Plectranthus amboinicus essential oil and carvacrol bioactive against planktonic and biofilm of oxacillin- and vancomycin-resistant Staphylococcus aureus.

BACKGROUND: The emergence of multidrug-resistant bacteria is a worldwide concern and in order to find an alternative to this problem, the occurrence of antimicrobial compounds in Plectranthus amboinicus essential oil was investigated. Thus, this study aims to determine susceptibility of Staphylococcus aureus isolated from food to antibiotics, P. amboinicus essential oil (PAEO) and carvacrol. METHODS: Leaves and stem of P. amboinicus were used for extraction of essential oil (PAEO) by hydrodistillation technique and EO chemical analysis was performed by gas chromatography coupled to a mass spectrometer. S. aureus strains (n = 35) isolated from food and S. aureus ATCC 6538 were used to evaluate the antimicrobial and antibiofilm activity of PAEO and carvacrol. All strains (n = 35) were submitted to antimicrobial susceptibility profile by disk diffusion method. Determination of MIC and MBC was performed by microdilution technique and antibiofilm activity was determined by microtiter-plate technique with crystal violet assay and counting viable cells in Colony Forming Units (CFU). RESULTS: Carvacrol (88.17%) was the major component in the PAEO. Antibiotic resistance was detected in 28 S. aureus strains (80%) and 12 strains (34.3%) were oxacillin and vancomycin-resistant (OVRSA). From the 28 resistant strains, 7 (25%) showed resistance plasmid of 12,000 bp. All strains (n = 35) were sensitive to PAEO and carvacrol, with inhibition zones ranging from 16 to 38 mm and 23 to 42 mm, respectively. The lowest MIC (0.25 mg mL-1) and MBC (0.5 mg mL-1) values were observed when carvacrol was used against OVRSA. When a 0.5 mg mL-1 concentration of PAEO and carvacrol was used, no viable cells were found on S. aureus biofilm. CONCLUSION: The antibacterial effect of carvacrol and PAEO proves to be a possible alternative against planktonic forms and staphylococcal biofilm.

In Vitro Antibacterial and Antibiofilm Activity of Lippia alba Essential Oil, Citral, and Carvone against Staphylococcus aureus.

In vitro antimicrobial and antibiofilm activities of the Lippia alba essential oil and its major components (citral and carvone) against Staphylococcus aureus were investigated. Essential oils (LA1EO, LA2EO, and LA3EO) were extracted from the aerial parts of three L. alba specimens by hydrodistillation and analyzed by gas chromatography coupled to a mass spectrometer. Minimum Inhibitory Concentrations (MIC) and Minimum Bacterial Concentration (MBC) were determined by the microdilution method. For the antibiofilm assays, the biomass formation in the biofilm was evaluated by the microtiter-plate technique with the crystal violet (CV) assay and the viability of the bacterial cells was analyzed. All oils and their major components presented antibacterial activity, and the lowest MIC and MBC values were 0.5 mg mL-1 when LA1EO and citral were used. Potential inhibition (100%) of S. aureus biofilm formation at the concentration of 0.5 mg mL-1 of all EOs was observed. However, the elimination of biofilm cells was confirmed at concentrations of 1 mg mL-1, 2 mg mL-1, 2 mg mL-1, and 0.5 mg mL-1 for LA1EO, LA2EO, LA3EO, and citral, respectively. The results obtained in the present research point to the promising antibacterial and antibiofilm potential of L. alba EOs against S. aureus, a species of recognized clinical interest.

Antibiofilm activity of the essential oil of citronella (Cymbopogon nardus) and its major component, geraniol, on the bacterial biofilms of Staphylococcus aureus.

Medicinal plants with antimicrobial action have been investigated for uses against biofilms, among which, Cymbopogon nardus, citronella, stands out as a promising species. The present study aims to evaluate the antimicrobial and antibiofilm action of the essential oil of C. nardus (EOCN) and geraniol on Gram-negative and positive bacteria from the determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration and inhibition of biofilms. In the results, the EOCN produced a 41 mm halo on S. aureus, which was susceptible with MIC values of 0.5 and 0.25 mg/mL for the EOCN and geraniol respectively, both with bactericidal effect. The antibiofilm action was confirmed, the EOCN and geraniol reduced the biofilm biomass of S. aureus up to 100% between 0.5 and 4 mg/mL concentrations. The reduction of cell viability was 0.25 and 1 mg/mL, of EOCN and geraniol, respectively. EOCN and geraniol were shown to be promising antibiotic against S. aureus.

Avaliação citotóxica, genotóxica e mutagênica do extrato de Morinda citrifolia em diferentes concentrações sobre o teste Allium Cepa / Cytotoxic, genotoxic and mutagenic evaluation of Morinda citrifolia extract in different concentrations about the test Allium Cepa

Introdução: o uso de Morinda citrifolia (noni) realizado com várias finalidades, no entanto, sua eficácia ainda não é, plenamente, comprovada. Segundo a Agência Nacional de Vigilância Sanitária (2007), as publicações científicas sobre o suco de noni têm trazido muita controvérsia sobre sua segurança como alimento. Objetivos: o objetivo do presente trabalho foi avaliar quais concentrações de Morinda citrifolia não apresentam efeitos citotóxicos, genotóxicos e mutagênicos, possibilitando seu uso em futuras formas farmacêuticas. Metodologia: os frutos foram picados e desidratados em estufa. Em seguida o material foi pulverizado, obtendo-se o extrato seco. Foram utilizados bulbos de Alium cepa para testar as seguintes concentrações: controle negativo (água filtrada), 1 mg/mL (Tratamento 1), 1,5 mg/mL (Tratamento 2), 2 mg/mL (Tratamento 3), controle positivo (paracetamol 90 mg/mL). Resultados: os resultados encontrados na análise dos dados do extrato aquoso, demonstram que as três concentrações testadas de Morinda citrifolia apresenta atividade tóxica pela inibição do comprimento e pela diminuição do ciclo celular das raízes. Além disso, a Morinda citrifolia apresenta atividade citotóxica, devido à redução do índice mitótico, em todas as concentrações analisadas. Bem como, apresenta atividade genotóxica, nas duas maiores concentrações do extrato (1,5 mg/mL e 2,0 mg/mL). Conclusão: o presente estudo demonstrou que os extratos de Morinda citrifolia apresenta atividade citotóxica e genotóxica em todas as concentrações analisadas. É necessário realizar outros trabalhos para a avaliação da Morinda citrifolia em concentrações menores, para assim se estabelecer quais são as concentrações seguras de utilização do suco desse fruto