Avaliação in vitro de atividade antimicrobiana de óleos essenciais contra Salmonella typhimurium e Staphylococcus aureus / In vitro evaluation of antimicrobial activity of essential oils against Salmonella typhimurium and Staphylococcus aureus

O objetivo do trabalho foi avaliar a atividade antimicrobiana in vitro de diferentes óleos essenciais e suas combinações contra linhagens patogênicas de Salmonella typhimurium ATCC 13311 e Staphylococcus aureus ATCC 13565. Foram testados ao todo 41 óleos essenciais e as combinações em pares dos óleos de alecrim-pimenta (Lippia sidoides Cham.), capim-limão (Cymbopogon citratus Stapf.), tomilho (Thymus vulgaris L.), orégano (Origanum vulgare L.) e canela (Cinnamomum cassia (L.) D.Don. para observar efeitos adicionais ou não na inibição dos microrganismos. Os resultados mostraram que as melhores atividades antimicrobianas para os dois microrganismos foram obtidas utilizando os óleos de Thymus vulgaris L. (tomilho), Origanum vulgare L. (orégano) e Lippia sidoides Cham. (alecrim-pimenta). As combinações de cada par dos óleos de alecrim-pimenta, capim-limão, tomilho, orégano e canela não apresentaram uma melhora adicional no efeito para os patógenos estudados quando comparados com os seus óleos testados isoladamente. As composições químicas dos óleos essenciais mais ativos foram obtidas por meio de análises por cromatografia gasosa acoplada à espectrometria de massas (CG-EM), sendo que os compostos majoritários do óleo de orégano foram carvacrol (69,1%) e p-cimeno (18,8%), do óleo essencial de tomilho foram timol (45,5%) e p-cimeno (35,6%) e do alecrim-pimenta foram o timol (77,2%) e p-cimeno (14,2%). Análises quantitativas de p-cimeno, carvacrol e timol nos três óleos foram realizadas e comparadas com as composições químicas mostrando resultados proporcionalmente coerentes, exceto para p-cimeno, que foi quantificado com menores porcentagens por esse método. A aplicabilidade dos óleos selecionados, ou das substâncias presentes isoladas seria diretamente nos alimentos, com a finalidade de inibir ou controlar o crescimento desses patógenos, contribuindo assim para a segurança dos alimentos. (AU)

The aim of this study was to evaluate the in vitro antimicrobial activity of several essential oils and their combination against pathogenic strains of Salmonella typhimurium ATCC 13311 and Staphylococcus aureus ATCC 13565. A total of 41 essential oils and the combinations in pairs of the oils of rosemary pepper (Lippia sidoides Cham.), lemongrass (Cymbopogon citratus Stapf.), thyme (Thymus vulgaris L.), origanum (Origanum vulgare L.) and cinnamon (Cinnamomum cassia (L.) D.Don) were tested to observe additional effects or not in the inhibition of microorganisms. The results showed that the best antimicrobial activities for the two microorganisms were obtained using the oils of Thymus vulgaris L. (thyme), Origanum vulgare L. (origanum) and Lippia sidoides Cham. (rosemary pepper). The combinations of each pair of rosemary pepper, lemongrass, thyme, origanum and cinnamon oils did not show any further improvement in the effect for the studied pathogens when compared to their oils tested alone. The compositions of the most active essential oils were obtained by gas chromatography coupled to mass spectrometry (GC-MS). The major compounds in origanum oil were carvacrol (69.1%) and p-cymene (18.8%), thyme essential oil were thymol (45.5%) and p-cymene (35.6%) and rosemary pepper were thymol (77.2%) and p-cymene (14.2%). Quantitative analyses of p-cymene, carvacrol and thymol confirmed the presence in thyme, oregano and pepper rosemary oils and were compared with the chemical composition showing similar results, except for p-cymene, which was quantified with lower percentages in these oils. One of the possible applications of the results of this work is the use of essential oils, or the isolated substances, directly in foods, with the purpose of inhibiting or controlling the growth of these pathogens, thus contributing to the food safety.Keywords: Bioassay. GC-MS. Inhibition. Carvacrol. Thymol. p-cymene(AU)

Simultaneous determination of acrylamide and 4-hydroxy-2,5-dimethyl-3(2H)-furanone in baby food by liquid chromatography-tandem mass spectrometry.

A liquid chromatography triple quadrupole mass spectrometry method was developed and validated for the simultaneous determination of acrylamide and 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF) in baby food. The sample preparation involves acetonitrile-based extraction combined with dispersive primary secondary amine (PSA) cleanup and cation-exchange solid-phase extraction (SPE), which promotes efficient removal of matrix interferences. Analytical selectivity and sensitivity were achieved for the quantification of acrylamide and HDMF in complex matrices such as fruit, cereal and milk-based baby foods; furthermore, adequate linearity (range 10-300µgkg-1) in solvent and matrix-matched calibration curves, and appropriate recoveries (94-110%) and precision (RSD≤10%), under repeatability and within-laboratory reproducibility conditions, were also obtained. Expanded measurement uncertainty was estimated at the 20µgkg-1 level (limit of quantification) on the basis of data obtained from in-house validation, with values of 25.5 and 16.5% for acrylamide and HDMF, respectively. The fitness for purpose of developed method was verified by analyzing 15 commercial baby foods available in the Brazilian market. Acrylamide was detected in one plum-based baby food (35µgkg-1) while HDMF in 67% of the samples analyzed (levels between 25 and 262µgkg-1).

Estimation of herbicide bioconcentration in sugarcane (Saccharum officinarum L. ) / Modelagem de bioconcentração de herbicidas em cana (Saccharum officinarum L. )

Sugarcane is an important crop for sugar and biofuel production in Brazil. Growers depend greatly on herbicides to produce it. This experiment used herbicide physical-chemical and sugarcane plant physiological properties to simulate herbicide uptake and estimate the bioconcentration factor (BCF). The (BCF) was calculated for the steady state chemical equilibrium between the plant herbicide concentration and soil solution. Plant-water partition coefficient (sugarcane bagasse-water partition coefficient), herbicide dilution rate, metabolism and dissipation in the soil-plant system, as well as total plant biomass factors were used. In addition, we added Tebuthiuron at rate of 5.0kg a.i. ha-1 to physically test the model. In conclusion, the model showed the following ranking of herbicide uptake: sulfentrazone > picloram >tebuthiuron > hexazinone > metribuzin > simazine > ametryn > diuron > clomazone > acetochlor. Furthermore, the highest BCF herbicides showed higher Groundwater Ubiquity Score (GUS) index indicating high leaching potential. We did not find tebuthiuron in plants after three months of herbicide application.(AU)

A cana de açúcar é uma cultura importante para produção de açúcar e biocombustíveis no Brasil e exige elevada utilização de herbicidas. Utilizamos modelo matemático para ajudar na compreensão da absorção de herbicida dessa cultura. Propriedades físico-químicas dos herbicidas e propriedades fisiológicas das plantas de cana foram usados para estimar a absorção e também o fator de bioconcentração, bioconcentration factor (BCF), calculado para o equilíbrio químico entre a concentração do herbicida na planta e na solução do solo. O coeficiente de partição planta/água, a taxa de diluição de herbicida, o metabolismo e a dissipação no sistema solo-planta e biomassa total das plantas foram adicionados ao modelo. O herbicida tebuthiuron aplicado ao solo na dose de 5,0kg ha-1 i.a. foi utilizado para testar o modelo. A absorção dos herbicidas mostrada pelo modelo indicou em ordem o seguinte: sulfentrazone> picloram> tebuthiuron> hexazinone> metribuzin> simazina> ametryn> diuron> clomazone> acetochlor. Esses herbicidas com alto índice (BCF) também apresentaram alto índice de potencial de lixiviação para água subterrânea "Groundwater Ubiquity Score" (GUS). Tebuthiuron não foi encontrado nas plantas após três meses de aplicação.(AU)

Estimation of herbicide bioconcentration in sugarcane (Saccharum officinarum L.) / Modelagem de bioconcentração de herbicidas em cana (Saccharum officinarum L.)

Sugarcane is an important crop for sugar and biofuel production in Brazil. Growers depend greatly on herbicides to produce it. This experiment used herbicide physical-chemical and sugarcane plant physiological properties to simulate herbicide uptake and estimate the bioconcentration factor (BCF). The (BCF) was calculated for the steady state chemical equilibrium between the plant herbicide concentration and soil solution. Plant-water partition coefficient (sugarcane bagasse-water partition coefficient), herbicide dilution rate, metabolism and dissipation in the soil-plant system, as well as total plant biomass factors were used. In addition, we added Tebuthiuron at rate of 5.0kg a.i. ha-1 to physically test the model. In conclusion, the model showed the following ranking of herbicide uptake: sulfentrazone > picloram >tebuthiuron > hexazinone > metribuzin > simazine > ametryn > diuron > clomazone > acetochlor. Furthermore, the highest BCF herbicides showed higher Groundwater Ubiquity Score (GUS) index indicating high leaching potential. We did not find tebuthiuron in plants after three months of herbicide application.

A cana de açúcar é uma cultura importante para produção de açúcar e biocombustíveis no Brasil e exige elevada utilização de herbicidas. Utilizamos modelo matemático para ajudar na compreensão da absorção de herbicida dessa cultura. Propriedades físico-químicas dos herbicidas e propriedades fisiológicas das plantas de cana foram usados para estimar a absorção e também o fator de bioconcentração, bioconcentration factor (BCF), calculado para o equilíbrio químico entre a concentração do herbicida na planta e na solução do solo. O coeficiente de partição planta/água, a taxa de diluição de herbicida, o metabolismo e a dissipação no sistema solo-planta e biomassa total das plantas foram adicionados ao modelo. O herbicida tebuthiuron aplicado ao solo na dose de 5,0kg ha-1 i.a. foi utilizado para testar o modelo. A absorção dos herbicidas mostrada pelo modelo indicou em ordem o seguinte: sulfentrazone> picloram> tebuthiuron> hexazinone> metribuzin> simazina> ametryn> diuron> clomazone> acetochlor. Esses herbicidas com alto índice (BCF) também apresentaram alto índice de potencial de lixiviação para água subterrânea "Groundwater Ubiquity Score" (GUS). Tebuthiuron não foi encontrado nas plantas após três meses de aplicação.

Bioconcentration factor estimates of polycyclic aromatic hydrocarbons in grains of corn plants cultivated in soils treated with sewage sludge.

This study presents a model to simulate the organic substance concentrations in corn grains assuming that the substances in soil solution are absorbed via the transpiration stream by plants growing in soils fertilized with sewage sludge (SS). The model was applied and validated using soil and corn grain samples from a long-term field experiment with six successive yearly applications of SS to the soil. The following polycyclic aromatic hydrocarbons (PAHs) were simulated and evaluated in soil and grain samples: acenaphthene, acenaphthylene, anthracene, benz(a)anthracene, benz(a)pyrene, benz(b)fluoranthene, benz(g,h,i)perylene, benz(k)fluoranthene, chrysene, dibenz(a,h)anthracene, fluoranthene, fluorene, indeno(1,2,3-c,d)pyrene, naphthalene, phenanthrene and pyrene. The PAH bioconcentration factors (BCF) in corn grains ranged from 1.57 to 10.97 L kg(-1). Polycyclic aromatic hydrocarbons with low soil distribution coefficients and high values of transpiration stream concentration factors (TSCF) are more likely to be absorbed by corn plants and accumulated in grains. It was possible to estimate and observe that highly lipophilic PAH molecules (heavy PAHs) show lower accumulative potential in corn grains than the less lipophilic ones (light PAHs). Sewage sludges containing significant concentrations of light PAHs with two, three or four benzene rings should be avoided as fertilizers in alimentary field crops.