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Antibacterial activity of prenylated benzopyrans from Peperomia obtusifolia (Piperaceae)
No full textPeperomia obtusifolia is a herbaceous perennial plant native to the Americas reported as a traditional medicine to treat snake bites and as a skin cleanser. The bioassay-guided fractionation of crude extracts from aerial parts of P. obtusifolia against a panel of clinically important fungi and bacteria, showed that hexane and dichloromethane extracts demonstrated selective bacterial inhibition, allowing the isolation of the known compounds peperobtusin A (1), and 3,4-dihydro-5-hydroxy-2,7-dimethyl-8-(3”-methyl-2”-butenyl)-2-(4’-methyl-1’,3’-pentadienyl)-2H-1-benzopyran-6-carboxylic acid (2) from dichloromethane extract. Compound 2 was active against Gram-positive bacteria including community acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) isolates and an Enterococcus faecalis vancomycin-resistant strain, with minimal inhibitory concentration (MIC) values of 4 μg/mL (10.8 μM) and 8 μg/mL (21.6 μM) respectively. The interaction of compound 2 with the bacterial membrane was demonstrated by means of Zeta potential experiments on S. aureus, then confirming the membrane damage by fluorescent microscopy experiments.Fil: Ruiz Mostacero, Nathalie. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Química Orgánica. Área Farmacognosia; ArgentinaFil: Castelli, Maria Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Química Orgánica. Área Farmacognosia; ArgentinaFil: Cutró, Andrea Carla. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Centro de Investigación en Biofísica Aplicada y Alimentos. - Universidad Nacional de Santiago del Estero. Centro de Investigación en Biofísica Aplicada y Alimentos; ArgentinaFil: Hollmann, Axel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Centro de Investigación en Biofísica Aplicada y Alimentos. - Universidad Nacional de Santiago del Estero. Centro de Investigación en Biofísica Aplicada y Alimentos; ArgentinaFil: Batista, João Marcos. Universidade Federal de Sao Paulo; BrasilFil: Furlan, Maysa. Universidade Federal de Sao Paulo; BrasilFil: Valles, Julieta. Provincia de Santa Fe. Municipalidad de Rosario. Secretaría de Salud. Centro de Especialidades Médicas Ambulatorias de Rosario; ArgentinaFil: Fulgueira, Cecilia Luisa. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Microbiología; ArgentinaFil: López, Silvia Noelí. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Química Orgánica. Área Farmacognosia; Argentin
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Investigação da origem biossintética de cromenos e cromanos em Piper aduncum e Peperomia obtusifolia (Piperaceae)
No full textChromanes and chromenes are secondary metabolites commonly found in species of the genera Piper and Peperomia, belonging to the Piperaceae family. They are characterized by the presence of a benzopyran core showing a benzene ring fused to a pyran ring. This class of compounds is pharmacologically important, since they from shown a broad range of biological activities including antifungal, trypanocidal, antioxidant and anti-parasitic. The benzopyrans isolated from Piper and Peperomia species showed diversity biosynthetic pathways, mainly related to the aromatic moieties. The biosynthesis of Piper species involve the shikimic pathway showing as the first precursor the p-hydroxybenzoic acid, whereas in Peperomia species would be operating the route of acetate. The present work aimed to study the biosynthetic relationship of benzopyrans present in Piper aduncum and Peperomia obtusifolia as well as to determine the metabolic dynamics involved in their formation related to metabolic and enzymatic levels, since the chromenes isolated from Piper aduncum describe well-defined circadian rhythm. Studies of circadian rhythm performed in Peperomia obtusifolia, aiming to follow the formation of chromane 3,4 -dihydro- 5 -hydroxy -2 ,7- dimethyl-8- (3-methyl -2- butenyl) -2 - (4 -methyl -1 ,3- pentadienyl )-2H -1- benzopyran carboxylic acid (4) from P. obtusifolia showed no uniform sigmoidal curve, common to the chromenes isolated from Piper aduncum. The accumulation of the chromane 4 showed a maximum at 18:00 pm, but others peaks of the same concentration were observed at 06:00 am and 15:00 pm, corroborating to establish a random pace. To evaluate the biosynthetic origin of the chromane 4, feeding experiments were conducted using a precursor enriched with stable isotopes (ethyl [2-13C ]-sodium acetate) in the leaves of P. obtusifolia. Experiments were performed using seedlings of P. obtusifolia. The enriched extracts...Cromanos e cromenos são metabólitos secundários comumente encontrados em espécies dos gêneros Piper e Peperomia, pertencentes à família Piperaceae. São caracterizados pela presença de um núcleo benzopirânico (um anel benzeno fundido a um anel pirano). Essa classe de substâncias é importante do ponto de vista farmacológico, uma vez que apresenta vasta gama de atividades biológicas, incluindo antifúngica, tripanocida, antioxidante e antiparasitária. Os benzopiranos isolados de espécies de Piper e Peperomia apresentam diversidade quanto aos substituintes da unidade aromática de suas estruturas químicas. Baseado no exposto, rotas biossintéticas distintas foram propostas. Em espécies de Piper essas rotas envolveriam a via do ácido chiquímico pela atuação do ácido para-hidroxibenzóico, enquanto que em espécies de Peperomia estaria operando a via do acetato. O presente trabalho teve como objetivo estudar a relação biossintética dos benzopiranos presentes nas espécies Piper aduncum e Peperomia obtusifolia, bem como a determinação da dinâmica metabólica envolvida na formação dos mesmos, tanto em nível metabólico como enzimático, uma vez que os cromenos isolados de Piper aduncum descrevem ritmo circadiano bem determinado. Estudos de variação circadiana realizados em Peperomia obtusifolia com o objetivo de acompanhar a formação do cromano ácido 3,4-diidro-5-hidróxi-2,7-dimetil-8-(3-metil-2-butenil)-2-(4-metil-1,3-pentadienil)-2H-1-benzopirano carboxílico (4) não demonstraram ritmo uniforme, do tipo sigmoidal, comum aos cromenos isolados de P. aduncum. O acúmulo do cromano 4 mostrou um máximo às 18h00, mas outros picos de concentração do mesmo foram observados às 06h00 e 15h00 e corroboram para o estabelecimento de um ritmo aleatório. Para a avaliação da origem biossintética de 4, foram realizados experimentos de incorporação utilizando precursor enriquecido..
Estudo de aspectos químicos, biológicos e biossintéticos em Piper fuligineum Kunth(Piperaceae)
No full textThe chemical profile of leaves and fruits of Piper fuligineum was analyzed by high performance liquid chromatography. The chemical composition of medium polarity related to leaves and fruits showed great similarity. The analysis also showed that the chemical composition of the fruits was more complex, mainly due to the presence of more polar substances. These analyzes allowed the selection of the leaves of P. fuligineum to continue the chemical studies. The chemical studies of the leaves of Piper fuligienum resulted in the isolation of six compunds, including two kavalactones (4- methoxy-6- [(E)-2-phenyl -vinyl] -2H-pyran-2-one and 6-(1,2-dihydroxy-2-phenyl- ethyl)-4-methoxy-2H- pyran-2-one), one chromanone (methyl-2,2-dimethyl-4-oxo-6- cromanacarboxylate) and two prenylated derivatives of benzoic acid (methyl-4-hydroxy-3-(3-methyl-2- buten-1-yl) benzoate and methyl-4-methoxy-3-(3-methyl -2-butenoyl) benzoate. The chemical structures of the isolated compounds were determined using spectrometric techniques, including 1D and 2D NMR. All compounds were described for the first time in Piper fuligineum, and the compound 4 is a new natural product. The ethanolic leaf extract and fractions obtained from P. fuligineum were evaluated for trypanocidal potential against epimastigote form of Trypanosoma cruzi Y strain, showing promising activity of the ethanol extract with IC50 of 26.67 g.mL-1 compared with the positive control benznidazole, with IC50 of 11.11 g.mL-1. The ethyl acetate extract, the chloroform fraction and substance 1 underwent antifungal drugs against fungi Candida albicans, C.krusei, C. tropicalis, C. parapsilosis and Cryptococcus neoformans yeast. The extract showed strong activity against the fungus Candida tropicalis and moderate activity against fungi C. krusei, C. parapsilosis and Cryptococcus neoformans yeast while the chloroform fraction showed strong activity against the fungus C. krusei, and moderate activity against...O perfil químico de folhas e frutos de Piper fuligineum foi analisado por cromatografia líquida de alta eficiência. A composição química de média polaridade dos dois órgãos vegetais apresentou semelhança. As análises demonstraram também que os frutos apresentavam composição química complexa, principalmente devido a presença de substâncias de maior polaridade. Essas análises permitiram selecionar as folhas de P. fuligineum para dar continuidade aos estudos químicos. Estes estudos resultaram no isolamento de cinco substâncias, sendo duas kavalactonas: (E)-6-(8-feniletil)-4-metoxi-2H-piran-2-ona e 6-(2-fenil-7,8-diidroxetil)-4-metoxi-2H-piran-2-ona; uma cromanona: (2,2-dimetil-4-oxocromano-6-carboxilato de metila) e dois derivados prenilados do acido benzoico: 4-hidroxi-3-(3-metilbutil-2-en-1-il)benzoato de metila e 4-metoxi-3-(3-metil-1-oxobut-2-en-1-il) benzoato de metila. As estruturas químicas das substâncias foram determinadas utilizando técnicas espectrométricas, incluindo RMN 1D e 2D. Todas as substâncias estão sendo descritas pela primeira vez em Piper fuligineum. A substância 4 é inédita como produto natural. O extrato etanolico das folhas e as frações obtidas de P. fuligineum foram avaliadas quanto ao potencial tripanocida frente à forma epimastigota da cepa Y de Trypanosoma cruzi, mostrando promissora atividade do extrato etanólico com IC50 de 26,67 g.mL-1 quando comparado com o controle positivo, benznidazol, com IC50 de 11,11 g.mL-1. O extrato acetato de etila, a fração clorofórmica e a substância 1 foram submetidos a testes antifúngicos frente aos fungos Candida albicans, C.krusei, C. tropicalis, C. parapsilosis e a levedura Cryptococcus neoformans. O extrato apresentou forte atividade frente ao fungo Candida tropicalis e moderada atividade frente aos fungos C. krusei, C. parapsilosis e a levedura Cryptococcus neoformans, enquanto a fração clorofórmica apresentou forte atividade frente ao..
Mapping Biochemical Pathways in Maytenus ilicifolia (Celastraceae) through Integrated Proteomics and Histochemistry
Get PDFThis work was supported by the Sao Paulo Research Foundation (FAPESP), grant numbers: CIBFar-2013/07600-3, INCT-FAPESP-2014/50926-0. This study was also financed by INCT-CNPq-2014/465637-0. V. A. F. F. M. S. thanks FAPESP and CNPq for the provision of fellowships (2011/0154-9 and 150201/2015-0, respectively). M. F., S. P. T., and M. S. P. thank CNPq for their fellowship. V. A. F. F. M. S. is also grateful to the Pro-Rectory for research of UNESP (PROPe) for financial support
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