Codakia orbicularis est un mollusque bivalve appartenant à la famille des Lucinidae et établissant des symbioses avec des bactéries sulfo-oxydantes (symbiotes) au sein de ses branchies. Dans l’hypothèse où toute symbiose nécessite une régulation par des molécules de dialogue, une étude chimique exhaustive pourrait aboutir à la mise en évidence des métabolites impliqués. Le travail de ce manuscrit porte donc sur l'isolement de métabolites secondaires à partir des branchies de ce bivalve et sur l'évaluation de l'activité antibactérienne des molécules isolées. Douze composés ont été isolés des branchies de Codakia orbicularis et leurs structures ont été déterminées par les méthodes spectroscopiques usuelles. Parmi ces molécules, une seule est nouvelle et a été nommée orbicularisine. Elle présente un squelette indolone spirotetracyclique inédit. Parmi les molécules isolées, seules quatre d’entre elles présentent une activité antibactérienne à savoir le soufre S8, la 4-hydroxybenzaldéhyde et deux monoglycérolipides. L'orbicularisine s'est révélée inactive contre un panel de lignées cellulaires cancéreuses et de kinases. Le nouveau squelette de l’orbicularisine pourrait permettre d'aboutir à une nouvelle famille de molécules par synthèse organique et ainsi accroître la diversité moléculaire autour de ce motif inédit. Il sera également intéressant de déterminer l'origine des molécules isolées et de connaître leur(s) implication(s) dans la régulation des symbiotes du bivalve. Les résultats chimiques obtenus sur C. orbicularis et sur les Lucinidae en général sont intéressants puisque les espèces côtières appartenant aux bivalves ont été peu exploitées en chimie jusqu’à ce jour. / Codakia orbicularis is a bivalve mollusc belonging to the family Lucinidae and establishing symbiosis with sulfooxidizing bacteria (symbionts) within its gills. In the hypothesis that any symbiosis requires a regulation by molecules of dialogue, an exhaustive chemical study could lead to the demonstration of the metabolites involved. The work of this manuscript focuses on the isolation of secondary metabolites from the gills of this bivalve and on the evaluation of the antibacterial activity of the isolated molecules. Twelve compounds were isolated from the gills of Codakia orbicularis and their structures were determined by the usual spectroscopic methods. Of these molecules, only one is new and has been named orbicularisin. It presents an indolone spirotetracyclic skeleton unpublished. Among the isolated molecules, only four of them have antibacterial activity, namely sulfur S8, 4-hydroxybenzaldehyde and two monoglycerolipids. Orbicularisin has been shown to be inactive against a panel of cancer cell lines and kinases. The new skeleton of orbicularisin could lead to a new family of molecules by organic synthesis and thus increase the molecular diversity around this original motif. It will also be interesting to determine the origin of the isolated molecules and know their involvement (s) in the regulation of the bivalve symbionts. The chemical results obtained on C. orbicularis and on Lucinidae in general are interesting because the coastal species belonging to bivalves have been little exploited in chemistry to date.

Cette thèse développe de nouvelles séquences réactionnelles divergentes vers les lactones sesquiterpéniques, ainsi que leurs analogues. La réactivité multiple d’un substrat linéaire face à divers catalyseurs a tout d’abord permis d’obtenir différentes structures polycyliques dont la fonctionnalisation a permis d’isoler plusieurs produits naturels et des analogues. De nouvelles méthodologies ont été étudiées pour accéder aux gamma-butyrolactones, une fonctionnalité prépondérante dans les lactones sesquiterpéniques, ainsi qu’au noyau hydroazulène contenu dans les guaianes. Enfin, une synthèse divergente courte et performante a été mise au point pour accéder à divers analogues de la déoxyéléphantopine, un sesquiterpène aux propriétés anti-cancéreuses, afin de moduler et étudier son activité biologique. En parallèle de ces travaux sur les sesquiterpènes, une autre chimie a été explorée visant à réaliser la glycosylation de cystéines avec des carbohydrates non protégés. / The main thread throughout this thesis is to develop reaction sequences that could provide facile access to the sesquiterpene lactones, or analogs thereof, using strategies that would be compatible with divergent reaction pathways. A first project harnessed the multiple reactivity mode of a linea rsubstrate to obtain different polycyclic frameworks found in sesquiterpenes whose functionalisation led to several natural products and their analogs. New methodologies were studied to access gamma-butyrolactones, a preponderant functionality in sesquiterpene lactones, and hydroazulene core, the bicyclic framework of guaianes. Finally, a short divergent pathway was designed to access diverse analogs of deoxyelephantopin, a sesquiterpene showing anti-cancer effects, so as to modulate and study its biological activity. In parallel to this work on sesquiterpenes, a different chemistry was explored aiming at performing glycosylation of cysteines with unprotected carbohydrates.

The recently isolated bacterial metabolites, belactosins A-C from a fermentation broth of Streptomyces sp. UCK14, uniquely contain a β-lactone dipeptide motif and exhibit anticancer activities. The enantioselective synthesis of (-)-belactosin C and derivatives was accomplished in a concise manner employing the tandem, Mukaiyama aldol-lactonizaton (TMAL) process and test their bioactivities. . One approach involved a distal double diastereoselective TMAL reaction with a dipeptide glyoxamide, whereas a second approach involved amide coupling of a dipeptide with a β-lactone carboxylic acid, obtained via the TMAL process employing a chiral silyl ketene acetal. Enzymatic assays showed that the belactosins act as the dual inhibitors of the proteasome and the thioesterase domain of fatty acid synthase. Spongiolactone which uniquely contains a cyclopentyl-fused β-lactone was isolated in 1986 from Spongi-onellagracilis No biological activity have been reported for this compound; however, the acylating potential of the resident β-lactone warrants screening for potential activity. After many setbacks in the synthesis of spongiolactone, significant progress has been made. Importantly, NCAL process also enabled a concise construction of [3.2.0]-bicyclo β-lactone, which is the key structure in the spongiolactone synthesis and only a few steps remained to complete the synthesis.

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Gram-negative bacteria use N-acyl homoserine lactones (AHLs) to sense population density and regulate gene expression, including virulent phenotypes. The quorum-quenching AHL lactonase from Bacillus thuringiensis cleaves the lactone ring of AHLs, disabling this mode of gene regulation. Despite the potential applications of this enzyme as an antibacterial weapon, little was known about it's lactone ring-opening mechanism. As a member of the metallo-beta-lactamase superfamily, AHL lactonase requires two divalent metal ions for catalysis. NMR experiments confirm that these metal ions are also involved in proper enzyme folding. The chemical mechanism of ring opening was explored using isotope incorporation studies, and hydrolysis was determined to proceed via a nucleophilic attack by a solvent-derived hydroxide at the carbonyl of the lactone ring. A transient, kinetically significant metal-leaving group interaction was detected in steady-state kinetic assays with AHL lactonase containing alternative divalent metal ions hydrolyzing a sulfur-containing substrate. High-resolution crystal structures implicated two residues in substrate binding and hydrolysis, Tyr194 and Asp108. Site-directed mutagenesis of these residues followed by steady-state kinetic studies with wild-type and mutant enzymes hydrolyzing a spectrum of AHL substrates revealed that mutations Y194F and D108N significantly affect catalysis. Combining these results allows the proposal of a detailed hydrolytic mechanism. The binding site for the N-acyl hydrophobic moiety was probed using steady-state kinetics with a variety of naturally occurring and non-natural AHL substrates, and these studies indicate that AHL lactonase will accept a broad range of homoserine lactone containing substrates. Crystal structures with AHL substrates and non-hydrolyzable analogs reveal two distinct binding sites for this N-acyl group. Based on the ability of this enzyme to accommodate a variety of substrates, AHL lactonase was shown to have the ability to quench quorum sensing regulated by a newly discovered class of homoserine lactone signal molecules possessing an N-aryl group using a bioassay. Steady-state kinetic studies confirm that this class of signal molecules are indeed substrates for AHL lactonase. / text

Les composés hydrophobes sont connus comme des sources de carbone qui peuvent être utilisées par les levures comme Yarrowia lipolytica pour de multiples applications. Ces composés causent parfois des perturbations aux levures mais sont aussi rapportés comme conférant aux cellules une certaine résistance contre les stress environnementaux. Dans le cadre de cette thèse, nous avons étudié le rôle de l'oléate de méthyle comme source de carbone sur la résistance de la levure Y. lipolytica en réponse au choc d'un composé amphiphile, la -dodécalactone, et au stress thermique. Les résultats obtenus montrent que les cellules ayant poussé sur oléate sont beaucoup plus résistantes au choc lactone ainsi qu'au stress thermique que les cellules ayant poussé sur glucose. L'action de la lactone se trouve au niveau de la membrane où elle cause une fluidification membranaire et une déplétion de stérols qui sont considérés comme la cause de la mort cellulaire. Ce travail met en évidence le rôle des corps lipidiques dans la réponse cellulaire qui se manifeste de différentes manières en réponse à ces stress. Une accumulation des corps lipidiques est importante pour la résistance de la cellule aux stress. Les cellules ayant poussé sur glucose transforment leur stérol libre en esters de stéryle pour former les corps lipidiques en réponse au choc lactone, ce qui augmente leur sensibilité. Tandis que les cellules ayant poussé sur oléate qui ont accumulé des corps lipidiques pendant leur croissance ont tendance à convertir leurs esters de stéryle en stérol libre pour compenser la déplétion de stérol membranaire causée par la lactone ce qui diminue leur sensibilité. L'homéostasie de l'ergostérol, liée à la présence de corps lipidiques, semble donc jouer un rôle clé dans la résistance cellulaire à ces stress. Ce travail relève aussi que la présence de lipides modifie le processus de mort cellulaire programmée de Y. lipolytica en réponse à un stress thermique.

Zugl.: Dortmund, Techn. Univ., Diss., 2008

Orientador: Rosângela da Silva de Laurentiz / Resumo: Reações multicomponentes são processos sintéticos em que se aplicam três ou mais reagentes em um sistema one-pot com formação de apenas um produto final, o qual possui em sua estrutura todos ou a maioria dos átomos de carbono pertencentes aos reagentes. Esse tipo de reação vem sendo muito explorada em síntese orgânica devido às facilidades do processo, como menor número de etapas, economia de reagentes, maiores rendimentos, menor tempo reacional (em comparação às sínteses tradicionais) e economia de energia. A utilização das reações multicomponentes tem facilitado a obtenção de compostos heterocíclicos de grande complexidade cuja estruturas seriam muito difíceis de serem obtidas por procedimentos multietapas. Desta forma, uma adaptação da reação de Hantzsch foi realizada a partir da reação entre ácido tetrônico (1), aldeído aromático (2) e aminoantraceno (3), sob aquecimento por micro-ondas, para a obtenção de lactonas dihidronaftoquinolínicas 4. Foram utilizados aldeídos aromáticos contendo grupos sacadores e doadores de elétrons que forneceram os compostos 4a-l em rendimentos variando de 67 a 96%. Lactonas naftoquinolínicas 5 foram obtidas por duas diferentes rotas sintéticas: 1) a partir da oxidação de 4 com DDQ/etanol em micro-ondas e 2) a partir do intermediário antracelidenoamino lactona 6 e aldeído aromático em TFA. Ambas as rotas forneceram os compostos 5 em excelentes rendimentos, porém a rota 1 fornece 5 como único produto, enquanto a rota 2 fornece 5 como produto m... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre

Orientador: Ronaldo Aloise Pilli / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-10T13:11:39Z (GMT). No. of bitstreams: 1 Salvador_MayraBeloti_M.pdf: 2010457 bytes, checksum: 350e267c8a65621fe41d0da941852b62 (MD5) Previous issue date: 2007 / Resumo: Esta dissertação de mestrado trata da síntese da Criptomoscatona D2, uma lactona isolada pelo grupo de pesquisa dos Profs. Cavalheiro e Yoshida a partir da Cryptocarya moschata, planta encontrada em território brasileiro, cujas configurações relativa e absoluta ainda não foram determinadas. Além de auxiliar em sua elucidação estrutural a síntese desta molécula nos permitiria realizar estudos sobre sua atividade citotóxica, dando prosseguimento a estudos anteriores desenvolvidos em nosso laboratório com essa classe de compostos. Partindo-se do benziloxiacetaldeído obteve-se o álcool homoalílico quiral correspondente através de uma reação de alilação assimétrica com alilestanana e (S)-binaftol. Clivagem oxidativa da dupla ligação e reação de alilação mediada por InCl3 e estanho metálico na presença de brometo de alila forneceu uma mistura de álcoois homoalílicos sin/anti 1:1 cuja separação cromatográfica permitiu o prosseguimento da síntese racêmica com cada um dos diasteroisômeros. A reação de proteção das hidroxilas com o grupo TBS, seguida de clivagem oxidativa da dupla ligação e reação de alilação com BF3.Et2O e alilestanana forneceu o terceiro álcool homoalílico com mistura diastereoisomérica de cerca de 2:1 em ambas as rotas. Por fim, uma reação de esterificação do álcool remanescente na forma de acrilato seguida de reação de metátese de olefinas para formação do anel lactônico nos possibilitou o mapeamento de grande parte da rota sintética da Criptomoscatona D2 em sua forma racêmica / Abstract: This work describes the preliminary studies on the racemic and the asymmetric synthesis of Cryptomoscatone D2 based on sequential allylation reactions for the construction of its three stereogenic centers and ring-closing methatesis reaction to construct the lactone scaffold. Besides allowing the structure elucidation of the molecule isolated from a typical brazilian plant by the research groups of Profs. Cavalheiro and Yoshida, the synthesis of such a lactone would allow us to carry new cytotoxic studies which are being lately developed with this class of compound. The synthesis started with the allylation reaction of benzyloxyacetaldehyde under the conditions described by Keck and coworkers to furnish corresponding homoallylic alcohol. After an oxidative cleavage of the double bond, an InCl3 promoted allylation reaction allowed the preparation a 1:1 mixture of syn/anti homoallylic alcohols which were as the TBS ethers and submitted separately to double bond oxidative cleavages. These aldehydes were used as substrates for another allylation reaction with BF3.Et2O and allyltri-n-butyltin and the homolallylic alcohols (2:1 diatereoisomeric mixtures) were converted to the corresponding acrylates in order to carry out the planned RCM reaction. Several allylation reactions were tested and the homoallylic alcohols were prepared in 1:1 diasteroisomeric excesses. Efforts will be carried out in order to enhance the distereoselectivity of the allylation reactions for an efficient approach to Cryptomoscatone D2 (12) backbone / Mestrado / Quimica Organica / Mestre em Química

Orientador: Gabriela Alves Macedo / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-23T15:45:42Z (GMT). No. of bitstreams: 1 Lopes_DanielleBranta_D.pdf: 3780152 bytes, checksum: ba7b4a54629ff27a24abae14e788d60c (MD5) Previous issue date: 2013 / Resumo: Os aromas despertam grande interesse entre consumidores e indústrias de alimentos, especialmente por estarem diretamente relacionados ao sabor dos alimentos. Dentre os aromas de maior importância industrial destaca-se o grupo das lactonas, presentes em uma grande variedade de produtos naturais e compostos biologicamente ativos. Em virtude do destaque apresentado por essa classe de substâncias, diversos métodos para sua produção têm sido relatados. Como alternativa aos processos químicos tradicionais, propõe-se nesta pesquisa a utilização da biotecnologia de micro-organismos e enzimas para a produção de compostos aromáticos a partir de substratos naturais, como óleos vegetais hidrolisados.A fermentação microbiana é considerada um caminho potencial para a produção de aromas naturais, sendo o grupo formado pelos fungos um dos mais utilizados para esse fim. A biocatálise também é uma alternativa muito vantajosa e capaz de catalisar um grande número de reações estéreo- e regiosseletivas, o que não é alcançado por meio de síntese química clássica. O uso de enzimas isoladas torna-se preferível em relação ao uso de micro-organismos quando existem limitações relacionadas à permeabilidade do substrato na membrana da célula ou quando ocorrem reações secundárias indesejáveis.Considerando-se os argumentos citados, neste trabalho foram estudados dois métodos para a produção de lactonas. O primeiro deles, a biotransformação, foi feita a partir do uso de micro-organismos para a produção dos compostos em questão. O segundo método, a biocatálise, foi realizado através da reação de lactonização com o uso de lipases microbianas brutas isoladas e liofilizadas. Os substratos utilizados no estudo foram os óleos vegetais de mamona e linhaça previamente hidrolisados por lipases fúngicas produzidas por Rhizopus sp. e Geotrichum sp. A produção de lactonas foi alcançada em ambos os métodos. Com o uso da biotransformação, todos os micro-organismos testados (Geotrichum sp., Rhizopus sp., Aspergillus sp. (Linhagens 1068 e 1099) e Fusarium oxysporum) foram capazes de produzir diferentes tipos de lactonas, com destaque para o fungo Fusarium oxysporum, que produziu maior variedade delas (&61543;-decalactona, 2-cumaranona, mevalonolactona e pantolactona), além de alcançar o maior rendimento na produção de &61543;-decalactona (18,93 &956;L L-1), após 48 horas de reação e empregando-se os óleos de mamona e linhaça previamente hidrolisados pela lipase produzida pelo fungo Rhizopus sp.. Através do uso da biocatálise, ótimos resultados também foram alcançados, e a produção de lactonas foi possível ao se utilizar as lipases produzidas pelos fungos Rhizopus sp., Aspergillus sp. (Linhagem 1068) e Fusarium oxysporum, sendo possível a produção de &61543;-undecalactona, &61543;-decalactona e &61543;-dodecalactona, dependendo da lipase empregada e do tempo de reação. A maior produtividade foi obtida na produção de &61543;-undecalactona ao se utilizar a lipase produzida pelo fungo Rhizopus sp. após 24 horas de reação, obtendo-se um rendimento de 21,78 &956;L L-1, também a partir do uso dos óleos de mamona e linhaça hidrolisados previamente pela lipase produzida por Rhizopus sp. As lipases produzidas pelos fungos Geotrichum sp. e Aspergillus sp. (Linhagem 1099), também estudadas neste trabalho, não foram capazes de produzir lactonas / Abstract: Aromas arouse great interest among consumers and food industry, especially because heir direct relationship with food taste. In the midst of the most important industrial flavorings stands lactones group, which are present in a wide variety of natural products and biologically active compounds. Due to the prominence of this class of substances, several methods for the production of lactones have been reported. As an alternative to traditional chemical processes, it is proposed in this research the use of microbial and enzyme biotechnology for the production of aromatic compounds natural substrates, such as hydrolyzed vegetable oils. The microbial fermentation is considered a potential pathway for the production of natural flavor, and fungi group is the most widely used for this purpose. Biocatalysis is also a very useful alternative and is able to catalyze a large number of stereo- and regioive reactions, which is not achieved by classical chemical synthesis. The use of isolated enzymes is preferable over the use of microorganisms when there are limitations concerning the permeability of the substrate in the cell membrane or when undesired side reactions occur. Considering these arguments, two methods were investigated in this work for the production of lactones. The first one, biotransformation, was made the use of microorganisms for the production of these compounds. The second method, biocatalysis, was performed by lactonization reaction using crude microbial lipases that was isolated and lyophilized. Substrates used were the vegetable castor and linseed oils previously hydrolyzed by fungal lipases produced by Rhizopus sp. and Geotrichum sp. Lactones production was achieved in both methods. Using biotransformation, all microorganisms tested (Geotrichum sp., Rhizopus sp., Aspergillus sp. (Strains 1068 and 1099) and Fusarium oxysporum) were able to produce different lactone types, especially using the fungus Fusarium oxysporum, which produced a greater variety (&61543;-decalactone, 2-cumaranone, mevalonolactone and pantolactone), achieving the best performance in y-x decalactone production (18.93 &956;L L-1), after 48 h employing castor and linseed oils hydrolyzed by lipase Rhizopus sp. Through the biocatalysis use, excellent results were also obtained, and the lactones production was possible using lipases produced by fungi Rhizopus sp., Aspergillus sp. (Strain 1068) and Fusarium oxysporum. The production of y-undecalactone, y-decalactone and y-dodecalactone was achieved depending on the lipase employed and the reaction time used. Highest yield was obtained in the &61543;-undecalactone production (21.78 &956;L L-1), using castor and linseed oils hydrolyzed by Rhizopus sp. lipase. Lipases produced by Geotrichum sp. and Aspergillus sp. (Strain 1099) was also studied in this work, but were unable to produce lactones / Doutorado / Ciência de Alimentos / Doutora em Ciência de Alimentos