The ability of human polymorphonuclear leukocytes (PMNL; neutrophils), to sense and move to sites of infection is essential for our defense against pathogens. Cell motility is critically dependent on a dynamic remodeling of morphology. The morphological polarization toward chemoattractants, such as N-formyl-Met-Leu-Phe (fMLF), is associated with temporary extension and stabilization of lamellipodia in the direction of movement. The underlying mechanisms of cell motility are, however, still not entirely elucidated. It is therefore an urgent task to extend the present experimental evidence to give solid basis for a comprehensive model. Here it is shown that nitric oxide (NO) stimulates the morphological response of neutrophils, most likely due to transient increases in [Ca2+]i, following addition of NO-donors. This will, hypothetically, activate gelsolin and other actin filament severing proteins, leading to a subsequent decrease in filamentous actin. The incapability to efficiently turnover the actin filament network then blocks all motile activity. It is also shown that N-formyl peptide receptors on polarized neutrophils accumulate non-uniformly towards regions involved in motility. It is suggested that neutrophils use the asymmetric receptor distribution for directional sensing and sustained migration. A model for lamellipodium extension, where water fluxes play a pivotal role is presented. It is suggested that water fluxes through water-selective aquaporin (AQP) channels, contribute to the propulsive force for formation of various membrane protrusions and, thus, cell motility. It is well known that small G proteins of the Rho family GTPases play important roles in the intracellular signaling underlying cell motility. In morphologically polarized neutrophils it is shown that Cdc42, Rac2 and RhoA display spatially distinct distributions, which allows for sequential chemoattractant stimulation of neutrophil motility. The specific localizations of Rac2, Cdc42 and RhoA relative to each other and filamentous actin and fMLF receptors support the hypothesized order of activation and regulation of neutrophil cell motility. In conclusion, the detailed analysis of motility-related issues presented here provide new data allowing further refinement of previous models of neutrophil motility.

LEU pasižymi puikiomis sporto tradicijomis ir per savo gyvavimo laikotarpį yra išugdę ne vieną Lietuvą garsinusį sportininką. Tyrinėjant LEU sporto raidą, masiškumą ir sporto pasiekimus, iškyla mokslinė problema – koks yra sporto mokslo vaidmuo studentų mokymui, užimtumui, saviraiškai ir mokymo programų viešinimui. Tyrimo tikslas – atskleisti, LEU studentų dalyvavimą vidaus varžybose, kaip masinio užimtumo reiškinį, įvertinti jų sportinius pasiekimus Lietuvos ir tarptautiniu lygmeniu bei aptarti jų laimėjimų kaitos tendencijas. Tyrimo uždaviniai: 1. Apibūdinti masinį LEU studentų sportą per 2002 –2013 metus, apibendrinant jų pokyčius bei įvairovę, domėjimąsi renkantis mokymosi dalykus. 2. Atlikti LEU studentų, dalyvavusių įvairaus rango Lietuvos studentų varžybose, rezultatų analizę, bei juos apibendrinti. 3. Įvertinti LEU studentų pasiekimus Europos, pasaulio čempionatuose ir olimpinėse žaidynėse, jų reikšmę universiteto bei Lietuvos prestižui. Tyrimas buvo atliktas 2012 – 2014 mokslo metais Lietuvos edukologijos universitete. Analizei pasirinkti 2002-2013 metai, per kuriuos buvo surengtos LEU (VPU) vidaus varžybos ir masiniai sporto renginiai, aprašyti LEU studentai ir jų veikla, apžvelgti informaciniai-istoriniai sporto biuleteniai. Taip pat ištirtos Lietuvos aukštųjų mokyklų varžybos, kuriose dalyvavo LEU studentai, SELL studentų žaidynės, ir LEU sportininkai. Per tyrimui pasirinktą laikotarpį, LEU studentai dalyvavo dvejose Universiadose, pasaulio... [toliau žr. visą tekstą] / LEU is well known for its sport traditions and throughout its existence it prepared many well – known Lithuanian sportsmen. Under investigation of LEUs sports development, the mass of it, sport achievements we come to a scientific issue – what role does it take in teaching, busyness, self-expression and publicity of educational programs. The goal of research – to reveal the activity of LEU students in universities contests as act of mass busyness, to evaluate their sport achievements comparing to local and international level, to discuss the trend of their victory changes. Research tasks: 1. Describe the mass sport in LEU during year of 2002 – 2013, summing up the changes and variety in choosing the educational subjects. 2. Analyze the results of LEU students in various categories of competitions and sum them up. 3. Evaluate the achievements of LEU students in Europe’s, world’s championships and Olympic Games, their importance of universities Lithuania’s prestige. Research took place at Lithuania’s University of educational sciences in 2012 – 2014. The information for analysis was gathered from the event records of 2002-2013. Throughout this period of time there were many mass sport events, students and their activities were archived and informational-historical bulletins of LEU (VPU) were reviewed. Events of Lithuania’s universities, SELL student games where LEU students and sportsmen took place, were investigated. During this period of time LEU students attended two... [to full text]

The development of peptides as therapeutic agents has been hampered by their poor enzymatic stability and bioavailability. Many strategies, such as chemical modification, synthesis of peptidomimetics and formulation, have been employed to overcome these issues. For central nervous system (CNS) active peptides, the blood brain barrier is an added hurdle. Nasal delivery is believed to provide a direct access to the brain via the olfactory nerve, which would bypass the blood brain barrier. This route of administration, however, is dependant on the size and physico-chemical properties of the administered drug. For these reasons, three CNS active peptides were chosen as models. Leu-enkephalin, endomorphin-1 and a-conotoxin MII are three peptides that differ in their size, amino acid sequence and conformation. Using chemical modifications to improve their stability and ability to cross biological membranes, in vitro assessments of derivatives of these peptides were performed and in vivo nasal delivery was attempted on the most promising candidates. The chemical modifications consisted in the addition of lipids and/or sugars to the N- or C-terminus of the peptides. Assessment of the in vivo bioavailability after nasal administration, however, proved to be challenging. The initial method chosen for this purpose was the use of tritiated acetic anhydride which would radiolabel the peptide via acetylation at the N-terminus of the peptide derivatives. Consequently, in vitro stability and permeability of each acetylated derivatives was also studied. Acetylation of the lipidic derivatives, which formed an amide bond, proved to be beneficial for the stability of the lipidic peptides. In contrast, acetylation of the Nterminus sugar derivatives, which formed an ester bond at one or several positions of the sugar, was an unstable modification. Thus, an extraction method for the tested peptides from rat tissues was developed, and LC-MS/MS analyses were conducted to measure the level of peptide in the olfactory bulbs, brain and blood. Leu-enkephalin derivatives were all amide derivatives at the C-terminus of the peptide. The most successful Leu-enkephalinamide derivatives were C8-LeuEnk (2), C12- LeuEnk (3) and Lac-LeuEnk (8), which are the Leu-enphelinamide peptide modified with a C8 lipoamino acid, a C12 lipoamino acid and a lactose moiety respectively. They all exhibited improved permeability across Caco-2 monolayers and stability in Caco-2 cell homogenate and/or plasma. Problems of solubility encountered with C12-LeuEnk (3), however, hampered its testing in vivo after nasal administration. C8-LeuEnk (2) and Lac-LeuEnk (8) were administered intranasally to male Sprague-Dawley rats. Both peptides were found in the olfactory bulbs after 10 minutes administration (2: 49.2 ± 15.6 nM; 8: 40.6 ± 14.6 nM) while blood concentration remained low, showing that the peptide reached the olfactory bulbs directly from the nasal cavity via the olfactory nerve. Brain concentrations were 13.5 ± 10.1 nM for C8-LeuEnk (2) and 13.6 ± 6.9 nM for Lac-LeuEnk (8). These two peptides brain concentrations seemed to be high enough to exhibit analgesic effect when compared to their binding affinity in vitro. This was not statistically significant, however, due to the high standard deviations observed (Kiμ C8-LeuEnk (2) = 7.74 ± 1.15 nM; Kiμ Lac-LeuEnk (8) = 6.69 ± 1.81 nM). Endomorphin-1 was only modified at the N-terminus as previous results have shown that the activity of the peptide is strongly decreased by C-terminus modifications. The most successful modification, regarding permeability across Caco-2 monolayers and water solubility, was shown to be the addition of a lactose moiety to the N-terminus of the peptide. Lac-Endo1 (16) exhibited a permeability of 1.91 ± 0.76 x 10-6 cm/s and was soluble at the concentration used for in vivo nasal administration (2 mg/Kg, 50 μL administration). After 10 minutes administration, Lac-Endo1 (16) was found in the olfactory bulbs (418 ± 410 nM), in the brain (4.01 ± 4.61 nM) and in the blood (1.58 ± 1.85 nM). The large standard deviations observed reflect the difficulties encountered with the extraction process of this peptide. A direct transport for the nasal cavity to the olfactory bulb was observed as illustrated by the low blood concentrations. Brain concentrations, however, were too low to expect a strong analgesic effect from this compound after nasal administration (Kiμ Lac-Endo1 (16) = 11.3 ± 1.2 nM). a-Conotoxin MII is a 16 amino acid long peptide containing two disulfide bonds. The formation of these two disulfide bonds leads to low yields in the synthesis of the derivatives of this peptide. Addition of a lipidic moiety to the peptide did not seem to improve its permeability through biological membranes. This modification resulted in highly lipophilic peptides with dissolution issues in water based media such as those used in the permeability experiments. The most successful a-conotoxin MII derivative was GS-Ctx (25) which exhibited a permeability of 4.22 ± 0.53 x 10-7 cm/s across Caco-2 monolayers. This permeability, however, was too low to consider in vivo administration. In conclusion, we successfully synthesised a series of derivatives of Leu-enkephalin, endomorphin-1 and a-conotoxin MII and screened them through Caco-2 monolayers for permeability and Caco-2 cell homogenates and human plasma for stability. Three derivatives (C8-LeuEnk (2), Lac-LeuEnk (8) and Lac-Endo1 (16)) were intranasally administered and found in the olfactory bulbs 10 minutes after administration. The low blood concentrations observed show that a direct transport from the nasal cavity to the brain occurs. Thus, nasal administration could be an option for delivering to the brain low molecular weight peptides exhibiting increased stability and permeability in vitro.

The development of peptides as therapeutic agents has been hampered by their poor enzymatic stability and bioavailability. Many strategies, such as chemical modification, synthesis of peptidomimetics and formulation, have been employed to overcome these issues. For central nervous system (CNS) active peptides, the blood brain barrier is an added hurdle. Nasal delivery is believed to provide a direct access to the brain via the olfactory nerve, which would bypass the blood brain barrier. This route of administration, however, is dependant on the size and physico-chemical properties of the administered drug. For these reasons, three CNS active peptides were chosen as models. Leu-enkephalin, endomorphin-1 and a-conotoxin MII are three peptides that differ in their size, amino acid sequence and conformation. Using chemical modifications to improve their stability and ability to cross biological membranes, in vitro assessments of derivatives of these peptides were performed and in vivo nasal delivery was attempted on the most promising candidates. The chemical modifications consisted in the addition of lipids and/or sugars to the N- or C-terminus of the peptides. Assessment of the in vivo bioavailability after nasal administration, however, proved to be challenging. The initial method chosen for this purpose was the use of tritiated acetic anhydride which would radiolabel the peptide via acetylation at the N-terminus of the peptide derivatives. Consequently, in vitro stability and permeability of each acetylated derivatives was also studied. Acetylation of the lipidic derivatives, which formed an amide bond, proved to be beneficial for the stability of the lipidic peptides. In contrast, acetylation of the Nterminus sugar derivatives, which formed an ester bond at one or several positions of the sugar, was an unstable modification. Thus, an extraction method for the tested peptides from rat tissues was developed, and LC-MS/MS analyses were conducted to measure the level of peptide in the olfactory bulbs, brain and blood. Leu-enkephalin derivatives were all amide derivatives at the C-terminus of the peptide. The most successful Leu-enkephalinamide derivatives were C8-LeuEnk (2), C12- LeuEnk (3) and Lac-LeuEnk (8), which are the Leu-enphelinamide peptide modified with a C8 lipoamino acid, a C12 lipoamino acid and a lactose moiety respectively. They all exhibited improved permeability across Caco-2 monolayers and stability in Caco-2 cell homogenate and/or plasma. Problems of solubility encountered with C12-LeuEnk (3), however, hampered its testing in vivo after nasal administration. C8-LeuEnk (2) and Lac-LeuEnk (8) were administered intranasally to male Sprague-Dawley rats. Both peptides were found in the olfactory bulbs after 10 minutes administration (2: 49.2 ± 15.6 nM; 8: 40.6 ± 14.6 nM) while blood concentration remained low, showing that the peptide reached the olfactory bulbs directly from the nasal cavity via the olfactory nerve. Brain concentrations were 13.5 ± 10.1 nM for C8-LeuEnk (2) and 13.6 ± 6.9 nM for Lac-LeuEnk (8). These two peptides brain concentrations seemed to be high enough to exhibit analgesic effect when compared to their binding affinity in vitro. This was not statistically significant, however, due to the high standard deviations observed (Kiμ C8-LeuEnk (2) = 7.74 ± 1.15 nM; Kiμ Lac-LeuEnk (8) = 6.69 ± 1.81 nM). Endomorphin-1 was only modified at the N-terminus as previous results have shown that the activity of the peptide is strongly decreased by C-terminus modifications. The most successful modification, regarding permeability across Caco-2 monolayers and water solubility, was shown to be the addition of a lactose moiety to the N-terminus of the peptide. Lac-Endo1 (16) exhibited a permeability of 1.91 ± 0.76 x 10-6 cm/s and was soluble at the concentration used for in vivo nasal administration (2 mg/Kg, 50 μL administration). After 10 minutes administration, Lac-Endo1 (16) was found in the olfactory bulbs (418 ± 410 nM), in the brain (4.01 ± 4.61 nM) and in the blood (1.58 ± 1.85 nM). The large standard deviations observed reflect the difficulties encountered with the extraction process of this peptide. A direct transport for the nasal cavity to the olfactory bulb was observed as illustrated by the low blood concentrations. Brain concentrations, however, were too low to expect a strong analgesic effect from this compound after nasal administration (Kiμ Lac-Endo1 (16) = 11.3 ± 1.2 nM). a-Conotoxin MII is a 16 amino acid long peptide containing two disulfide bonds. The formation of these two disulfide bonds leads to low yields in the synthesis of the derivatives of this peptide. Addition of a lipidic moiety to the peptide did not seem to improve its permeability through biological membranes. This modification resulted in highly lipophilic peptides with dissolution issues in water based media such as those used in the permeability experiments. The most successful a-conotoxin MII derivative was GS-Ctx (25) which exhibited a permeability of 4.22 ± 0.53 x 10-7 cm/s across Caco-2 monolayers. This permeability, however, was too low to consider in vivo administration. In conclusion, we successfully synthesised a series of derivatives of Leu-enkephalin, endomorphin-1 and a-conotoxin MII and screened them through Caco-2 monolayers for permeability and Caco-2 cell homogenates and human plasma for stability. Three derivatives (C8-LeuEnk (2), Lac-LeuEnk (8) and Lac-Endo1 (16)) were intranasally administered and found in the olfactory bulbs 10 minutes after administration. The low blood concentrations observed show that a direct transport from the nasal cavity to the brain occurs. Thus, nasal administration could be an option for delivering to the brain low molecular weight peptides exhibiting increased stability and permeability in vitro.

In 2008, the Oregon State TRIGA�� Reactor (OSTR) was converted from highly-enriched uranium (HEU) fuel lifetime improvement plan (FLIP) fuel to low-enriched uranium (LEU) fuel. This effort was driven and supported by the Department of Energy's (DoE's) Reduced Enrichment for Research and Test Reactors (RERTR) program. The basis behind the RERTR program's ongoing conversion effort is to reduce the nuclear proliferation risk of civilian research and test reactors. The original intent of the HEU FLIP fuel was to provide fuel to research reactors that could be utilized for many years before a necessary refueling cycle. As a research reactor, the OSTR provides irradiation facilities for a variety of applications, such as: activation analysis, fission-track dating, commercial isotope production, neutron radiography, prompt gamma characterization, and many others. In order to accurately perform these research functions, several studies have been conducted on the HEU FLIP fuel core to characterize the neutron spectra in various experimental facilities of the OSTR. As useful as these analyses were, they are no longer valid due to the change in fuel composition and the resulting alteration of core performance characteristics. The purpose of this study is to characterize the neutron spectra in various experimental facilities within the new LEU core so as to provide data that is representative of the OSTR's current state. / Graduation date: 2013

Despite the unfavorable pharmacokinetic properties associated with peptides, they are still of great interest in drug development due to a multitude of interesting biological functions. The development of peptidomimetics strives to maintain or improve the biological activity of a peptide concurrently with removing the unwanted properties. This thesis describes two synthetic approaches to peptidomimetics with particular emphasis on secondary structure mimetics. First the design, synthesis and evaluation of two beta-turn mimetics incorporated in the endorphin Leu-enkephalin is presented. The beta-turn mimetics were stabilized by replacement of the intramolecular hydrogen bond with an ethylene bridge, and the amide bond between Tyr and Gly was replaced with an ether linkage. Linear analogues of the two mimetics were also synthesized. The peptidomimetics and their linear analogues were evaluated in a competitive binding assay at two opiate receptors, my and delta. One of the cyclized beta-turn mimetics was found to be a delta receptor antagonist with an IC50 value of 160 nM. Second a synthetic strategy to a beta-strand mimetic using 2-fluoro-4-iodopyridine as scaffold is described. The synthesis involved a Grignard exchange reaction on the pyridine scaffold using an amino acid derivative as electrophile followed by an SNAr reaction using an amine as nucleophile. The synthesis of a tripeptidomimetic of Leu-Gly-Gly and attempts to introduce chiral building blocks at the C-terminal, as well as studies towards elongated mimetics are presented. Two additional studies deal with the synthesis of two classes of potential thrombin inhibitors based on the pyridine scaffold. The first class contain pyridine as central fragment (P2 residue) substituted with a para-amidinobenzylamine group as P1 residue and various benzoyl groups as P3 residues. Three potential thrombin inhibitors were synthesized and found to be microM inhibitors in an enzymatic assay. In the second class, the pyridine ring serves as P3 residue. This class also lacks a strongly basic group in the P1 position. A small library of eight compounds were synthesized and evaluated in the enzymatic assay. Unfortunately, these compounds lacked inhibitory activity.

Dans des travaux précédents, les liens amides de la Leu-enképhaline, un pentapeptide endogène agoniste des récepteurs opioïdergiques, ont été substitués séquentiellement et systématiquement par des alcènes trans, des esters, des N-méthylamides et des thioamides. Des essais pharmacologiques sur l’affinité et sur l’activité (inhibition de la contraction du mouse vas deferens et phosphorylation de ERK 1 et ERK 2) des composés peptidomimétiques résultants envers le récepteur opioïdergique δ ont démontré que la substitution de l’amide 1 par un alcène, la substitution de l’amide 2 par un thioamide et la substitution de l’amide 4 par un ester, un N-méthylamide ou un thioamide sont des modifications tolérées pour l’obtention de composés ayant une activité agoniste. Cet ouvrage traite de la conception, de la synthèse et de la caractérisation chimique, pharmacologique et physico-chimique de molécules peptidomimétiques dotées de plusieurs de ces isostères (à la même position que celle menant à des composés actifs). Un composé peptidomimétique de la Leu-enképhaline a aussi été synthétisé en substituant l’amide 3 par un fluoroalcène, un isostère jusqu’ici inexploré par notre laboratoire. Les résultats démontrent que les molécules peptidomimétiques dotées de plus d’un isostère gardent, dans certains cas, une bonne affinité pour le récepteur δ. Cependant, des pertes au niveau de l’activité sont observées dans la majorité des cas. D’un point de vue pharmacocinétique, l’approche a permis la synthèse de composés peptidomimétiques ayant un profil plus favorable que celui de la Leu-enképhaline. En effet, tous les composés synthétisés ont démontré une lipophilicité et une résistance enzymatique (sauf dans un cas) accrue par rapport à la Leu-enképhaline.

In the last decades NMR spectroscopy has become an invaluable tool both in academic research and in the pharmaceutical industry. This thesis describes applications of NMR spectroscopy in biomedicinal research for structure elucidation of biologically active peptides and peptidomimetics as well as in studies of ligand-protein interactions. The first part of this thesis describes the theory and methodology of structure calculations of peptides using experimental restraints derived from NMR spectroscopy. This methodology has been applied to novel mimetics of the peptide hormones desmopressin and Leu-enkephalin. The results of these studies highlight the complicating issue of conformational exchange often encountered in structural determination of peptides and how careful analysis of experimental data as well as optimization of experimental conditions can enable structure determinations in such instances. Although the mimetics of both desmopressin and Leu-enkephalin were found to adopt the wanted conformations, they exhibited no or very poor biological activity. These results demonstrate the difficulties in designing peptidomimetics without detailed structural information of the receptors. A stereoselective synthetic route towards XxxΨ[CH2O]Ala pseudodipeptides is also presented. Such pseudodipeptides can be used as isosteric amide bond replacements in peptides in order to increase their resistance towards proteolytic degradation. The second part of this thesis describes the study of the interaction between compounds that inhibit pilius assembly, pilicides, and periplasmic chaperones from uropathogenic Escherichia coli. Periplasmic chaperones are key components in assembly of pili, i.e. hair-like protein complexes located on the surface of Escherichia coli that cause urinary tract infections. Detailed knowledge about this interaction is important in understanding how pilicides can inhibit pilus assembly by binding to chaperones. Relaxation-edited NMR experiments were used to confirm the affinity of the pilicides for the chaperones and chemical shift mapping was used to study the pilicide-chaperone interaction surface. These studies show that at least two interaction sites are present on the chaperone surface and consequently that two different mechanisms resulting in inhibition of pilus assembly may exist.

Worldwide, malaria is one of the deadliest diseases. In 2016 it sickened 216 million people and caused 445,000 deaths. In order to control the spread of this deadly diseases to human, we can either target the mosquito vector (Anopheles gambiae) or the parasite (Plasmodium falciparum). Due to recent emergence of resistance to current insecticides and antimalarial drugs there is a pressing need to discover and develop new agents that engage new targets in these organisms. To circumvent the effect of resistance to pyrethroid insecticides on the efficacy of insecticide treated nets (ITNs), the use of acetylcholinesterase (AChE) inhibitors on ITNs has drawn attention. In the first project, we explored a small library of γ- substituted oxoisoxazole- 2(3H)-carboxamides and isoxazol-3-yl carbamates, and nitriles as AChE inhibitors targeting wild- type (G3) and resistant (Akron) An. gambiae mosquito. In total 23 compounds were synthesized and evaluated. Both carbamates and carboximides with a 2-cyclopropylethyl side chain (1-87a and 1-88a) were extremely toxic to Akron mosquitos, yet these compounds did not exhibit appreciable selectivity between human and An. gambiae AChE. Unfortunately, none of the nitriles showed appreciable toxicity to G3 strain of the mosquitoes, nor did they inhibit An. gambiae AChE. In the second project, conducted in collaboration with Professor Michael Klemba, we focused on the mode of action of an established antimalarial drug, Mefloquine (MQ). Dr. Klemba's recently developed amino acid efflux assay was used to determine the effect of MQ and its open-ring analogs on hemoglobin endocytosis and catabolism in P. falciparum-infected erythrocytes. In total 26 MQ analogs were synthesized and 18 were studied in depth to determine their potency to inhibit leucine (Leu) efflux and parasite growth (SYBR Green). An excellent correlation (R² = 0.98) over nearly 4 log units was seen for these 18 compounds in the two assays. These data are consistent with the hypothesis that the antimalarial action of these compounds principally derives from inhibition of hemoglobin endocytosis. After this observation, a number of photo-affinity probes were designed and synthesized in hopes of isolating the molecular target of MQ. These analogs are currently being used by Dr. Klemba in pull-down experiments. In the third project, conducted in collaboration with Professor Belen Cassera, we sought to optimize a new antimalarial drug lead that would circumvent current resistance mechanisms. In Plasmodium parasites, the methylerythritol phosphate (MEP) pathway is known to be essential for its growth. This pathway is absent in humans, presenting the opportunity to develop potentially safe and effective therapeutic candidates. Previous work in the Cassera and Carlier lab had established that MMV008138 was the only compound in the Malaria Box that targeted the MEP pathway and that it was (1R,3S)-configured. My research expanded previous efforts in the Carlier group and produced synthesis of 73 analogs of MMV008138 (3-21a'1) that were tested for growth inhibition. These analogs featured variation at the A-, B-, C- and D-ring. In the process, a novel Pictet-Spengler ring expansion reaction of ortho-substituted acetphenones was discovered. The ring-expanded products were identified by means of 1D and 2D NMR experiments, HRMS, and X-ray crystallography. Among the 73 analogs prepared, four compounds showed similar growth inhibition potency to the lead 3-21a'1. In particular, the methoxyamide 3-80a, and the fluorinated A-ring analogs 3-124a, 3-124c and 3-124d all showed excellent (500-700 nM) growth IC₅₀ values against P. falciparum. All four showed full rescue upon co-application of IPP (200 μM), confirming that they target the MEP pathway. ADME-Tox evaluation of these new analogs will soon be underway. / PHD

Nous avons démontré l’utilité du groupement protecteur tert-butylsulfonyle (N-Bus) pour la chimie des acides aminés et des peptides. Celui-ci est préparé en deux étapes, impliquant la réaction d’une amine avec le chlorure de tert-butylsulfinyle, suivie par l’oxydation par du m-CPBA, pour obtenir les tert-butylsulfonamides correspondants avec d’excellents rendements. Le groupement N-Bus peut être clivé par traitement avec 0.1 N TfOH/DCM/anisole à 0oC en 10h pour régénérer le sel d’ammonium. Une variété d’acides aminés N-Bus protégés ainsi que d’autres aminoacides peuvent alors être utilisés pour préparer divers dipeptides et tripeptides. A l’exception du groupe N-Fmoc, les conditions de déprotection du groupe N-Bus clivent également les groupements N-Boc, N-Cbz et O-Bn. Une déprotection sélective et orthogonale des groupes N-Boc, N-Cbz, N-Fmoc et O-Bn est également possible en présence du groupe protecteur N-Bus. Le nouvel acide aminé non-naturel (3R, 2R) 3–méthyl-D-leucine (β-Me-Leu) et son régioisomère 2-méthyle ont été synthétisés par ouverture d’une N-Ts aziridine en présence d’un excès de LiMe2Cu. Chacun des régioisomères du mélange (1:1,2) a été converti en la méthylleucine correspondante, puis couplé à l’acide D-phényllactique puis au motif 2-carboxyperhydroindole 4-amidinobenzamide en présence de DEPBT. Des élaborations ultérieures ont conduit à des analogues peptidiques non-naturels d’aeruginosines telles que la chlorodysinosine A. Les deux analogues ont ensuite été évalués pour leur activité inhibitrice de la thrombine et la trypsine. La présumée aeruginosine 3-sulfate 205B et son anomère β ont été synthétisés avec succès à partir de 5 sous-unités : la 3-chloroleucine, l’acide D-phényllactique, le D-xylose, le 2-carboxy-6-hydroxyoctahydroindole et l’agmatine. La comparaison des données RMN 1H et 13C reportées avec celles obtenues avec l’aeruginosine synthétique 205B révèle une différence majeure pour la position du groupe présumé 3'-sulfate sur l’unité D-xylopyranosyle. Nous avons alors synthétisés les dérivés méthyl-α-D-xylopyranosides avec un groupement sulfate à chacune des positions hydroxyles, afin de démontrer sans ambiguïté la présence du sulfate en position C-4' par comparaison des données spectroscopiques RMN 1H et 13C. La structure de l’aeruginosine 205B a alors été révisée. Une des étapes-clés de cette synthèse consiste en la formation du glycoside avec le groupe hydroxyle en C-6 orienté en axial sur la sous-unité Choi. Le 2-thiopyridylcarbonate s’est avéré une méthode efficace pour l’activation anomérique. Le traitement par AgOTf et la tétraméthylurée en solution dans un mélange éther-DCM permet d’obtenir l’anomère α désiré, qui peut alors être aisément séparé de l’anomère β par chromatographie / We have demonstrated the usefulness of tert-butylsulfonyl (N-Bus) protecting group in amino acid and peptide chemistry. It is formed in a 2-step procedure involving reaction of an amine with tert-butylsulfinyl chloride, followed by oxidation with m-CPBA to obtain the corresponding tert-butyl- sulfonamides in excellent yields. The N-Bus group can be cleaved to regenerate the corresponding amino salt in 0.1 N TfOH/DCM/anisole at 0 oC for 10 h. A variety of N-Bus protected amino acids and other common amino acids can be used to form dipeptides and tripeptides. With the exception of the N-Fmoc group, the conditions required for the N-Bus group cleavage also cleaved the N-Boc, N-Cbz and O-Bn groups. Selective and orthogonal deprotection of N-Boc, N-Cbz, N-Fmoc and O-Bn groups could be achieved in the presence of the N-Bus protecting group. The new unnatural amino acids (3R, 2R) 3–methyl-D-leucine (β-Me-Leu) and its 2-methyl regioisomer were synthesized by ring opening of an N-Ts aziridine intermediate with excess LiMe2Cu. The 1:1.2 mixture of regioisomers were each converted to the corresponding methyl leucines, then coupled to D-phenyllactic acid, followed by coupling with 2-carboxyperhydroindole 4-amidino-benzamide core in the presence of DEPBT. Further elaboration led to linear peptidic unnatural analogues of known aeruginosins such as chlorodysinosin A. The two analogues were also evaluated in enzymatic assays for their inhibitory activity against thrombin and trypsin. The presumed 3-sulfated aeruginosin 205B and its β–anomer were successfully synthesized from 5 subunits: 3-chloroleucine, D-phenyllactic acid, D-xylose, 2-carboxy-6-hydroxyoctahydroindole, and agmatine. Comparison of 1H and 13C NMR reported data with that of synthetic aeruginosin 205B revealed a disturbing discrepancy with regard to the position of the presumed 3'-sulfate on the D-xylopyranosyl unit. We synthesized methyl α-D-xylopyranosides with sulfates at each of the hydroxyl groups and conclusively demonstrated the the presence of a C-4'-sulfate by comparison of the 1H and 13C NMR spectroscopic data. Thus, the structure of aeruginosin 205B should be revised. One of the key steps in the synthesis is glycoside formation of the axially oriented C-6 hydroxyl group in the Choi subunit. The 2-thiopyridyl carbonate was a suitable method for anomeric activation, followed by treatment with AgOTf and tetramethylurea in ether-DCM solution to give the desired α-anomer, which was easily separable from the β-anomer by column chromatography.