Inhibition of Pancreatic α-amylase by Resveratrol Derivatives : Biological Activity and Molecular Modelling Evidence for Cooperativity between Viniferin Enantiomers

To improve the current understanding of the role of stilbenoids in the management of diabetes, the inhibition of the pancreatic \u3b1-amylase by resveratrol derivatives was investigated. To approach in a systematic way, the mechanistic and structural aspects of the interaction, potential bioactive agents were prepared as single molecules, that were used for the biological evaluation of the determinants of inhibitory binding. Some dimeric stilbenoids\u2014in particular, viniferin isomers\u2014 were found to be better than the reference drug acarbose in inhibiting the pancreatic \u3b1-amylase. Racemic mixtures of viniferins were more effective inhibitors than the respective isolated pure enantiomers at an equivalent total concentration, and displayed cooperative effects not observed with the individual enantiomers. The molecular docking analysis provided a thermodynamics-based rationale for the measured inhibitory ability and for the observed synergistic effects. Indeed, the binding of additional ligands on the surface of the alpha-amylase was found to decrease the dissociation constant of inhibitors bound to the active site of the enzyme, thus providing a mechanistic rationale for the observed inhibitory synergies

Caracterización de Xylella fastidiosa a partir de materiales vegetales y cepas aisladas de olivo (Olea europaea L.) e implementación de un sistema de diagnóstico serológico en Argentina

Xylella fastidiosa está considerada plaga cuarentenaria de importancia global por el grave impacto económico y social que ocasiona en cultivos de importancia agrícola. El objetivo de este trabajo fue aislar y caracterizar cepas bacterianas y muestras vegetales infectadas con X. fastidiosa de plantas de olivo (Olea europaea L.) e implementar un sistema de diagnóstico serológico para su detección. Para la caracterización molecular se utilizó el sistema de tipificación multilocus de secuencias (MLST). Se logró el aislamiento de la bacteria desde olivo y se determinó que todos los materiales caracterizados corresponden a X. fastidiosa subespecie pauca ST69, un grupo genético solo presente en Argentina. Se elaboraron reactivos serológicos fundamentales para la puesta a punto de técnicas de diagnóstico. Con la técnica DAS ELISA se logró un sistema de diagnóstico rápido, robusto y económico, permitiendo resolver la ausencia de disponibilidad continua de reactivos serológicos específicos para X. fastidiosa.Xylella fastidiosa is considered a quarantine pest of global significance due to the severe economic and social damage it causes on most valuable crops. The objective of this work was to isolate and characterize bacterial strains of infected with X. fastidiosa of olive (Olea europaea L.) samples and implement a serological diagnostic system for their detection. For the molecular characterization, the multilocus sequence typing system (MLST) was used. The isolation of the bacterium from the olive tree was achieved and it was determined that all materials characterized correspond to X. fastidiosa subsp. pauca ST69, a genetic subgroup that has been detected only in Argentina. An antiserum was produced and serological diagnosis systems were adjusted. A solid, fast and economical diagnostic method DAS ELISA system was achieved, solving the continuous lack of availability of serological reagents for X. fastidiosa.Fil: Tolocka, Patricia Andrea. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; ArgentinaFil: Giolitti, Fabián José. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; ArgentinaFil: Guzmán, F. A.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Córdoba. Estación Experimental Agropecuaria Manfredi; ArgentinaFil: Mattio, Maria Fernanda. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Nome, C. F.. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; ArgentinaFil: Ortega, Leandro Ismael. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Fisiología y Recursos Genéticos Vegetales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Paccioretti, M. A.. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; ArgentinaFil: Roca, Monica Esther María. Ministerio de Agricultura, Ganadería, Pesca y Alimento. Servicio Nacional de Sanidad y Calidad Agroalimentaria; Argentina. Universidad Nacional de La Rioja; ArgentinaFil: Otero, M. L.. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; ArgentinaFil: Haelterman, Raquel Mercedes. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Unidad de Fitopatología y Modelización Agrícola - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Unidad de Fitopatología y Modelización Agrícola; Argentin

Identification and biological characterization of Barley yellow striate mosaic virus (BYSMV): a new wheat disease in Argentina

Wheat (Triticum aestivum L.) is the most important winter grain in Argentina. Its production is limited by several factors, including viral diseases. The aim of this study was to identify and characterize a recently detected disease of wheat crops in Argentina. Symptomatic plants were collected from different locations from the wheat production area, Miramar and Balcarce (Buenos Aires), Río Cuarto, Rosales and Marcos Juarez (Córdoba), Paraná (Entre Ríos) and General Pico (La Pampa). Samples were characterized by: electron microscopy (leaf-dip and ultrathin sections), serological tests (with antiserum reacting against different wheat viruses by DAS-ELISA and indirect ELISA), mechanical, seed and vector transmission assays, differential host range, and susceptibility of different wheat cultivars in natural infections. The results showed that this new disease is caused by Barley yellow striate mosaic virus (BYSMV) (Rhabdoviridae-Cytorhabdovirus), a widely distributed virus that can be transmitted to other crops such as barley, oat and triticale. This work representsthe first report of BYSMV in Argentina.El cultivo de trigo (Triticum aestivum L.), es el cereal de invierno de mayor importancia económica en Argentina. Su producción se halla limitada por diversos factores, entre ellos las enfermedades virales. El objetivo del presente trabajo fue identificar y caracterizar biológicamente una enfermedad viral detectada recientemente en el cultivo de trigo en Argentina, que ha presentado elevada incidencia en los últimos años. Para ello, se recolectaron plantas con síntomas en localidades de: Miramar y Balcarce (Buenos Aires), Río Cuarto, Rosales y Marcos Juárez (Córdoba), Paraná (Entre Ríos) y General Pico (La Pampa) de la región triguera Argentina. Las muestras fueron caracterizadas a través de: microscopia electrónica ("leaf-dip" y cortes ultrafinos), serología (con antisueros para diferentes virosis del trigo por DAS-ELISA y ELISA indirecto), transmisión mecánica, por semilla y por vectores (delfácidos), rango de hospedantes diferenciales y susceptibilidad diferencial de diferentes cultivares de trigo en infecciones naturales. Los resultados obtenidos evidenciaron que esta nueva enfermedad es causada por el Barley yellow striate mosaic virus (BYSMV) (Rhabdoviridae-Cytorhabdovirus), un virus ampliamente distribuido a nivel mundial y que representa un riesgo potencial para otros cultivos como cebada, avena y triticale. Este trabajo representa el primer reporte del BYSMV en Argentina.Fil: Dumón, Analía Delina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Unidad de Fitopatología y Modelización Agrícola - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Unidad de Fitopatología y Modelización Agrícola; ArgentinaFil: Argüello Caro, Evangelina Beatriz. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; ArgentinaFil: Alemandri, María V.. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; ArgentinaFil: Bainotti, Carlos Tomas. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; ArgentinaFil: Mattio, María F.. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; ArgentinaFil: Rodríguez, Sandra M.. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; ArgentinaFil: del Vas, Mariana. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Biotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Truol, Graciela Ana. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Patología Vegetal; Argentin

Abundance and Species Richness of Leafhoppers and Planthoppers (Hemiptera: Cicadellidae and Delphacidae) in Brazilian Maize Crops

Fil: De Oliveira, Charles Martins. Embrapa Cerrados. Planaltina. Brasília/DF; BrazilFil: De Oliveira, Elizabeth. Embrapa Milho e Sorgo. Sete Lagoas/MG; BrazilFil: Prazeres De Souza, Isabel Regina. Embrapa Milho e Sorgo. Sete Lagoas/MG; BrazilFil: Alves, Elcio. DuPont do Brazil S.A. DivisÆo Pioneer Sementes. Itumbiara/GO; BrazilFil: Dolezal, William. Pioneer Hi-Bred International. Itumbiara/GO; BrazilFil: Paradell, Susana Liria. División Entomología. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Marino de Remes Lenicov, Ana María. División Entomología. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Frizzas, Marina Regina. Universidade de Brasília. Departamento de Zoologia. Instituto de Ciências Biológicas. Brasília/DF; Brazi

Structure-dependent biological activities of food-related stilbene derivatives isomers

Resveratrol, piceatannol and pterostilbene are stilbene derivatives in which two aromatic rings linked by an olefin bridge. Many stilbene derivatives have proven beneficial to human health, acting on risk factors for cancer, on cardiovascular and neurodegenerative diseases, on diabetes, and on osteoporosis. All these monomeric polyphenols are particularly prone to oligomerization processes through oxidative coupling, originating complex structures such as dimers or oligomers that may be responsible for their beneficial effects. These natural oligomers present stereogenic centers, that could play a pivotal role in the interaction of this class of molecules with biological targets. In this study, isomers of these compounds were synthesized, purified, and tested as for their ability to inhibit enzymes relevant to glucose metabolism (such as brush-border glucosidase and pancreatic alpha amylase), and to control inflammatory response in a suitable Caco-2 cell model. Results highlight the requirement for peculiar structural features as for eliciting individual effects, both in terms of the polymerization state of these phenolics and in terms of their three-dimensional structure

Inhibition of pancreatic α-amylase by resveratrol-derived viniferins relates to their geometrical features and implies co-operative binding

To improve current understanding of the role of stilbenoids in the management of diabetes, the hypoglycaemic potential of resveratrol derivatives was investigated in terms of alpha-amylase inhibition. To tackle the mechanistic and structural issues of the interaction with the target protein, bioactive agents were prepared as single molecules, to be used for biological evaluation of the binding determinants. Some dimeric stilbenoids \u2013 trans-delta-viniferins, in particular \u2013 were found to be much better inhibitors of pancreatic \u3b1-amylase.than the reference drug, acarbose. Racemic mixtures of viniferins were more effective than the respective isolated pure enantiomers at equivalent total concentration. A markedly sigmoidal inhibition curve was observed for the (S, S) enantiomer of trans-delta-viniferin, with a Hill cooperativity coefficient (n ) close to 4 and a relatively high Kiapp (0.058 mM). In contrast, values of n were close to unity for the (R, R) enantiomer (n = 1.5; Kiapp = 0.043 mM) and for the high-affinity binding of an equimolar mixture of the (R, R) and (S, S) enantiomers (n = 1.2; Kiapp = 0.012 mM). Molecular docking analysis provided a thermodynamics-based rationale for the inhibitory ability of individual stilbenoids, for the cooperative behavior of viniferin enantiomers, and for the synergistic inhibition discussed above. Indeed, binding of additional ligands on the surface of alpha-amylase was found to decrease the dissociation constant of inhibitors bound to the active site of the enzyme. Finally, viniferins do not appear to compete with acarbose in the inhibition of pancreatic \u3b1-amylase. Rather, the evidence gathered so far points to a possible synergy among these classes of inhibitors, in spite of their remarkable structural differences. Studies are in progress to assess whether these synergistic effects could be relevant to developing therapeutic or preventive strategies for diabetes management

Diversity and assemblage structure of tropical marine flora on lava flows of different ages

Recent volcanic lava flows extending into the ocean represent an ideal opportunity to study the long-term successional development of marine floral assemblages on the bare new substratum. We describe the floral assemblages of nine lava flows of different ages (prehistoric to 2007) at Piton de la Fournaise (Reunion Island, Indian Ocean) based on a survey of 37 stations. We identified 159 species including 148 macroalgae, 1 seagrass, and 10 cyanobacteria. Fifty-one of those represent new records for Reunion Island, and at least 9 taxa were identified as new to science. Recent lava flows were characterized by the dominance of ephemeral, opportunistic species, such as Pseudobryopsis hainanensis and Acrocladus dotyanus, while prehistoric lava flows were mainly characterized by perennial species, particularly Sargassum portiericuzum and Turbinaria ornata. A canonical correspondence analysis revealed that the environmental factor that most significantly correlated to the variation in floral assemblages was the distance to the most recent lava flow (2007). This factor was also highly correlated to coral cover. The composition of the different floral assemblages is discussed in relation to abiotic and biotic factors to explain ecological succession in a tropical environment