Diabetes mellitus (DM) has become a global threat in developing and developed countries, where diabetic patients are more prone to cardiovascular complications, a condition called diabetic cardiomyopathy. Studies have shown a direct link between hyperglycaemia and an increase in the production of reactive oxygen species in cardiac cells leading to diabetic cardiomyopathy. This study tests oleanolic acid, a bioactive compound from the plant Syzigium aromaticum as an antioxidant which could have a potential role in management of DM. Aims i) To extract Oleanolic acid (OA) from Syzigium aromaticim, ii) Investigate the antioxidant effects of plant derived OA in an in-vitro model of hyperglycaemia induced oxidative stress. Methods The flower buds of the Syzigium aromaticim [(Linnaeus) Merrill & Perry] (Myrtaceae) plant (commonly called cloves) were used to isolate OA. The ethyl acetate solubles from the cloves were subjected to chromatographic fractionation to yield OA powder. Spectroscopic analysis was done using 1D and 2D 1H and 13C NMR techniques for the identification of the structure of the compound. This compound was then used in vitro to test for its antioxidative properties. H9C2 cardiac myoblasts were employed which were treated with normoglycaemic (5.5 mM) and hyperglycaemic (33 mM) glucose conditions. The cells were then treated with oleanolic acid to test for its antioxidant properties. We looked at a dose-dependent (0, 20, 50 μM) and time-dependent effects of OA treatment (6 and 24 hrs) following 48 hours glucose exposure. ROS levels were measured using H2DCF-DA fluorescence staining using microscopy and flow cytometry techniques for analysis. xviii Results Recrystallisation of the powder with ethanol and inspection of the 1 and 2- dimensional 1H- and 13C-NMR spectra of the compound with comparison to literature data confirmed OA molecular structure and IUPAC numbering similar to that of literature characterized and confirmed the structure of oleanolic acid. In cell specific data high glucose treatments on H9C2 cells showed increased ROS production (22 ± 6 % and 20 ± 7 % n= 3 p< 0.01) for 6 and 24 hrs treatments, respectively, compared to their normoglycaemic control groups. The 6 h OA treated group showed a decrease in ROS production with 26.6 ± 17.4 % for the 20 μM while for 50 μM there was a 37.7 ± 14.3% decrease. A ROS reduction trend was observed in the normoglycaemic group, but this was significant at 24 hrs with 46.8 ± 45.3% and 57.3 ± 9 % for both 20 and 50 μM treatments, respectively. The 24 hrs OA treated group showed a dose-dependent decrease in ROS with 50 μM more pronounced (80.7% ± 4.5 %). The 20 μM OA treatments also showed a 15.7 ± 19 % decrease in ROS. Discussion In the present study, we have evaluated the antioxidant effects of OA in vitro following extraction of the compound from Syzigium aromaticim. The oxidative stress induced by hyperglycaemia was attenuated by oleanolic acid and this also translated into decreased ROS suggesting its use as an antioxidant in alleviating cardiovascular complications associated with diabetes mellitus.

Yip Pui Ying. / Thesis submitted in: November 2004. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 147-184). / Abstracts in English and Chinese. / Abstract --- p.i / 摘要 --- p.iii / Acknowledgment --- p.v / Abbreviations --- p.vii / Table of contents --- p.viii / List of Figures --- p.xii / List of Tables --- p.xvii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1. --- The importance of characterization of Chinese medicinal materials and the development of Chinese medicine in Hong Kong --- p.1 / Chapter 1.2. --- Methods for characterization of Chinese medicinal materials --- p.5 / Chapter 1.3. --- Molecular characterization of Chinese medicinal materials --- p.8 / Chapter 1.3.1. --- DNA sequencing --- p.9 / Chapter 1.3.2. --- DNA fingerprinting --- p.14 / Chapter 1.3.3. --- Nucleic acid hybridization --- p.19 / Chapter 1.4. --- Objectives --- p.20 / Chapter Chapter 2 --- Characterization of Plant and Fungal Materials by rDNA ITS Sequence Analysis --- p.22 / Chapter 2.1. --- Introduction --- p.22 / Chapter 2.2. --- Materials and Methods --- p.22 / Chapter 2.2.1. --- Chinese medicinal materials used in this study --- p.22 / Chapter 2.2.1.1. --- Plants and fungi for interspecific ITS study --- p.22 / Chapter 2.2.1.2. --- Plant for intraspecific ITS study and locality study --- p.33 / Chapter 2.2.2. --- Extraction of total DNA --- p.35 / Chapter 2.2.3. --- PCR amplification of ITS1 and ITS2 regions of rRNA gene --- p.35 / Chapter 2.2.4. --- Purification of PCR products --- p.38 / Chapter 2.2.5. --- Cloning using pCR-Script´ёØ Amp SK(+) Cloning Kit --- p.38 / Chapter 2.2.5.1. --- Polishing --- p.38 / Chapter 2.2.5.2. --- Ligation of inserts into pCR-Script´ёØ Amp SK(+) cloning vector --- p.38 / Chapter 2.2.5.3. --- Transformation --- p.40 / Chapter 2.2.5.4. --- PCR screening of white colonies --- p.40 / Chapter 2.2.5.5. --- Purification of PCR screening products --- p.41 / Chapter 2.2.6. --- Sequencing of ITS regions --- p.41 / Chapter 2.2.6.1. --- Cycle sequencing reaction --- p.41 / Chapter 2.2.6.2. --- Purification of sequencing extension products --- p.41 / Chapter 2.2.6.3. --- Electrophoresis by genetic analyzer --- p.42 / Chapter 2.2.7. --- Sequence analysis and alignment --- p.42 / Chapter 2.3. --- Results --- p.42 / Chapter 2.3.1. --- Extraction of total DNA --- p.42 / Chapter 2.3.2. --- PCR amplification of ITS1 and ITS2 regions of rRNA gene --- p.44 / Chapter 2.3.2.1. --- Interspecific ITS study --- p.44 / Chapter 2.3.2.2. --- Intraspecific ITS study --- p.46 / Chapter 2.3.3. --- Sequence analysis and alignment --- p.47 / Chapter 2.3.3.1. --- Interspecific ITS study --- p.47 / Chapter 2.3.3.2. --- Intraspecific ITS study --- p.56 / Chapter 2.4. --- Discussions --- p.60 / Chapter 2.4.1. --- rDNA regions used for studying Chinese medicinal materials --- p.60 / Chapter 2.4.2. --- The results agreed with previously published works --- p.60 / Chapter 2.4.3. --- Explanation of interspecific results within the Ganoderma genus --- p.60 / Chapter 2.4.4. --- Implications from interspecific comparisons --- p.60 / Chapter 2.4.5. --- Implications from intraspecific comparisons --- p.61 / Chapter Chapter 3 --- .Characterization of Astragalus membranaceus by DNA Fingerprinting / Chapter 3.1 --- Introduction --- p.62 / Chapter 3.2 --- Materials and Methods --- p.62 / Chapter 3.2.1 --- Extraction of total DNA --- p.62 / Chapter 3.2.2 --- Generation and detection of DNA fingerprints by AP-PCR --- p.63 / Chapter 3.2.3 --- Analysis of DNA fingerprints --- p.63 / Chapter 3.3 --- Results --- p.63 / Chapter 3.3.1 --- Generation of DNA fingerprints by AP-PCR --- p.63 / Chapter 3.3.2 --- Fingerprint analysis --- p.69 / Chapter 3.4 --- Discussion --- p.85 / Chapter 3.4.1 --- RP-PCR has been used on Chinese medicinal materials --- p.85 / Chapter 3.4.2 --- AP-PCR used instead of RAPD --- p.85 / Chapter 3.4.3 --- Reproducibility and amount of bands --- p.86 / Chapter 3.4.4 --- Alternatives of electrophoresis process --- p.88 / Chapter 3.4.5 --- Explanation of results --- p.88 / Chapter 3.4.6 --- Distinguishing Neimengu and Shanxi samples --- p.89 / Chapter 3.4.7 --- Further studies --- p.90 / Chapter Chapter 4 --- Characterization of Plant and Fungal Materials by DNA-DNA Hybridization on Microarrays --- p.91 / Chapter 4.1 --- Introduction --- p.91 / Chapter 4.2 --- Materials and Methods --- p.92 / Chapter 4.2.1 --- Samples for microarray study --- p.92 / Chapter 4.2.2 --- Extraction of total DNA --- p.95 / Chapter 4.2.3 --- Amplification and sequencing of ITS 1 region of rRNA gene --- p.95 / Chapter 4.2.4 --- Preparation of labeled probe --- p.95 / Chapter 4.2.5 --- Amplification of ITS1 fragments --- p.97 / Chapter 4.2.6 --- Preparation of slides --- p.103 / Chapter 4.2.7 --- Hybridization and washing --- p.104 / Chapter 4.2.8 --- Scanning and data analysis --- p.105 / Chapter 4.3 --- Results --- p.105 / Chapter 4.3.1 --- DNA extraction --- p.105 / Chapter 4.3.2 --- Amplification and sequencing of ITS1 region of rRNA gene --- p.107 / Chapter 4.3.3 --- Preparation of labeled probe and amplification of ITS1 fragments… --- p.112 / Chapter 4.3.4 --- Preparation of slides --- p.112 / Chapter 4.3.5 --- Scanning and data analysis --- p.116 / Chapter 4.4 --- Discussion --- p.134 / Chapter 4.4.1 --- Implications --- p.134 / Chapter 4.4.2 --- Applying the findings --- p.134 / Chapter 4.4.3 --- Ways to maximize specificity --- p.137 / Chapter 4.4.4 --- Optimisation --- p.138 / Chapter 4.4.5 --- Microarray may be more advantageous over sequencing --- p.138 / Chapter Chapter Five --- General Discussion and Summary --- p.140 / Chapter 5.1. --- Objectives of this study --- p.140 / Chapter 5.2. --- rDNA ITS sequencing --- p.140 / Chapter 5.2.1. --- Description of the approach and summary of the results --- p.140 / Chapter 5.2.2. --- Implications from the results --- p.140 / Chapter 5.2.3. --- Advantages and limitations of DNA sequencing --- p.141 / Chapter 5.3. --- AP-PCR fingerprinting --- p.141 / Chapter 5.3.1. --- Description of the approach and summary of the results --- p.141 / Chapter 5.3.2. --- Advantages and limitations of DNA fingerprinting --- p.142 / Chapter 5.4. --- DNA-DNA hybridization on microarrays --- p.143 / Chapter 5.4.1. --- Description of the approach and summary of the results --- p.143 / Chapter 5.4.2. --- Implications from the results --- p.143 / Chapter 5.4.3. --- Advantages and limitations of DNA hybridization on microarrays. --- p.144 / Chapter 5.5. --- Overall summary --- p.144 / Chapter 5.6. --- Future studies --- p.146 / References --- p.147 / Appendix --- p.185