L'huile d'olive est la principale source d’apports lipidique dans le régime méditerranéen. Elle est reconnue comme une source de nutriments et est à l’origine de plusieurs effets biologiques bénéfiques pour la santé. Plusieurs études montrent notamment que la consommation d'huile d'olive peut être efficace dans le traitement de maladies cardiovasculaires. Cependant, peu d'études mettent en évidence un effet antiinflammatoire, antiallergique et anti-Alzheimer de l’huile d’olive. De même, aucune étude n’a déterminé un lien entre ces effets et les variétés d’olives dont sont issues les huiles ainsi que les composés présents responsables de ces effets. Le but de ce travail est donc d'évaluer l'effet biologique, et plus particulièrement le potentiel antiinflammatoire et antiallergique des composés hydrophiles obtenus après extraction en phase solide (SPE-Diol), à partir de plusieurs variétés d’huiles d'olive extra vierge (EVOO) issues de trois années de récolte différentes. L'effet neuroprotecteur de la variété Picholine, contre la maladie d'Alzheimer a également été évalué. Les résultats montrent que l'effet anti-inflammatoire et l’effet anti-allergique varies de façon concentration dépendante et en fonction de la variété d’EVOO. De plus, nous avons mis en évidence que la variété de Picholine a un effet neuroprotecteur. L’ensemble de ce travail a établi une corrélation entre des activités anti-inflammatoire, anti-allergique et anti-Alzheimer des huiles d’olives issues de plusieurs variétés et les différents composés présents, ce qui a permis de mettre en avant la variété Picholine. / Olive oil is the primary source of fat in the Mediterranean diet. It is not only known as a distinctive source of nutrients but also as an origin of several biological effects that represent a very important factor for the health. Several studies demonstrate that olive oil consumption has to be effective against heart and cardiovascular diseases. Few studies show up the anti-inflammatory, the anti-allergic and the anti-Alzheimer effects of olive oil but there is no study about the cultivar effect and the interference that could occur between the different olive oil compounds. The aim of this work is to evaluate the biological effect and more particularly the potential anti-inflammatory and anti-allergic of hydrophilic components obtained by solid phase extraction (SPE-Diol) of different extra virgin olive oil (EVOO) cultivars and from three different harvest years. Moreover the neuroprotective effect of Picholine cultivar against Alzheimer’s disease was also studied. The results show that the anti-inflammatory and the anti-allergic activities differ depending on the EVOO cultivar and they are concentration-dependent. The results show also that Picholine cultivar has an anti-Alzheimer activity. All of these studies have established a correlation between the anti-inflammatory, the anti-allergic and the anti-Alzheimer effects of different EVOO cultivars and different compounds present, which enabled us to highlight the Picholine cultivar.

L'objectif de la thèse était de regarder l'acétylcholinestérase (AChE) en mouvement. L'AChE est une enzyme très rapide qui met fin à la transmission de l'influx nerveux au sein des synapses cholinergiques. À l'aide de la cristallographie aux rayons X, des sous-états conformationnels de l'AChE de Torpedo californica (Tc) ont été piégés par sa liaison à des drogues anti-Alzheimer putatives. Les formes, non vieillie et vieillie, de la TcAChE conjuguée au soman ont été caractérisées structuralement, éclairant ainsi le mécanisme de vieillissement de la TcAChE inhibée par les organophosphorés (OP). La structure du complexe ternaire du conjugué vieilli avec un réactivateur a également été résolue. Toutes ces structures guideront l'élaboration de médicaments (drogues anti-Alzheimer ou antidotes contre l'empoisonnement par des OP) en prenant en compte la flexibilité de l'enzyme et ses conformations minoritaires. La structure du complexe de la TcAChE avec un inhibiteur de son site périphérique (PAS), l'aflatoxine B1 (AB1), a été résolue dans deux formes cristallines. Ce travail a mis en évidence des artefacts de la cristallographie nuisibles à l'interprétation biologique des structures. La mesure du temps de vie de phosphorescence de l'AB1 a permis de sonder les mouvements du PAS à l'échelle de la seconde et de révéler des différences de flexibilité liées à l'empilement cristallin de la TcAChE. Cette méthode spectroscopique est complémentaire à la cristallographie cinétique. La gamme de températures cryogéniques identifiée pourrait en effet faciliter l'exploration du mécanisme réactionnel de l'AChE, en ralentissant l'enzyme sans pour autant la figer.

Doctor of Philosophy / Department of Chemistry / Duy H. Hua / Three research projects were carried out and they are described below. The synthesis of substituted phenolic compounds including halogenated di- and trihydroxybenzenes, aminophenols, and substituted di-tert-butylphenols are described. Redox potentials of the synthesized molecules along with various known laccase substrates were measured, and an inverse relationship between the oxidation potential and the efficiency of oxidation by laccase of halogenated hydroxybenzenes and aminophenols is demonstrated. The synthesized substituted phenols were found to be substrates but not inhibitors of laccase. We discovered a new class of di-tert-butylphenols compounds that inhibits the growth of mosquito larvae at low concentrations. Compound 17, 2,4-di-tert-butyl-6-(3-methyl-2-butenyl) phenol caused greater than 98% mortality of third-instar larvae of Anopheles gambiae in the concentration of 0.18 µM. These compounds do not inhibit laccases. It appears that they affect a new target of the mosquito that is different from those of currently existing pesticides. Two anti-Alzheimer molecules, CP2 and TP70, discovered in our laboratory were studied for their pharmacokinetics and distribution. The distribution of CP2 and TP70 in mouse brain region and various tissues of mice were examined. HPLC analysis revealed that CP2 treatment in primary neurons accumulates in mitochondria fraction. Similarly, the amount of CP2 in the brain tissue from wild type and APP/PS1 mice treated with 25 mg/kg/daily for 2 months also have the highest concentration in the mitochondria fractions in the hippocampus. The results show that CP2 and TP70 can penetrate the blood brain barrier and accumulate in the tissue in significant amounts. Pharmacokinetics and bioavailability of compound TP70 were determined. Area under the curve and bioavailability value F were calculated, and data show that TP70 has a good PK profile and bioavailability. For the preparation of a novel tripeptidyl norovirus 3C-like protease (3CL[superscript]pro) inhibitor, the P3 unnatural amino acid, (S)-3-hydroxyphenylalanine was synthesized. The P3 is designed to increase the polarity with the addition of the alcohol group. After combining the P3 unnatural amino acid with the P1 and P2 to form the novel tripeptidyl compound, a study comparing the relations between the structure and its activity (SAR) will confirm whether prediction is correct in our pursuit for an antiviral therapeutic drug in the form of a protease inhibitor.

Doctor of Philosophy / Department of Chemistry / Duy H. Hua / The objectives of this research project were to (i) synthesize different bicyclic and tricyclic pyrone and pyridinone compounds; (ii) study the mechanism of action of these compounds in solution as anti-Aβ (amyloid β) agents using different biophysical techniques; and (iii) study the biological activity of pyrone compounds for the counteraction of Aβ toxicity using MC65 cells, a human neuroblastoma cell line and 5X- familial Alzheimer’s disease (5X FAD, a transgenic mice with five different mutations) mice. A series of tricyclic pyrone and pyridinone compounds were investigated. The tricyclic pyrones and pyridinones were synthesized utilizing a condensation reaction between cyclohexenecarboxaldehye (25) and 4-hydroxy-6-methyl-2-pyone (24) or 4-hydroxy-6-methyl-2-pyridinone (51), respectively. A tricylic pyrone molecule CP2 (2, code name) was synthesized and has an adenine base unit attached to the pyrone core. For structure activity relationship (SAR) studies, the adenine group of CP2 was replaced with other DNA base units (thymine, cytosine and guanine) and various heterocyclic moieties. Since nitrogen containing compounds often exhibit increased bioactivity and brain-penetrating abilities, oxygen atom (O5’) was displaced with a nitrogen atom in the middle ring of the tricyclic pyrone. A condensation reaction of pyrone 51 and 25 was carried out to give the linear pyranoquinoline (52) and the L-shaped pyranoisoquinoline (53). The neurotoxicity of amyloid-β protein (Aβ) is widely regarded as one of the fundamental causes of neurodegeneration in Alzheimer’s disease (AD). Recent studies suggest that soluble Aβ oligomers rather then protofibrils and fibrils may be the primary toxic species. Different biophysical techniques including atomic force microscopy (AFM), circular dichroism (CD), surface plasmon resonance (SPR) spectroscopy, and protein quantification assays were used to study the mechanism of aggregation of Alzheimer Aβ peptide in solution. In search of potentially bioactive compounds for AD therapies, MC65 cell line was used as a screening model. Different tricyclic pyrone and pyridinone compounds protect MC65 cells from death. We studied the efficacy of CP2 in vivo by treatment of 5X FAD mice, a robust Aβ42-producing animal model of AD, with a 2-week course of CP2, which resulted in 40% and 50% decreases in non-fibrillar and fibrillar Aβ species respectively.