Antimicrobial activity and acute and chronic toxicity of the essential oil of Lippia origanoides

Currently, there is a growing interest in medicinal plants, because of an increased demand for alternate therapies. In this study, the antimicrobial activity and toxicity of the essential oil of Lippia origanoides (L. origanoides) were investigated. The essential oil of L. origanoides was extracted by steam-dragging distillation and its constituents were identified by chromatography coupled with mass spectrometry. Among the 15 compounds identified, the most abundant were carvacrol (29.00%), o-cymene (25.57%), and thymol methyl ether (11.50%). The essential oil was studied in antimicrobial assays to determine the MIC and MBC. The results indicated that a concentration of 120μL/mL of oil was sufficient to inhibit the growth of the following microorganisms: Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923) and Salmonella cholerasuis (ATCC 10708). Acute and chronic toxic effects of orally administered oil were investigated in Wistar rats by using standard methods. Doses of 30, 60 and 120mg/kg of the essential oil did not induce significant changes in weight, behavior or hematological and biochemical parameters in the animals. There were no signs of any histopathological changes to the liver, kidneys or heart of the treated rats, suggesting that Lippia origanoides oil is non-toxic after oral administration in acute or chronic toxicity studies. The results obtained in this study show that the essential oil of L. origanoides has a high safety margin, with no detectable toxic effects in rats treated with doses to 120mg/kg. In addition, L. origanoides oil demonstrated potent antimicrobial activity against S. aureus, E. coli and S. cholerasuis. Based on these findings, this essential oil may have practical application as a veterinary antimicrobial

A SPECT study of the effect of vagal nerve stimulation on thalamic activity in patients with epilepsy

AbstractThe mechanism by which vagal nerve stimulation (VNS) exerts an anticonvulsant effect in humans is unknown. This study used99 mTc-HMPAO single photon emission tomography (SPECT) to examine the effects of VNS on regional cerebral activity in thalamic and insular regions. Seven subjects with epilepsy who had been receiving vagal nerve stimulation for at least 6 months underwent SPECT scanning with simultaneous scalp electroencephalographic (EEG) recording. Subjects were studied in two states; during VNS activity and during a comparison condition of VNS inactivity. A region of interest analysis demonstrated that rapid cycling stimulation (7 seconds on, 12 seconds off) was associated with relatively decreased activity in left and right medial thalamic regions. No systematic stimulation-related changes were observed on visual or spectral analysis of EEG data. The thalamus is involved in modulation of ongoing cortical EEG activity in animals. Our results support the hypothesis that VNS may exert an antiepileptic action by an effect on thalamic activity

Controle e susceptibilidade de capim-braquiária e capim-ruziziensis ao glyphosate e fluazifop-p-butil

Este estudo teve como objetivo avaliar o controle e susceptibilidade de capim-braquiária e capim-ruziziensis em crescimento inicial submetidos a diferentes doses dos herbicidas glyphosate e fluazifop-p-butil. Os tratamentos foram arranjados no esquema fatorial 2 × 6, com cinco repetições, sendo duas gramíneas: Brachiaria decumbens cv. Basilisk (capim-braquiária) e B. ruziziensis (capim-ruziziensis), e seis doses dos herbicidas: 0,00; 0,25; 0,50; 1,00; 1,5 e 2,00 vezes a dose comercial indicada pelos fabricantes. Aos 7, 15, 21 e 30 dias após aplicação dos herbicidas (DAA) foram avaliadas visualmente a intoxicação em capim-braquiária e capim-ruziziensis. O glyphosate causou intoxicação de 100% em plantas de capim-braquiária e capim-ruziziensis, mesmo na menor dose (90 g ha-1), podendo ser utilizado com eficiência para o controle dessas espécies no início de desenvolvimento. Foi observado que as plantas submetidas ao fluazifop-p-butil apresentaram rebrota apenas nas doses aplicadas até 100 g ha-1 para capim-braquiária e 50 g ha-1 para o capim-ruziziensis. Esses resultados confirmam a eficiência dessa molécula herbicida no controle dessas duas espécies a partir das doses de 200 g ha-1 e 100 g ha-1 para capim-braquiária e capim-ruziziensis, respectivamente.</jats:p