ABSTRACT:Staphylococcus aureus is a classical pathogen microorganism and it is commonly recognized as etiological agent of many community and nosocomial infections. Regarding the knowledge about the biological properties of Lippia sidoides Cham. (Verbenaceae), this study aimed to evaluate the effectiveness of its essential oil in inhibiting the growth of S. aureus strains isolated from clinical materials and with different profi les of antibiotic resistance. The results showed prominent anti-S. aureus activity of L. sidoides essential oil noted by large growth inhibition zones (15-21 mm). MIC found was of 0.4 L/mL for all assayed strains. MIC presented prominent effectiveness in inhibiting the viability of S. aureus in broth during twenty-four hours of exposure characterizing a bacteriostatic effect. These results show the promising anti-staphylococcal property of L. sidoides essential oil and support the possibility of its rational use as alternative antibacterial agent.

The genus Acinetobacter has gained importance in recent years due to involvement in serious infections and antimicrobial resistance. Many plants have been evaluated not only for direct antimicrobial activity, but also as resistance modifying agents. The Essential oil of Citrus limon (EOCL) addition at 156.25 µgmL(-1) (MIC/8) sub-inhibitory concentration in the growth medium led to MIC decrease for amikacin, imipenem and meropenem. The Essential oil of Cinnamomum zeylanicum (EOCZ) addition at 78.125 µg mL(-1) (MIC/8) sub-inhibitory concentrations in the growth medium caused drastic MIC reduction of amikacin. Results of combining antibiotics and essential oils had shown us a synergistic effect with both essential oils/amikacin combinations. An additive effect was observed with the combinations of both essential oils and gentamicin. The results of this study suggest that essential oil of C. limon and C. zeylanicum may suppress the growth of Acinetobacter species and could be a source of metabolites with antibacterial modifying activity.

This study aimed to evaluate the antibacterial activity of Origanum vulgare L. and O. majorana L. essential oils on Staphylococcus aureus, S. coagulase negative, Enterobacter spp., Proteus spp., Acinetobacter spp., Klebsiella spp. isolated from the patients with conjunctivitis. The results showed a prominent inhibitory effect of both the essential oils on all the bacterial strains, noted by the large bacterial growth inhibition zones (15-32mm). The Minimum Inhibitory Concentrations (MIC) values were between 5-20µL/mL and 2.5-10 µL/mL for O. vulgare and O. majorana essential oil, respectively. The MIC were able to cause significant (P<0.05) inhibitory effect on the cell viability of Klebsiella spp., Proteus spp. and S. aureus providing a total elimination of the bacterial inoculum in a maximum time of 24 h of exposure. These results showed the antibacterial effectiveness of O. vulgare and O. marjorana essential oils and supported the possibility of their use as the sources of alternative antimicrobial compounds.
Este estudo objetivou analisar a atividade antibacteriana do óleo essencial de O. vulgare L. and O. majorana L. sobre cepas bacterianas (Staphylococcus aureus, S. coagulase negative, Enterobacter spp., Proteus spp., Acinetobacter spp., Klebsiella spp.) isoladas de pacientes com conjuntivite. Os resultados mostraram um destacável efeito inibitório de ambos os óleos essenciais ensaiadossobre todas as cepas bacterianas, notado pela formação de amplas zonas de inibição do crescimento bacteriano (15-32 mm). Os valores de Concentração Inibitória Mínima - CIM encontradas estiveram entre 5-20µL/mL e 2.5-10 µL/mL para o óleo essencial de O. vulgare e O. majorana, respectivamente. Os valores de CIM foram capazes de causar significante efeito inibitório sobre a viabilidade celular de Klebisiella spp., Proteus spp. e S. aureus causando uma total eliminação do inóculo microbiano em um tempo máximo de 24 h de exposição. Estes resultados mostraram a efetividade antibacteriana dos óleos essenciais de O. vulgare e O. majorana, bem como suporta a possibilidade do uso de tais produtos como fontes de compostos antimicrobianos

The aim of the present study was to evaluate, in vitro, the photoprotective activity of the ethanolic extract of Rhaphiodon (R.) echinus. The experiment was carried out with different concentrations of the natural product (50, 100, 500 and 1000 μg / mL). Through scans with the aid of an spectrophotometer, in the ranges (290 to 320 nm) with 5 nm intervals. The data were submitted to Mansur et al. (1986) equation. According to the results obtained, only the two highest concentrations (500 μg / mL and 1000 μg / mL) showed considerable photoprotection values and above the minimum protection factor of 6 (SPF), being 23.65 and 25.00 respectively. Thus, the photoprotective activity of the ethanol extract, in vitro, of R. echinusdemonstra uma importante característica bioativa. Além disso, o resultado ainda sugere um possível uso dessa planta em formulações fitocosméticas, uma vez que o uso de plantas como fotoprotetores é uma das alternativas acessíveis.

The present work aims to evaluate the Minimum Inhibitory Concentration of Adherence (MICA) of the essential oils of Eucalyptus globulus and Eucalyptus citriodora against the bacterium Klebsiella pneumoniae. It was performed the determination of the Minimum Inhibitory Concentration of Adherence (MICA) using the inclined tube technique, in the presence of 5% sucrose. After 24 hours, the reading was performed through visual observation of the bacterium's adherence to the tube walls. It was observed that the essential oil of Eucalyptus globulus showed a good antiadherent efficiency to the strain of Klebsiella pneumoniae, showing biofilm inhibition at a concentration of 1:8 similar to the 0.12% chlorhexidine digluconate control. Eucalyptus citriodora oil did not inhibit biofilm formation in any of the tested concentrations. It was concluded that only the essential oil belonging to the Eucalyptus globulus species, showed antiadherent action against the strain of Klebsiella pneumoniae, which can be used as an alternative method to combat biofilms produced by K. pneumoniae.