Screening of plants with antimicrobial activity against enterobacteria, Pseudomonas spp. and Staphylococcus spp.

AIM: This study screened plants for antibacterial properties against bacteria of medical importance. MATERIALS & METHODS: 60 extracts were obtained from the leaves of ten plants (Jatropha weddelliana, Attalea phalerata, Buchenavia tomentosa, Croton doctoris, Mouriri elliptica, Mascagnia benthamiana, Senna aculeata, Unonopis guatterioides, Allagoptera leucocalyx and Bactris glaucescens) using different extraction methods: A) Ethanol 70°C/72 h; B) Water/5 min/100°C; C) Water/1 h/55°C; D) Water/72 h; E) Hexane/72 h and F) Ethanol 99°C/72 h. Enterobacteria/Pseudomonas and staphylococci reference strains and 201 clinical isolates were used. Primary screening was done using agar well-diffusion assay. MIC/minimum bactericidal concentration and chemical characterization were determined. RESULTS: Extracts 5F and 3A showed the best MIC/minimum bactericidal concentration against clinical isolates and showed the presence of phenols. CONCLUSION: The present study demonstrated that Mouriri elliptica and Buchenavia tomentosa were the most active plants against the studied bacteria.

Cymbopogon citratus essential oil: effect on polymicrobial caries-related biofilm with low cytotoxicity

Abstract The objective of this study was to evaluate the effects of Cymbopogon citratus essential oil and its main compound (citral) against primary dental colonizers and caries-related species. Chemical characterization of the essential oil was performed by gas chromatography/mass spectroscopy (GC/MS), and the main compound was determined. Antimicrobial activity was tested against Actinomyces naeslundii, Lactobacillus acidophilus, S. gordonii, S. mitis, S. mutans, S. sanguinis and S. sobrinus. Minimum inhibitory and bactericide concentrations were determined by broth microdilution assay for streptococci and lactobacilli reference, and for clinical strains. The effect of the essential oil on bacterial adhesion and biofilm formation/disruption was investigated. Negative (without treatment) and positive controls (chlorhexidine) were used. The effect of citral on preformed biofilm was also tested using the same methodology. Monospecies and microcosm biofilms were tested. ANOVA or Kruskal-Wallis tests were used (α=0.05). Cytotoxicity of the essential oil to human keratinocytes was performed by MTT assay. GC/MS demonstrated one major component (citral). The essential oil showed an inhibitory effect on all tested bacterial species, including S. mutans and L. acidophilus. Essential oil of C. citratus (10X MIC) reduced the number of viable cells of lactobacilli and streptococci biofilms (p < 0.05). The essential oil inhibited adhesion of caries-related polymicrobial biofilm to dental enamel (p < 0.01). Citral significantly reduced the number of viable cells of streptococci biofilm (p < 0.001). The essential oil showed low cytotoxicity to human keratinocytes. Based on these findings, this study can contribute to the development of new formulations for products like mouthwash, against dental biofilms.

Investigação das propriedades antimicrobianas de frações obtidas a partir dos extratos hidroalcoólico e etanólico de Croton doctoris S. Moore / Evaluation of antimicrobial properties of fractions obtained from hydroalcoholic and ethanolic extracts from Croton doctoris S. Moore

Na última década, tratamentos com plantas medicinais se expandiram pelo mundo e ganharam popularidade. O objetivo desse trabalho foi avaliar o efeito antimicrobiano de frações de extratos de Croton doctoris S. Moore sobre micro-organismos envolvidos na etiologia cárie dentária e identificar substâncias com efeito antimicrobiano dentro das frações mais ativas. Extratos foram obtidos por maceração do pó das folhas em etanol 70º ou etanol 99,5º (1 g / 20 ml de solvente; 72h). Em seguida, frações foram obtidas por extração líquido-líquido dos extratos com diferentes solventes. As frações mais ativas foram selecionadas através do teste de difusão em ágar utilizando cepas de referência (Actinomyces naeslundii ATCC 19039, Lactobacillus acidophilus ATCC 4356, Streptococcus gordonii ATCC 10558, Streptococcus mitis ATCC 9811, Streptococcus mutans ATCC 35688, Streptococcus sanguinis ATCC 10556, Streptococcus sobrinus ATCC 33478). As concentrações inibitórias e bactericidas mínimas (CIM e CBM) das frações mais ativas foram determinadas para as cepas de referência e isolados clínicos de dentina cariada de estreptococos do grupo mutans e lactobacilos. O efeito sobre biofilme em modelo de microcosmo a partir da saliva foi avaliado para as frações mais ativas em concentrações 2, 4 e 10 vezes o valor de CIM. As mesmas frações, em concentração referente a ½ CIM, foram analisadas quanto a capacidade de inibir a adesão de micro-organismos ao esmalte dentário em modelo de microcosmo. A caracterização química das frações ativas foi realizada através de espectometria de massas. A triagem mostrou que as frações diclorometânicas dos extratos hidroalcoólico (HD) e etanólico (ED) e a fração hexânica do extrato hidroalcoólico (HH) apresentaram atividade antimicrobiana. Os valores de CIM variaram de 0,1 a 3,1 mg/ml e CBM de 0,1 a >50 mg/ml para as cepas de referências, sendo que os melhores resultados foram encontrados nas frações HD e ED. Os valores de CIM e CBM para isolados clínicos ...

In the past decade, treatment with medicinal plants expanded worldwide and gained popularity. The aim of this study was to evaluate the antimicrobial effect of fractions from extracts of Croton doctoris S. Moore against microorganisms of cariogenic relevance and to identify substances with antimicrobial action in the most active fractions. Crude extracts was obtained by maceration of powdered leaves in 70% ethanol or 99.5% ethanol (1 g / 20 ml, 72 h).The fractions were obtained by liquid-liquid extraction with different solvents. The most active fractions were selected by agar well diffusion test against reference strains (Actinomyces naeslundii ATCC 19039, Lactobacillus acidophilus ATCC 4356, Streptococcus gordonii ATCC 10558, Streptococcus mitis ATCC 9811, Streptococcus mutans ATCC 35688, Streptococcus sanguinis ATCC 10556, Streptococcus sobrinus ATCC 33478). Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of most active fractions were evaluated against reference strains and clinical isolates of lactobacilus and mutans streptococci. The activity against microcosm biofilm obtained from human saliva was evaluated for the most active fractions at 2, 4 and 10 times MIC. These fractions (½ MIC) were also tested for inhibition of microorganism adhesion to enamel. Chemical characterization of most active fractions was made using mass spectrometry. The screening showed that dichoromethanic fractions of hydroalcoholic and ethanolic extracts (HD and ED) and hexanic fration of hydroalcoholic extract (HH) had antimicrobial activity. The MIC and MBC values for reference strains ranged from 0.1 to 3.1 mg/ml and 0.1 to >50 mg/ml. HD and ED fractions showed the best values. For lactobacilli clinical isolates MIC and MBC ranged from 0.1 to 25 mg/ml and 0.2 to >50 mg/ml. MIC and MBC for mutans streptococci clinical isolates ranged from 0.8 to 25 mg/ml and 3.1 a >50 mg/ml. Activity against biofilms showed that HD fraction...