Thesis (Ph. D.)--Columbia University, 1924. / Biographical note. "Chronological bibliography": p. 24.

Thesis (Ph. D.)--Columbia University, 1931. / Biographical. Bibliography: p. 45.

L’isobutylthiazole est un composé volatil à l’arôme de verdure important pour la flaveur de la tomate. D’après sa structure moléculaire, il serait synthétisé à partir d’un composé azoté issu de la leucine et d’un composé soufré issu de la cystéine. Cependant, cette hypothèse n’a pas été confirmée et la voie de synthèse de l’isobutylthiazole reste méconnue. Ce projet avait donc pour objectif d’apporter de nouvelles connaissances sur le sentier du composé volatil. Un locus de 5 Mb sur le chromosome 4 a été ciblé pour son impact sur la production de l’isobutylthiazole. Une cartographie de précision a permis de réduire ce QTL à une région de 25 kb permettant ainsi d’identifier un gène candidat, appelé isobutylthiazole synthase 1(IBST1). Le gène IBTS1 code pour une protéine de la famille des pathogénesis-related 10 (PR10), qui sont connues pour jouer des rôles divers chez les végétaux. La fonction du gène IBTS1 dans la synthèse de l’isobutylthiazole a été confirmée par transgénèse. L’ajout de précurseurs potentiels dans la tomate et dans les feuilles de N. benthamania agroinfiltrées a par la suite apporté des connaissances sur le sentier métabolique. Les composés azotés issus de la leucine ne permettent pas la synthèse de l’isobutylthiazole contrairement à certains composés non azotés issus du même acide aminé. Un enrichissement en leucine et en cystéine marqués a par ailleurs permis de confirmer que ces derniers sont les précurseurs de l’isobutylthiazole et que l’azote provient de la cystéine et non de la leucine. Un composé issu de la condensation entre l’isovaleraldéhyde, un composé non-azoté dérivé de la leucine, et la cystéine a été identifié dans la tomate, l’acide isobutylthiazolidine-4-carboxylique. Un enrichissement en acide isobutylthiazolidine-4-carboxylique a été réalisé dans les feuilles de N. benthamania exprimant IBTS1 et FMO, une Flavin monooxygénase responsable de la synthèse des composés azotés volatils chez la tomate. La combinaison des deux protéines avec le substrat a permis la production d’isobutylthiazole et des autres composés azotés volatils issus de la leucine. Cette étude a donc permis d’identifier un gène responsable de la synthèse de l’isobutylthiazole dans la tomate et d’améliorer les connaissances sur le sentier des composés volatils azotés issus de la leucine. / Isobutylthiazole, which has a green aroma, is an important volatile in tomato that contributes positively to the flavor of the fruits. The biosynthetic pathway of this compound is still largely unknown. The most logical hypothesis is that isobutylthiazole results from the combination of a nitrogenous compound derived from leucine and a sulfurous compound derived from cysteine. This thesis goal was to verify this hypothesis and to improve our knowledge of the isobutylthiazole metabolic pathway. A locus of 5Mb on chromosome 4 was targeted for its high impact on the production of isobutylthiazole. Fine mapping allowed defining the locus to a smaller region of 25 kilobases containing only a single gene expressed in the fruit. The gene was named isobutylthiazole synthase 1 (IBTS1) and codes for a small protein belonging to the PR-10 group (Pathogenesis-related), a family of proteins with diverse functions. The role of IBTS1 in isobutylthiazole synthesis was confirmed by overexpressing and silencing the gene. Feeding experiments further allowed the identification of potential precursors in the metabolic pathway. Nitrogenous compounds derived from leucine did not result in higher isobutylthiazole, in contrast to the non-nitrogenous leucine-derived compounds. Labelled amino acid feeding experiment confirmed that leucine and cysteine are precursors of isobutylthiazole, and that nitrogen comes from cysteine instead of the leucine. A compound resulting from the condensation of isovaleraldehyde (leucine-derived) and cysteine was identified in tomato, isobutylthiazolidine-4-carboxylic acid. Feeding of isobutylthiazolidine-4-carboxylic acid was realized in agroinfiltrated N. benthamania leaves expressing IBTS1 and FMO, a flavin monooxygenase responsible for the synthesis of nitrogenous volatiles compounds in tomato. The combination of FMO, IBTS1 and the compound resulted in the production of isobutylthiazole and the other nitrogenous volatiles derived from leucine (isovaleronitrile, 3-methylbutanal oxime, 1-nitro-3-methylbutane). This study allowed to identify a new gene involved in the synthesis of isobutylthiazole and to expand knowledge of the synthesis of nitrogenous volatiles.

Thesis (M.S.)--Mississippi State University. Department of Chemistry. / Title from title screen. Includes bibliographical references.

Malaria, a mosquito-borne infectious disease, caused by the protozoan Plasmodium genus, is the greatest health challenges worldwide. The plasmodial vitamin B1 biosynthetic enzyme PfThzK diverges significantly, both structurally and functionally from its counterpart in higher eukaryotes, thereby making it particularly attractive as a biomedical target. In the present study, PfThzK was recombinantly produced as 6×His fusion protein in E. coli BL21, purified using nickel affinity chromatography and size exclusion chromatography resulting in 1.03% yield and specific activity 0.28 U/mg. The enzyme was found to be a monomer with a molecular mass of 34 kDa. Characterization of the PfThzK showed an optimum temperature and pH of 37°C and 7.5 respectively, and it is relatively stable (t₁/₂=2.66 h). Ag nanoparticles were synthesized by NaBH₄/tannic acid, and characterized by UV-vis spectroscopy and transmission electron microscopy. The morphologies of these Ag nanoparticles (in terms of size) synthesized by tannic acid appeared to be more controlled with the size of 7.06±2.41 nm, compared with those synthesized by NaBH₄, with the sized of 12.9±4.21 nm. The purified PfThzK was challenged with Ag NPs synthesized by tannic acid, and the results suggested that they competitively inhibited PfThzK (89 %) at low concentrations (5-10 μM) with a Ki = 6.45 μM.

M.Sc. / This study comprised the synthesis and characterization of new carbonyl carbene complexes of chromium, molybdenum and tungsten, prepared from thiazole precursors. In addition, the preparation and characterization of coordination compounds of chromium, tungsten and iron with new thiazole dithiocarboxylester ligands are reported.

Thesis (MSc)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: Please see fulltext for abstract / AFRIKAANSE OPSOMMING: Sien asb volteks vir opsomming

Os radicais livres são espécies químicas que reagem rapidamente com diversos compostos e alvos celulares, por possuírem tempo de meia vida muito curto e serem espécies altamente instáveis. A formação destes compostos constitui uma ação contínua e fisiológica, cumprindo funções biológicas essenciais as quais ocorrem pela perda ou adição de um único elétron a um composto não radicalar. Estas reações podem ocorrer em processos bioquímicos do sistema imune ou químicos, causando prejuízo às células através da destruição de componentes, como proteínas, lipídios, açúcares e nucleotídeos. Sabe-se que existem compostos que são efetivos contra tais espécies, prevenindo os danos provocados pelo estresse oxidativo. O objetivo deste trabalho foi estudar compostos heterocíclicos que possuam nitrogênio em sua estrutura (azóis), que figuram na literatura como moléculas exemplares de compostos de aplicação farmacológica de amplo espectro. Dentre estes compostos foram analisados os derivados de pirazóis (26 compostos), tiazóis (7 compostos) e 1 isoxazol (3,5-dimetilisoxazol). Estes 34 compostos foram avaliados pela metodologia ORAC (Capacidade de Absorção de Radicais Oxigênio) a fim de determinar e/ou de avaliar seu potencial antioxidante. A escolha do método ORAC se deu pelo fato das moléculas estudadas apresentarem características hidrofílicas e lipofílicas, além de ser um método validado pela literatura, disponível e de ampla aplicação. O método ORAC avalia a capacidade antioxidante da amostra, medindo sua habilidade de proteger a fluoresceína (FL) da oxidação pelo AAPH no meio reacional. O AAPH é um gerador de radicais livres que a 37°C retira hidrogênio do meio, promovendo a redução da fluorescência da fluoresceína em λ medido pelo tempo. Seis compostos apresentaram atividade antioxidante de boa à moderada: 3,5-dimetil-1H-pirazol (2.382 µmol eq.Trolox/g); 3-fenil-5-(4-fluorfenil)-1-tiocarbamoil-4,5-diidro-1H-pirazol (6.354 µmol eq.Trolox/g); 3-fenil-5-(2-metoxifenil)-1-tiocarbamoil-4,5-diidro-1H-pirazol (8.739 µmol eq.Trolox/g); 5-(2,4-diclorofenil)-3-fenil-1-tiocarbamoil-4,5-diidro-1H-pirazol (6.022,226 µmol eq.Trolox/g); 2-[5-(4-metoxifenil)-3-fenil-4,5-diidro-1H-pirazol-1-il]-4-feniltiazol (3.135 µmol eq.Trolox/g); e finalmente 2-[5-(3-nitrofenil)-3-fenil-4,5-diidro-1H-pirazol-1-il]-4-feniltiazol (2.700 µmol eq.Trolox/g). Os experimentos com o método ORAC para os azóis estudados apresentaram reprodutibilidade na execução experimental e demonstraram ser uma alternativa viável para estudos de moléculas sintéticas de potencial antioxidante. / Free radicals are chemical species that react rapidly with various compounds and target cells, as they have a very short half life and are highly unstable. The formation of these compounds consists of a continuous, physiological action, which includes essential biological functions and occurs through the loss or addition of a single electron to a non-radical compound. These reactions may occur in biochemical processes of the immune system, or by chemical reactions, causing damage to the cells through the destruction of components such as proteins, lipids, sugars and nucleotides. It is known that compounds exist which are effective against these species, preventing damage caused by oxidative stress. The object of this work was to study heterocyclic compounds that have nitrogen in their structure (azoles), which appear in the literature as exemplary molecules of compounds with a wide spectrum of pharmacological applications. Of these compounds, derivatives of pyrazoles (26 compounds), thiazoles (7 compounds) and 1 isoxazole (3,5-dimethylisoxazole) were analyzed. These 34 compounds were evaluated by the ORAC (Oxygen Radicals Absorption Capacity) in order to determine and/or evaluate its antioxidant potential. The choice of ORAC method is based on the fact that the molecules studied have hydrophilic and lipophilic characteristics, as well as a method validated by the literature, which is available and widely used. The ORAC method evaluates the antioxidant capacity of the sample, measuring its ability to protect the fluorescence (FL) of the oxidation by the AAPH in the reaction medium. AAPH is a generator of free radicals which, at 37°C, removes hydrogen from the medium, promoting the reduction of fluorescence from fluorescein in λ measured by time. Six compounds present good to moderate antioxidant activity: 3,5-dimethyl-1H-pyrazole (2.382 µmol eq.Trolox/g); 3-phenyl-5-(4-fluorphenyl)-1-thiocarbamoyl-4,5-dihydro-1H-pyrazole (6.354 µmol eq.Trolox/g); 3-phenyl-5-(2-methoxyphenyl)-1-thiocarbamoyl-4,5-dihydro-1H-pyrazole (8.739 µmol eq.Trolox/g); 5-(2,4-diclorophenyl)-3-phenyl-1-thiocarbamoyl-4,5-dihydro-1H-pyrazole (6.022,226 µmol eq.Trolox/g); 2-[5-(4-methoxyphenyl)-3-phenyl-4,5-dihydro-1H-pyrazole-1-il]-4-phenylthiazole (3.135 µmol eq.Trolox/g); and finally, 2-[5-(3-nitrophenyl)-3-phenyl-4,5-dihydro-1H-pyrazole-1-il]- 4-phenylthiazole (2.700 µmol eq.Trolox/g). Experiments with the ORAC method for the azoles studied present reproducibility in the experimental execution, and have proven to be a viable alternative for studies of synthetic molecules with antioxidant potential.

<p>Ostvarene su vi&scaron;efazne stereospecifične sinteze tiazolnih C-nukleozida, novih analoga, odnosno mimetika tiazofurina polazeći iz D-glukoze i D-ksiloze. Ispitana je <em>in vitro </em>citotoksična aktivnost sintetizovanih C-nukleozida prema odabranim humanim tumorskim ćelijskim linijama (K562, HL 60, Jurkat, Raji, PC 3, HT-29, MCF-7, MDA-MB-231, HeLa i Hs 294T) kao i prema ćelijama normalnih fetalnih fibroblasta pluća (MRC-5).</p> / <p>Multiphase stereospecific synthesis of thiazole C-nucleosides, new analogues and mimics of tiazofurin,&nbsp;has been achives starting from D-glucose and D-xylose.&nbsp;<br />We examined the in vitrocytotoxic activity of&nbsp;synthesized C-nucleosides by selected human tumor cell&nbsp;lines (K562, HL 60, Jurkat, Raji, PC 3, HT-29, MCF-7,&nbsp;<br />MDA-MB-231, HeLa and Hs 294T) and the cells of&nbsp;normal fetal lung fibroblasts (MRC-5).</p>

<p>U ovom radu efikasnost odabranih derivata tiazola u inhibiciji korozije bakra u kiseloj<br />sulfatnoj sredini određena je u funkciji koncentracije inhibitora metodom merenja<br />gubitka mase, elektrohemijskom impedansnom spektroskopijom i potenciostatskom<br />polarizacijom. Polarizacionim merenjima takođe je određena zavisnost inhibitorske<br />efikasnosti od&nbsp; temperature i kinetički parametri procesa korozije bakra&nbsp; kao i&nbsp; model<br />adsorpcione izoterme prema kojem se odigrava proces adsorpcije&nbsp; inhibitora i&nbsp;odgovarajući termodinamički parametri. Merenjima kvarc kristalnom mikrovagom&nbsp;<em>in&nbsp;</em><br /><em>situ&nbsp; </em>je praćen proces elektrohemijskog rastvaranja bakra i adsorpcije ispitivanih<br />inhibitora. SEM/EDX analizom&nbsp; proučavana&nbsp; je promena morfologije bakarne povr&scaron;ine<br />usled dejstva korozione sredine i rastvora inhibitora.&nbsp; Rezultati eksperimentalnih<br />ispitivanja korelirani su&nbsp; sa teorijskim proračunima na nivou teorije funkcionala<br />gustine.</p> / <p>In this work, the efficiency of selected thiazole derivatives in&nbsp; the inhibition of corrosion of copper in the acidic sulfate solution is determined in&nbsp; the function ofthe inhibitors&nbsp; concentration by weight loss method,&nbsp; electrochemical impedance spectroscopy and potentiostatic polarization. The dependence of the inhibition efficiency of temperature and kinetic parameters of the process of corrosion ofcopper&nbsp; as well as&nbsp; adsorption isotherm model&nbsp; according to which takes place the process of adsorption of inhibitors and the corresponding thermodynamic parameters were also&nbsp; determined by polarization measurements.&nbsp; A process of electrochemical copper&nbsp; dissolution and&nbsp; adsorption of tested inhibitors is followedin situ&nbsp; by&nbsp; quartz crystal microbalance&nbsp; measurements Changes in the morphology of the copper surface due to the effects of corrosive environment and the solutions of the&nbsp; inhibitors were studied by SEM/EDX analysis.The experimental results were correlated with theoretical calculations at the density functional theory level.</p>