Chemical Composition and Antibacterial Activity of the Lippia origanoides Kunth Essential Oil from the Carajás National Forest, Brazil.

Species of the genus Lippia are rich in essential oils and have shown antibacterial properties, which may be related to oils' chemical composition. The present work aimed to evaluate the antimicrobial potential of Lippia origanoides Kunth against two bacteria strains: Escherichia coli and Staphylococcus aureus. Leaf essential oils were obtained by hydrodistillation in a modified Clevenger-type apparatus, and their chemical composition was determined by gas chromatography coupled to mass spectrometry (GC/MS) and flame ionization detection (GC/FID). We identified 28 compounds, representing 98.87% of the total concentration of the essential oil. The compounds identified at the highest concentrations were 1,8-cineole (35.04%), carvacrol (11.32%), p-cymene (8.53%), α-pinene (7.17%), and γ-terpinene (7.16%). The leaf essential oil of L. origanoides showed antibacterial action on biological isolates of Escherichia coli and Staphylococcus aureus. For Escherichia coli, the oil presented bactericidal action at concentrations of 5-20 µL/mL. Regarding Staphylococcus aureus, the bactericidal effect was noted at 20 µL/mL and the bacteriostatic action was noted around 2.5-10 µL/mL. Given the results obtained, L. origanoides essential oil showed promising biological potential against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria, thus encouraging further studies on substances isolated from this species to contribute to the development of new antimicrobial drugs.

Evaluation of acute and subacute toxicity of ethanolic extract and fraction of alkaloids from bark of Aspidosperma nitidum in mice.

This study investigated the acute and subacute toxicity of the ethanolic extract (EE) and alkaloid fraction (FA) from A. nitidum. The EE was obtained from trunk bark with ethanol, FA was obtained from the fractionation of EE. To test the acute toxicity, mice were divided into four groups, and the negative controls received water or aqueous solution of dimethyl sulfoxide, whereas the others received EE or FA (2000 mg/kg, orally, single dose). The same controls were used in the subacute trial. However, the animals were treated for 28 days, and the dose used was 1000 mg/kg per day of EE and FA. Daily clinical evaluations of the animals were performed. At the end of the experiment, hematological, biochemical, and histopathological assessments (liver, lung, heart, and kidney) were performed. In the acute and subacute toxicity studies, mice treated with EE and FA did not show any clinical changes, there were no changes in weight gain, hematological and biochemical parameters compared to the control groups (p > 0.05). In the histopathological examination, there was no abnormality in the organs of the treated animals. Therefore, EE and FA did not produce toxic effects in mice after acute and subacute treatment.