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Complexo de inclusão óleo essencial de Lippia Gracilis e ß-Ciclidextrina : uma alternativa no controle das larvas de Aedes Aegypti

2013-02-20T00:00:00Z

Título: Complexo de inclusão óleo essencial de Lippia Gracilis e ß-Ciclidextrina : uma alternativa no controle das larvas de Aedes Aegypti Autor(es): Cerpe, Patricia Abstract: In terms of morbidity and mortality, dengue is considered the important human viral disease transmitted by mosquitoes, caused by virus of the family Flaviridae, one of the main problems in public health in the world, due to the great potential for the development of several forma and lethal disease. Another problem about dengue control is the population of Aedes aegypti resistant to toxicity of chemical insecticides, such as temephos. This work involved the formulation and characterization of inclusion complex of essential of Lippia gracilis (LGEO), with potent larvicidal effect against Aedes Aegypti Linnaeus larvae in β-cyclodextrin (β-CD), aiming to improve oil solubility in aqueous serving as a strategy for obtaining new products larvicides. Inclusion complexes were obtained by kneading and coevaporation. The complexes obtained by paste and co-evaporation was assessed the influence of the co-solvent used to preparation the complexes by paste with water (PMW), kneading with ethanol / water (PME) co-evaporation with water (COW) and co-evaporation of ethanol / water (COE) methods. The chemical LGEO constituents were identified by gas chromatography coupled to mass spectrometer (GC / MS) where the complex (PMW) was superior in the inclusion of carvacrol with a content of 15.25% compared with the another techniques preparation. The complexes were characterized by thermogravimetry (TG / DTG), the moisture content by Karl-Fischer, differential scanning calorimetry (DSC), X-ray diffraction (X-RD), spectroscopy in the infrared with Fourier transform ( FTIR) and ultra violet (UV-vis), scanning electron microscopy (SEM) and solubility tests. According to the results obtained by GC / MS the major constituent of OELG was carvacrol (46.7%). In TG / DTG and DSC revealed the complex displacement in the range of thermal degradation of the oil to higher temperature ranges indicating a gain of thermal stability. In the analyzes of (X-RD) of the complexes showed the loss of crystalline order compared to pure β-CD. The scanning electron microscopy (SEM) showed changes in particle shapes and morphology of the complex when compared with pure β-CD. The larvicidal assay against Aedes aegypti larvae were carried out with the Rockefeller strain in the third stage (L3), and mortality was observed after 24 hs. The phase solubility diagram at different temperatures, the values of the stability complex of the constant (PMW), was demonstrates be stable and water soluble the interaction complex OELG / β-CD. Aedes aegypti larvae were susceptible to the composition of OELG, carvacrol and complex (PMW) using the method of Probit analysis. The larvicidal activity of the complex (PMW) LC50 was 33 ppm, close to that of pure oil LC50 39 ppm and may be a suitable alternative to biolarvicida dengue control programs.

Análise química e efeitos letais e sub-letais do óleo essencial de patchouli e sua nanoemulsão em populações de Sithopilus zeamais (Coleoptera: Curculionidae)

2013-02-27T00:00:00Z

Título: Análise química e efeitos letais e sub-letais do óleo essencial de patchouli e sua nanoemulsão em populações de Sithopilus zeamais (Coleoptera: Curculionidae) Autor(es): Santos, Álvaro Marcio de Oliveira Abstract: The maize weevil (Sitophilus zeamais) is one of the stored grain pests of major importance in the world. The indiscriminate use of conventional insecticides has led to the selection of populations of resistant S. zeamais. Although the essential oils (EO) of plants are considered an alternative to conventional insecticides, their range of use due to insect populations with different capacities resistance has not been determined. We examined the toxicity of the EO of Pogostemon cablin and its nanoemulsion on nine populations of S. zeamais from different regions of Brazil. For that were performed bioassays topical application, contact, fumigation, and repellency effects on population growth. Fifteen compounds were identified the EO of P. cablin, and patchoulol was major component (55.04%). The EO of P. cablin showed average activity against the nine populations of S. zeamais when applied topically. The time required to cause 50% mortality of the population was 33.4 hours. The nine populations of S. zeamais responded similarly to EO of P. cablin. The lethal dose to kill 50% of the population resulted in low toxicity index (<2). The population of Viçosa-MG was more susceptible the EO of P. cablin, with LD50 of 9.17 and 8.01 μg mg-1 after 48 and 72 hours exposure respectively. The greater tolerance of EO P. cablin was detected in the population of Sete Lagoas, Minas Gerais, which increased the LD50 of 1.77 and 1.53 times. The concentration the EO of P. cablin required to cause 50% mortality of the population by contact and fumigation ranged from 0.34 to 0.43 μl ml-1 and from 28.6 to 33.5 μl l-1, respectively. Already the nanoemulsion P. cablin showed LC50 ranging from 1.28 to 8.84 μl ml-1 and from 32.7 to 39.5 μl l-1. There was an increase in toxicity by contact and fumigation (LC50) of the nanoemulsion of P. cablin from 48 to 72 hours of exposure. Toxicity (LC50) for contact and fumigation on populations of Viçosa-MG and Sete Lagoas-MG after 48 and 72 hours of exposure to EO P. cablin was in most cases greater than the toxicity caused by nanoemulsion of P. cablin. The EO and the nanoemulsion of P. cablin were LC50 and LC70 repellents in at all times of exposure for the population of Viçosa-MG. The same occurred with the population of Sete Lagoas, Minas Gerais, except for LC50 after 4, 6 and 8 hours of exposure and the LC70 after 24 hours of exposure to nanoemulsion of P. cablin. For the population of Viçosa-MG, there was no difference in repellency caused by EO and nanoemulsion of P. cablin. As for the population of Sete Lagoas, Minas Gerais, EO P. cablin caused greater repellency to this population compared to this oil nanoemulsion. Increasing concentrations of nanoemulsion of P. cablin resulted in reduction and consumption of grains of the two populations. Populations of Viçosa-MG and Sete Lagoas-MG entered decline (ri <0) using concentrations of 50.15 and 67.29 μl kg-1, respectively.

Ocorrência, distribuição e caracterização de fungos entomopatogênicos em solo natural e cultivado

2013-02-28T00:00:00Z

Título: Ocorrência, distribuição e caracterização de fungos entomopatogênicos em solo natural e cultivado Autor(es): Azevedo, Ana Gorete Campos de Abstract: This study aimed to evaluate the occurrence and diversity of entomopathogenic fungi at Sergipe state, considering the factors that affect their distribution. The analysis was done using soil samples collected in the three mesoregions of the state in two periods of collection, comprising a wet and a dry season, and in two different habitats (agricultural and natural). Parameters such as pH, organic matter and argil soil were considered in the analyzes. For the soil fungi isolation, two methods were used, the soil solution in culture medium and selective insect bait. In a total of 48 soil samples, 41.7% were positive for the presence of entomopathogenic fungi. The isolates were belonging to the genera Beauveria, Metarhizium and Isaria, from order Hypocreales. It was found that the factors related to soil sampling location (region, period, and habitat) showed no significant difference in their variables for the presence of entomopathogenic fungi, however other soil factors (pH, amount of organic matter and argil) showed significance. The isolates were submitted to genetic variability analysis by RAPD markers, where 15 primers were selected, producing a total of 179 bands (Beauveria) and 131 bands (Metarhizium) and the similarity matrices were made using the Jaccard coefficient, which generated dendrogram by the UPGMA method, for each fungus. There was low genetic similarity among isolates of both genders. In this work, the entomopathogenic fungi isolated can be useful for biological control in agriculture once these isolates show certain persistence in adverse conditions of temperature, humidity and UV radiation.

Atividade específica do extrato bruto e estabilidade a diferentes temperaturas e valores de pH de xilanases extracelulares bacterianas

2014-02-27T00:00:00Z

Título: Atividade específica do extrato bruto e estabilidade a diferentes temperaturas e valores de pH de xilanases extracelulares bacterianas Autor(es): Sampaio, Carlos Rodolfo Abstract: Xylanases have an important role as biocatalysts in different agroindustrial processes, such as saccharification of plant residues for the production of ethanol and bleaching of wood pulp for the production of pulp. On an industrial scale, these processes may require extreme pH or temperature, which require enzymes compatible with these conditions. Most enzymes available or showing commercial potential is synthesized by fungi or bacteria belonging to a few genera. Evaluation of rare isolation bacteria is an important strategy to expand the diversity of xylanases and their potential in terms of activity, stability and technological application. The aim of this study was to evaluate a collection of common and rare isolation soil bacteria regarding to xylanase activity and characterize the stability conditions of temperature and pH. The analyzed collection consists of 120 isolates with representatives from six phyla that were subjected to screening for xylanase activity in pure cultures and in the extracellular proteic extract (EPE). The ratio between the halos diameters of xylan hydrolysis and in the colonies on solid medium (ratio H:C), incubated at 30 ° C for up to 14 days, was used for the evaluation of cultures as a selection criteria. The effects of different sources of variation in the bacteria isolation stage (original soil, culture medium, solidifying agent, inoculum dilution and plating method and incubation time to colony appearance) and the group of bacterial isolation (rare or common) on the frequency of isolates with high xylanase activity were evaluated based on the ratio H:C. EPEs were obtained in liquid media containing xylan inoculated with the eleven isolates with highest ratios H:C. The extracts were evaluated for the specific xylanase activity at 50 °C for 1 h. Extracts of the three isolates with the highest potential for activity under this condition were evaluated for optimum activity, stability, activity at 60 oC and at pH 4.0, 5.5 and 8.0. Twenty-two isolates (25%), including eight from rare isolation, showed xylanase activity under the conditions evaluated, and found a high variability (> 230%) between these isolates. No isolation factor or rare or common isolation condition were associated with efficiency of xylanase activity in solid medium. High variability in specific xylanase activity in EPEs was also found among isolates (1500%), highlighting two rare isolates (TC119 and TC21), from Alfaproteobacteria class, and one common isolate (TC99), from Ralstoniaceae family. Extracellular xylanases from TC21 and TC119 showed high relative activity at temperatures up to 70 oC and were insensitive to pH in the range 4.0 to 8.0; however, TC99 isolate showed optimum temperature at 40 °C and low stability to temperature and pH. Extracellular xylanases from TC119 showed no cellulolytic activity. Rare isolation soil bacteria show high potential as a source of extracellular xylanases adapted to extreme pH and temperature conditions, which are required in agroindustrial processes.