Cashew nut shell liquids: Antimicrobial compounds in prevention and control of the oral biofilms.

OBJECTIVE: The aim was to evaluate the antibacterial and antibiofilm activity of natural (n-CNSL) and technical (t-CNSL) cashew nut shell liquid against streptococci and enterococci related to dental caries and chronic apical periodontitis, respectively. MATERIAL AND METHODS: Minimum inhibitory concentrations (MIC) and minimal bactericidal concentration (MBC) were determined to assess the antimicrobial effect of both CNSLs (n-CSNL and t-CNSL) against S. oralis ATCC 10557, S. sobrinus ATCC 6715, S. parasanguinis ATCC 903, S. mutans UA 159 and E. faecalis ATCC 19433. The antibiofilm activity was evaluated by total biomass quantification, colony forming unit (CFU) counting and scanning electron microscopy (SEM). Furthermore, cytotoxic effect of the substances was evaluated on L929 and HaCat cell lines by MTS assay. RESULTS: The n-CNSL and t-CNSL showed inhibitory and bactericidal effect against all strains tested in this study, with MIC and MBC values ranging from 1.5 to 25 µg/mL. Overall, both CNSLs showed significant reduction in biomass quantification and enumeration of biofilm-entrapped cells for the strains analyzed, in biofilm formation and preformed biofilms (p < 0.05). In biofilm inhibition assay, the t-CNSL and n-CNSL showed reduction in biomass and CFU number for all bacteria, except in cell viability of S. parasanguinis treated with t-CNSL (p > 0.05). Indeed, SEM images showed a reduction in the amount of biomass, bacterial cells and changes in cellular morphology of S. mutans. CONCLUSION: In conclusion, both substances showed effective antibacterial and antibiofilm activity against the strains used in the study, except in viability of S. parasanguinis cells treated with t-CNSL.

Evaluation of Antimicrobial and Antioxidant Potential of Essential Oil from Croton piauhiensis Müll. Arg.

A large number of infections are caused by Gram-positive and Gram-negative multi-resistant bacteria worldwide, adding up to a figure of around 700,000 deaths per year. The indiscriminate uses of antibiotics, as well as their misuse, resulted in the selection of bacteria resistant to known antibiotics, for which it has little or no treatment. In this way, the strategies to combat the resistance of microorganisms are extremely important and, essential oils of Croton species have been extensively studied for this purpose. The aim of this study was to carry the evaluation of antibacterial, antibiofilm, antioxidant activities, and spectroscopic investigation of essential oil from Croton piauhiensis (EOCp). The EOCp exhibited antimicrobial activity against Gram-positive and Gram-negative bacteria with required MICs ranging from 0.15 to 5% (v/v). In addition, the MBC of the EOCp for Staphylococcus aureus ATCC 25923 and ATCC 700698, were 0.15 and 1.25%, respectively. Moreover, the EOCp significantly reduced significantly the biofilm production and the number of viable cells from the biofilm of all bacterial strains tested. The antioxidant potential of the EOCp showed EC50 values ranging from 171.21 to 4623.83 µg/mL. The EOCp caused hemolysis (>45%) at the higher concentrations tested (1.25 to 5%), and minor hemolysis (17.6%) at a concentration of 0.07%. In addition, docking studies indicated D-limonene as a phytochemical with potential for antimicrobial activity. This study indicated that the EOCp may be a potential agent against infections caused by bacterial biofilms, and act as a protective agent against ROS and oxidative stress.

Chemical composition, antioxidant, antimicrobial and antibiofilm activities of Vitex gardneriana schauer leaves's essential oil.

This study aimed to determinate the chemical composition and evaluate the antimicrobial and antioxidant activity of the essential oil obtained from leaves of V. gardneriana. The Vitex gardneriana leaves's were hydrodistilled to obtain the essential oil and the chemical composition determined by GC/MS analysis. The antimicrobial activities were determined by microdilution method. The activity of essential oil on biofilm was evaluated by quantification of total biomass and enumeration of biofilm-entrapped viable cells. The antioxidant activity was assessed by DPPH free radical assay, ferrous ion chelating assay, ferric-reducing antioxidant power and ß-carotene bleaching assay. Furthermore, the essential oil was tested on viability of health human, animal cells and the microcrustacean Artemia sp. The essential oil showed high content of sesquiterpenes and very low content of monoterpenes. Regarding activity on planktonic cells, the essential oil reduced the growth of the all species tested but showed MIC values only to S. aureus (0.31%). In general, the essential oil reduced significantly the biofilm biomass and the number of viable cells of bacteria and yeasts, mainly on biofilm formation. The essential oil showed a potential antioxidant activity, mainly on ß-carotene oxidation. Moreover, the essential oil reduced the cell viability of murine fibroblasts but not show viability reduction of human keratinocytes. Furthermore, the oil not show toxicity against the microcrustacean. Thus, the essential oil from V. gardneriana leaves may be considered as an important alternative against biofilms formed by bacteria and yeasts related to infections, as well as a natural antioxidant and non-toxic substance on human cells.

Isolation, biochemical characterization and antibiofilm effect of a lectin from the marine sponge Aplysina lactuca.

A new lectin was isolated from the marine sponge Aplysina lactuca (ALL) by combining ammonium sulfate precipitation and affinity chromatography on guar gum matrix. ALL showed affinity for the disaccharides α-lactose, ß-lactose and lactulose (Ka=12.5, 31.9 and 145.5M-1, respectively), as well as the glycoprotein porcine stomach mucin. Its hemagglutinating activity was stable in neutral acid pH values and temperatures below 60°C. ALL is a dimeric protein formed by two covalently linked polypeptide chains. The average molecular mass, as determined by Electrospray Ionization Mass Spectrometry (ESI-MS), was 31,810±2Da. ESI-MS data also indicated the presence of three cysteines involved in one intrachain and one interchain disulfide bond. The partial amino acid sequence of ALL was determined by tandem mass spectrometry. Eight tryptic peptides presented similarity with lectin I isolated from Axinella polypoides. Its secondary structure is predominantly ß-sheet, as indicated by circular dichroism (CD) spectroscopy. ALL agglutinated gram-positive and gram-negative bacterial cells, and it were able to significantly reduce the biomass of the bacterial biofilm tested at dose- dependent effect.