Escherichia coli biofilm formation and control by phenolic compounds from Salvia officinalis L. Extracts

Biofilm is recognized as one of the virulence factors of uropathogenic Escherichia coli. It offers bacteria significantly increased tolerance to antibiotics and makes difficulties in infection eradication. In this study, the biofilm formation ability of clinical isolates of uropathogenic E. coli as well as the antibiofilm activity of the common Garden sage, Salvia officinalis L. extracts were investigated in vitro. The influence of growth conditions (nutrient composition and incubation period) on biofilm formation of E. coli strains was evaluated using crystal violet staining procedure. The tested strains better formed biofilms after a longer incubation period (48 h). In addition, biofilm formation depended on nutrient medium composition. The eight strains were slime producers (Congo red agar assay). The water, ethanol, acetone and diethyl ether S. officinalis extracts were screened for their ability to inhibit the formation and metabolic activity of E. coli biofilms using crystal violet and resazurin assay, respectively. The water extract was not active, while ethanol, acetone and diethyl ether extract exhibited antibiofilm activity (MBIC= 2.5-10 mg/mL). The microscopic visualization of treated E. coli LM1 biofilm has shown morphological and density changes. In addition, the concentrations of phenolic compounds were determined spectrophotometrically. The highest content of total phenolics was found in acetone extract while the flavonoids in water extract

Antimicrobial, Antioxidant and Antibiofilm Potential of Peppermint (Mentha piperita) Essential Oil for Application in Meat Products

The current study was carried out to examine in-vitro antimicrobial, antioxidant and antibiofilm efficacy of Peppermint essential oil (PEO) for its potential application in meat products. Antimicrobial activity was measured by using zone inhibition assay (ZOI) and Minimum Inhibitory Concentration (MIC) against ten food borne pathogens including four Gram-positive viz. Listeria monocytogenes, Enterococcus faecalis, Bacillus cereus and Staphylococcus aureus and six Gram-negative viz. Proteus mirabilis, Salmonella enterica serovar Typhi, Klebsiella pneumonia, Shigella flexneri, Escherichia coli and Pseudomonas aeruginosa whereas antioxidant assay was measured using 1,1 diphenyl-2 picrylhydrazyl (DPPH) and 2-2- azinobis-3 ethylbenthiazoline-6-sulphonic acid (ABTS) radical scavenging activity. Maximum zone size was observed for Proteus mirabilis whereas, MIC values ranged from 5000-20000 ppm for all tested organisms. The oil was found to be more effective against Pseudomonas aeruginosa and Salmonella enterica serovar Typhi. Antibiofilm activity (%) was also performed against pure cultures of two pathogens i.e. Listeria monocytogenes and Proteus mirabilis as positive control. The results exhibited that with application of PEO, biofilm formation of both Listeria monocytogenes and Proteus mirabilis was inhibited by 45.80% and 73.01%, respectively in contrast to their respective controls. ABTS and DPPH radical scavenging activity of PEO was measured at five different concentrations and values were ranging from 17.24-49.07% for ABTS whereas 35.16 – 60.70% for DPPH under investigation. It can be concluded that peppermint essential oil possesses potent antimicrobial, antioxidant and antibiofilm activity and can be further used as a natural alternative for preservation in meat industry

Antibiofilm activity of alpha-mangostin loaded nanoparticles against Streptococcus mutans

Objective: To investigate the antibiofilm activity of alpha-mangostin (AMG) loaded nanoparticle (nanoAMG) against dental caries pathogen Streptococcus mutans. Methods: AMG was isolated from the peels of Garcinia mangostana L. using silica gel columns and chemically analysed by high performance liquid chromatography and nuclear magnetic resonance. NanoAMG was prepared using the solvent evaporation method combined with high-speed homogenization. The nanoparticles were characterized using dynamic light scattering, field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared spectroscopy (FTIR). The toxicity of nanoAMG in fibroblast NIH/3T3 cell line was determined using MTT method. The antibiofilm effect of nanoAMG was determined through the evaluation of biofilm formation by Streptococcus mutans using a 96-well plate. Biofilm biomass was quantified using crystal violet. Cell viability was observed under confocal microscopy using LIVE/DEAD BacLight staining. Moreover, gene expression was determined by quantitative real-time PCR and membrane permeabilization activity by measuring the uptake of o-nitrophenol-β-D-galactoside. Results: NanoAMG size was in a range of 10-50 nm with a polydispersity index of < 0.3 and zeta potential value of -35.2 mV. The size and the incorporation of AMG in the nanoparticles were confirmed by FE-SEM and FTIR analyses. The IC50 values of the test agents on NIH/3T3 cells were (9.80 ± 0.63) μg/mL for AMG and (8.70 ± 0.81) μg/mL for nanoAMG, while no toxicity was generated from excipients used to prepare nanoparticles. In the early stage of biofilm formation, treatment with 6.25 μmol/L nanoAMG caused a reduction in biofilm biomass up to 49.1％, compared to 33.4％ for AMG. In contrast, biofilms at the late stage were more resistant to the test agents. At 96 μmol/L (= 10 × MIC), nanoAMG reduced only 20.7％ of biofilm biomass while AMG did not show any effect. Expressions of gtfB and gtfC genes involved in biofilm formation were down-regulated 3.3 and 12.5 folds, respectively, compared to AMG (2.4 and 7.6 folds, respectively). LIVE/DEAD BacLight fluorescence staining and microscopy observation indicated that biofilm cells were killed by both nanoAMG andAMG at 48 μmol/L (= 5 × MIC). In addition, membrane permeabilization activity was increased in a time dependent manner and higher in nanoAMG treated cells compared toAMG.Conclusions: AMG coated nanoparticle can enhance AMG bioactivity and can be used as a new and promising antibiofilm agent.

Antibiofilm activity of alpha-mangostin loaded nanoparticles against Streptococcus mutans

Objective: To investigate the antibiofilm activity of alpha- mangostin (AMG) loaded nanoparticle (nanoAMG) against dental caries pathogen Streptococcus mutans. Methods: AMG was isolated from the peels of Garcinia mangostana L. using silica gel columns and chemically analysed by high performance liquid chromatography and nuclear magnetic resonance. NanoAMG was prepared using the solvent evaporation method combined with high-speed homogenization. The nanoparticles were characterized using dynamic light scattering, field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared spectroscopy (FTIR). The toxicity of nanoAMG in fibroblast NIH/3T3 cell line was determined using MTT method. The antibiofilm effect of nanoAMG was determined through the evaluation of biofilm formation by Streptococcus mutans using a 96-well plate. Biofilm biomass was quantified using crystal violet. Cell viability was observed under confocal microscopy using LIVE/DEAD BacLight staining. Moreover, gene expression was determined by quantitative real-time PCR and membrane permeabilization activity by measuring the uptake of o-nitrophenol- β-D-galactoside. Results: NanoAMG size was in a range of 10-50 nm with a polydispersity index of < 0.3 and zeta potential value of -35.2 mV The size and the incorporation of AMG in the nanoparticles were confirmed by FE-SEM and FTIR analyses. The IC

Antimicrobial and Antibiofilm Activity of Essential Oil of Cymbopogon citratus against Oral Microflora Associated with Dental Plaque

Aims: Dental biofilms are complex, multi-species microorganism communities that inhabit the oral cavity in the form of dental plaque which causes dental caries and periodontal diseases. The present study aims to explore the potential of Lemon Grass Essential Oil (LGEO) extracted from Cymbopogon citratus as antimicrobial and antibiofilm agent against the microorganisms responsible for dental plaque. Study Design: Observational and comparison study. Place and Duration of Study: Research centre, Department of Microbiology, Abasaheb Garware college, Pune, India, between Dec 2012 to Jan 2017. Methodology: Three bacterial species primarily responsible for the biofilm formation were isolated from dental plaque and identified using 16S ribosomal RNA sequences. Five most primary colonizer of dental plaque organisms were acquired from the Microbial Type Culture Collection cultures. Antimicrobial as well as antibiofilm activity of LGEO, was determined against these eight biofilm forming microorganism. The antibiofilm activity of LGEO was evaluated against oral flora individually, as well as in consortium. Results: LGEO displayed excellent antimicrobial activity against eight test organisms associated with dental plaque, representing four genera namely Streptococcus, Staphylococcus, Lactobacillus and Candida. MIC of LGEO for all test organisms was determined as 1.5% (v/v). The LGEO was found to exhibit as high as 76% biofilm inhibitory activity even in the consortium, where the biofilm formation sometimes has been noted to be comparatively more than that of the individual organism, making LGEO a very promising antibiofilm agent. Conclusion: LGEO present in rampantly grown plant, Cymbopogon citratus, has remarkable antimicrobial and antibiofilm activity against the dental plaque organism and thus can be the economical, convenient, natural and nontoxic herbal material to effectively control the oral microflora associated with dental plaque.

Antimicrobial and antibiofilm activity of the essential oil from dried leaves of Eucalyptus staigeriana / Atividade antimicrobiana e antibiofilme do óleo essencial de folhas secas de Eucalyptus staigeriana

In recent years, compounds with biological properties produced by plants have received attention as an alternative to control microorganisms. Essential oils extracted from green leaves of Eucalyptus sp. have been demonstrated to have antimicrobial activities, but so far there are no reports of antimicrobial activity of essential oils extracted from dried leaves of Eucalyptus staigeriana. So, the objectives of this study were to determine the chemical composition of the essential oils obtained from dried leaves of E. staigeriana (EOdlES) and to evaluate in vitro antimicrobial and antibiofilm activities of EOdlES against gram-positive and gram-negative, resistance and multiresistant Enterococcus faecalis isolated from food and clinical samples. The characterization of EOdlES was performed by gas chromatography-mass spectrometry (GC/MS). For this study, 26 bacterial strains were used, which included 11 reference strains and 15 antibiotic resistant and multiresistant E. faecalis strains. Antimicrobial activities of EOdlES against gram-positive and gram-negative were determined using the disc diffusion method. The minimum inhibitory concentration (MIC) value was evaluated by a microbroth dilution technique. The antibiofilm effects were assessed by microtiter plate method. As a result, 21 compounds were identified, being oxygenated monoterpenes (69.58%) the major chemical family. EOdlES showed only antimicrobial activity against gram-positive strains. E. faecalis resistant and multiresistant strains show the lowest MIC (3.12 to 6.25%), when compared with reference E. faecalis strain. EOdlES has the ability to inhibit the biofilm formation, but little or none ability to inhibit the preformed biofilm. This study demonstrates that EOdlES is a promising alternative to control important foodborne and clinic gram-positive resistant bacteria.(AU)

Nos últimos anos, compostos com propriedades biológicas produzidas por plantas têm recebido atenção como alternativa de controle de micro-organismos. Óleos essenciais extraídos de folhas verdes de Eucalyptus sp. têm demonstrado atividades antimicrobianas. No entanto, até o momento não há nenhum relato de atividade antimicrobiana de óleos essenciais extraídos de folhas secas de Eucalyptus staigeriana. O objetivo deste estudo foi determinar a composição química dos óleos essenciais obtidos de folhas secas de E. staigeriana e avaliar in vitro a sua atividade antimicrobiana e de antibiofilme contra gram-positivas e gram-negativas e também resistentes e multirresistentes de Enterococcus faecalis isolados de amostras de alimentos e clínicas. A caracterização de E. staigeriana foi realizada por CG-EM. Para este estudo foram utilizadas 26 cepas bacterianas, que incluíram 11 cepas referência e 15 cepas de E. faecalis resistentes a antibióticos. A atividade antimicrobiana de E. staigeriana contra gram-positivas e gram-negativas foi determinada utilizando o método de disco-difusão. Os valores da concentração inibitória mínima foram avaliados pela técnica de microdiluição. Os efeitos de antibiofilme foram avaliados pelo método de placa de microtitulação. Como resultado, 21 compostos foram identificados, sendo monoterpenos oxigenados (69,58%) a grande família química. E. staigeriana mostrou apenas atividade antimicrobiana contra cepas gram-positivas. Cepas de E. faecalis resistentes e multirresistentes mostraram a menor concentração inibitória mínima (3,12 para 6,25%) quando comparado com a cepa referência de E. faecalis. E. staigeriana apresentou a capacidade de inibir a formação de biofilme, mas pouca ou nenhuma capacidade de inibir o biofilme pré-formado. Este estudo demonstra que o óleo essencial obtido de folhas secas de E. staigeriana é uma alternativa promissora para controle importante de bactérias gram-positivas resistentes de origem alimentar e clínicas.(AU)

Antimicrobial and antibiofilm activities of phenolic compounds extracted from Populus nigra and Populus alba buds (Algeria)

The interest of this work is the discovery of new antimicrobial agents of plant origin to inhibit the formation of microbial biofilms. The present research was conducted to identify and quantify the phenolic compounds extracted from Populus nigra and Populus alba buds harvested in the area of Tizi-Ouzou (Algeria), and to evaluate their antimicrobial and antibiofilm activity. High performance liquid chromatography (HPLC) was performed to identify the phenolic compounds in the ethyl acetate fraction of P. nigra and the methanolic extracts of P. nigra and P. alba. The antimicrobial activity of the crude extracts and the fractions of these two species was tested against 11 microorganisms, using the disk diffusion method, while the antibiofilm effect of certain extracts was carried out in a 96-well microplate and on a biomaterial (catheter). HPLC analysis revealed the presence of 10 bioactive compounds. The main phenolic compounds identified in the three extracts were p-coumaric acid, ellagic acid, and Kaempferol. This study was able to demonstrate that the extracts of P. nigra and P. alba buds have interesting antimicrobial properties, with diameters ranging from 6.6 to 21.3 mm. In addition, extracts of P. nigra exhibited antibiofilm effects greater than 70%. Our results provide evidence for the antimicrobial and antibiofilm potential of bud extracts from both poplar species. Thus, these results will pave the way for further research on these two plants.

Three new anthraquinone derivatives isolated from Symplocos racemosa and their antibiofilm activity / 中国天然药物

Three new alkyl substituted anthraquinone derivatives, trivially named as symploquinones A-C (Compounds 1-3) were isolated from Symplocos racemosa. The structures of these compounds were determined on the basis of extensive spectroscopic analyses (UV, IR, Mass, H- and C-NMR, and two-dimensional (2D) NMR techniques). The resulting data were also compared with the reported literature. These compounds were then subjected to antibacterial or antibiofilm testing. Compounds 1 and 3 exhibited good antibacterial activity in the concentration range of 160-83 μg·mL against Streptococcus mutans, methicillin resistant Staphylococcus aureus and Proteus mirabilis. Both compounds were further screened for anti-biofilm activity, which revealed promising activities at sub-MIC concentrations. None of the compounds were found to be active against Klebsiella pneumoniae.

Effect of electron‑beam irradiation on antimicrobial, antibiofilm activity, and cytotoxicity of mouth rinses.

Background: Oral health diseases are common in all regions of the world. Mouth rinses are widely used generally by population as a port of daily oral care regimen. In addition to antimicrobial activity, mouth rinses possess certain cytotoxic effects. Electron‑beam (E‑beam) radiation is a form of ionizing energy known to induce structural, physical, and chemical changes in irradiated products. In this study, the modulatory effects of E‑beam in irradiated mouth rinses were evaluated for its biological activities. Materials and Methods: The antimicrobial activities of nonirradiated and irradiated mouth rinses were evaluated for its antimicrobial and antibiofilm activities against oral pathogens, Enterococcus faecalis, Streptococcus mutans, Staphylococcus aureus, and Candida albicans. The antimicrobial activity was evaluated by disc diffusion method and antibiofilm activity was evaluated by O’Toole method. The cytotoxicity was evaluated against human gingival fibroblast (HGF) cells by 3‑(4, 5 Dimethythiazol‑yl)‑2,5‑Diphenyl‑tetrazolium bromide assay. Results: Colgate Plax (CP) exhibited the antimicrobial activity against the tested pathogens, and a significant (P < 0.05) increase was observed against S. aureus at 750 Gy irradiation. Further, CP significantly (P < 0.05) suppressed S. mutans, S. aureus, and C. albicans biofilm. Listerine (LS) inhibited S. mutans and C. albicans biofilm. Whereas irradiated CP and LS significantly (P < 0.05) suppressed the biofilm formed by oral pathogens. The suppression of biofilm by irradiated mouth rinses was dose‑ and species‑dependent. There was no significant (P > 0.05) difference in the cytotoxicity of irradiated and nonirradiated mouth rinses on HGF cells. However, an increased percentage viability of HGF cells was observed by mouth rinses irradiated at 750 Gy. Conclusion: The E‑beam irradiation enhanced the antibiofilm activity of mouth rinses without modifying the cytotoxicity.

Antibiofilm, Antioxidant, Antimutagenic Activities and Phenolic Compounds of Allium orientale BOISS.

ABSTRACT This is the first study to investigate the antibiofilm, antioxidant and antimutagenic activities and phenolic compounds of Allium orientale. Antimicrobial activity of ethanolic extracts of A. orientale was determined by a broth microdilution method. Antibiofilm activity was evaluated by microplate biofilm assay. The antioxidant activity was determined using three complementary assays; namely, DPPH scavenging, β-carotene-linoleic acid, and total phenolic compounds assays. Phenolic compounds were evaluated by reverse-phase high-performance liquid chromatography. The antimutagenic effect of extracts was analyzed by the Ames test. In RP-HPLC analysis, (+)-catechin, apigenin and caffeic acid were identified as major phenolic compounds in the aerial parts of A. orientale. The aerial parts extract possessed the highest total phenolic content (120.979 ± 1.05 mg gallic acid equivalent/g), which were in good correlation with its significant DPPH (IC50 42.18 ± 1.68 mg/mL) and lipid peroxidation (89.98 ± 0.69% at 10 mg/mL concentration) capacities. A. orientale exhibited potent antimicrobial activity against the organisms tested with MICs ranging from 3.125 to 25 mg/mL. Escherichia coli biofilm formation was inhibited maximum by the aerial parts extract to an extent of 68.51%. The strongest antimutagenic activity was observed at 2.5 mg/plate concentration of aerial parts extract against Salmonella typhimurium TA98.These results suggested that the ethanolic extract of the aerial parts of A.orientale could become useful supplement for pharmaceutical products as a new antioxidant, antibiofilm and antimutagenic agent.

Antibacterial and antibiofilm activities of polysaccharides, essential oil, and fatty oil extracted from Laurus nobilis growing in Lebanon

OBJECTIVE@#To evaluate the antibacterial activity of the extracts of Laurus nobilis against three Gram-positive bacteria (Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212 and Staphylococcus epidermidis CIP 444) and two Gram-negative bacteria (Escherichia coli ATCC 35218 and Pseudomonas aeruginosa ATCC 27853). Also, the antibiofilm activity has been investigated against the biofilm produced by Staphylococcus epidermidis CIP 444.@*MATERIALS@#The polysaccharides, essential oil, and fatty oils extracted from the plant were used in broth microdilution methods to study the minimal inhibitory concentration, and then the minimal bactericidal concentration was determined.@*RESULTS@#The results showed that alginate, fucoidan, fatty oils and essential oil have good antibacterial activities against the 5 bacterial strains, and a negligible biofilm eradication activity of fucoidan, laminaran, fatty oil, and essential oil was observed, but a promising biofilm eradication activity was obtained with alginate, which showed a reduced biofilm mass even at low concentration.@*CONCLUSIONS@#The extracts obtained have promising antibacterial capacities which need further investigation for them to be incorporated in medical or nutritional applications.

Antibacterial and antibiofilm activities of polysaccharides, essential oil, and fatty oil extracted from Laurus nobilis growing in Lebanon

Objective: To evaluate the antibacterial activity of the extracts of Laurus nobilis against three Gram-positive bacteria (Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212 and Staphylococcus epidermidis CIP 444) and two Gram-negative bacteria (Escherichia coli ATCC 35218 and Pseudomonas aeruginosa ATCC 27853). Also, the antibiofilm activity has been investigated against the biofilm produced by Staphylococcus epidermidis CIP 444. Materials: The polysaccharides, essential oil, and fatty oils extracted from the plant were used in broth microdilution methods to study the minimal inhibitory concentration, and then the minimal bactericidal concentration was determined. Results: The results showed that alginate, fucoidan, fatty oils and essential oil have good antibacterial activities against the 5 bacterial strains, and a negligible biofilm eradication activity of fucoidan, laminaran, fatty oil, and essential oil was observed, but a promising biofilm eradication activity was obtained with alginate, which showed a reduced biofilm mass even at low concentration. Conclusions: The extracts obtained have promising antibacterial capacities which need further investigation for them to be incorporated in medical or nutritional applications.

Antibiofilm activity of Cobetia marina filtrate upon Staphylococcus epidermidis catheter-related isolates

We report the antibiofilm activity by the sponge-associated bacterium Cobetia marina upon Staphylococcus epidermidis clinical isolates obtained from central venous catheters. Antibiofilm activity/antimicrobial susceptibility correlation might predict the action of the metabolite(s) upon Staphylococcus epidermidis in the clinic, making it a possible adjuvant in therapies against biofilm-associated infections.

Antibiofilm activity of Cobetia marina filtrate upon Staphylococcus epidermidis catheter-related isolates

We report the antibiofilm activity by the sponge-associated bacterium Cobetia marina upon Staphylococcus epidermidis clinical isolates obtained from central venous catheters. Antibiofilm activity/antimicrobial susceptibility correlation might predict the action of the metabolite(s) upon Staphylococcus epidermidis in the clinic, making it a possible adjuvant in therapies against biofilm-associated infections.