3-Hydroxypropionic Acid as an Antibacterial Agent from Endophytic Fungi Diaporthe phaseolorum

Endophytic fungi are considered a rich source of active compounds resulting from their secondary metabolism. Fungi from marine environment grow in a habitat with unique conditions that can contribute to the activation of metabolic pathways of synthesis of different unknown molecules. The production of these compounds may support the adaptation and survival of the fungi in the marine ecosystem. Mangroves are ecosystems situated between land and sea. They are frequently found in tropical and subtropical areas and enclose approximately 18.1 million hectares of the planet. The great biodiversity found in these ecosystems shows the importance of researching them, including studies regarding new compounds derived from the endophytic fungi that inhabit these ecosystems. 3-hydroxypropionic acid (3-HPA) has been isolated from the mangrove endophytic fungus Diaporthe phaseolorum, which was obtained from branches of Laguncularia racemosa. The structure of this compound was elucidated by spectroscopic methods, mainly 1D and 2D NMR. In bioassays, 3-HPA showed antimicrobial activities against both Staphylococcus aureus and Salmonella typhi. The structure of this antibiotic was modified by the chemical reaction of Fischer-Speier esterification to evaluate the biologic activity of its chemical analog. The esterified product, 3-hydroxypropanoic ethyl ester, did not exhibit antibiotic activity, suggesting that the free carboxylic acid group is important to the pharmacological activity. The antibiotic-producing strain was identified with internal transcribed spacer sequence data. To the best of our knowledge, this is the first report of antibacterial activity by 3-HPA against the growth of medically important pathogens.

Synthesis and antibacterial study of some s-substituted aliphatic analogues of 2-mercapto-5-(1-(4-toluenesulfonyl) piperidin-4-yl)-1,3,4-oxadiazole

Purpose: To synthesize a series of analogues of 1,3,4-oxadiazole and to evaluate their antibacterial activity. Methods: Ethyl piperidin-4-carboxylate (1) was mixed with 4-toluenesulfonyl chloride (2) in benignant conditions to yield ethyl 1-(4-toluenesulfonyl)piperidin-4-carboxylate (3) and then 1-(4- toluenesulfonyl)piperidin-4-carbohydrazide (4). Intermolecular cyclization of 4 into 2-mercapto-5-(1-(4- toluenesulfonyl) piperidin-4-yl)-1,3,4-oxadiazole (5) was obtained on reflux with CS2 in the presence of KOH. Molecule 5 was stirred with alkyl halides, 6a-i, in DMF in the presence of LiH to synthesize the final compounds, 7a-i. The structures of these molecules were elucidated by Fourier transform infra-red (FTIR) spectroscopy, proton nuclear magnetic resonance (1H-NMR) and electron impact mass spectrometry (EI-MS). Antibacterial activity was evaluated against five bacterial strains, namely, Salmonella typhi, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis, with ciprofloxacin used as standard antibacterial agent. Results: Out of nine synthesized derivatives, compound 7a was the most active against three bacterial strains, S. typhi, E. coli and P. aeruginosa, with minimum inhibitory concentration (MIC) of 9.11 ± 0.40, 9.89 ± 0.45 and 9.14 ± 0.72 μM, respectively, compared with 7.45 ± 0.58, 7.16 ± 0.58 and 7.14 ± 0.18 μM, respectively, for the reference standard (ciprofloxacin). Similarly, compounds 7a - 7c showed relatively good antibacterial activity against B. subtilis strain while compound 7e - 7g revealed good results against S. typhi bacterial strain. Conclusion: The results indicate that S-substituted derivatives of the parent compound are more effective antibacterial agents than the parent compound, even with minor differences in substituents

Quantitative Determination of Gemifloxacin Mesylate in Tablets by Capillary Zone Electrophoresis and High Performance Liquid Chromatography

The aim of this study was to develop and validate selective and sensitive methods for quantitative determination of an antibacterial agent, gemifloxacin, in tablets by high performance liquid chromatography (HPLC) and capillary zone electrophoresis (CZE). The HPLC method was carried out on a LiChrospher (R) 100 RP-8e, 5 mu m (125 x 4 mm) column with a mobile phase composed of tetrahydrofuran-water (25:75, v/v) with 0.5 % of triethylamine and pH adjusted to 3.0 with orthophosphoric acid. The CZE method was performed using 50 mM sodium tetraborate buffer (pH 8.6). Samples were injected hydrodynamicaly (0.5 psi, 5 s) and the electrophoretic system was operated under normal polarity, at +20 kV and capillary temperature of 18 degrees C. A fused-silica capillary 40.2 cm (30 cm effective length) x 75 mu m i.d. was used. Both, HPLC and CZE could be interesting and efficient techniques to be applied for quality control in pharmaceutical industries.

Production and characterization of ZrCN-Ag coatings deposited by mganetron sputtering

Tese de Doutoramento (Programa doutoral em Engenharia de Materiais)

Characterization of a plant-derived peptide displaying water clarifying and antimicrobial activities

SUMMARY Drinking water is currently a scarce world resource, the preparation of which requires complex treatments that include clarification of suspended particles and disinfection. Seed extracts of Moringa oleifera Lam., a tropical tree, have been proposed as an environment- friendly alternative, due to their traditional use for the clarification of drinking water. However, the precise nature of the active components was unknown. Here, we show that recombinant or synthetic forms of a cationic seed polypeptide mediate efficient sedimentation of suspended mineral particles and bacteria. Unexpectedly, the polypeptide was also found to possesses a bactericidal activity capable of disinfecting heavily contaminated water. Furthermore, the polypeptide has been shown to efficiently kill several pathogenic bacteria, including antibiotic-resistant isolates of Pseudomona, Streptococcus and Legionella species. Structural modeling of the peptide coupled to the functional analysis of synthetic peptide derivatives delineated distinct structural determinants for the flocculation and antibacterial activities. Our results suggest that a glutamine-rich portion of the polypeptide is involved in the sedimentation process; alternatively, the antibacterial activity depends on a amphiphilic loop. Assembly of multiple copies of this loop into a branched peptide derivative strongly enhances antibacterial activity without displaying hemolytic effect. In conclusion, this polypeptide displays the unprecedented feature of combining efficient water purification and disinfectant properties indicating different molecular mechanisms involved in each case. This work not only identified the features responsible for these activities but also provides useful information that has implications for the further development of this cationic polypeptide as a potent antibacterial agent. RESUME L'eau potable est actuellement une ressource limitée dans le monde. La production d'eau propre à la consommation exige des traitements complexes, incluant la clarification des particules en suspension ainsi que sa désinfection par des additifs chimiques. Les extraits de la graine d'un arbre tropical, Moringa oleifera, sont utilisés traditionnellement en Afrique afin de clarifier l'eau. Quoique la nature exacte des composants actifs était inconnue, on a pu mettre en évidence un polypeptide cationique contenu dans ces graines, capable de sédimenter de manière efficace des particules minérales en suspension ainsi que des bactéries. Ce travail a aussi mis en évidence que ce polypeptide a une activité bactéricide, permettant une désinfection d'eau fortement contaminée. De plus, nous avons démontré que ce polypeptide est efficace contre de nombreuses souches bactériennes pathogènes, également celles résistantes aux antibiotiques comme Pseudomonas, Streptococcus et Legionella. L'analyse de la structure moléculaire de ce polypeptide, couplée à son analyse fonctionnelle a mis en évidence deux domaines structuraux distinct, un pour l'activité de floculation et l'autre pour l'activité antibactérienne. Nos résultats suggèrent que le domaine riche en glutamine est impliqué dans le processus de sédimentation et que l'activité antimicrobienne dépend d'un domaine formant une boucle amphiphilique. En ramifiant plusieurs copies de cette boucle on a pu augmenter de manière significative l'activité antibactérienne. En conclusion, nous avons pu démontrer que ce polypeptide à la capacité unique de combiner des propriétés de purification et de désinfection de l'eau, ce qui implique des mécanismes moléculaires distincts pour ces deux activités. Ce travail a permis d'identifier les domaines du polypeptide qui sont responsables de ses activités et offre une perspective pour le développement d'un nouvel agent antimicrobien.

In vitro effect of malachite green on Candida albicans involves multiple pathways and transcriptional regulators UPC2 and STP2.

In this study, we show that a chemical dye, malachite green (MG), which is commonly used in the fish industry as an antifungal, antiparasitic, and antibacterial agent, could effectively kill Candida albicans and non-C. albicans species. We have demonstrated that Candida cells are susceptible to MG at a very low concentration (MIC that reduces growth by 50% [MIC(50)], 100 ng ml(-1)) and that the effect of MG is independent of known antifungal targets, such as ergosterol metabolism and major drug efflux pump proteins. Transcriptional profiling in response to MG treatment of C. albicans cells revealed that of a total of 207 responsive genes, 167 genes involved in oxidative stress, virulence, carbohydrate metabolism, heat shock, amino acid metabolism, etc., were upregulated, while 37 genes involved in iron acquisition, filamentous growth, mitochondrial respiration, etc., were downregulated. We confirmed experimentally that Candida cells exposed to MG resort to a fermentative mode of metabolism, perhaps due to defective respiration. In addition, we showed that MG triggers depletion of intracellular iron pools and enhances reactive oxygen species (ROS) levels. These effects could be reversed by the addition of iron or antioxidants, respectively. We provided evidence that the antifungal effect of MG is exerted through the transcription regulators UPC2 (regulating ergosterol biosynthesis and azole resistance) and STP2 (regulating amino acid permease genes). Taken together, our transcriptome, genetic, and biochemical results allowed us to decipher the multiple mechanisms by which MG exerts its anti-Candida effects, leading to a metabolic shift toward fermentation, increased generation of ROS, labile iron deprivation, and cell necrosis.

Physiopathologie et prévention des infections liées aux accès vasculaires [Pathophysiology and prevention of intravascular catheter-related infection]

Les infections liées aux accès vasculaires sont à l'origine d'une proportion importante des infections nosocomiales. Elles comprennent leur colonisation par des micro-organismes, les infections du site d'insertion et les bactériémies et fongémies qui leur sont associées ou attribuées. Une bactériémie complique l'insertion de 3 à 5 % des voies veineuses, correspondant à une incidence de 2 à 14 épisodes pour 1000 jourcathéters. Cette proportion ne représente toutefois que la partie visible de l'iceberg puisque la plupart des épisodes de sepsis clinique sans foyer infectieux associé sont également considérés comme liés aux accès vasculaires. Après un rappel de leur physiopathologie, cet article passe en revue les éléments importants pour leur prévention, y compris ceux concernant l'utilisation de cathéters imprégnés de désinfectants ou d'antibiotiques. Pour terminer, nous discutons en détail les stratégies préventives globales. Fondées sur la prise en compte d'un ensemble d'éléments spécifiques, ces approches sont centrées sur l'éducation du personnel au respect des règles d'hygiène de base et sur l'introduction de recommandations précises pour l'insertion et l'utilisation des accès vasculaires.

Synthèse totale de la pactamycine et d’une sélection d’analogues, progrès vers la synthèse totale de la daphniglaucine C et brève étude d’une transposition allylique réductrice

Il y a plus de cinquante ans, la pactamycine a été isolée en tant qu’agent antitumoral potentiel. Il a été réalisé plus tard qu’il s’agissait en fait d’un agent antibactérien capable d’inhiber la synthèse de protéines lors du procédé de traduction. Récemment, il a même été démontré que certains de ses analogues possèdent des propriétés antiprotozoaires prometteuses. La présente thèse détaille la première synthèse totale de la pactamycine, entreprise au sein du groupe Hanessian, ainsi que la préparation d’une sélection d’analogues testés pour leurs propriétés biologiques. En outre, la daphniglaucine C appartient à une vaste famille de composés naturels isolés des feuilles du daphniphyllum au cours des dix dernières années. Bien que relativement peu d’information soit connue par rapport à l’activité biologique de la daphniglaucine C, la synthèse de celle-ci représente certainement un défi intéressant pour un chimiste organicien. Au passage, nos efforts vers la synthèse totale du composé cible auront permis d’explorer l’emploi de plusieurs méthodes en vue de la formation de centres quaternaires. De plus, un réarrangement réductif atypique, catalysé au palladium à partir d’alcools allyliques non-activés, a été étudié et employé afin de générer une sélection de pyrrolidines polysubstituées.

Experimental paracoccidioidomycosis: alternative therapy with ajoene, compound from Allium sativum, associated with sulfamethoxazole/trimethoprim

Ajoene has been described as an antithrombotic, anti-tumour, antifungal, antiparasitic and antibacterial agent. This study deals with the efficacy of ajoene to treat mice intratracheally infected with Paracoccidioides brasiliensis. The results indicate that ajoene therapy is effective in association with antifungal drugs (sulfametoxazol/trimethoprim), showing a positive additive effect. Ajoene-treated mice developed Th1-type cytokine responses producing higher levels of IFN-gamma and IL-12 when compared to the infected but untreated members of the control group. Antifungal activity of ajoene involves a direct effect on fungi and a protective pro-inflammatory immune response. Reduction of fungal load is additive to chemotherapy and therefore the combined treatment is mostly effective against experimental paracoccidioidomycosis.

UTILIZAÇÃO da PRÓPOLIS E ÁLCOOL ETÍLICO NO CONTROLE DE Salmonella em RAÇÕES AVÍCOLAS

Em quatro experimentos foram avaliados como agentes antibacterianos os produtos própolis em solução alcoólica e álcool etílico, adicionados às rações artificialmente contaminadas com os respectivos sorotipos: Salmonella typhimurium Nalr - Specr, (resistentes ao ácido Nalidíxico e a Spectinomicina) nos três primeiros experimentos e Salmonella agona Nalr - Specr, Salmonella infantis Nalr - Specr e Salmonella enteritidis Nalr - Specr no quarto experimento. As rações foram fornecidas a grupos de 10-16 pintos de corte de um dia. em todos os experimentos os produtos testados foram adicionados na base de 2% da ração. Quando se utilizou solução hidroalcóolica de própolis (exp. 1), seguidas 120 horas após o desafio, detectou-se a presença da bactéria nos cecos. No segundo experimento, testou-se a solução de própolis e seu diluente, o álcool etílico; seguidas 96 horas após o desafio, não foi observada a presença da bactéria nos cecos (< 2,0 log10). Avaliou-se, no terceiro experimento, a ação da solução de própolis e do álcool etílico no tempo, adicionados na ração 14 dias e 28 dias antes do fornecimento às aves. Após 72 horas do desafio, a leitura nas placas acusou a presença da bactéria nos cecos. Dentro deste último período, também se avaliou a ação da própolis em pó (extrato seco) e esse mesmo extrato em uma solução aquosa, adicionados à ração 48 horas antes do fornecimento às aves sendo que os resultados confirmaram a presença da bactéria nos cecos. No quarto experimento avaliou-se somente o álcool etílico nas rações artificialmente contaminadas com os sorotipos S. agona, S. enteritidis e S. infantis, registrando-se contagem zero (<2,0 log10) apenas com o último sorotipo. Os resultados obtidos permitem concluir que o tratamento com a solução de própolis apresentou ação sobre a S. typhimurium somente quando em solução alcóolica, dentro de um período de 48 horas, indicando que o efeito bactericida se deveu ao álcool etílico presente na solução. A ação do tratamento com o álcool etílico sobre os demais sorotipos demonstrou resultado parcial sendo observado efeito bactericida nos sorotipos S. typhimurium e S. enteritidis artificialmente inoculados na ração.

Chlorine dioxide against bacteria and yeasts from the alcoholic fermentation

The ethanol production in Brazil is carried out by fed-batch or continuous process with cell recycle, in such way that bacterial contaminants are also recycled and may be troublesome due to the substrate competition. Addition of sulphuric acid when inoculum cells are washed can control the bacterial growth or alternatively biocides are used. This work aimed to verify the effect of chlorine dioxide, a well-known biocide for bacterial decontamination of water and equipments, against contaminant bacteria ( Bacillus subtilis, Lactobacillus plantarum, Lactobacillus fermentum and Leuconostoc mesenteroides) from alcoholic fermentation, through the method of minimum inhibitory concentration ( MIC), as well as its effect on the industrial yeast inoculum. Lower MIC was found for B. subtilis ( 10 ppm) and Leuconostoc mesenteroides ( 50 ppm) than for Lactobacillus fermentum ( 75 ppm) and Lactobacillus plantarum ( 125 ppm). Additionally, these concentrations of chlorine dioxide had similar effects on bacteria as 3 ppm of Kamoran (R) ( recommended dosage for fermentation tanks), exception for B. subtilis, which could not be controlled at this Kamoran (R) dosage. The growth of industrial yeasts was affected when the concentration of chlorine dioxide was higher than 50 ppm, but the effect was slightly dependent on the type of yeast strain. Smooth yeast colonies ( dispersed cells) seemed to be more sensitive than wrinkled yeast colonies ( clustered cells/pseudohyphal growth), both isolated from an alcohol-producing unit during the 2006/2007 sugar cane harvest. The main advantage in the usage of chlorine dioxide that it can replace antibiotics, avoiding the selection of resistant populations of microorganisms.

Analise citotoxica de esparfloxacino e seus produtos de degradaçao em células mononucleares humanas

Sparfloxacin, a difluorquinolone derivative, is a potent antibacterial agent active against a wide range of gram-positive and gram-negative organisms including Streptococcus pneumoniae, Staphylococcus aureus, methicillin resistant S. aureus, Legionella spp, Mycoplasma spp; Chlamydia spp. and Mycobacteria. A drawback of fluorquinolones is their photoreactivity. Sparfloxacin has been studied in terms of therapeutic activities. However, few reports about analytical methods of sparfloxacin are available in the literature. The aim of this study was to determine cytotoxic effects, using sparfloxacin reference substance (SPAX-SR), sparfloxacin tablets (SPAX-COMP) and sparfloxacin tablets submitted UV light during 36 hours (SPAX-COMP.36) solution, and two isolated products (7 and 9) of SPAX-SR submitted UV-C light, in concentrations of 31.25, 62.5, 125 and 250 μg/mL by in vitro mononuclear humane culture cells. The results, statistically analyzed by Teste de Tukey, showed SPAX, SPAX-COMP and SPAX-COMP.36 solutions could reduce the cells number in these conditions. These results could not be observed for products 7 or 9. These results can suggest that isolated product can be less cytotoxic than SPAX-SR, is method can also be used to identified products degradation of sparfloxacin in stability study. However, the low activity achieved with sparfloxacin submitted to UV-light is a source of concern and requires further investigation about its photodegradation mechanism.

Photodegradation of sparfloxacin and isolation of its degradation products by preparative HPLC

Sparfloxacin, a third generation fluoroquinolone derivative, is a potent antibacterial agent active against a wide range of Gram-positive and Gram-negative organisms including Streptococcus pneuinoniae, Staphylococcus aureus, methicillin resistant S. aureus, Legionella spp., Mycoplasina spp., Chlamydia spp. and Mycobacterium spp. A drawback of fluoroquinolones is their photoreactivity. Sparfloxacin has been studied in terms of therapeutic activities. However, there are few published of analytical methods being applied to sparfloxacin. The aim in this study was to determine the photodegradation products of sparfloxacin, when submitted to UV light, and to characterize two of these products, designated SPAX-PDP1 and SPAX-PDP2. An accelerated study of stability in methanol solution was carried out by exposing a solution of sparfloxacin to UV light (peak wavelength 290 nm) for 36 hours at room temperature. The products were analyzed by NMR spectrophotometry, IR spectrometry and mass spectrophotometry. The results suggest that the products isolated here could be used to estimate the degradation of sparfloxacin in a stability study. However, the low activity exhibited by UV-irradiated sparfloxacin is a source of concern that demands further investigation of the mechanism of its photodegradation mechanism.

Análise térmica de esparfloxacino

Sparfloxacin, a third-generation fluoroquinolone, is a potent antibacterial agent against a wide range of Gram-positive and Gram-negative organisms, for example Streptococcus pneumonias, Staphylococcus aureus (including methicillin-resistant strains), Legionella spp., Mycoplasma spp., Chlamydia spp. and Mycobacterium spp. This compound has been submitted to thermal analysis and the results are presented here. The DSC curve of sparfloxacin has an endothermic peak that indicates a melting point at 276.5 °C. The DTA curve of the sample in synthetic air shows two exothermic peaks, at 341.6 and 579.2 °C, attributed to compound decomposition. In the TG curve, the loss of mass can be seen to occur in two steps between 285.5 and 645.3 °C. The DTA curve obtained in a nitrogen atmosphere shows an exothermic peak, with decomposition of sparfloxacin at 340.0 °C; from the corresponding TG plot, the loss of mass starts at 254.4 °C.

Silver(I) complexes with symmetrical Schiff bases: Synthesis, structural characterization, DFT studies and antimycobacterial assays

Synthesis, structural and spectroscopic characterizations, molecular modeling and antimycobacterial assays of new silver(I) complexes with two Schiff bases - MBDA and MBDB - are reported. The complexes [Ag(MBDA) 2]NO3, or AgMBDA, and [Ag(MBDB)NO3] or AgMBDB, were obtained by the reaction of the respective ligands with silver(I) nitrate in methanol. The Schiff bases were previously obtained by mixing ethylenediamine or 1,3-diaminopropane with p-anisaldehyde. The characterizations of the complexes were based on elemental (C, H and N) and thermal (TG-DTA) analyses and 13C and 1H NMR and FT-IR spectroscopic measurements, as well as X-ray structure determination for AgMBDA. Spectroscopic data predicted by DFT calculations are in agreement with the experimental data for the AgMBDA complex. The AgMBDA complex has a monomeric structure with a molar proportion 1:2 Ag/ligand, while AgMBDB presents a 1:1 proportion. The complexes AgMBDA and AgMBDB showed to be more effective against Mycobacterium tuberculosis than antibacterial agent silver sulfadiazine - SSD. © 2013 Elsevier Ltd. All rights reserved.