylogram study --- p.81 / Chapter 3.4 --- Results -psbA-trnH --- p.85 / Chapter 3.4.1 --- Sequence information --- p.85 / Chapter 3.4.2 --- Sequence similarity --- p.85 / Chapter 3.4.3 --- Phylogram study --- p.87 / Chapter 3.5 --- Discussion --- p.91 / Chapter 3.5.1 --- Overview of nuclear ribosomal 5S spacer --- p.91 / Chapter 3.5.2 --- Extensive polymorphism of 5S spacer --- p.91 / Chapter 3.5.3 --- Distribution of samples in the phylograms constructed by 5S spacer --- p.93 / Chapter 3.5.4 --- Utility of 5S spacer for authentication --- p.94 / Chapter 3.5.5 --- Overview of psbA-trnH spacer --- p.94 / Chapter 3.5.6 --- Distribution of samples in the phylograms constructed by psbA-trnH spacer --- p.95 / Chapter 3.5.7 --- A distinctive region of inversion --- p.96 / Chapter 3.5.8 --- Utility of psbA-trnH for authentication --- p.97 / Chapter Chapter 4. --- Screening for Novel Markers for Authentication of Aconitum --- p.98 / Chapter 4.1 --- Introduction --- p.98 / Chapter 4.2 --- Methods --- p.99 / Chapter 4.3 --- Results - subtracted clones --- p.99 / Chapter 4.4 --- Results - SSH6 --- p.104 / Chapter 4.4.1 --- Sequence information --- p.104 / Chapter 4.4.2 --- Sequence similarity --- p.105 / Chapter 4.5 --- Results-SSH15 --- p.107 / Chapter 4.5.1 --- Sequence information --- p.107 / Chapter 4.5.2 --- Sequence similarity --- p.107 / Chapter 4.5.3 --- Phylogram study --- p.109 / Chapter 4.6 --- Results-SSH45 --- p.113 / Chapter 4.6.1 --- Sequence information --- p.113 / Chapter 4.6.2 --- Sequence similarity --- p.113 / Chapter 4.6.3 --- Phylogram study --- p.115 / Chapter 4.7 --- Discussion --- p.119 / Chapter 4.7.1 --- Utility of subtraction in screening markers --- p.119 / Chapter 4.7.2 --- SSH6 --- p.121 / Chapter 4.7.3 --- SSH15 --- p.122 / Chapter 4.7.4 --- SSH45 --- p.123 / Chapter 4.7.5 --- Hybridization in Aconitum --- p.124 / Chapter 4.7.6 --- Inferring species identities of samples from the market --- p.126 / Chapter 4.8 --- Conclusion --- p.128 / Chapter Chapter 5. --- Assessment of Aucklandia lappa and Related Species by GC-MS --- p.129 / Chapter 5.1 --- Introduction --- p.129 / Chapter 5.2 --- Methods --- p.130 / Chapter 5.3 --- Results --- p.130 / Chapter 5.3.1 --- Extraction of essential oil --- p.130 / Chapter 5.3.2 --- GC-MS analysis --- p.131 / Chapter 5.3.3 --- Peak alignment and hierarchical cluster analysis --- p.133 / Chapter 5.3.4 --- Purification of chemical markers from Aucklandia lappa --- p.148 / Chapter 5.3.5 --- Standardization of the purified chemical markers --- p.148 / Chapter 5.3.6 --- Quantitative analysis of chemical markers --- p.152 / Chapter 5.4 --- Discussion --- p.154 / Chapter 5.4.1 --- Analysis of chemical composition --- p.154 / Chapter 5.4.2 --- A comparison on chemometric methods --- p.154 / Chapter 5.4.3 --- Similarity of chemical profiles --- p.156 / Chapter 5.4.4 --- Dendrogram analysis --- p.157 / Chapter 5.4.5 --- Utility of GC-MS in authentication of A. lappa and related species --- p.159 / Chapter 5.4.6 --- Limitations --- p.159 / Chapter 5.4.7 --- Comparison with molecular data --- p.161 / Chapter 5.4.8 --- Contents of dehydrocostuslactone and costunolide --- p.163 / Chapter 5.4.9 --- Locality study --- p.164 / Chapter 5.5 --- Conclusion --- p.165 / Chapter Chapter 6. --- General Discussion --- p.167 / Chapter 6.1 --- DNA sequencing --- p.168 / Chapter 6.2 --- Genomic subtraction --- p.169 / Chapter 6.3 --- Future work on molecular authentication --- p.170 / Chapter 6.4 --- Future work on authentication of Aconitum --- p.170 / Chapter 6.5 --- Gas chromatography- mass spectrometry --- p.171 / Chapter 6.6 --- Future work on authentication by GC-MS --- p.172 / Chapter 6.7 --- Future work on authentication of Aucklandia lappa and related species … --- p.173 / References --- p.174 / Appendix A. Sequence Alignment of 5S Spacer from Aconitum Species --- p.183 / Appendix B. Sequence Alignment of psbA- trnH Spacer from Aconitum Species --- p.188 / Appendix C. Sequences of Subtracted Clones from Aconitum --- p.191 / Appendix D. Sequence Alignment of SSH6 from Aconitum Species --- p.194 / Appendix E. Sequence Alignment of SSH15 from Aconitum Species --- p.195 / Appendix F. Sequence Alignment of SSH45 from Aconitum Species --- p.200 / Appendix G. Gas Chromatograms of Essential Oil Extracts of Aucklandia lappa and Related Species --- p.202

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