Chemical composition and biological activities of essential oils of seven Cultivated Apiaceae species.

The Apiaceae family contains many species used as food, spice and medicinal purposes. Different parts of plants including seeds could be used to obtain essential (EO) oils from members of the Apiaceae family. In the present study, EOs were components obtained through hydrodistillation from the seeds of anise (Pimpinella anisum), carrot (Daucus carota), celery (Apium graveolens), dill (Anethum graveolens), coriander (Coriandrum sativum), fennel (Foeniculum vulgare), and cumin (Cuminum cyminum). EO constituents were determined with Gas Chromatography/Mass Spectrometry (GC-MS) and Gas Chromatography/Flame Ionization Detector (GC-FID) and their antioxidant capacities were determined with the cupric reducing antioxidant capacity (CUPRAC) and 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) methods. The antimicrobial activity of EOs were tested against four pathogenic bacteria. Phenylpropanoids in anise (94.87%) and fennel (92.52%), oxygenated monoterpenes in dill (67.59%) and coriander (98.96%), monoterpene hydrocarbons in celery (75.42%), mono- (45.42%) and sesquiterpene- (43.25%) hydrocarbons in carrots, monoterpene hydrocarbon (34.30%) and aromatic hydrocarbons (32.92%) in cumin were the major compounds in the EOs. Anethole in anise and fennel, carotol in carrot, limonene in celery, carvone in dill, linalool in coriander, and cumin aldehyde in cumin were predominant compounds in these EOs. The high hydrocarbon content in cumin EO gave high CUPRAC activity (89.07 µmol Trolox g-1), and the moderate monoterpene hydrocarbon and oxygenated monoterpene content in dill EO resulted in higher DPPH activity (9.86 µmol Trolox g-1). The in vitro antibacterial activity of EOs against Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli was evaluated using the agar diffusion method and the minimum bactericidal concentration was determined. Coriander, cumin and dill EOs showed inhibitory effect against all tested strains except P. aeruginosa. While fennel and celery EOs were effective against E. coli and B. cereus strains, respectively, anise and carrot EOs did not show any antibacterial effect against the tested bacteria. Hierarchical Cluster Analysis (HCA) produced four groups based on EO constituents of seven species. The potential adoption of the cultivated Apiaceae species for EO extraction could be beneficial for the wild species that are endangered by over collection and consumption.

Zeolite 4A as a jammer of bacterial communication in Chromobacterium violaceum and Pseudomonas aeruginosa.

Aim: To investigate the hypothesis that zeolites interfere with quorum-sensing (QS) systems of Chromobacterium violaceum and Pseudomonas aeruginosa by adsorbing N-acyl homoserine lactone (AHL) signal molecules. Methods: QS inhibition by zeolite 4A was investigated using an AHL-based bioreporter assay. The adsorption of the AHLs was evaluated by performing inductively coupled plasma-optical emission spectroscopy and confirmed by Monte Carlo and molecular dynamic simulations. Results: Zeolite 4A reduced the violacein production in C. violaceum by over 90% and the biofilm formation, elastase and pyocyanin production in P. aeruginosa by 87, 68 and 98%, respectively. Conclusion: Zeolite 4A disrupts the QS systems of C. violaceum and P. aeruginosa by means of adsorbing 3-oxo-C6-AHL and 3-oxo-C12-AHL signaling molecules and can be developed as a novel QS jammer to combat P. aeruginosa-related infections.

Characterization of Exopolysaccharides (EPSs) Obtained from Ligilactobacillus salivarius Strains and Investigation at the Prebiotic Potential as an Alternative to Plant Prebiotics at Poultry.

In this study, it was aimed to reveal the potential of using exopolysaccharides (EPS) obtained from Ligilactobacillus salivarius as a prebiotic that regulates chicken intestinal microbiota. Characterization of EPS obtained from L. salivarius BIS312 (EPSBIS312) and BIS722 (EPSBIS722) strains was demonstrated by high performance liquid chromatography (HPLC), nuclear magnetic resonance (NMR), and size-exclusion chromatography (SEC) analyses. It was determined that the molecular weight of both EPS is in the range of 104-106 Daltons, and there are 4 types of monomers in their structure. Anti-biofilm and anti-quorum sensing effects of EPSBIS312 and EPSBIS722 were determined. EPSBIS312 and EPSBIS722 showed a strong anti-biofilm effect on Enterococcus faecalis ATCC 29212, Staphylococcus aureus EB-1, and Escherichia coli ATCC 11229. The anti-quorum sensing study revealed that the EPSBIS722 had a higher effect than the EPSBIS312. The effect of different concentrations of EPS (2.5%, 5%, 10%) on lactobacilli growth stimulator (LGS) was evaluated. The highest LGS was promoted at 10% concentration while the lowest LGS was promoted at 2.5% concentration by EPSBIS722. In addition, adhesion abilities of EPSBIS312 and EPSBIS722 in HT-29 colorectal adenocarcinoma cell line were tested. EPSs significantly increased the ability to adhere to HT-29 cells. The characterized EPSs may be an alternative to plant prebiotics such as inulin at poultry.

Tocopherol, carotene, phenolic contents and antibacterial properties of rose essential oil, hydrosol and absolute.

The antioxidant and antibacterial activities, and total phenolic contents of Rosa damascena Mill. flower extracts (absolute, essential oil and hydrosol) were investigated. The chemical compositions of these extracts were analysed by GC-MS. Phenylethyl alcohol (78.38%) was found to be the main constituent of rose absolute, while citrenellol and geraniol were the major compounds (>55%) of rose essential oil and hydrosol. Tocopherol and carotene levels were determined by high performance liquid chromatography (HPLC) analysis. The levels of beta carotene (422.3+/-35.6 ppm), alpha tocopherol (2397.1+/-72.5 ppm) and gamma tocopherol (343.1+/-28.4 ppm) of rose absolute were found to be higher than that of essential oil and hydrosol. Their total phenolic contents were also evaluated. The total phenolic content of the tested extracts varied from 5.2 to 2134.3 GAE/mg L(-1). Rose absolute and essential oil contained high levels of phenolics and demonstrated strong antibacterial activity against Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Bacillus subtilis (ATCC 6633), Staphylococcus aureus (ATCC 6538), Chromobacterium violaceum (ATCC 12472) and Erwinia carotovora (ATCC 39048) strains.

N-butanoyl-L-homoserine lactone (BHL) deficient Pseudomonas aeruginosa isolates from an intensive care unit.

Acylated homoserine lactones (AHLs) are self-generated diffusible signal molecules that mediate population density dependent gene expression (quorum sensing) in a variety of Gram-negative bacteria, and several virulence genes of human pathogens are known to be controlled by AHLs. In this study, strains of Pseudomonas aeruginosa, Acinetobacter baumannii, Escherichia coli and Klebsiella pneumoniae, isolated from intensive care patients, were screened for AHL production by using AHL responsive indicator strains of Chromobacterium violaceum CV026 and Agrobacterium tumefaciens NT1. Positive reactions were recorded for all 50 isolates of P. aeruginosa and 10 isolates of Acinetobacter baumannii with Agrobacterium tumefaciens NT1. Surprisingly, most P. aeruginosa isolates gave negative results with C. violaceum CV026 in contrast to previous reports. This suggests that the new isolates of P. aeruginosa either failed to make short chain AHLs or the level of the signal molecule is very low.

Inhibition of Pseudomonas aeruginosa biofilm formation by 2,2'-bipyridyl, lipoic, kojic and picolinic acids.

OBJECTIVES: The inhibitory effects of iron chelators, and FeCl3 chelation on biofilm formation and swarming motility were investigated against an opportunistic human pathogen Pseudomonas aeruginosa. MATERIALS AND METHODS: The inhibitory activity of 2,2'-bipyridyl, lipoic acid, kojic acid and picolinic acid on biofilm formation of P. aeruginosa strain PAO1 and three clinical isolates (P. aeruginosa PAK01, P. aeruginosa PAK02 and P. aeruginosa PAK03) were investigated, based on crystal violet assay, and swarming motility test. RESULTS: The kojic, lipoic and picolinic acid inhibited biofilm formation by 5-33% in all tested P. aeruginosa isolates. When chelated iron was added, biofilm inhibition rates were determined to be 39-57%. Among the tested chelators against P. aeruginosa, lipoic acid (84%) and kojic acid (68%) presented the highest inhibition of swarming motility. This is the first study to report the inhibitory effect of lipoic acid on biofilm formation and swarming motility of P. aeruginosa. CONCLUSION: It is considered that lipoic and picolinic acids can serve as alternatives for the treatment of the P. aeruginosa infections by inhibiting biofilm formation.

Electrospun chitosan/PEDOT nanofibers.

Plasma-modified chitosan and poly(3,4-ethylenedioxythiophene) were blended to obtain conducting nanofibers with polyvinyl alcohol as a supporting polymer at various volumetric ratios by electrospinning method. Chemical compositions and molecular interactions among nanofiber blend components were determined using Fourier transform infrared spectroscopy (FTIR). The conducting blends containing plasma-modified chitosan resulted in a superior antibacterial activity and thinner fiber formation than those containing chitosan without plasma-modification. The obtained nanofiber diameters of plasma-modified chitosan were in the range of 170 to 200 nm and those obtained from unmodified chitosan were in the range of 190 to 246 nm. The electrical and electrochemical properties of nanofibers were also investigated by four-point probe conductivity and cyclic voltammetry measurements.

Quorum sensing and virulence of Pseudomonas aeruginosa during urinary tract infections.

INTRODUCTION: In the opportunistic pathogen Pseudomonas aeruginosa, the production of several virulence factors depends on quorum sensing (QS) involving N-acylhomoserine lactone signal molecules. In vitro studies have suggested that the QS system is crucial in the pathogenesis of P. aeruginosa. However, it is unclear whether QS systems of P. aeruginosa play the same role during infections. METHODOLOGY: In this study, to explore the contribution of QS systems to the pathogenesis of P. aeruginosa during urinary tract infections, we collected 82 clinical isolates. Detection of N-acyl-homoserine lactones (C12-HSL and C4-HSL) was performed on agar plates employing biosensor strains C. violaceum. Elastase and biofilm production were determined spectrophotometrically. QS genes were detected by PCR and subsequently underwent sequencing. RESULTS AND CONCLUSION: Six isolates were found to be negative in the production of both C12-HSL and C4-HSL and all virulence factors tested.  PCR analysis of these isolates revealed that four isolates contained all four QS genes while one isolate was negative for lasR gene, and one isolate negative for lasI, lasR and rhlR genes. Sequence analyses of these isolates showed that the lasR, lasI, rhlR and rhlI genes had point mutations. The combination of these mutations probably explains their C12-HSL, C4-HSL and virulence factor deficiencies. Results of this study suggest that QS deficient clinical isolates occur and are still capable of causing clinical infections in humans. 

RF hydrazine plasma modification of chitosan for antibacterial activity and nanofiber applications.

Chitosan nano powders were modified using RF hydrazine plasma produced at low pressure (26.66Pa) with 13.56MHz frequency at a power of 100W for 30min. Characterization and investigation of the properties of plasma-modified chitosan (PMCh) and non-modified chitosan (Ch) were carried out using an optical monochromator, FTIR, florescence analysis, TGA, SEM, and X-ray techniques. FTIR spectra of PMCh indicated a band broadening at 3436cm(-1) that confirmed increasing functional groups based on H-bonding. The number of NH(2) groups was determined from fluorescence analysis. TGA analysis shows that the moisture absorption is three times higher in the PMCh structure. Ch and PMCh in PVA solutions were used to produce nanofibers by the electrospinning method; average fiber diameters were 480 and 280nm for Ch and PMCh, respectively. It was found that the antibacterial effect of PMCh is better than the Ch for Gram-positive strains.

Characterization of N-butanoyl-L-homoserine lactone (C4-HSL) deficient clinical isolates of Pseudomonas aeruginosa.

In the opportunistic pathogen Pseudomonas aeruginosa, the production of several virulence factors such as elastase, rhamnolipids and pyocyanin depends on cell-to-cell signaling or quorum sensing (QS) involving N-acylhomoserine lactone (AHL) signal molecules. In vitro studies with laboratory strains and virulence studies in animals with these same strains have demonstrated the contribution of QS to the pathogenesis of P. aeruginosa. However, the importance of P. aeruginosa QS systems in the development of human infections is not clearly known. In order to determine if deficiency within the QS system compromises the ability of P. aeruginosa to cause infections in humans, we collected 50 P. aeruginosa clinical isolates. Phenotypic characterization showed that isolates I-457, I-458, I-459 and I-461 were defective in the production of N-butanoyl-l-homoserine lactone (C4-HSL) signaling molecule and virulence factors elastase, protease, pyocyanin and rhamnolipids. Analysis of the sequences of the lasR, lasI, rhlR and rhlI genes of these four isolates showed that two of the four isolates had mutational defects in both rhlR and rhlI genes while other two isolates were only mutated in the rhlI gene. The combination of rhlR and rhlI mutations or only rhlI mutation probably explains their C4-HSL and virulence factors deficiencies. These observations suggest that QS deficient P. aeruginosa clinical isolates are able to cause infections and that in addition to known virulence factors, factors yet unidentified may contribute to the pathogenesis of P. aeruginosa.

Inhibition of quorum sensing-regulated behaviors by Scorzonera sandrasica.

Many Gram-negative bacteria use N-acyl homoserine lactone signal molecules to monitor their own population density and coordinate gene regulation in a process called quorum sensing (QS). Increasing evidence implies that certain eukaryotes produce QS-inhibitory compounds. In this work, we tested 46 terrestrial plants materials for their ability to inhibit QS-regulated behaviors in different bacterial species. Plant materials were dried and extracted using different solvents. The chloroform-soluble compounds extracted from Scorzonera sandrasica were found to inhibit violacein production, a QS-regulated behavior in Chromobacterium violaceum. In addition, the chloroform extract was also able to inhibit QS-regulated carbapenem antibiotic production in Erwinia carotovora. Because the regulation of many bacterial processes is controlled by QS systems, the finding of natural compounds acting as QS inhibitors suggests an attractive tool to control and handle detrimental infections caused by human, animal, and plant pathogens.