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Background: Emergence of drug-resistant bacteria has highlighted the need to identify new and more efficient antibacterial agents. The aims of this study were to evaluate the antibacterial activity of dill (Anethum graveolens) seeds essential oil and to investigate the effect of cumin (Cuminum cyminum) seeds alcoholic extract on biofilm formation ability of Klebsiella pneumoniae.
Materials and methods: This experimental study was carried out at the Faculty of Medicine of Kurdistan University of Medical Sciences in 2014. Activity of dill seeds essential oil was evaluated based on the inhibition zone diameter and minimum inhibitory concentration (MIC) against some important pathogenic bacteria including: Vibrio cholerae, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. Furthermore, the effect of sub-inhibitory concentrations of cumin seeds alcoholic extract was evaluated on biofilm formation ability of K. pneumoniae. The biofilms were formed on semi-glass lamellas and observed by a scanning electron microscope.
Results: Dill essential oil showed a good to moderate activity against the tested strains. The highest antibacterial activity was observed against S. aureus (inhibition zone of 15 mm and MIC of 0.62 mg.mL^-1) and V. cholerae (inhibition zone of 14 mm and MIC of 0.7 mg..mL^-1). The cumin alcoholic extract had no effect on biofilm formation ability of K. pneumoniae.
Conclusion: The results of this study showed the presence of antimicrobial compounds in dill extract. The cumin alcoholic extract was not able to inhibit biofilm formation ability of K. pneumoniae. Because of the medicinal plants properties, it is valuable to search for promising herbs and novel chemical compounds.

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Brazilian peppertree (Schinus terebinthifolius) leaf extract was applied against two strains of the crown gall disease agent (Agrobacterium tumefaciens); strains C58 and AR125. In vitro, we used the agar well diffusion method and the extract was tested in different solvents selected according to their polarity indices, at different concentrations and different incubation temperatures. In vivo, we tested the extract prepared in different solvents on the stems of young tomato plants (cv. Firenze) which were inoculated with the strain C58.The best results were obtained with the extract prepared in hot sterile distilled water and in methanol (0.3 g.ml^-1) incubated at 25 °C and 30 °C. The minimum inhibitory concentration (MIC) was evaluated to be 10^-4 g.ml^-1. In another aspect, to identify the nature of certain substances from S. terebinthifolius leaf extracts, we made a test of fractionation using the Thin Layer Chromatography (TLC) method and phytochemical screening of the crude methanol leaf extract. We noticed the presence of alkaloids and flavonoid compounds which may be responsible for the antibacterial activity. These tests indicated that false pepper leaf extract has an antibiotic effect against Agrobacterium tumefaciens both in vitro and in vivo, which represents a conceptual approach with great promise for future biological control.  

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Research Subject: One of the important methods in the treatment of skin wounds is the use of wound dressings. Recently, the use of polymer-based wound dressings has become increasingly common. The use of natural polymers is very important in wound dressings. The aim of the present study is to design and manufacture a polyvinyl alcohol/aloe vera wound dressing with the capability of healing skin wounds.
Research Approach: The electrospinning method was applied to prepare the samples. Aloe vera gel was first extracted, purified, and powdered by freeze-drying. In all samples, the amount of polyvinyl alcohol and aloe vera powder was fixed at 8 wt.%. This value was selected empirically based on the quality of the produced fibers. Different samples including different amounts of polyvinyl alcohol and aloe vera were produced and their properties including morphology, tensile strength, swelling, degradability, and antimicrobial properties were investigated.
Main Results: The results showed that the dropless random oriented fibers with uniform diameter were produced. The diameter increased with increasing aloe vera contribution, which was attributed to an increase in viscosity due to the presence of aloe vera. With increasing aloe vera contribution in the samples, tensile strength decreased and the elongation percentage increased. The swelling behavior of the specimens was evaluated by measuring the weight of the specimens in a simulated skin environment and the results showed that the presence of aloe vera increased the hydrophilic properties of the specimens. Antimicrobial activity of the samples against two gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa was investigated using the disk diffusion method and it was found that the presence of Aloe vera in the samples brought antimicrobial activity against Pseudomonas aeruginosa. Finally, the findings of this study confirm the feasibility of using polyvinyl alcohol /aloe vera for the production of the electrospun wound dressing.

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In this study the effect of edible coating containing pomegranate peel extract (PPE) on the quality and shelf life of silver carp (Hypophthalmichthysmolitrix)fillet was investigated during refrigerated storage at 4 C^º. The total phenolic content (262.5 mg tannic acid/g sample) and DPPH free radical scavenging activity (87%) of PPE using methanol as solvent were determined. The mixture of edible coating was prepared (60% cool water + 30% wheat flour + 10% corn flour). Freshly fish fillet were assigned to three treatments: control (fillet without PPE); fillet treated with 5% PPE (T1) and 10% PPE (T2). Chemical (pH, and thiobarbituric acid (TBA)) and microbiological (total viable count (TVC) and psychrotrophic count (PTC)) analysis were used to evaluated the effect of PPE during refrigerated storage. The results show that addition of PPE considerably delayed lipid oxidation in silver carp fillet in T1 and T2 compared with control samples. According to microbiological assay, T1 and T2 samples on 12th of storage reached to maximum acceptability limit (7 log₁₀ CFU/g) while it was happened on 9th of storage for control samples.

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Aims: The use of medications with plant origin covers a wide variety of maladies and constitutes an alternative way to antibiotic therapy, which seems to be no longer promising due to the widespread antibiotics resistance among the pathogenic microorganisms.
Active principles having antimicrobial activity could be extracted and purified from plants and used in developing new medications. Among several diseases which have historically scourged man, some of the gram-negative bacteria are potentially epidemic and considered as one of the most outstanding causes of diarrhea. Therefore, this study aimed to evaluate the antibacterial activity of Thymus kotschyanus extracts.
Materials & Methods: The antimicrobial effect of T.  kotschyanus  Boiss leaves extract on some gram-negative bacteria strains was assayed in vitro by the disk diffusion technique. Dried and crushed plant materials were extracted from distilled water by evaporation and distillation. Finally, the antimicrobial assays were carried out for the plant, and the results were compared with an ampicillin disk results.
Findings: Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella typhimurium, Entrobacter cloacae, Proteus mirabilis, and Shigella dysenteriae were apparently killed by the extract, as judged by the presence of growth inhibition halos in the assays.
The results of minimum inhibitory concentrations (MICs) showed that E. coli and E. cloacae strains were better inhibited by the extract.
Conclusion: The above results were similar to those from ampicillin disk, suggesting that T. kotschyanus Boiss could be used as a source of active principles against some gram-negative bacteria. Therefore, the tested Thymus extract could be considered as a valuable natural antibacterial source, which seems to be applicable in both medicine and food industry.

 

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The fungal genus Paecilomyces comprises numerous pathogenic and saprobic species, which are regularly isolated from insects, nematodes, soil, air, food, paper and many other materials. Some of the Paecilomyces species have been known to exhibit capabilities for curing human diseases. Here, bioactivities of metabolites from some soil inhabitant and invertebrate pathogenic Paecilomyces species were explored against a panel of target prokaryotic and eukaryotic microorganisms. First, Petri plate assays indicated that all tested Paecilomyces species were capable of producing diffusible metabolites and volatile compounds with antifungal activities against Pyricularia oryzae and Saccharomyces cerevisiae. Subsequently, the metabolites of the Paecilomyces species were extracted and the growth inhibitory and antimitotic effects of extra-cellular metabolites were shown using the yeast S. cerevisiae as a model. Further research indicated some antibacterial activity of extra-cellular metabolites from Paecilomyces species against human pathogenic bacteria Staphylococcus aureus, Bacillus subtilis, Streptococcus pyogenes (G⁺) and Escherichia coli, Pseudomonas aeruginosa and Salmonella typhi (G^-). These findings indicate that the Paecilomyces species, either saprobic or pathogenic, have a strong arsenal of bioactive metabolites which show inhibitory or cytotoxic effects against other microorganisms, with a potential for application in agroforestry and medicine.
 

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Background: Due to the side effects of chemical and synthetic antibiotics and the increase in bacterial resistance, extensive research has been conducted to obtain natural compounds without side effects from natural sources such as insects, especially Diptera order, because these insects require to live and survive on rotting food and be in direct contact with pathogenic and dangerous microorganisms because of their special diet.
Materials & Methods: In this study, hemolymphs were extracted from Musca domestica, Drosophila melanogaster, and Sarcophaga nodosa, and then the anti-bactericidal activity of these extracts against important pathogenic bacteria was investigated separately by the minimum inhibitory concentration (MIC) method using resazurin indicator.
Findings: S. nodosa and M. domestica larvae were not able to prevent the growth of any of the bacteria. D. melanogaster larvae extract completely inhibited the growth of Escherichia coli and Pseudomonas aeruginosa bacteria at all densities, while Staphylococcus aureus was completely resistant to all concentrations. The minimum inhibitory concentration of D. melanogaster larvae extract against two bacteria of Listeria monocytogenes and Salmonella typhimurium was determined as 125 and 500  μL/mL, respectively.
D. melanogaster pupae extract was unable to inhibit the growth of E. coli and S. typhimurium but prevented the growth of P. aeruginosa at all concentrations. Also, the minimum inhibitory concentration of this extract against both S. aureus and L. monocytogenes was determined as 1000 μL/mL.
Conclusion: These outcomes show that D. melanogaster holds a high potential of antibacterial effects, and the purification and evaluation of this extract active substances are recommended for future utilization as antibacterial agents and food preservatives to fight pathogenic and toxigenic microorganisms.

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Aims: 16S ribosomal RNA methyltransferases (RMTases) confer high-level resistance to aminoglycosides and are increasingly reported among Gram-negative bacilli, especially Klebsiella pneumoniae isolates. The objectives of the present study were to assess the resistance to aminoglycosides, the presence of RMTase genes, and the multilocus sequence typing (MLST) in urinary K. pneumoniae isolates.
Materials & Methods: In this study, 100 K. pneumoniae isolates were tested for susceptibility to amikacin and gentamicin by broth microdilution test according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. Then the prevalence of RMTase genes was determined, and alleles and ST type of two selected isolates were identified by MLST. Finally, the isolates were genetically typed using Enterobacterial Repetitive Intergenic Consensus (ERIC) method.
Findings: Broth microdilution assay showed that resistance to amikacin and gentamicin was 70 and 52%, respectively. In addition, 40% of the strains were resistant to both aminoglycosides. Also, rmtC (59.8%) gene was the most common type of RMTase genes investigated, followed by rmtA (51.2%), rmtD (47.6%), rmtF (43.9%), rmtE (41.5%), armA (41.5%), and rmtB (7.3%). K. pneumoniae isolates were assigned into two sequence types: ST51 and ST149. Using ERIC-PCR method, 3-7 different bands and 21 ERIC-PCR profiles were detected among the studied isolates.
Conclusion: The high frequency of aminoglycoside resistance and the increased presence of 16S RMTases in K. pneumoniae strains are of great concern in Iran. Molecular typing showed high genetic diversity among the studied isolates. However, ST51 and ST149 were reported for the first time in Iran and could be considered as emerging strains.

 

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Background: This study aimed to determine antibacterial activity of ethanolic extract of Matricaria chamomilla (chamomile) against methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant (MDR) Pseudomonas aeruginosa strains isolated from clinical specimens.
Materials & Methods: The plant samples were collected, and the flowers and leaves were separated and dried completely in the shade. After grinding, extraction was performed using the maceration method. The extracts of both flowers and leaves were dried at 37°C for 24 hrs. About 500 mg of the dried plant extract was dissolved in 10 mL of 5% dimethyl sulfoxide and sterilized by filtration through a 0.45 µm membrane filter. For the antibacterial assay, agar well diffusion and broth microdilution methods were used.
Findings: No inhibitory effect was observed for both extracts against MDR P. aeruginosa isolates in agar well diffusion method. In broth microdilution method, the leaves extract showed inhibitory effect, and its MIC and MBC were determined at 12.5 and 25 mg/mL concentrations, respectively. The flowers extract showed antibacterial activity against most MRSA isolates. The extract of leaves demonstrated inhibitory effect on 7 MRSA isolates. The MIC and MBC of flowers extract were determined at concentrations of 6.25 and 12.5 mg/mL for most MRSA isolates, while MIC and MBC of leaves extract were 12.5 and 25 mg/mL for a few MRSA isolates, respectively.
Conclusion: In this study, the ethanolic extract of chamomile leaves showed antibacterial activity against MDR P. aeruginosa isolates; meanwhile, the flowers extract showed better activity against MRSA isolates.

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Nanotechnology is a principally attractive area of research related with production of nanoparticles of variable sizes, shapes, chemical compositions and their possible application for human being benefits. Creation, manipulation and utilization of metallic nanoparticles, because of reduction of materials dimensions, affect the physical properties and results in displaying extraordinary thermal, optical and electronic properties of nonmaterial. The biological approaches to synthesis of nanoparticles are better than chemical and physical procedures because of low energy and time expenditure.
In this study the possibility of production of nano-silver particles from dried flower buds of Clove was investigated and antibacterial and anti-fungal activities of produced nanoparticles were studied by diffusion disc and well methods. The displayed UV-visible spectra, with a wavelength of 300 to 600 nm, identifies formation of silver nanoparticles, whenever the colorless initial acclimated mixture turned to brown. The centrifuged powder samples were examined using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) methods. Based on the results of this study, produced silver nanoparticles were spherical in the range of 27 to 69 nm and showed effective antimicrobial activity against Bacillus subtilis, Escherichia coli, Staphylococcus aureus and Saccharomyces cerevisiae. Therefore clove can be used as a biological source for the synthesis of nanoparticles in an industrial scale with a very low cost.

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Aims: This study aims to investigate the in-vitro antibacterial activity, mineral and vitamin compositions, proximate composition, and organoleptic properties of a syrup derived from Vitex doniana fruits.
Materials and Methods: V. doniana fruits were mashed, mixed with water, strained, and boiled to thicken the filtrate.  The syrup’s antibacterial activity was tested on 7 clinical and 6 American Type Culture Collection (ATCC) isolates using well-in-agar diffusion method on Mueller Hinton agar. The fruit juice underwent mineral analysis using atomic spectroscopy and mass spectrometry. Proximate composition, vitamin, and organoleptic properties of a syrup were evaluated.
Findings: Clinical Escherichia coli 0157:H7 and Staphylococcus aureus isolates were susceptible to the syrup, with inhibition zone of 25 mm each while S. aureus ATCC 25923had the highest susceptibility with a 33 mm inhibition zone. The syrup showed varying minimum inhibitory concentrations (12.5-50 mg/ml) and minimum bactericidal concentrations (25-150 mg/ml) against tested bacteria. The syrup contained 18.4±0.36 mg calcium, 36.92±0.14 mg magnesium, 3.21±0.30 mg iron, 4.80±0.24 mg sodium, and 43.56±1.05 mg potassium as mineral composition per 100 g. Although the prepared syrup had higher calcium, magnesium and iron values prepared to the commercial sample, there was no significant difference between the two. Proximate composition analysis revealed moisture content was measured at 20.83±1.08% moisture content, pH=4.76, 0.20±0.01% crude fiber, 2.40±0.35% crude protein, 3.18±1.12% ash, 0.62±0.24% crude fat, and 76.70±0.16% carbohydrate levels in the syrup. Significant difference was only found in ash and carbohydrate values, with the prepared sample showing higher levels. The syrup exhibited higher vitamin content, including vitamin C, B₁, B₂, B₆ and A, compared to the commercial sample. In terms of organoleptic properties, the prepared syrup scored slightly better in taste, flavor, and overall acceptability (0.18%) compared to the commercial product.
Conclusions: Based on these finding, the syrup derived from V doniana shows potential as a nutrient food product with antimicrobial properties. It could be used in healthcare, industrial applications (such as preservatives or sweeteners), and as a base for pharmaceutical formulations. Furthermore, the syrup may find applications in the confectionery, bakery industries, and traditional medicine.

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Pseudomonas tolaasii Paine and Ewingella americana Grimont are considered as devastating pathogens in mushroom cultivation. Due to the short shelf life of button mushrooms, safe methods should be used to control these pathogens to avoid any toxic residues on the products. Plant secondary metabolites are assumed as important sources for biopesticides development. The aim of this study was to screen plant species for antibacterial properties against P. tolaasii and E. americana. Antibacterial activity of aqueous extract of 17 plant species on two pathogens was investigated in vitro using the disc diffusion method at 10 and 20 mg active ingredients per disc. Then the effect of extracts possessing antibacterial activity was tested on mycelial growth of button mushroom Agaricus bisporus (Lange) using the disc diffusion method. Analysis through measuring the diameter of growth inhibition zones revealed that the extract of Hymenocrater longiflorus Benth. and the other extracts including H. longiflorus, Achillea millefolium L., Eucalyptus sp. and Teucrium polium L. had significant antibacterial activity on E. americana and P. tolaasii, respectively. However, they had no inhibitory activity on mycelial growth of A. bisporus. The efficacy of four mentioned extracts was evaluated in the control of mushroom brown blotch disease caused by P. tolaasii, in vivo. Assessment of disease severity showed that all four extracts, at tested concentrations, had some level of preventive effect on P. tolaasii with no adverse effects on A. bisporus. It is noteworthy that the strength of the A. millefolium extract at 10% did not differ significantly from the 1% household bleach in reducing the disease severity. Therefore, it is possible that some plant extracts have the power to be considered as alternatives to chemical bleaches. Moreover, findings suggest that H. longiflorus extract is a promising candidate for control of P. tolaasii and E. americana in mushroom cultivation.

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The chemical composition of the essential oil of Cinnamomum zeylanicum (Nees) that has been used in food indusries were analysed by GC–MS and 21 components were detected. The major component characterized in the essential oil was E-cinnamaldehyde (60.41%). The other components were linalool (6.46%), Ortho methoxy cinnamic aldehyde (3.63%), βcaryophyllene (3.5%), 1, 8-cineole (3.32%), Eugenol (3.19%) and etc. The antimicrobial activity including minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of cinnamon essential oil were evaluated against five food born pathogenic and spoilage bacteria including Listeria monocytogenes, Escherichia coli, Pseudomonas fluorescens, Lactobacillus plantarum and Lactobacillus sakei. The MICs of cinnamon essential oil against L. sakei and the other bacteria were observed 250 and 500 µg/ml respectively. The MBC of cinnamon essential oil against Pseudomonas fluorescens and Lactobacillus sakei was 1000 µg/ml. The MBCs for the other bacteria were more than 1500 µg/ml.

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Aims: Recently, polymer-based nanofibrous scaffolds have attracted great attention due to their significant antibacterial properties in the field of dermatological applications. In this study, a polycaprolactone-based nanofibrous scaffold has been fabricated using the electrospinning method. The aim of this study was to evaluate the antibacterial effect of electrospun nanofibrous structures. Materials and Methods: In this experimental study, the structure and bacterial attachment on polymeric nanofibrous scaffolds were studied by Scanning Electron Microscopy (SEM). In addition, antibacterial properties of nanofibrous scaffolds were studied on two gram-negative bacteria of Escherichia coli and Pseudomonas aeruginosa and two gram-positive bacteria of Staphylococcus aureus and Streptococcus mutans, using microdilution method and biofilm assay. Moreover, MTT assay was performed on HeLa and human fibrosarcoma cell line (HT1080) cancerous cell lines to evaluate the cell viability.
Findings: The results of this study showed that nanofibrous scaffold revealed a significant antimicrobial and anti-biofilm formation effect on all of the studied bacterial strains, but in microscopic observations and microdilution assay was observed on Pseudomonas aeruginosa in 1mg/ml of nanofibrous scaffold extract concentration, while the major effect in biofilm assay was observed in 8µg/ml of extract concentration. Moreover, the cell viability studies showed that the most significant effect was shown on HT1080 cell line which has drastically decreased by 40% after 48 hours in comparison with the control.
Conclusion: These results show that electrospun nanofibrous PCL-based scaffolds are potentially promising for dermal tissue engineering applications, due to anti-biofilm effects and capability of reducing the number of cancerous cells in the wound site.

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