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Abstract The NorA efflux pump of Staphylococcus aureus is known to play a major role in the development of resistance against quinolone drugs by reducing their concentration inside target pathogens. The objective of this study was to evaluate the ability of tannic acid to inhibit the gene expression of the NorA efflux pump in Staphylococcus aureus and to evaluate the in silico effect on the pump. Efflux pump inhibition was evaluated by fluorimetry. The checkerboard method evaluates the effect of the test substance in combination with an antimicrobial at different concentrations. To gene expression evaluation NorA the assay was performed using: a sub-inhibitory concentration preparation (MIC/4) of the antibiotic; a sub-inhibitory concentration preparation (MIC/4) of the antibiotic associated with tannic acid at a sub-inhibitory concentration (MIC/4). In this study, docking simulations were performed by the SWISSDOCK webserver. The ability of tannic acid to inhibit the NorA efflux pump can be related to both the ability to inhibit the gene expression of this protein, acting on signaling pathways involving the ArlRS membrane sensor. As well as acting directly through direct interaction with the NorA protein, as seen in the approach and in silico and in vitro per checkerboard method and fluorimetry of bromide accumulated in the cell.

A espécie Hyptis martiusii Benth é popularmente conhecida como “cidreira do campo”. Possui várias atividades biológicas, dentre elas atividades antifúngica, antiin amatória e inseticida. O objetivo deste trabalho foi investigar a atividade moduladora do óleo essencial das folhas frescas de Hyptis martiusii em associação com diferentes antibióticos frente às bactérias Staphylococcus aureus, Escherichia coli e Pseudomonas aeruginosa, como também a atividade citotóxica da espécie. O estudo utilizou a cim (con- centração inibitória mínima) como forma de avaliação da modulação usando uma inoculação de 100 microlitros de cada estirpe bacteriana. Os ensaios de citotoxicidade foram realizados in vitro utilizando a cultura de linhagem de células do tecido conectivo de camundongo ( broblastos de mamíferos). A pesquisa demonstrou que o Óleo Essencial das folhas de Hyptis martiusii Benth —oehm— apresentou sinergismo apenas em associação com os antibióticos gentamicina e imipenem frente às bactérias Pseudomonas aeruginosa e Escherichia coli. No entanto, apresentou antagonismo em associação com amicacina, gentamicina e imipenem frente às três bactérias estudadas. Em junção com o cipro oxaci- no não apresentou resultados relevantes. Em relação à atividade citotóxica a concentração letal média (LC50) expôs um valor de 263,12 μg/ml. Por m, revelou-se que H. martiusii apresenta atividade citotóxica e baixa atividade sinérgica frente às bactérias avaliadas.

Mauritia flexuosa (buriti) is a typical Brazilian palm tree found in swampy regions with many plant forms. The fruit has various purposes with the pulps to the seeds being used for ice creams, sweets, creams, jellies, liqueurs, and vitamin production. A physicochemical characterization of the fixed pulp oil and its antibacterial and aminoglycoside antibiotic modifying activity against Gram-positive and Gram-negative multiresistant bacterial strains were performed using broth microdilution assays. Physical properties, such as moisture, pH, acidity, peroxide index, relative density, and refractive index, indicated oil stability and chemical quality. In the GC/MS chemical composition analysis, a high content of unsaturated fatty acids (89.81%) in relation to saturated fatty acids (10.19%) was observed. Oleic acid (89.81%) was the main fatty acid identified. In the antibacterial test, the fixed oil obtained the Minimum Inhibitory Concentration (MIC) ≥ 1024 μg/mL for all standard and multiresistant bacterial strains. The synergic effect of fixed pulp oil combined was observed only in Staphylococcus aureus SA⁻10, with an MIC reduction of the gentamicin and amikacin by 40.00% and 60.55%, respectively. The data indicates the M. flexuosa fixed oil as a valuable source of oleic acid and modulator of aminoglycoside activity.