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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.
71

On the Prevalence and Role of Addition Reactions in Lipid Peroxidation

Abou-Zaid, Anas Mamdouh 15 July 2021 (has links)
Plasmalogens have been reported to possess antioxidant activity; a paradoxical finding given that plasmalogens often comprise highly oxidizable polyunsaturated fatty acids esterified to the central position of the glycerol backbone. However a reasonable mechanism accounting for plasmenyl lipid activity has yet to be advanced, despite the fact that other monounsaturated lipids including cholesterol and oleate have been extensively studied. Plasmenylcholine was synthesized de novo to resolve its antioxidant activity as well as to carry out mechanistic studies to understand its basis. Autoxidation of a vinyl ether model substrate yielded a kp of 6 M-1 s-1, which affirmed it was as slower than cholesterol. However, corresponding experiments with a deuterated substrate yielded a value of 89 M-1 s-1, questioning the reliability of these studies. Our studies of plasmenyl lipid peroxidation inspired us to look into the mechanism of autoxidation of the monounsaturated lipid, oleate (using LC-MS/MS with APCI+), which was reported to proceed exclusively via H-atom transfer (HAT). Herein we have shown for the first time that oleate epoxides are formed in the autoxidation of the monounsaturated lipid.
72

Antioxidants and the inhibition of lypoxygenase and cyclooxygenase enzyme systems /

Gwebu, Ephraim Tobela January 1978 (has links)
No description available.
73

The assessment of Solanum lycopersicum cv. Micro-Tom tomato fruit antioxidant content and capacity under differing temperatures, irrigation regimes, and light hours

Burkhead, Tineka 07 August 2020 (has links) (PDF)
The impacts of climate change on agriculture have been observable for years, particularly with declining yields and reduced productivity. Much research has been performed to examine the relationships between yield and climatic variables, especially temperature and precipitation. By comparison, little research has been conducted to assess the impact that climate change has on the nutrition, particularly the antioxidant content and capacity, of crops. This research project aims to fulfill this knowledge gap. Solanum lycopersicum cv. Micro-Tom plants were cultivated in five growth chambers with different temperatures, hours of light, and watering regimes to simulate different environments. The three temperature regimes were 25°, 32°, and 40°C during the day. The two chosen light durations were 12 and 16 hours (h), and the selected watering frequencies were 3 and 5 days (d). Lycopene and phenolics were quantified via spectrophotometry. Color was assessed via the CIELAB color space, specifically the a* value. The ferric reducing ability of plasma (FRAP) assay assessed the ability of the compounds in each tomato sample to serve as antioxidants. Upon analysis, the highest lycopene concentration (72.68 mg per kg fresh weight) was found in tomatoes exposed to 32°C, three days between irrigation cycles, and 16 hours of light. The highest level of phenolics (0.41660 mg gallic acid equivalent per g fresh weight) was observed in tomatoes exposed to 32°C with three days between watering cycles. The largest a* value (11.21), which corresponds to an intense red hue, was seen in tomatoes exposed to 32°C with 16 hours of light. The greatest level of antioxidant capacity [162.12 micromolar Fe(II)] as measured by the FRAP assay occurred in tomatoes exposed to 32°C with three days between irrigation cycles. Overall, antioxidant content and capacity increased the most at 32°C with three days between watering periods. Photoperiod was unimportant. By varying environmental conditions, “designer crops” with specific antioxidant content can seemingly be produced without genetic manipulation. This work enhances the body of knowledge concerning effects of abiotic stress on food crop antioxidants, which is important given the gravity of climate change.
74

Chemical evaluation, isolation and characterization of antioxidants from two lesser-known edible mushrooms: Pleurotus eryngii and Agrocybe aegerita.

January 2003 (has links)
Lo Kit Man. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 193-208). / Abstracts in English and Chinese. / THESIS COMMITTEE --- p.i / ACKNOWLEDGEMENTS --- p.ii / ABSTRACT --- p.iii / ABSTRACT (Chinese version) --- p.v / CONTENT --- p.vii / LIST OF TABLES --- p.xiii / LIST OF FIGURES --- p.xviii / LIST OF ABBREVIATIONS --- p.xx / Chapter CHAPTER 1: --- INTRODUCTION --- p.1 / Chapter 1.1 --- An introduction of natural antioxidants --- p.1 / Chapter 1.1.1 --- Definition of antioxidants --- p.1 / Chapter 1.1.2 --- Application of natural antioxidants in foods --- p.3 / Chapter 1.1.2.1 --- Oxidation of foods --- p.3 / Chapter 1.1.2.1.1 --- Autoxidation of food --- p.3 / Chapter 1.1.2.1.2 --- Photo-oxidation of food --- p.4 / Chapter 1.1.3 --- Free radicals and antioxidants --- p.6 / Chapter 1.1.3.1 --- Free radicals and reactive oxygen species --- p.6 / Chapter 1.1.3.1.1 --- Superoxide anion radical --- p.8 / Chapter 1.1.3.1.2 --- Hydrogen peroxide --- p.9 / Chapter 1.1.3.1.3 --- Hydroxyl radical --- p.10 / Chapter 1.1.3.1.4 --- Peroxyl radical --- p.12 / Chapter 1.1.3.1.5 --- Lipid peroxidation of cell membranes --- p.13 / Chapter 1.1.3.1.6 --- Oxidation of LDL and atherosclerosis --- p.16 / Chapter 1.1.4 --- Natural antioxidants and their mechanisms --- p.18 / Chapter 1.1.4.1 --- Carotenoids --- p.18 / Chapter 1.1.4.2 --- Phenolic compounds --- p.20 / Chapter 1.1.4.2.1 --- Flavonoids --- p.21 / Chapter 1.1.4.2.2 --- Phenolic acids --- p.22 / Chapter 1.1.4.3 --- Sterols --- p.24 / Chapter 1.1.4.4 --- Vitamins --- p.25 / Chapter 1.2 --- Antioxidant in mushrooms --- p.27 / Chapter 1.2.1 --- Antioxidant properties of mushrooms --- p.27 / Chapter 1.2.2 --- Characterization of mushroom phenolic antioxidants --- p.30 / Chapter 1.2.3 --- Biosynthesis of phenolic compounds in mushrooms or fungi --- p.33 / Chapter 1.3 --- Assays for evaluation of antioxidants --- p.35 / Chapter 1.3.1 --- Beta-carotene bleaching method --- p.35 / Chapter 1.3.2 --- Scavenging activity of DPPH radical --- p.36 / Chapter 1.3.3 --- Erythrocyte hemolysis --- p.36 / Chapter 1.3.4 --- Scavenging activity of ABTS ´Ø + radical cation --- p.37 / Chapter 1.3.5 --- Scavenging activity of hydroxyl radical --- p.37 / Chapter 1.3.6 --- Assay for lipid peroxidation of rat brain homogenate --- p.38 / Chapter 1.3.7 --- Inhibition of low-density lipoproteins (LDLs) oxidation --- p.39 / Chapter 1.4 --- Analysis of phenolic antioxidants --- p.41 / Chapter 1.4.1 --- Extraction of phenolic compounds --- p.41 / Chapter 1.4.2 --- Determination of total phenolic content --- p.43 / Chapter 1.4.3 --- Chromatographic fractionation of phenolic compounds --- p.44 / Chapter 1.4.4 --- Characterization of phenolic compounds --- p.45 / Chapter 1.4.4.1 --- Thin-layer chromatography (TLC) --- p.45 / Chapter 1.4.4.2 --- High performance liquid chromatography (HPLC) --- p.46 / Chapter 1.4.4.3 --- Liquid chromatography-Mass spectrometry (LC-MS) --- p.47 / Chapter 1.5 --- Objectives --- p.49 / Chapter CHAPTER 2: --- MATERIALS AND METHODS --- p.50 / Chapter 2.1 --- Sample preparation --- p.50 / Chapter 2.2 --- Sample extraction. --- p.51 / Chapter 2.2.1 --- Small-scale methanol and water extraction --- p.51 / Chapter 2.2.2 --- Large-scale methanol and water extraction and fractionation --- p.54 / Chapter 2.2.2.1 --- Large-scale methanol and water extraction --- p.54 / Chapter 2.2.2.2 --- Fractionation of crude extracts --- p.55 / Chapter 2.2.2.2.1 --- Fractionation of methanol crude extract --- p.55 / Chapter 2.2.2.2.2 --- Fractionation of water crude extract --- p.55 / Chapter 2.3 --- Fractionation by column chromatography --- p.58 / Chapter 2.4 --- Assays for measuring antioxidant activity --- p.60 / Chapter 2.4.1 --- Beta-carotene bleaching method --- p.60 / Chapter 2.4.2 --- Scavenging activity of DPPH radical --- p.62 / Chapter 2.4.3 --- Erythrocyte hemolysis --- p.63 / Chapter 2.4.4 --- Scavenging activity of ABTS ´Ø + radical cation --- p.64 / Chapter 2.4.5 --- Scavenging activity of hydroxyl radical --- p.65 / Chapter 2.4.6 --- Assay for lipid peroxidation of rat brain homogenate --- p.66 / Chapter 2.4.7 --- Inhibition of human low-density lipoproteins (LDLs) oxidation --- p.67 / Chapter 2.4.7.1 --- Isolation of human LDLs --- p.67 / Chapter 2.4.7.2 --- Calculation of density --- p.68 / Chapter 2.4.7.3 --- Lowry's method for determination of protein content --- p.69 / Chapter 2.4.7.4 --- Preparation of reagents --- p.69 / Chapter 2.4.7.5 --- Determination of thiobarbituric acid reactive substance (TBARS) --- p.70 / Chapter 2.5 --- Total phenolic content --- p.70 / Chapter 2.6 --- Total carbohydrate content --- p.71 / Chapter 2.7 --- Determination of protein content- the Biuret method --- p.71 / Chapter 2.8 --- Thin-layer chromatography (TLC) --- p.72 / Chapter 2.9 --- High performance liquid chromatography (HPLC) --- p.73 / Chapter 2.9.1 --- Analysis of subfractions of methanol crude extract --- p.73 / Chapter 2.9.2 --- Analysis of fractionated subfractions and subfractions of Pevf and Aa mushrooms --- p.74 / Chapter 2.10 --- Liquid chromatography- Mass spectrometry (LC-MS) --- p.74 / Chapter 2.10.1 --- Liquid chromatography --- p.74 / Chapter 2.10.2 --- Mass spectrometry --- p.75 / Chapter 2.11 --- Data analysis --- p.75 / Chapter CHAPTER 3: --- RESULTS AND DISCUSSION --- p.77 / Chapter 3.1 --- Small-scale extraction scheme --- p.77 / Chapter 3.1.1 --- Extraction yield --- p.77 / Chapter 3.1.2 --- Assays for measuring antioxidant activity --- p.80 / Chapter 3.1.2.1 --- Beta-carotene bleaching method --- p.80 / Chapter 3.1.2.2 --- Scavenging activity of DPPH radical --- p.91 / Chapter 3.1.2.3 --- Erythrocyte hemolysis --- p.98 / Chapter 3.1.2.4 --- Summary for small-scale extraction --- p.105 / Chapter 3.2 --- Large-scale extraction and fractionation scheme --- p.107 / Chapter 3.2.1 --- Extraction yield for crude extracts and subfractions --- p.107 / Chapter 3.2.2 --- Antioxidant activity of subfractions and crude extracts of Aa and Pevf mushrooms --- p.111 / Chapter 3.2.2.1 --- Scavenging activity of ABTS ´Ø + radical cation --- p.111 / Chapter 3.2.2.2 --- Scavenging activity of hydroxyl radical --- p.114 / Chapter 3.2.2.3 --- Assay for lipid peroxidation of rat brain homogenate --- p.125 / Chapter 3.2.2.4 --- Summary for large-scale extraction --- p.135 / Chapter 3.2.3 --- Chemical characterization of the crude extracts and their sub fractions of Aa and Pevf mushrooms --- p.13 8 / Chapter 3.2.3.1 --- Total phenolic content --- p.139 / Chapter 3.2.3.1.1 --- Total phenolic content of crude extract and their sub fractions of Aa and Pevf mushrooms --- p.139 / Chapter 3.2.3.1.2 --- Correlation between total phenolic content and antioxidant activity --- p.140 / Chapter 3.2.3.2 --- Total carbohydrate content --- p.144 / Chapter 3.2.3.2.1 --- Total carbohydrate content of water crude extract and their sub fractions of Aa and Pevf mushrooms --- p.144 / Chapter 3.2.3.2.2 --- Correlation between total carbohydrate content and antioxidant activity --- p.144 / Chapter 3.2.3.3 --- Determination of protein content- the Biuret method --- p.146 / Chapter 3.2.3.3.1 --- Protein content of water crude extract and their sub fractions of Aa and Pevf mushrooms --- p.146 / Chapter 3.2.3.3.2 --- Correlation between protein content and antioxidant activity --- p.147 / Chapter 3.2.3.4 --- Summary of correlation between chemical components and antioxidant activity --- p.148 / Chapter 3.3 --- Column fractionation of ethyl acetate and butanol subfractions of Aa mushroom --- p.151 / Chapter 3.3.1 --- Rf value in TLC and yield of fractionated subfractions --- p.151 / Chapter 3.3.2 --- Total phenolic content of fractionated subfractions --- p.153 / Chapter 3.3.3 --- Antioxidant activity of fractionated subfractions --- p.155 / Chapter 3.3.3.1 --- Scavenging activity of ABTS ´Ø + radical cation --- p.155 / Chapter 3.3.3.2 --- Scavenging activity of DPPH radical --- p.158 / Chapter 3.3.3.3 --- Inhibition of human low-density lipoprotein (LDL) oxidation --- p.163 / Chapter 3.4 --- Chromatographic characterization of the subfractions of methanol crude extract of Aa and Pevf mushrooms --- p.167 / Chapter 3.4.1 --- Thin-layer chromatography (TLC) --- p.167 / Chapter 3.4.2 --- High performance liquid chromatography (HPLC) --- p.172 / Chapter 3.5 --- Chromatographic and spectrometric characterization of the fractionated subfractions of the ethyl acetate and butanol subfractions of Aa --- p.177 / Chapter 3.5.1 --- High performance liquid chromatography (HPLC) --- p.177 / Chapter 3.5.2 --- Liquid chromatography- Mass spectrometry (LC-MS) --- p.186 / Chapter CHAPTER 4: --- CONCLUSION --- p.189 / REFERENCES --- p.193 / RELATED PUBLICATION --- p.209
75

Anti-oxidative and anti-atherosclerotic properties of compound danshen (radix salviae miltiorrhizae) and gegen (radix puerariae) water extract. / CUHK electronic theses & dissertations collection

January 2006 (has links)
Atherosclerosis is the chief cause of acute coronary syndromes and may progress for many years before any noticeable clinical syndromes occur. Hyperlipidemia is the common clinical problem for people adopting a western style of living and it can initiate a series of vascular events that result in atherosclerosis. The pathological processes include the accumulation of modified lipid, mainly oxidized low-density lipoprotein (oxLDL), endothelial cell dysfunction and activation, increase in expression of adhesion molecules, activation and recruitment of inflammatory cells and induction of proliferation and migration of vascular smooth muscle cells. / Endothelial-monocyte adhesion is crucial process for the recruitment of monocyte into intima. DG (7:3), Danshen and SAB were found to inhibit TNF-alpha-induced endothelial-monocyte adhesion. They also showed inhibition on TNF-alpha induced production of chemokines, MCP-1 which promotes the transmigration of monocyte. However, it did not inhibit the production of cytokine, IL-6 which stimulates the expression of adhesion molecules such as VCAM-1 and ICAM-1. / For the in vivo study, DG (7:3) exhibited no anti-hyperlipidemic or hypolipidemic effect against diet-induced hyperlipidemia, nor did it lower cholesterol level in hamsters. Also, it did not inhibit HMG-CoA reductase activity or increase the total fecal sterols excretion. However, DG (7:3) exhibited hypocholesterolemic effect on diet-induced hyperlipidemia in the rabbit model, wherein it could lower plasma total cholesterol and liver cholesterol level. Moreover, it could significantly decrease the atheroma formation. / In the present study, the anti-oxidative effects of herbal extract/compound were measured by three in vitro assays, namely the inhibition of 2,2'-azobis(2-amidinopropane)dihydrochloride (AAPH)-induced red blood cells hemolysis, AAPH-induced cardiomyocyte (H9c2) cells death and Cu2+-induced low-density lipoprotein oxidation. The results showed that the aqueous extract of the compound formula Danshen (D) and Gegen (G) (7:3), abbreviated as DG (7:3), and an aqueous extract of Danshen as well as salvianolic acid B (SAB) exhibited anti-oxidant effect, but Gegen did not produce such effect. It was found that SAB showed a stronger anti-oxidant effect than that of ascorbic acid. / Proliferation and migration of vascular smooth muscle cells (vSMCs) are important pathological processes involved in the development of atherosclerosis. DG (7:3), Danshen and SAB were found to inhibit PDGF-induced vSMCs proliferation through G1/S cell cycle arrest. Cyclin D, a main component that governs the transition of G1 phase to S phase, was found to be down-regulated by DG (7:3), Danshen and SAB, as assessed by measurements of both protein and mRNA levels. Moreover, DG (7:3), Danshen and SAB showed anti-migratory effect against platelet-derived growth factor-induced vSMCs migration. / To summarize, DG (7:3) was found to have potential to produce anti-atherosclerotic effect by inhibiting the LDL oxidation, proliferation and migration of vascular SMC, thereby preventing the formation of atheroma plaque. / Koon Chi Man. / "March 2006." / Adviser: Kwok Pui Fung. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6324. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 246-264). / 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.
76

Antioxidative and vascular relaxing effects of black tea theaflavins. / CUHK electronic theses & dissertations collection

January 2003 (has links)
by Su Ya Lun. / "August 2003." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (p. 163-181). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.
77

Evaluation of the antioxidant activity and characterization of extracts from three edible Chinese mushrooms.

January 2001 (has links)
Cheung Lai Ming. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 153-161). / Abstracts in English and Chinese. / THESIS COMMITTEE --- p.i / ACKNOWLEDGEMENTS --- p.ii / ABSTRACT --- p.iii / ABSTRACT (Chinese version) --- p.v / CONTENTS --- p.vi / LIST OF TABLES --- p.xi / LIST OF FIGURES --- p.xiii / LIST OF ABBREVIATIONS --- p.xv / Chapter CHAPTER ONE: --- INTRODUCTION --- p.1 / Chapter 1.1 --- Free radical --- p.2 / Chapter 1.1.1 --- Definition --- p.2 / Chapter 1.1.2 --- Reaction mechanism --- p.3 / Chapter 1.1.3 --- Sources of oxygen reactive species --- p.4 / Chapter 1.1.3.1 --- Enzymes --- p.4 / Chapter 1.1.3.2 --- The auto-oxidation of small molecules --- p.4 / Chapter 1.1.3.3 --- Haem proteins --- p.5 / Chapter 1.1.3.4 --- Endoplasmic reticulum sources --- p.5 / Chapter 1.1.3.5 --- Mitochondrial sources --- p.5 / Chapter 1.1.3.6 --- Nucleus --- p.6 / Chapter 1.1.4 --- Lipid peroxidation --- p.6 / Chapter 1.1.4.1 --- Initiation of lipid peroxidation --- p.7 / Chapter 1.1.4.2 --- Propagation of lipid peroxidation --- p.8 / Chapter 1.1.4.3 --- Products of lipid peroxidation --- p.9 / Chapter 1.1.5 --- Human diseases associated with free radicals --- p.10 / Chapter 1.2 --- Antioxidants --- p.12 / Chapter 1.2.1 --- Definition --- p.12 / Chapter 1.2.2 --- Defence against free radical damage --- p.13 / Chapter 1.2.2.1 --- Catalytic free radical removal --- p.13 / Chapter 1.2.2.2 --- Free radical scavenging --- p.14 / Chapter 1.2.2.3 --- Removal of catalytic iron and copper ions --- p.14 / Chapter 1.2.3 --- Synthetic vs. natural antioxidant --- p.15 / Chapter 1.2.3.1 --- Synthetic antioxidants --- p.15 / Chapter 1.2.3.2 --- Natural antioxidants --- p.16 / Chapter 1.3 --- Measurement of antioxidant activity --- p.17 / Chapter 1.3.1 --- Loss of substrate --- p.17 / Chapter 1.3.1.1 --- Beta-carotene bleaching method --- p.17 / Chapter 1.3.2 --- Measurement of free radical scavenging --- p.17 / Chapter 1.3.2.1 --- "Scavenging of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH´Ø)" --- p.17 / Chapter 1.3.2.2 --- Superoxide scavenging --- p.18 / Chapter 1.3.2.3 --- Hydrogen peroxide scavenging --- p.18 / Chapter 1.3.2.4 --- Hydroxyl radical scavenging --- p.19 / Chapter 1.3.2.5 --- Peroxyl radical --- p.19 / Chapter 1.3.3 --- Measurement of end product --- p.21 / Chapter 1.3.3.1 --- Diene conjugation --- p.21 / Chapter 1.3.3.2 --- Light emission --- p.21 / Chapter 1.3.3.3 --- The thiobarbituric acid (TBA) test --- p.22 / Chapter 1.3.4 --- Low-density lipoprotein oxidation --- p.22 / Chapter 1.4 --- Phenolic antioxidant --- p.24 / Chapter 1.4.1 --- Chemistry --- p.24 / Chapter 1.4.2 --- Mechanism of action of phenolic antioxidants --- p.25 / Chapter 1.4.3 --- Isolation and characterization --- p.25 / Chapter 1.4.3.1 --- Extraction --- p.25 / Chapter 1.4.3.2 --- Analysis of phenolic compounds --- p.27 / Chapter 1.4.3.2.1 --- Colorimetric method --- p.27 / Chapter 1.4.3.2.2 --- Enzymatic method --- p.28 / Chapter 1.4.3.2.3 --- Paper chromatography --- p.28 / Chapter 1.4.3.2.4 --- Thin-layer chromatography --- p.29 / Chapter 1.4.3.2.5 --- UV-Vis absorption spectroscopy --- p.29 / Chapter 1.4.3.2.6 --- High-performance liquid chromatography --- p.30 / Chapter 1.4.4 --- Natural sources of phenolic antioxidants --- p.31 / Chapter 1.4.4.1 --- Olive oil --- p.31 / Chapter 1.4.4.2 --- Berry --- p.32 / Chapter 1.4.4.3 --- Cherry --- p.32 / Chapter 1.4.4.4 --- Red wine --- p.32 / Chapter 1.4.4.5 --- Herb --- p.33 / Chapter 1.4.4.6 --- Vegetables --- p.33 / Chapter 1.5 --- Mushroom Sample --- p.34 / Chapter 1.5.1 --- Pleurotus tuber-regium --- p.34 / Chapter 1.5.2 --- Lentinus edodes --- p.34 / Chapter 1.5.3 --- Volvariella volvacea --- p.35 / Chapter 1.5.4 --- Antioxidants in fungi or mushroom --- p.37 / Chapter 1.5.5 --- Phenolic compounds in mushrooms --- p.39 / Chapter 1.6 --- Objectives --- p.42 / Chapter CHAPTER TWO: --- MATERIALS AND METHODS --- p.43 / Chapter 2.1 --- Sample Collection --- p.43 / Chapter 2.2 --- Sample Preparation --- p.43 / Chapter 2.3 --- Moisture Content --- p.43 / Chapter 2.4 --- Solvent Extraction --- p.44 / Chapter 2.4.1 --- Scheme I (Aqueous extraction only) --- p.44 / Chapter 2.4.2 --- Scheme II (Methanol and water extraction) --- p.45 / Chapter 2.4.3 --- Scheme III (Differential solvent extraction) --- p.46 / Chapter 2.4.4 --- Scheme IV (Scaled-up extraction) --- p.47 / Chapter 2.5 --- Antioxidant activity assays --- p.50 / Chapter 2.5.1 --- Beta-carotene bleaching method --- p.50 / Chapter 2.5.2 --- "Scavenging activity on 1,1 -diphenyl-2-picrylhydrazyl radicals" --- p.51 / Chapter 2.5.3 --- Assay for erythrocyte hemolysis --- p.51 / Chapter 2.5.4 --- Assay of lipid peroxidation using rat brain --- p.52 / Chapter 2.5.5 --- LDL oxidation (TBARS) --- p.53 / Chapter 2.5.5.1 --- LDL Isolation --- p.53 / Chapter 2.5.5.2 --- Calculation of density --- p.54 / Chapter 2.5.5.3 --- Lowry Method for Protein Determination --- p.55 / Chapter 2.5.5.4 --- Reagents for TBARS assay --- p.55 / Chapter 2.5.5.5 --- TBARS formation --- p.56 / Chapter 2.6 --- Determination of total polyphenolic compounds --- p.56 / Chapter 2.7 --- Fractionation --- p.57 / Chapter 2.7.1 --- Fractionation of the methanol crude extracts obtained under reflux by solvent --- p.57 / Chapter 2.7.2 --- Fractionation of boiling water crude extracts by ultrafiltration --- p.57 / Chapter 2.8 --- Crude Protein Content (Kjeldahl method) --- p.58 / Chapter 2.9 --- Total carbohydrate content --- p.59 / Chapter 2.10 --- Thin-layer chromatography --- p.59 / Chapter 2.11 --- High performance liquid chromatography --- p.60 / Chapter 2.11.1 --- Analysis of methanol fractions --- p.60 / Chapter 2.11.2 --- Analysis of water fractions --- p.61 / Chapter 2.12 --- Liquid chromatography-Mass spectrometry --- p.61 / Chapter 2.12.1 --- Liquid chromatography --- p.61 / Chapter 2.12.2 --- Mass spectrometric analysis --- p.62 / Chapter 2.13 --- Data analysis --- p.62 / Chapter CHAPTER THREE: --- RESULTS AND DISCUSSION --- p.63 / Chapter 3.1 --- Mushroom sample --- p.63 / Chapter 3.2 --- Extraction scheme I --- p.65 / Chapter 3.2.1 --- Antioxidant activity --- p.65 / Chapter 3.2.1.1 --- Effect of extraction temperature --- p.65 / Chapter 3.2.1.2 --- Effect of concentration of extracts --- p.66 / Chapter 3.3 --- Extraction scheme II --- p.69 / Chapter 3.3.1 --- Antioxidant activity --- p.69 / Chapter 3.3.1.1 --- Effect of extraction temperature --- p.69 / Chapter 3.3.1.2 --- Effect of concentration of extracts --- p.72 / Chapter 3.3.1.3 --- Effect of solvent --- p.72 / Chapter 3.4 --- Extraction scheme III --- p.75 / Chapter 3.4.1 --- Extraction yield --- p.75 / Chapter 3.4.2 --- Total phenolic content --- p.76 / Chapter 3.4.3 --- Antioxidant activity --- p.80 / Chapter 3.4.3.1 --- Beta-carotene bleaching method --- p.80 / Chapter 3.4.3.1.1 --- Effect of extract concentration --- p.80 / Chapter 3.4.3.1.2 --- Relation between total phenolic content and antioxidant activity --- p.82 / Chapter 3.4.3.2 --- "Scavenging activity of 1,1 -diphenyl-2-picrylhydrazyl (DPPH) radical" --- p.85 / Chapter 3.4.3.3 --- Assay for erythrocyte hemolysis --- p.88 / Chapter 3.5 --- Extraction scheme IV --- p.91 / Chapter 3.5.1 --- Yield and Fractionation --- p.91 / Chapter 3.5.2 --- Chemical characterization of fractions --- p.93 / Chapter 3.5.2.1 --- Protein content --- p.93 / Chapter 3.5.2.2 --- Total carbohydrate content --- p.93 / Chapter 3.5.2.3 --- Total phenolic content --- p.94 / Chapter 3.5.3 --- Antioxidant activity --- p.99 / Chapter 3.5.3.1 --- Assay for lipid peroxidation of rat brain --- p.99 / Chapter 3.5.3.2 --- LDL oxidation --- p.118 / Chapter 3.5.4 --- Identification of antioxidant by chromatographic methods --- p.126 / Chapter 3.5.4.1 --- Thin-layer chromatography --- p.126 / Chapter 3.5.4.2 --- High-performance liquid chromatography --- p.132 / Chapter 3.5.4.3 --- Liquid chromatography-Mass spectrometry --- p.142 / Chapter CHAPTER FOUR: --- CONCLUSION --- p.148 / REFERENCES --- p.153 / RELATED PUBLICATION --- p.161
78

In vitro antioxidant and anti-angiogenic effects of mushroom water extracts.

January 2011 (has links)
Lai, Tsz Ching. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 121-136). / Abstracts in English and Chinese. / Acknowledgements / Abstract / 摘要 / Content / List of tables / List of figures / List of abbreviations / Chapter Chapter 1: --- Introduction --- p.1 / Chapter 1.1 --- Introduction of food market trends in Hong Kong and mushroom productivity in the world --- p.1 / Chapter 1.1.1 --- Agrocybe aegerita --- p.1 / Chapter 1.1.2 --- Pleurotus spp --- p.2 / Chapter 1.1.3 --- Pholiota nameko --- p.3 / Chapter 1.2 --- Objectives --- p.5 / Chapter Chapter 2: --- Chemical assays for in vitro antioxidative properties of mushroom extracts --- p.6 / Chapter 2.1 --- Introduction --- p.6 / Chapter 2.1.1 --- Reactive oxygen species (ROS) --- p.6 / Chapter 2.1.1.1 --- Definition of ROS --- p.6 / Chapter 2.1.1.2 --- Sources of ROS --- p.6 / Chapter 2.1.1.2.1 --- Endogenous sources of ROS --- p.6 / Chapter 2.1.1.2.2 --- Exogenous sources of ROS --- p.8 / Chapter 2.1.1.3 --- Damaging effects of ROS --- p.8 / Chapter 2.1.2 --- Antioxidants --- p.10 / Chapter 2.1.2.1 --- Mechanism of action --- p.10 / Chapter 2.1.2.2 --- Sources of antioxidants --- p.11 / Chapter 2.1.2.2.1 --- Dietary antioxidants --- p.11 / Chapter 2.1.2.2.2 --- Antioxidants in edible mushrooms --- p.12 / Chapter 2.1.2.2.3 --- Phenolic compounds in mushrooms --- p.13 / Chapter 2.2 --- Materials and Methods --- p.16 / Chapter 2.2.1 --- Materials --- p.16 / Chapter 2.2.1.1 --- Mushroom fruiting bodies --- p.16 / Chapter 2.2.2 --- Principles of Methods and Experimental Protocols --- p.17 / Chapter 2.2.2.1 --- Sample preparation --- p.17 / Chapter 2.2.2.2 --- Evaluation of antioxidant capacity --- p.18 / Chapter 2.2.2.2.1 --- DPPH radical scavenging activity --- p.18 / Chapter 2.2.2.2.2 --- Superoxide anion scavenging activity --- p.19 / Chapter 2.2.2.2.3 --- Hydroxyl radical scavenging activity --- p.20 / Chapter 2.2.2.2.4 --- Hydrogen peroxide scavenging activity --- p.22 / Chapter 2.2.2.3 --- Determination of phenolic compounds --- p.24 / Chapter 2.2.2.3.1 --- Total phenolic content --- p.24 / Chapter 2.2.2.3.2 --- Identification of phenolic acids --- p.25 / Chapter 2.2.3 --- Statistical analysis --- p.27 / Chapter 2.3 --- Results and Discussion --- p.28 / Chapter 2.3.1 --- Extraction yield --- p.28 / Chapter 2.3.2 --- Evaluation of antioxidant capacity --- p.29 / Chapter 2.3.2.1 --- DPPH radical scavenging activity --- p.29 / Chapter 2.3.2.2 --- Superoxide anion scavenging activity --- p.31 / Chapter 2.3.2.3 --- Hydroxyl radical scavenging activity --- p.33 / Chapter 2.3.2.4 --- Hydrogen peroxide scavenging activity --- p.35 / Chapter 2.3.2.5 --- Comparison of the effective concentrations (EC50) of mushroom water extracts in different antioxidant assays --- p.37 / Chapter 2.3.3 --- Determination of phenolic compounds --- p.38 / Chapter 2.3.3.1 --- Total phenolic content --- p.38 / Chapter 2.3.3.2 --- Identification of phenolic acids --- p.39 / Chapter 2.4 --- Summary --- p.45 / Chapter Chapter 3: --- Anti-angiogenic properties of the Aa water extract --- p.46 / Chapter 3.1 --- Introduction --- p.46 / Chapter 3.1.1 --- Angiogenesis --- p.46 / Chapter 3.1.1.1 --- Process of angiogenesis --- p.46 / Chapter 3.1.1.2 --- Regulations of angiogenesis --- p.47 / Chapter 3.1.1.2.1 --- Fibroblast growth factor (bFGF) --- p.47 / Chapter 3.1.1.2.2 --- Vascular endothelial growth factor (VEGF) --- p.48 / Chapter 3.1.2 --- Tumor angiogenesis --- p.49 / Chapter 3.1.2.1 --- ROS generation in tumor cells --- p.50 / Chapter 3.1.2.2 --- Hydrogen peroxide and VEGF --- p.51 / Chapter 3.1.2.3 --- Previous studies on tumor angiogenesis --- p.52 / Chapter 3.1.2.3.1 --- ROS and endothelial cells proliferation --- p.52 / Chapter 3.1.2.3.2 --- VEGF and endothelial cells functions --- p.53 / Chapter 3.1.3 --- Use of antioxidants in cancer treatment --- p.53 / Chapter 3.1.3.1 --- Antioxidant use of cancer therapy --- p.53 / Chapter 3.1.3.2 --- Antioxidant and endothelial cells functions --- p.54 / Chapter 3.1.3.3 --- Anti-angiogenic effects of polyphenols --- p.56 / Chapter 3.1.3.3.1 --- Phenolic acids --- p.56 / Chapter 3.1.3.3.2 --- Tea catechin --- p.57 / Chapter 3.1.3.3.3 --- Resveratrol --- p.57 / Chapter 3.1.3.3.4 --- Genistein --- p.58 / Chapter 3.2 --- Principles of Methods and Experimental Protocols --- p.60 / Chapter 3.2.1 --- Sample preparation --- p.60 / Chapter 3.2.2 --- Toxicity of the Aa water extract --- p.60 / Chapter 3.2.2.1 --- Limulus amebocyte lysate (LAL) test --- p.60 / Chapter 3.2.2.2 --- Toxicity towards normal cells --- p.61 / Chapter 3.2.2.2.1 --- Cell line and its subculture --- p.61 / Chapter 3.2.2.2.2 --- Colorimetric (MTT) assay --- p.62 / Chapter 3.2.3 --- Effect of the Aa water extract on cancer cells --- p.63 / Chapter 3.2.3.1 --- Cell line and its subculture --- p.63 / Chapter 3.2.3.2 --- Redox status --- p.63 / Chapter 3.2.3.3 --- VEGF secretion --- p.65 / Chapter 3.2.4 --- In vitro cell culture anti-angioenesis analysis --- p.66 / Chapter 3.2.4.1 --- Cell line and its subculture --- p.66 / Chapter 3.2.4.2 --- Endothelial cells proliferation --- p.67 / Chapter 3.2.4.3 --- Endothelial cells migration --- p.68 / Chapter 3.2.4.3.1 --- Wound healing assay --- p.68 / Chapter 3.2.4.3.2 --- Transwell culture insert assay --- p.69 / Chapter 3.2.4.4 --- Endothelial cells tubule formation --- p.71 / Chapter 3.2.5 --- In vitro organ culture anti-angiogenesis analysis --- p.72 / Chapter 3.2.5.1 --- Aortic ring assay --- p.72 / Chapter 3.2.6 --- Statistical analysis --- p.74 / Chapter 3.3 --- Results and Discussions --- p.75 / Chapter 3.3.1 --- Toxicity of the Aa water extract --- p.75 / Chapter 3.3.1.1 --- Limulus amebocyte lysate (LAL) test --- p.75 / Chapter 3.3.1.2 --- Toxicity towards normal cells --- p.75 / Chapter 3.3.2 --- Effect of the Aa water extract on cancer cells --- p.77 / Chapter 3.3.2.1 --- Redox status --- p.77 / Chapter 3.3.2.2 --- VEGF secretion --- p.79 / Chapter 3.3.2.3 --- Relationship between intracellular ROS and VEGF secretion detected --- p.80 / Chapter 3.3.3 --- Effect of the Aa water extract on angiogenesis --- p.82 / Chapter 3.3.3.1 --- Endothelial cells proliferation --- p.82 / Chapter 3.3.3.2 --- Endothelial cells migration --- p.84 / Chapter 3.3.3.2.1 --- Wound healing assay --- p.84 / Chapter 3.3.3.2.2 --- Transwell culture insert assay --- p.87 / Chapter 3.3.3.3 --- Endothelial cells tubule formation --- p.90 / Chapter 3.3.3.4 --- Aortic ring assay --- p.97 / Chapter 3.3.4 --- Effect of phenolic acids on endothelial cells --- p.101 / Chapter 3.3.4.1 --- Endothelial cells proliferation --- p.101 / Chapter 3.3.4.2 --- Endothelial cells migration --- p.102 / Chapter 3.3.4.2.1 --- Wound healing assay --- p.102 / Chapter 3.3.4.2.2 --- Transwell culture insert assay --- p.105 / Chapter 3.3.4.3 --- Endothelial cells tubule formation --- p.106 / Chapter 3.3.4.4 --- Aortic ring assay --- p.112 / Chapter 3.4 --- Summary --- p.116 / Chapter Chapter 4 --- Conclusions and future works --- p.118 / References --- p.121
79

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