by Vincent Wing-Fai Tai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1993. / Includes bibliographical references (leaves 79-83). / Acknowledgements --- p.i / Contents --- p.ii / Abstract --- p.iii / Abbreviations --- p.iv / Chapter I --- Introduction / Chapter I-1 --- General Background --- p.1 / Chapter I-2 --- Review on Epoxycyclohexanes --- p.2 / Chapter I-3 --- Mechanistic Aspect of Glycosidase Inhibitors --- p.5 / Chapter I-4 --- Previous Synthesis of cyclophellitol and its diastereoisomers 1-4 --- p.12 / Chapter II --- Results and Discussion / Chapter II-l --- General Strategy --- p.19 / Chapter II-2 --- Synthesis of the diol 57 --- p.21 / Chapter II-3 --- Synthesis of the allylic alcohol 54 --- p.25 / Chapter II-4 --- "Synthesis of Cyclophellitol 1 and its (lR,6S)-diastereoisomer 2" --- p.29 / Chapter II-5 --- "Synthesis of the (2S)- and (lR,2S,6S)-diasteroeisomers 3 and 4" --- p.34 / Chapter II-6 --- Comments on the MCPBA Epoxidation --- p.37 / Chapter II-7 --- Synthesis of the Epoxy Analogues of Cyclophellitol 104 and 105. --- p.40 / Chapter II-8 --- Results of biological assays --- p.43 / Chapter III --- Conclusion --- p.48 / Chapter IV --- Experimental --- p.50 / Chapter V --- References --- p.79 / Chapter VI --- Spectra --- p.84

No description available.

Kynurenine (KYN) is the first stable metabolite of the kynurenine pathway, which accounts for over 95% of tryptophan metabolism. Two previous studies by this research group reported elevated plasma KYN in Tourette syndrome (TS) patients when compared with age and sex matched controls and another study showed that KYN potentiated 5-HT2A-mediated head-shakes (HS) in rodents. These movements have been suggested to model tics in TS. This raised the questions how KYN acts in eliciting this response and whether it is an action of its own or of a further metabolite along the kynurenine pathway. In the liver, where most of the kynurenine pathway metabolism takes place under physiological conditions, the first and the rate limiting enzyme is tryptophan-dioxygenase (TDO) which can be induced by cortisol. In extrahepatic tissues the same step of the pathway is catalyzed by indoleamine-dioxygenase (IDO), which is induced by cytokines, predominantly interferon-y (INF-y). Plasma neopterin, which shows parallel increase with KYN following immune stimulation, was also found elevated in one of these studies positively correlating with KYN. In the present work animal studies suggested that KYN potentiates and quinolinic acid (QUINA) dose dependently inhibits the 5-HT2A-mediated HS response in mice. The potentiating effect seen with KYN was suggested to be an effect of KYN itself. Radioligand binding and phosphoinositide (PI) hydrolysis studies were done to explore the mechanisms by which kynurenine pathway metabolites could alter a 5-HT2A-receptor mediated response. None of the kynurenine pathway metabolites tested showed direct binding to 5-HT2A-receptors. PI hydrolysis studies with KYN and QUINA showed that KYN did not have any effect while QUINA inhibited 5-HT2A-mediated PI hydrolysis. Plasma cortisol determination in TS patients with elevated plasma KYN did not show elevated plasma cortisol levels, suggesting that the increase of plasma KYN in these TS patients is unlikely to be due to an increased TDO activity induced by increased cortisol. Attention deficit hyperactivity disorder (ADHD) is commonly associated with TS. Salivary cortisol detected in a group of children primarily affected with ADHD showed significantly lower salivary cortisol levels when compared with age and sex matched controls. Plasma tryptophan, KYN, neopterin, INF-y and KYN/tryptophan ratio and night-time urinary 6-sulphatoxymelatonin (aMT6s) excretion measured in a group of TS patients did not show any difference in their levels when compared with age and sex matched controls, but TS patients failed to show the expected positive correlation seen between plasma INF-y, neopterin and KYN and the negative correlation seen between plasma KYN and night-time urinary aMT6s excretion seen in healthy controls. The relevance of the kynurenine pathway, melatonin secretion and cortisol to Tourette Syndrome and associated conditions and the mechanism by which KYN and QUINA alter the 5-HT2A-receptor mediated HS response are discussed.

by Eric Kwok Wai Tam. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references. / Table of Contents --- p.i / Acknowledgement --- p.iv / Abstract --- p.v / Abbreviation --- p.vii / Part A / Enantiospecific Syntheses of Cyclohexane Oxides from (-)-Quinic Acid / Chapter 1. --- Synthetic Application of (-)-Quinic Acid --- p.1 / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Syntheses of Cyclohexane Derivatives --- p.2 / Chapter 1.2.1 --- Syntheses of Shikimic Acid (2) and its Derivatives --- p.2 / Chapter 1.2.2 --- "Syntheses of D-myo-Inositol 1,4,5-Trisphosphate (52) & its analog" --- p.15 / Chapter 1.2.3 --- Syntheses of Mycosporins --- p.17 / Chapter 1.2.4 --- Synthesis of (+)-Palitantin (76) --- p.19 / Chapter 1.2.5 --- "Synthesis of 2-Crotonyloxy-(4R,5R,6R)-4,5,6-trihydroxy- cyclohex-2-enone (COTC) (82)" --- p.20 / Chapter 1.2.6 --- Syntheses of Cyclophellitol (83) and its Diastereomers --- p.21 / Chapter 1.2.7 --- Syntheses of Pseudo-sugars and its Derivatives --- p.24 / Chapter 1.2.8 --- Syntheses of Aminocyclitol Antibiotics --- p.34 / Chapter 1.2.9 --- Syntheses of A-ring Precursor of Daunomycin --- p.36 / Chapter 1.2.10 --- "Synthesis of 19-nor-lα,25-Dihydroxyvitamin D3" --- p.38 / Chapter 1.2.11 --- Synthesis of Isoquinuclidines --- p.41 / Chapter 1.2.12 --- Synthesis of Cyclohexenyl Iodide: Taxol CD-ring Precursor --- p.44 / Chapter 1.2.13 --- Synthesis of C-20 to C-34 Segment of FK-506 --- p.46 / Chapter 1.2.14 --- Synthesis of the Hexahydrobenzofuran Subunit of Avermectins --- p.49 / Chapter 1.2.15 --- Synthesis of Bicyclic Core of Enediyne --- p.50 / Chapter 1.2.16 --- Syntheses of Two Enantiopure Derivatives of 4-Hydroxy-2-cyclohexone --- p.53 / Chapter 1.3 --- Synthesis of Homochiral Linear Molecules --- p.57 / Chapter 1.3.1 --- Syntheses of (3S)-Mevalonolactone and its Derivatives --- p.57 / Chapter 1.3.2 --- Synthesis of the Subunit in Maytansinoids --- p.58 / Chapter 1.3.3 --- Synthesis of (+)-Negamycin --- p.59 / Chapter 1.3.4 --- Syntheses of Hepoxilins B3 and its Stereoisomers --- p.61 / Chapter 1.3.5 --- Synthesis of C-21 to C-25 Fragment of FK-506 --- p.62 / Chapter 1.4 --- Synthesis of Cyclopentane Derivatives --- p.63 / Chapter 1.4.1 --- Synthesis of 11 α-Hydroxy-13-oxaprostanoic Acid --- p.65 / Chapter 1.4.2 --- Synthesis of (-)-Pentenomycin I --- p.66 / Chapter 1.4.3 --- Syntheses of Carbovir and its Derivatives --- p.66 / Chapter 1.5 --- Synthesis of Cycloheptane Derivatives --- p.68 / Chapter 1.6 --- Conclusion --- p.70 / References --- p.71 / Chapter 2. --- Introduction of Cyclohexane Oxides --- p.81 / Chapter 2.1 --- General Background --- p.81 / Chapter 2.2 --- Previous Syntheses of Cyclohexane Oxides --- p.86 / Chapter 2.2.1 --- Racemic Syntheses of Crotepoxide --- p.86 / Chapter 2.2.2 --- Racemic Syntheses of Senepoxide --- p.89 / Chapter 2.2.3 --- A Racemic Synthesis of Pipoxide --- p.92 / Chapter 2.2.4 --- Syntheses of Enantiopure Cyclohexane Oxides --- p.93 / References --- p.96 / Chapter 3. --- Retrosynthetic Analysis and Strategy --- p.99 / Chapter 3.1 --- Antithetic Analysis of Cyclohexane Oxides --- p.99 / Chapter 3.2 --- Problems Encounter in the Conversion of Diene into Cyclohexane Oxides --- p.100 / Chapter 3.3 --- Photo-oxygenation Approach to Cyclohexane Oxides --- p.102 / Chapter 3.4 --- Reasons for Choosing the Silyl Ether as Blocking Group --- p.104 / Chapter 3.5 --- Strategy for Synthesis of Diene 373 from Quinic acid --- p.105 / References --- p.106 / Chapter 4. --- Results and discussion --- p.108 / Chapter 4.1 --- Synthesis of Silyl Benzoate381 --- p.108 / Chapter 4.2 --- Synthesis of Alkene373 --- p.111 / Chapter 4.3 --- Syntheses of (+)-Crotepoxide (289)，(+)-Bosenepoxide (290) and (-)-iso-Crotepoxide (304) --- p.115 / Chapter 4.4 --- "Syntheses of the (+)-β-Senepoxide (295)，(+)-Pipoxide Acetate (365), (-) Tintanoxide (294) and (-)-Senepoxide (291)" --- p.121 / References --- p.124 / Chapter 5. --- Conclusion --- p.126 / Chapter 6. --- Experimental Section --- p.128 / References --- p.142 / Part B / Ruthenium Catalyzed cis-Dihydroxylation of Alkene / Chapter 1. --- Introduction --- p.143 / Chapter 1.1 --- Background --- p.143 / Chapter 1.2 --- General cis-Dihydroxylation Methods --- p.144 / Chapter 1.2.1 --- Potassium Permanganate (KMnO4) --- p.144 / Chapter 1.2.2 --- Osmium Tetraoxide (OsO4) --- p.146 / Chapter 1.3 --- Ruthenium Tetraoxide Oxidations --- p.148 / Chapter 1.4 --- Previous Reports of Using Ruthenium Tetraoxide (RuO4) Mediated syn-Dihydroxylation of Olefins --- p.149 / Chapter 1.4.1 --- The Snatzke and Fehlhaber Work --- p.149 / Chapter 1.4.2 --- The Sharpless and Akashi Work --- p.150 / Chapter 1.4.3 --- The Sica and Co-workers Work --- p.150 / References --- p.152 / Chapter 2. --- Ruthenium-Catalyzed cis-Dihydroxylation of Alkenes --- p.155 / Chapter 2.1 --- """Flash"" Dihydroxylation" --- p.155 / Chapter 2.2 --- "Stereochemical Outcome of ""Flash"" Dihydroxylation" --- p.155 / References --- p.157 / Chapter 3. --- Results and Discussion --- p.158 / Chapter 3.1 --- "Scope and Limitations of ""Flash"" Dihydroxylation" --- p.158 / Chapter 3.2 --- "Study of the Diastereoselectivity of ""Flash"" Dihydroxylation" --- p.168 / Chapter 3.3 --- "Study of Co-oxidants for ""Flash"" Dihydroxylation" --- p.170 / Chapter 3.4 --- "Solvent Effect for ""Flash"" Dihydroxylation" --- p.171 / Chapter 3.5 --- "Synthetic Application of ""Flash"" Dihydroxylation" --- p.173 / References --- p.175 / Chapter 4. --- Conclusion --- p.176 / Chapter 5. --- Experimental Section --- p.177 / References --- p.185 / Appendix --- p.186

There is evidence that the excitotoxin quinolinic acid (QUIN) synthesized through the kynurenine pathway (KP) by activated microglia may play a role in the pathogenesis of several major neuroinflammatory diseases and more particularly in Alzheimer??s disease (AD). The hypothesis of this project is QUIN affects the function and morphology of astrocytes. In this study I used human foetal astrocytes stimulated with AD associated cytokines including IFN-gamma, TNF-alpha, TGF-alpha and different concentrations of QUIN ranging from low physiological to high excitotoxic concentrations. I found that QUIN induces IL-1beta expression in human astrocytes and subsequently, contribute to the inflammatory cascade that is present in AD pathology. Glial fibrillary acid protein (GFAP) and vimentin protein expression were complementary in expression to each other after 24 hr stimulation with different QUIN doses. However, there were marked increases in GFAP levels and reduction in vimentin levels compared to controls with QUIN treatment indicating that QUIN can trigger astrogliosis in human astrocytes. Glutamine synthetase (GS) activity was used as a functional metabolic test for astrocytes and I found a dose-dependent inhibition of GS activity by QUIN. This inhibition was inversely correlated with iNOS expression whereby reduced GS activity is accompanied with an increase expression of iNOS in human astrocytes. These results suggest that reduction in GS activity can lead to accumulation of extracellular glutamate then leading to exacerbated excitotoxicity via NMDA receptor over-activation and ultimately neuronal death. PCR array results showed that at least four different pathways were activated with pathological concentration of QUIN including p38 MAPK that is associated with pro-inflammatory cytokine production, ERK/MAPK growth and differentiation that can modulate structural proteins, mitochondrial-induced apoptotic cascade and cell cycle control pathway. QUIN-induced astrogliosis and excitotoxicity could lead to glial scar formation and prevention of axonal growth thus exacerbation of neurodegeneration via synaptosomal NMDA receptor over-activation. All together, this study showed that, in the context of AD, QUIN is an important factor for astroglial activation, dysregulation and death, which can be mediated by the previously mentioned pathways.

There is evidence that the excitotoxin quinolinic acid (QUIN) synthesized through the kynurenine pathway (KP) by activated microglia may play a role in the pathogenesis of several major neuroinflammatory diseases and more particularly in Alzheimer??s disease (AD). The hypothesis of this project is QUIN affects the function and morphology of astrocytes. In this study I used human foetal astrocytes stimulated with AD associated cytokines including IFN-gamma, TNF-alpha, TGF-alpha and different concentrations of QUIN ranging from low physiological to high excitotoxic concentrations. I found that QUIN induces IL-1beta expression in human astrocytes and subsequently, contribute to the inflammatory cascade that is present in AD pathology. Glial fibrillary acid protein (GFAP) and vimentin protein expression were complementary in expression to each other after 24 hr stimulation with different QUIN doses. However, there were marked increases in GFAP levels and reduction in vimentin levels compared to controls with QUIN treatment indicating that QUIN can trigger astrogliosis in human astrocytes. Glutamine synthetase (GS) activity was used as a functional metabolic test for astrocytes and I found a dose-dependent inhibition of GS activity by QUIN. This inhibition was inversely correlated with iNOS expression whereby reduced GS activity is accompanied with an increase expression of iNOS in human astrocytes. These results suggest that reduction in GS activity can lead to accumulation of extracellular glutamate then leading to exacerbated excitotoxicity via NMDA receptor over-activation and ultimately neuronal death. PCR array results showed that at least four different pathways were activated with pathological concentration of QUIN including p38 MAPK that is associated with pro-inflammatory cytokine production, ERK/MAPK growth and differentiation that can modulate structural proteins, mitochondrial-induced apoptotic cascade and cell cycle control pathway. QUIN-induced astrogliosis and excitotoxicity could lead to glial scar formation and prevention of axonal growth thus exacerbation of neurodegeneration via synaptosomal NMDA receptor over-activation. All together, this study showed that, in the context of AD, QUIN is an important factor for astroglial activation, dysregulation and death, which can be mediated by the previously mentioned pathways.

Amyotrophic lateral sclerosis (ALS) is a progressive and fatal motor neuron disease of unclear aetiology, although the general consensus is of a multifactorial disease. The kynurenine pathway (KP), activated during neuroinflammation, is emerging as a possible contributory factor in ALS. The KP is the major route for tryptophan (TRP) catabolism. The intermediates generated can be either neurotoxic, such as quinolinic acid (QUIN), or neuroprotective, such as picolinic acid (PIC), an important endogenous metal chelator. The first and inducible enzyme is indoleamine 2,3-dioxygenase (IDO). As the extent of the involvement of the KP in ALS is unknown, the main aim of this thesis was to attempt to answer that question. The techniques used in this work include HPLC, GC/MS, RT-PCR, immunohistochemistry and immunocyctochemsitry. The main findings of this project are: (1) the complete KP is present in the mouse motor neuron cell line, NSC-34; (2) QUIN toxicity on NSC-34 cells may be ameliorated through the administration of NMDA antagonists, neuroprotective kynurenines, kynurenine inhibitor and QUIN monoclonal antibody; (3) in ALS patients, QUIN CSF and serum levels are significantly elevated, while PIC serum levels are significantly reduced; (4) ALS brain and spinal cord tissue show extensive microglia activation and positive immunoreactivity IDO and QUIN in spinal motor neurons and Betz cells in the motor cortex; and (5) kynurenine pathway inhibitor and analogue, R061-8048 and tranilast, are able to prolong the survival in the G93A SOD1 ALS transgenic mouse model. In conclusion, this study provide the first strong evidence for the involvement of the KP in ALS, and these data point to an inflammation-driven excitotoxic-chelation defective mechanism in ALS, which is amenable to KP analogue and inhibitor in ALS transgenic mice.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1967. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph.D.) - University of St Andrews, December 2007. / Restricted until 12th December 2008.

The hippocampus, located in the medial temporal lobe, is an important region of the brain responsible for the formation of memory. Thus, any agent that induces stress in this area has detrimental effects and could lead to various types of dementia. Such agents include the neurotoxin, Quinolinic acid. Quinolinic acid (QUIN) is a neurotoxic metabolite of the tryptophan-kynurenine pathway and is an endogenous glutamate agonist that selectively injures and kills vulnerable neurons via the activation of the NMDA class of excitatory amino acid receptors. Estrogen is a female hormone that is responsible for reproduction. However, in the last decade estrogen has been shown to exhibit a wide range of actions on the brain, including neuroprotection. Estrogen has been shown to exhibit intrinsic antioxidant activity and protects cultured neurons against oxidative cell death. This is achieved by estrogen’s ability to scavenge free radicals, which is dependent on the presence of the hydroxyl group at the C3 position on the A ring of the steroid molecule. Numerous studies have shown that estrogen protects neurons against various toxic substances and may play a role in delaying the onset of neurodegenerative diseases, such as Alzheimer’s disease. Neuronal damage due to oxidative stress has been implicated in several neurodegenerative disorders. The detection and measurement of lipid peroxidation is the evidence most frequently cited to support the involvement of free radical reactions in toxicology and in human disease. The study aims to elucidate and further characterise the mechanism behind estrogen’s neuroprotection, using QUIN as a model of neurotoxicity. Initial studies confirm estrogen’s ability to scavenge potent free radicals. In addition, the results show that estrogen forms an interaction with iron (II) and also acts at the NMDA receptor as an agonist. Both mechanisms reduce the ability of QUIN to cause damage to neurons, since QUIN-induced toxicity is dependent on the activation of the NMDA receptor and the formation of a complex with iron (II) to induce lipid peroxidation. Heat shock proteins, especially Hsp 70 play a role in cytoprotection by capturing denatured proteins and facilitating the refolding of these proteins once the stress has been relieved. Estrogen has been shown to increase the level of expression of Hsp70, both inducible and cognate forms of the protein. This suggests that estrogen helps to protect against cellular protein damage induced by any form of stress the cell may encounter. The discovery of neuroprotective agents, such as estrogen, is becoming important as accumulating evidence indicates a protective role in vivo. Thus further research may favour the use of these agents in the treatment of several neurodegenerative disorders. Considering how devastating diseases, such as Alzheimer’s disease, are to a patient and the patient’s families, the discovery of new protective agents are a matter of urgency.