Use of essential oils from plants of Araripe National Forest against Aedes aegypti (Diptera: Culicidae).

Aedes aegypti control is achieved with chemical insecticides that can promote insecticide resistance. In the search for new forms of control, the use of botanical products is currently growing and many tests with oils have already been performed. The plant diversity of Araripe National Forest enables the study of several species against this vector. To evaluate the larvicidal effect of essential oils from plants of this forest, we used field rosemary, copaiba, bay leaf, cashew and pequi. The work was divided into three stages: all oils with the same dosage; the best oil at dosages of 0, 5, 10, 20, 50 and 75 µg/mL; and the best dosage at temperatures of 15, 20, 25, 30 and 35 °C. The oils of field rosemary, copaiba, bay leaf, cashew and pequi were good insecticides when used at dosages above 5 µg/mL. The bay leaf oil showed high larvicidal activity at all dosages tested, showing the highest efficiency at 75 µg/mL. Temperatures of 15 and 35 °C increased the susceptibility of the insect to the effect of the bay leaf oil. The essential oils of field rosemary, copaiba, bay leaf, cashew and pequi, from Araripe National Forest, applied at a dosage of 5µg/mL, showed insecticidal action, although with low efficiency.

Cholesterol and ergosterol affect the activity of Staphylococcus aureus antibiotic efflux pumps.

The aim of this study is to evaluate the effect of ergosterol on steroids and cholesterol efflux pumps in multidrug resistant strains of S. aureus. Were used RN4220 harboring plasmid pUL5054, which carries the gene encoding the MsrA macrolide efflux protein; and IS-58, which possesses the TetK tetracycline efflux protein; 1199B resists hydrophilic fluoroquinolones via a NorA-mediated mechanism and wild strain 1199B. The Minimal Inhibitory Concentration (MIC) was determined and the evaluation of possible inhibition of efflux pumps by reduction of MIC. Some of the detrimental effects on bacterial cells can be attributed to the detergent properties of cholesterol and ergosterol on account of their amphipathic structure. Besides the cholesterol did not affect directly the pump structure, a synergism was observed, maybe due the interaction with the cell membrane and interference in the lipid bilayer.

Avaliação das potenciais atividades tripanocida e antileishmania do extrato de folhas de Piper arboreum (Piperaceae) e de suas frações / Evaluation of the potential trypanocidal and antileishmanial activities in Piper arboreum (Piperaceae) leaf extract and its fractions

A leishmaniose e a tripanossomíase americana fazem parte de um grupo de doenças tropicais endêmicas, especialmente entre as populações pobres. São consideradas doenças negligenciadas por não despertarem interesse da indústria farmacêutica. Atualmente, a quimioterapia é o único tratamento específico disponível para estas doenças, onde os medicamentos utilizados são nifurtimox e benzonidazol. Este trabalho teve como objetivo avaliar a atividade antiparasitária e citotóxica do extrato bruto etanólico e frações de folhas de Piper arboreum, frente a linhagens de Leishmania brasiliensis e de Trypanosoma cruzi. Após a preparação do extrato etanólico bruto e as suas respectivas frações, testes in vitro foram realizados para avaliar atividade antiparasitária frente a T. cruzi, utilizado o clone epimastigota CL-B5 e contra L.brasiliensis foram utilizadas formas promastigotas. O ensaio de citotoxicidade foi realizado com linhagens de fibroblastos NCTC929. Os resultados indicaram que as amostras apresentaram toxidade elevada, com exceção da fração de acetato de etila. Já os resultados da atividade antiparasitária indicaram uma maior atividade da fração hexânica observando a morte de 62% e 51% de células epimastigotas e de 100% e 92% de células promastigotas, respectivamente. Através dos resultados conclui-se que a P. arboreum pode ser considerada uma fonte alternativa de produtos naturais com atividade contra T. cruzi e L. brasiliensis...

Leishmaniasis and South American trypanosomiasis (Chagas disease) are part of a group of related human diseases endemic in tropical regions, especially among the poor. They are referred to as neglected diseases, because of a lack of interest on the part of the pharmaceutical industry. Today, chemotherapy is the only specific treatment against these diseases, the most frequently used drugs being nifurtimox and benznidazole. The aim of this study was to assess the antiparasitic and cytotoxic activity of the crude ethanolic leaf extract of Piper arboreum and its fractions against strains of Leishmania brasiliensis and Trypanosoma cruzi. After preparing the crude ethanolic extract and fractions, in vitro tests were performed to assay antiparasitic activity against T. cruzi, using the epimastigote clone CL-B5, while against L. brasiliensis, promastigote forms were used. The cytotoxicity assay was performed with a fibroblast cell line, NCTC 929. The results indicate that the samples possessed high toxicity, except for the ethyl acetate fraction. The results for antiparasitic activity showed highest activity in the hexane fraction, which was lethal to 62% and 51% of the epimastigotes and 100% and 92% of the promastigotes, at 500 and 100µg/mL, respectively. From these results, it is concluded that P. arboreum can be considered an alternative source of natural products with activity against T. cruzi and L.brasiliensis...

Phenolic compounds and interaction between aminoglycosides and natural products of Lygodium venustum SW against multiresistant bacteria.

BACKGROUND: The aim of this work was to evaluate the interactions between aminoglycosides and the ethyl-acetate fraction of the fern Lygodium venustum SW (EAFLV) METHODS: The ethyl-acetate fraction was obtained from the ethanol extract of L. venustum and was assayed via the checkerboard method associated with aminoglycosides against two bacterial strains multiresistant to antibiotics. RESULTS: The antibiotic activity of all drugs, when associated with the ethyl-acetate fraction, was enhanced in an additive manner, except for the association between EAFLV and amikacin, which showed a synergistic interaction against the Escherichia coli strain. CONCLUSIONS: The results indicated that L. venustum can be a source of secondary metabolites to be used in association with antibiotics like aminoglycosides in antibiotic chemotherapy against resistant bacteria.