An Electrochemical Approach to Follow and Evaluate the Kinetic Catalysis of Ricin on hsDNA.

International authorities classify the ricin toxin, present in castor seeds, as a potential agent for use in bioterrorism. Therefore, the detection, identification, and characterization of ricin are considered the first actions for its risk assessment during a suspected exposure, parallel to the development of therapeutic and medical countermeasures. In this study, we report the kinetic analysis of electro-oxidation of adenine released from hsDNA by the catalytic action of ricin by square wave voltammetry. The results suggest that ricin-mediated adenine release exhibited an unusual kinetic profile, with a progress curve controlled by the accumulation of the product and the values of the kinetic constants of 46.6 µM for Km and 2000 min-1 for kcat, leading to a catalytic efficiency of 7.1 × 105 s-1 M-1.

A Simple, Fast and Portable Method for Electrochemical Detection of Adenine Released by Ricin Enzymatic Activity.

International authorities classify ricin toxin present in castor seed as a potential agent for use in bioterrorism. Therefore, the detection, identification, and characterization of ricin in various sample matrices are considered necessary actions for risk assessment during a suspected exposure. This study reports a portable electrochemical assay for detecting active ricin based on the adenine electro-oxidation released from herring sperm DNA substrate by its catalytic action. Also, kinetic parameters were calculated, and the values were Km of 3.14 µM and Kcat 2107 min-1. A linear response was found in optimized experimental conditions for ricin concentrations ranging from 8 to 120 ng/mL, and with a detection limit of 5.14 ng/mL. This proposed detection strategy emphasizes the possibility of field detection of active ricin in food matrices and can be applied to other endonucleolytic activities.

Evaluation of Kefir as a New Anodic Biocatalyst Consortium for Microbial Fuel Cell.

Kefir, a combined consortium of bacteria and yeast encapsulated by a polymeric matrix of exopolysaccharides, was used as anodic biocatalyst in a two-chamber microbial fuel cell (MFC). Fermentation was followed during 72 h and polarization curves were obtained from linear sweep voltammetry. The effect of methylene blue as charge-transfer mediator in the kefir metabolism was evaluated. UV/Vis spectrophotometry and cyclic voltammetry were applied to evaluate the redox state of the mediator and to characterize the electrochemical activity, whereas current interruption was used for internal resistance determination. Aiming to establish a relationship between the microbial development inside the anodic chamber with the generated power in the MFC, total titratable acidity, pH, viscosity, carbohydrate assimilation, and microbial counting were assayed. The kefir-based MFC demonstrated a maximum power density of 54 mW m-2 after 24 h fermentation, revealing the potential use of kefir as a biocatalyst for microbial fuel cells.

Bacteriostatic effect of copaiba oil (Copaifera officinalis) against Streptococcus mutans.

This study evaluated the inhibitory activity of copaiba oil (Copaifera officinalis against the cariogenic microorganism, Streptococcus mutans. For such purpose, a minimum inhibition concentration test of copaiba oil against S. mutans was performed, using the serial dilution in broth technique, with a negative control, a positive control (0.12% chlorhexidine) and a 10% copaíba oil solution as a test. A minimum bactericidal concentration test with tubes presenting microbial inhibition was also conduced. In the minimum inhibitory concentration test, copaiba oil showed inhibition of bacterial growth at all concentrations tested up to 0.78 µL/mL of the 10% copaiba oil solution in the broth. In addition, the negative control had no inhibition, and the 0.12% chlorhexidine solution was effective up to 6.25 µL/mL in the broth. Copaiba oil showed a bacteriostatic activity against S. mutans at low concentrations, and could be a an option of phytotherapic agent to be used against cariogenic bacteria in the prevention of caries disease.

Bacteriostatic effect of copaiba oil (Copaifera officinalis) against Streptococcus mutans

This study evaluated the inhibitory activity of copaiba oil (Copaifera officinalis against the cariogenic microorganism, Streptococcus mutans. For such purpose, a minimum inhibition concentration test of copaiba oil against S. mutans was performed, using the serial dilution in broth technique, with a negative control, a positive control (0.12 percent chlorhexidine) and a 10 percent copaíba oil solution as a test. A minimum bactericidal concentration test with tubes presenting microbial inhibition was also conduced. In the minimum inhibitory concentration test, copaiba oil showed inhibition of bacterial growth at all concentrations tested up to 0.78 µL/mL of the 10 percent copaiba oil solution in the broth. In addition, the negative control had no inhibition, and the 0.12 percent chlorhexidine solution was effective up to 6.25 µL/mL in the broth. Copaiba oil showed a bacteriostatic activity against S. mutans at low concentrations, and could be a an option of phytotherapic agent to be used against cariogenic bacteria in the prevention of caries disease.

Este estudo avaliou a atividade inibitória do óleo de copaíba (Copaifera officinalis contra o microrganismo cariogênico, Streptococcus mutans. Para isso, foi realizado um teste de concentração mínima inibitória do óleo de copaíba contra S. mutans, utilizando a técnica de diluição seriada em caldo, com um controle negativo, um controle positivo (clorexidina a 0,12 por cento) e uma solução de óleo de copaíba 10 por cento como teste. Também foi conduzido um teste de concentração mínima bactericida com os tubos que apresentaram inibição microbiana. No teste de concentração inibitória mínima, o óleo de copaíba mostrou inibição do crescimento bacteriano em todas as concentrações testadas até 0,78 µL/mL da solução a 10 por cento do óleo de copaíba no caldo. Além disso, o controle negativo não teve nenhuma inibição, e a solução de clorexidina 0,12 por cento foi eficaz até 6,25 µL/mL no caldo. O óleo de copaíba mostrou uma atividade bacteriostática contra S. mutans em baixas concentrações, apresentando-se assim como uma opção de fitoterápico a ser utilizado contra bactérias cariogênicas na prevenção de cáries.

Gingko biloba leaves extract on growth and morphology of trypanosomatids / Efecto del extracto de las hojas de Gingko biloba en el crecimiento y la morfología de tripanosomátidos

Gingko biloba has been one of the most used medicinal plants all over the world in the past years. In this study, our group has studied the effect of a hydroethanolic extract from the aerial parts of this plant on the growth and morphological differentiation of trypanosomatids. Herpetomonas samuelpessoai and Herpetomonas sp were used in this study. The extract was obtained in a Soxhlet apparatus (50 oC, 2 hours). This extract was aseptically added to Roitman’s medium in different concentrations (4, 20, 40, 60, 80 and 100 mg/ml). The growth rate was determined using a Newbauer chamber to count numbers of cells after the extract inoculation (24 and 72 hours later). Smears stained by the Panotic method was used to determine the percentages of pro, para and opisthomastigote forms. The extract inhibited Herpetomonas sp growth in concentrations higher than 20 mg/ml. H. samuelpessoai has been inhibited in doses higher than 40 mg/ml. No morphological differentiation was observed in Herpetomonas sp cell. However, morphological differentiations could be noticed in H. samuelpessoai cell using doses higher than 40 mg/ml. These alterations are probably related to the cell division process, since cells with 3 or 4 nucleus were observed. Also, cytoplasmatic expansions, representing unsuccessful process of cell division were frequently found out. Further ultrastructural analysis using a transmission electron microscope showed cells with homogeneous nucleus or the absence of it. Protozoan protein profile was also analyzed. It was possible to notice changes in both trypanosomatids used in this study. H. samuelpessoai has shown over expression and accumulation of proteins which its degradation is essential to continue the cell differentiation. Also, it is possible to suggest that this extract acts through the modulation of the genetic expression and may be harmful to human cells if not purified.

Gingko biloba es una de las plantas medicinales más utilizadas en todo el mundo en los últimos años. En este estudio, nuestro grupo ha estudiado el efecto de un extracto hidroetanólico de la parte aérea de esta planta sobre el crecimiento y la diferenciación morfológica de tripanosomátidos. Herpetomonas samuelpessoai y Herpetomonas sp se utilizaron en este estudio. El extracto se obtuvo en un aparato Soxhlet (50° C/2 horas). Este extracto se agregó asépticamente a medio Roitman en diferentes concentraciones (4, 20, 40, 60, 80 y 100 mg /ml). La tasa de crecimiento se determinó utilizando una cámara de Newbauer para contar el número de células después de la inoculación de extracto (24 y 72 horas más tarde). Frotis teñidos por el método Panotic se utilizó para determinar los porcentajes de pro, para y las formas opistomastigota. El extracto inhibió el crecimiento Herpetomonas sp en concentraciones superiores a 20 mg /ml. H. samuelpessoai se ha inhibido en dosis superiores a 40 mg /ml. No se observó diferenciación morfológica en la celda Herpetomonas sp. Sin embargo, las diferenciaciones morfológicas se pudo observar en la celda H. samuelpessoai con dosis superiores a 40 mg /ml. Estas alteraciones son probablemente relacionado con el proceso de división celular, ya que las células con 3 o 4 núcleos se observaron. Además, las expansiones citoplasmáticas, lo que representa el proceso fallido de la división celular se encontraron con frecuencia hacia fuera. Un análisis más detallado ultraestructural usando microscopio electrónico de transmisión mostró células con núcleo homogéneo o la ausencia de ella. El perfil de proteínas por Protozoarios también se ha analizado. Fue posible notar cambios tanto en tripanosomátidos utilizados en este estudio. H. samuelpessoai ha demostrado a lo largo de expresión y la acumulación de proteínas que su degradación es esencial para continuar con la diferenciación celular. Además, es posible sugerir que este extracto...

Gastric antiulcer and anti-inflammatory activities of the essential oil from Casearia sylvestris Sw.

To investigate the antiulcer and antiinflammatory activities of the essential oil from Casearia sylvestris leaves (EOCS) the following tests were used: rat paw edema, granulomatous tissue test, vascular permeability, writhing test, gastric ulcer stress-induced and evaluation of gastric secretion (pylorus ligation test). The total yield of EOCS was 2.5% with LD50 of 1100 mg/kg in mouse. The major compounds identified using gas chromatography were caryophyllene, thujopsene, alfa-humulene, beta-acoradiene, germacrene-d, bicyclogermacrene, calamenene, germacrene B, spathulenol and globulol. The EOCS orally administered to the rats at 125 mg/kg resulted 36% of inhibition in carrageenan-induced edema in the rat paw assay (p<0.05, Student's t-test). However, both rat paw edema dextran-induced and vascular permeability assay using histamine showed no significant inhibition. Mice submitted to the writhing test using acetic acid presented 58% and 56% of inhibition in writhes with EOCS and indomethacin, respectively. Furthermore, EOCS inhibited 90% of stress-induced gastric ulcer, while cimetidine inhibited 70% (p<0.05, Student's t-test). The volume of gastric secretion in the group treated with EOCS was greater than the group treated with cimetidine. The EOCS also showed no changes related to H+ levels in the gastric secretion. With the overall results obtained in this study the authors suggest an anti-inflammatory activity for the EOCS of Casearia sylvestris beyond its anti-ulcer activity.

Antimicrobial and healing activity of kefir and kefiran extract.

Kefir and its insoluble polysaccharide, kefiran, were both tested for antimicrobial and cicatrizing activities against several bacterial species and Candida albicans using an agar diffusion method. Comparator antimicrobials were also tested. Cicatrizing experiments were carried out on Wistar rats with induced skin lesions and Staphylococcus aureus inoculation, using a topical application of a 70% kefir gel. Both kefir and kefiran showed some activity against all organisms tested; the highest activity was against Streptococcus pyogenes. Cicatrizing experiments using 70% kefir gel had a protective effect on skin connective tissue and 7 days treatment enhanced wound healing compared with 5 mg/kg of neomycin-clostebol emulsion.

Cicatrizing and antimicrobial properties of an ozonised oil from sunflower seeds.

The ozonised sunflower oil, Bioperoxoil, was tested for its antimicrobial activity against some pathological strains in vitro together with its healing potential against Staphylococcus aureus in vivo. Bioperoxoil was tested against S. aureus, Pseudomonas aeroginosa, Candida albicans, S. typhimurium and Escherichia coli suspensions using the agar diffusion method. Healing experiments were carried out with Wistar rats through topical application of 3.5 mg/ml of the ozonised oil up to the 7th day after inoculation with S. aureus. Bioperoxoil showed anti-inflammatory effects against all strains tested, with MIC values ranging from 2.0 to 3.5 mg/ml. Bioperoxoil also demonstrated protective effects on skin connective tissue and to enhance wound healing during the treatment, as compared to a neomycin-clostebol association used as a positive control. The overall results indicated a significant antimicrobial activity, anti-inflammatory and wound-healing properties for Bioperoxoil, as compared to other antimicrobial agents commercially available.