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1.
Microb Pathog ; 192: 106680, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38729380

ABSTRACT

Biocontrol of phytopathogens involving the use of bioactive compounds produced by lactic acid bacteria (LAB), is a promising approach to manage many diseases in agriculture. In this study, a lactic acid bacterium designated YB1 was isolated from fermented olives and selected for its antagonistic activity against Verticillium dahliae (V. dahliae) and Agrobacterium tumefaciens (A. tumefaciens). Based on the 16S rRNA gene nucleotide sequence analysis (1565 pb, accession number: OR714267), the new isolate YB1 bacterium was assigned as Leuconostoc mesenteroides YB1 (OR714267) strain. This bacterium produces an active peptide "bacteriocin" called BacYB1, which was purified in four steps. Matrix-assisted lasers desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS) based approach was performed to identify and characterize BacYB1. The exact mass was 5470.75 Da, and the analysis of the N-terminal sequence (VTRASGASTPPGTASPFKTL) of BacYB1 revealed no significant similarity to currently available antimicrobial peptides. The BacYB1 displayed a bactericidal mode of action against A. tumefaciens. The potentiel role of BacYB1 to supress the growth of A. tumefaciens was confirmed by live-dead cells viability assay. In pot experiments, the biocontrol efficacy of BacYB1 against V. dahliae wilt on young olive trees was studied. The percentage of dead plants (PDP) and the final mean symptomes severity (FMS) of plants articifialy infected by V. dahliae and treated with the pre-purified peptide BacYB1 (preventive and curative treatments) were significantly inferior to untreated plants. Biochemical analysis of leaves of the plants has shown that polyophenols contents were highly detected in plants infected by V. dahliae and the highest contents of chlorophyl a, b and total chlorophyll were recorded in plants treated with the combination of BacYB1 with the biofertilisant Humivital. BacYB1 presents a promising alternative for the control of Verticillium wilt and crown gall diseases.


Subject(s)
Agrobacterium tumefaciens , Bacteriocins , Leuconostoc mesenteroides , Olea , Plant Diseases , RNA, Ribosomal, 16S , Agrobacterium tumefaciens/metabolism , Bacteriocins/pharmacology , Bacteriocins/metabolism , Olea/microbiology , Plant Diseases/microbiology , Plant Diseases/prevention & control , RNA, Ribosomal, 16S/genetics , Leuconostoc mesenteroides/metabolism , Leuconostoc mesenteroides/genetics , Biological Control Agents/metabolism , Biological Control Agents/pharmacology , Verticillium/drug effects , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization , Antibiosis , Phylogeny , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/metabolism
2.
Foods ; 13(6)2024 Mar 21.
Article in English | MEDLINE | ID: mdl-38540955

ABSTRACT

During the last few decades, there has existed an increased interest in and considerable consumer preference towards using natural and safe compounds derived from medicinal plants as alternatives to synthetic preservatives to combat microbial pathogenicity. In this regard, the present study investigated the possible synergistic interactions of the anti-foodborne bacterial capacity of linalool (L), eucalyptol (E), and camphor (C). The antibacterial synergistic effect was determined against Staphylococcus aureus, Listeria monocytogenes, Salmonella enterica Typhimurium, and Escherichia coli. The optimal predicted mixture showed the highest antibacterial activity at 33.5%, 33.2%, and 33.4% of L, E, and C, respectively. Molecular docking simulations displayed that the studied monoterpenes have effective antibacterial inhibitory effects by impeding specific virulence factors such as sortase A, listeriolysin O, L, D-Transpeptidase, and polyphosphate kinase. The selected triple combination of L, E, and C was applied as a natural preservative in minced chicken breast meat. In this regard, 1 MIC (16 µg/mL), 1.5 MIC (24 µg/mL), and 2 MIC (32 µg/mL) of L. monocytogenes were used, and the microbiological, physicochemical, and sensory analyses were monitored for 14 days of storage at 4 °C. The L/E/C mixture at different levels could delay lipid and protein oxidation, inhibit the microorganisms, and maintain the sensory attributes. Additionally, by using chemometric tools, strong connections between physicochemical properties, microbiological parameters, and organoleptic attributes were established. Concisely, this research confers the importance of the use of blended monoterpenes and highlights their antibacterial mode of action, effectiveness, and synergistic effects as a powerful and safe bio-preservative formulation in chicken meat products.

3.
Biomass Convers Biorefin ; : 1-15, 2022 Dec 13.
Article in English | MEDLINE | ID: mdl-36530596

ABSTRACT

Research on medicinal plants is developing each day due to inborn phytochemicals, which can encourage the progress of novel drugs. Most plant-based phytochemicals have valuable effects on well-being. Among them, beetroot leaves (BL) are known for their therapeutic properties. Here, three solvents, namely, acetonitrile, ethanol, and water, and their combinations were developed for BL extraction and simultaneous assessment of phytochemical compounds and antioxidant and antifoodborne pathogen bacteria activities. By using the augmented simplex-centroid mixture design, 40.40% acetonitrile diluted in water at 38.74% and ethanol at 20.86% favored the recovery of 49.28 mg GAE/mL (total phenolic content (TPC)) and 0.314 mg QE/mL (total flavonoid content (TFC)), respectively. Acetonitrile diluted in water at 50% guarantees the best antioxidant activity, whereas the optimal predicted mixture for the highest antibacterial activity matches 24.58, 50.17, and 25.25% of acetonitrile, ethanol, and water, respectively. These extraction conditions ensured inhibition of Staphylococcus aureus, Salmonella enterica, and Escherichia coli, respectively, at 0.402, 0.497, and 0.207 mg/mL. Under optimized conditions, at three concentrations of BL, minimal inhibitory concentration (MIC), 2 × MIC, and 4 × MIC, a linear model was employed to investigate the inhibition behavior against the three tested bacteria. The early logarithmic growth phase of these bacteria illustrated the bactericidal effect of optimized extracted BL with a logarithmic growth phase inferior to 6 h. Therefore, BL extract at 4 × MIC, which corresponds to 1.608, 1.988, and 0.828 mg/mL, was more efficient against S. aureus, S. enterica, and E. coli.

4.
Antioxidants (Basel) ; 11(11)2022 Oct 24.
Article in English | MEDLINE | ID: mdl-36358468

ABSTRACT

Currently, the exploration of natural colorants from vegetal waste has gained particular attention. Furthermore, incorporation of these natural sources into biopolymers is an encouraging environmentally friendly approach to establishing active films with biological activities for food packaging. The present study developed bioactive antioxidant films based on gelatin-sodium alginate (NaAlg) incorporated with aqueous beetroot peel extract (BPE). Firstly, the effects of combining gelatin-NaAlg and BPE at 0.25, 0.5, and 1% on the mechanical, physical, antioxidant, and antibacterial properties of the films were analyzed. With increasing BPE, mechanico-physical properties and antioxidant and anti-foodborne pathogen capacities were enhanced. Likewise, when added to gelatin-NaAlg films, BPE remarkably increased the instrumental color properties. Moreover, during 14 days of storage at 4 °C, the impact of gelatin-NaAlg coating impregnated with BPE on microbial and chemical oxidation and on the sensory characteristics of beef meat samples was periodically assessed. Interestingly, by the end of the storage, BPE at 1% limited the microbial deterioration, enhanced the instrumental color, delayed chemical oxidation, and improved sensory traits. By practicing chemometrics tools (principal component analysis and heat maps), all data provided valuable information for categorizing all samples regarding microbiological and oxidative properties, sensory features, and instrumental color. Our findings revealed the ability of gelatin-NaAlg with BPE as an antioxidant to be employed as food packaging for meat preservation.

5.
J Biomol Struct Dyn ; : 1-17, 2022 Sep 09.
Article in English | MEDLINE | ID: mdl-36082583

ABSTRACT

A series of novel 3-phenyl-1-(alkylphenyl)-9-oxa-4-azaphenanthren-10-ones and (E)-1-phenyl-3-(aryl)prop-2-en-1-ones were synthesized and characterized by IR, 1H NMR, 13C spectroscopy and elemental analysis. The synthesized Compounds 5a-f were subjected to molecular docking simulation with three proteins, namely, tyrosyl-tRNA synthetase, heme oxygenase 1 and acetylcholinesterase to evaluate the antibacterial, antioxidant and acetylcholinesterase inhibition, respectively. Moreover, the docked poses of all compounds inside the proteins were subjected to further dynamic simulation through the calculation of the binding free energy using MM-GBSA analysis. Compound 5d exhibits high potential inhibition against antibacterial, antioxidant and acetylcholinesterase activities. Compounds 3d, 3f, 5a and 5d recorded an important scavenging activity in DPPH and ABTS assays. Investigation of the anti-acetylcholinesterase activity of the synthesized compounds showed that Compounds 5a and 3d are the most potent inhibitors against AchE, with percent inhibition values of 38 and 30%, respectively.Communicated by Ramaswamy H. Sarma.

6.
Biomed Res Int ; 2022: 3368883, 2022.
Article in English | MEDLINE | ID: mdl-35909468

ABSTRACT

Questions have been raised apropos the emerging problem of microbial resistance, which may pose a great hazard to the human health. Among biosafe compounds are essential oils which captured consumer draw due to their multifunctional properties compared to chemical medication drugs. Here, we examined the chemical profile and the mechanism(s) of action of the Thymus vulgaris essential oil (TVEO) against a Gram-negative bacterium Salmonella enterica Typhimurium ATTCC 10028 (S. enterica Typhimurium ATTCC 10028) and two Gram-positive bacteria Staphyloccocus aureus ATCC 6538 (S. aureus ATCC 6538) and Listeria monocytogenes ATCC 19117 (L. monocytogenes ATCC 19117). Findings showed that TVEO was principally composed of thymol, o-cymene, and γ-terpinene with 47.44, 16.55, and 7.80%, respectively. Molecular docking simulations stipulated that thymol and ß-sesquiphellandrene (a minor compound at 1.37%) could target multiple bacterial pathways including topoisomerase II and DNA and RNA polymerases of the three tested bacteria. This result pointed plausible impairments of the pathogenic bacteria cell replication and transcription processes. Through computational approach, the VEGA quantitative structure-activity relationship (QSAR) model, we revealed that among twenty-six TVEO compounds, sixteen had no toxic effects and could be safe for human consumption as compared to the Food and Drug Administration (FDA) approved drugs (ciprofloxacin and rifamycin SV). Assessed by the SwissADME server, the pharmacokinetic profile of all identified TVEO compounds define their absorption, distribution, metabolism, and excretion (ADME) properties and were assessed. In order to predict their biological activity spectrum based on their chemical structure, all TVEO compounds were subjected to PASS (Prediction of Activity Spectra for Substances) online tool. Results indicated that the tested compounds could have multiple biological activities and various enzymatic targets. Findings of our study support that identified compounds of TVEO can be a safe and effective alternative to synthetic drugs and can easily combats hazardous multidrug-resistant bacteria.


Subject(s)
Listeria monocytogenes , Oils, Volatile , Thymus Plant , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Humans , Microbial Sensitivity Tests , Molecular Docking Simulation , Oils, Volatile/chemistry , Oils, Volatile/pharmacology , Staphylococcus aureus , Thymol/pharmacology , Thymus Plant/chemistry
7.
Molecules ; 27(9)2022 Apr 19.
Article in English | MEDLINE | ID: mdl-35565980

ABSTRACT

Nowadays, increasing interest has recently been given to the exploration of new food preservatives to avoid foodborne outbreaks or food spoilage. Likewise, new compounds that substitute the commonly used synthetic food preservatives are required to restrain the rising problem of microbial resistance. Accordingly, the present study was conducted to examine the chemical composition and the mechanism(s) of action of the Cupressus sempervirens essential oil (CSEO) against Salmonella enterica Typhimuriumand Staphyloccocus aureus. The gas chromatography analysis revealed α-pinene (38.47%) and δ-3-carene (25.14%) are the major components of the CSEO. By using computational methods, such as quantitative structure-activity relationship (QSAR), we revealed that many CSEO components had no toxic effects. Moreover, findings indicated that α-pinene, δ-3-carene and borneol, a minor compound of CSEO, could inhibit the AcrB-TolC and MepR efflux pump activity of S. enterica Typhimurium and S. aureus, respectively. In addition, our molecular docking predictions indicated the high affinity of these three compounds with active sites of bacterial DNA and RNA polymerases, pointing to plausible impairments of the pathogenic bacteria cell replication processes. As well, the safety profile was developed through the zebrafish model. The in vivo toxicological evaluation of (CSEO) exhibited a concentration-dependent manner, with a lethal concentration (LC50) equal to 6.6 µg/mL.


Subject(s)
Cupressus , Oils, Volatile , Animals , Anti-Bacterial Agents/pharmacology , Cupressus/chemistry , Food Preservatives , Microbial Sensitivity Tests , Molecular Docking Simulation , Oils, Volatile/chemistry , Oils, Volatile/pharmacology , Staphylococcus aureus , Zebrafish
8.
Meat Sci ; 170: 108246, 2020 Dec.
Article in English | MEDLINE | ID: mdl-32731034

ABSTRACT

The biopreservative effect of Ephedra alata aqueous extract (EAE), used at 0.156, 0.312 and 0.624%, on minced beef meat was evaluated by microbiological, physicochemical and sensory analyses during storage at 4 °C for 14 days. The results showed that EAE significantly (P < .05) delayed the formation of thiobarbituric acid-reactive substances and carbonyls and reduced the sulfhydryl loss in a dose-dependent manner, indicating that EAE had a protective effect against lipids and protein oxidation. Concomitantly, an increase of redness and loss of lightness and yellowness was observed. Furthermore, two multivariate exploratory techniques, namely Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were applied to all obtained data describing the main characteristics attributed to refrigerated meat samples. During storage time, the used chemometric approaches were useful in discriminating meat samples, and therefore offers an approach to underlay connections between meat quality features. The obtained findings demonstrated the strong potential of EAE as a natural preservative in meat and meat products.


Subject(s)
Ephedra/chemistry , Food Preservation/methods , Meat Products/analysis , Plant Extracts/pharmacology , Animals , Cattle , Colony Count, Microbial , Color , Meat Products/microbiology , Oxidation-Reduction/drug effects , Thiobarbituric Acid Reactive Substances/analysis
9.
Article in English | MEDLINE | ID: mdl-32419789

ABSTRACT

Growing worldwide, the genus Ephedra (family Ephedraceae) had a medicinal, ecological, and economic value. The extraordinary morphological diversity suggests that Ephedra was survivor of an ancient group, and its antiquity is also supported by fossil data. It has recently been suggested that Ephedra appeared 8-32 million years ago, and a few megafossils document its presence in the Early Cretaceous. Recently, the high analytical power provided by the new mass spectrometry (MS) instruments is making the characterization of Ephedra metabolites more feasible, such as ephedrine series. In this regard, the chemical compounds isolated from crude extracts, fractions, and few isolated compounds of Ephedra species were characterized by MS-based techniques (LC-MS, LC-ESI-MS, HPLC-PDA-ESI/MS, LC-DAD-ESI/MSn, LC/Orbitrap MS, etc.). Moreover, we carry out an exhaustive review of the scientific literature on biomedicine and pharmacotherapy (anticancer, antiproliferative, anti-inflammatory, antidiabetic, antihyperlipidemic, antiarthritic, and anti-influenza activities; proapoptotic and cytotoxic potential; and so on). Equally, antimicrobial and antioxidant activities were discussed. This review is focused on all these topics, along with current studies published in the last 5 years (2015-2019) providing in-depth information for readers.

10.
Microb Pathog ; 142: 104106, 2020 Feb 26.
Article in English | MEDLINE | ID: mdl-32109569

ABSTRACT

The strain TN638 was isolated from Tunisian soil contaminated with industrial wastewater and selected for its potent antimicrobial activity against the tested Gram positive bacteria: Staphylococcus aureus (S. aureus) ATCC 6538 and Listeria monocytogenes (L. monocytogenes) ATCCC 19117, and Gram negative bacteria: Agrobacterium tumefaciens (A. tumefaciens) ATCC 23308 and Salmonella typhimurium (S. typhimurium) ATCC 14028 and fungi: Candida albicans (C. albicans) ATCC 10231, Rhizoctonia solani (R. solani) ATCC 58938 and Fusarium sp. Solide-state fermentation (SSF) dry crude extract of the TN638 strain presents a strong inhibitory activity notably against the phytopathogenic microorganism A. tumefaciens ATCC 23308 and the two pathogenic bacteria S. aureus ATCC 6538 and L. monocytogenes ATCCC 19117 with a zone of inhibition of 48, 34 and 34 mm respectively. According to the morphological characteristic, the complete 16S rRNA gene nucleotide sequence determination [1492 bp deposited in National Center of Biotechnology Information (NCBI) database under the accession no. LN854629.1; https://www.ncbi.nlm.nih.gov/nuccore/LN854629.1/], and the phylogenetic analysis, we can deduce that our isolate is an actinomycete bacterium belonging to the genus Streptomyces and the most closely related strain was Streptomyces cavourensis (S. cavourensis) NRRL 2740T (99.9%). We propose the assignment of our strain as Streptomyces cavourensis (S. cavourensis) TN638 strain. Work-up and purification of the strain extract using different chromatographic techniques afforded seven bio-compounds namely: Cyclo-(Leu-Pro) (1), Cyclo-(Val-Pro) (2), Cyclo-(Phe-Pro) (3), nonactin (4), monactin (5), dinactin (6) and trinactin (7). The chemical structures of compounds 1-7 were confirmed by nuclear magnetic resonance (NMR) 1D and 2D spectroscopy, mass spectrometry, and comparison with literature data. The three purified diketopiperazine (DKP) derivatives (1-3), demonstrated significant antibacterial activity against A. tumefaciens ATCC 23308 and S. typhimurium ATCC 14028. The four pure macrotetrolides (4-7), exhibited strong inhibitory effect against all tested Gram positive and Gram negative bacteria notably against A. tumefaciens ATCC 23308 and S. typhimurium ATCC 14028 with a minimum inhibitory concentration (MIC) around 8 µg/mL quite similar to that of ampicillin. Thus, we propose the use of the (SSF) active extract of the S. cavourensis TN638 strain as safe biological product to control disease caused by plant pathogen A. tumefaciens. Also, the purified active molecules produced by this strain could be used in pharmaceutical field.

11.
Article in English | MEDLINE | ID: mdl-31737081

ABSTRACT

Pomegranate (Punica granatum L.) peel is a potential source of polyphenols known for their activity against foodborne pathogen bacteria. In this study, the effects of pomegranate peel extraction time (10-60 min), agitation speed (120-180 rpm), and solvent/solid ratio (10-30) on phytochemical content and antibacterial activity were determined. Response surface methodology (RSM) and artificial neural network (ANN) methods were used, respectively, for multiresponse optimization and predictive modelling. Compared with the original conditions, the total phenolic content (TPC), the total flavonoid content (TFC), and the total anthocyanin content (TAC) increased by 56.22, 63.47, and 64.6%, respectively. Defined by minimal inhibitory concentration (MIC), the maximum of antibacterial activity was higher than that from preoptimized conditions. With an extraction time of 11 min, an agitation speed 125 rpm, and a solvent/solid ratio of 12, anti-S. aureus activity remarkably decreased from 1.56 to 0.171 mg/mL. Model comparisons through the coefficient of determination (R 2) and mean square error (MSE) showed that ANN models were better than the RSM model in predicting the photochemical content and antibacterial activity. To explore the mode of action of the pomegranate peel extract (PPE) at optimal conditions against S. aureus and S. enterica, Chapman and Xylose Lysine Deoxycholate broth media were artificially contaminated at 104 CFU/mL. By using statistical approach, linear (ANOVA), and general (ANCOVA) models, PPE was demonstrated to control the two dominant foodborne pathogens by suppressing bacterial growth.

12.
Biomed Res Int ; 2018: 5308464, 2018.
Article in English | MEDLINE | ID: mdl-30515405

ABSTRACT

In previous work we have isolated and identified a new strain called Enterococcus faecium FL31. The active compound secreted by this strain, "BacFL31", has been purified and characterized. In the present study, safety aspect, assessed by microbiological and molecular tests, demonstrated that Enterococcus faecium FL31 was susceptible to relevant antibiotics, free of hemolytic, gelatinase, DNase, and lipase activities. In addition, it did not harbor virulence and antibiotic resistance genes. Combined SYTOX Green dye and UV-absorbing experiments, along with released extracellular potassium and transmembrane electrical potential measurements, showed that pure BacFL31 at a concentration of 1×MIC (50 µg/mL) could damage cytoplasmic membrane of the pathogen Listeria monocytogenes ATCC19117. The same concentration causes the leakage of its intracellular constituents and leads to the destruction of this pathogenic microorganism. In summary, this work reflected characteristics of Enterococcus faecium FL31 strain and its bacteriocin in terms of functional and safety perspectives.


Subject(s)
Anti-Bacterial Agents/pharmacology , Bacteriocins/pharmacology , Enterococcus faecium/chemistry , Listeria monocytogenes/drug effects , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/isolation & purification , Bacteriocins/chemistry , Bacteriocins/isolation & purification , Drug Resistance, Bacterial/drug effects , Humans , Hydroxylation , Listeria monocytogenes/pathogenicity , Listeriosis/drug therapy , Listeriosis/microbiology , Membrane Potentials/drug effects , Organic Chemicals/chemistry , Potassium/chemistry
13.
Microb Pathog ; 119: 19-27, 2018 Jun.
Article in English | MEDLINE | ID: mdl-29626659

ABSTRACT

A new aerobic bacterium TN71 was isolated from Tunisian Saharan soil and has been selected for its antimicrobial activity against phytopathogenic bacteria. Based on cellular morphology, physiological characterization and phylogenetic analysis, this isolate has been assigned as Streptomyces sp. TN71 strain. In an attempt to increase its anti-Agrobacterium tumefaciens activity, GYM + S (glucose, yeast extract, malt extract and starch) medium was selected out of five different production media and the medium composition was optimized. Plackett-Burman design (PBD) was used to select starch, malt extract and glucose as parameters having significant effects on antibacterial activity and a Box-Behnken design was applied for further optimization. The analysis revealed that the optimum concentrations for anti-A. tumefaciens activity of the tested variables were 19.49 g/L for starch, 5.06 g/L for malt extract and 2.07 g/L for glucose. Several Artificial Neural Networks (ANN): the Multilayer perceptron (MLP) and the Radial basis function (RBF) were also constructed to predict anti-A. tumefaciens activity. The comparison between experimental with predicted outputs from ANN and Response Surface Methodology (RSM) were studied. ANN model presents an improvement of 12.36% in terms of determination coefficients of anti A. tumefaciens activity. To our knowledge, this is the first work reporting the statistical versus artificial intelligence based modeling for optimization of bioactive molecules against phytopathogens.


Subject(s)
Agrobacterium tumefaciens/drug effects , Anti-Bacterial Agents/metabolism , Anti-Bacterial Agents/pharmacology , Streptomyces/metabolism , Anti-Bacterial Agents/isolation & purification , Culture Media/chemistry , DNA, Bacterial , Fermentation , Microbial Sensitivity Tests , Neural Networks, Computer , Phylogeny , RNA, Ribosomal, 16S/genetics , Secondary Metabolism , Soil , Soil Microbiology , Species Specificity , Streptomyces/classification , Streptomyces/genetics , Streptomyces/isolation & purification , Tunisia
14.
Biocontrol Sci ; 22(2): 67-77, 2017.
Article in English | MEDLINE | ID: mdl-28659558

ABSTRACT

 The effect of the semi purified bacteriocin BacFL31 at 200 and 400 AU/g on the shelf life of refrigerated raw ground turkey meat was investigated. The microbiological, physicochemical, and sensory properties of the meat samples were examined during refrigerated storage. The findings indicated that BacFL31 treatments were effective (p<0.05) against the proliferation of various spoilage microorganisms and suppressed the growth of Listeria monocytogenes and Salmonella Typhimurium. The pH, % Met-MB, and TBA-RS values of the treated samples were lower (p<0.05) than those of their control samples. The addition of BacFL31 extended the shelf life and enhanced the sensory attributes of the turkey meat samples during refrigerated storage. These results suggest that BacFL31 could be considered a promising candidate for future application as an additive to preserve the raw turkey meat during storage at 4℃.


Subject(s)
Bacteriocins/chemistry , Food Microbiology , Food Preservation/methods , Meat/standards , Humans , Listeria monocytogenes/drug effects , Listeria monocytogenes/growth & development , Meat/microbiology , Salmonella typhimurium/drug effects , Salmonella typhimurium/growth & development
15.
Molecules ; 22(3)2017 Mar 07.
Article in English | MEDLINE | ID: mdl-28272376

ABSTRACT

New benzimidazolium salts 1a-c and their palladium bis-N-heterocyclic carbene complexes 2a-c and palladium PEPPSI-type complexes 3a-c were designed, synthesized and structurally characterized by NMR (1H and 13C), IR, DART-TOF mass spectrometry and elemental analysis. Then these complexes 2-3 were employed in the Suzuki-Miyaura cross-coupling reaction of substituted arenes with phenylboronic acid under mild conditions in toluene and DMF/H2O (1/1) to afford functionalized biaryl derivatives in good to excellent yields. The antibacterial activity of palladium bis-N-heterocyclic carbene complexes 2a-c and palladium PEPPSI-type complexes 3a-c was measured by disc diffusion method against Gram positive and Gram negative bacteria. Compounds 2a, 2c and 3a-c exhibited potential antibacterial activity against four bacterial species among the five used indicator cells. The product 2b inhibits the growth of the all five tested microorganisms. Moreover, the antioxidant activity determination of these complexes 2-3, using 2.2-diphenyl-1-picrylhydrazyl (DPPH) as a reagent, showed that compounds 2a-c and 3b possess DPPH antiradical activity. The higher antioxidant activity was obtained from the product 2b which has radical scavenging activity comparable to that of the two used positive controls (gallic acid "GA" and tutylatedhydroxytoluene "BHT"). Investigation of the anti-acetylcholinesterase activity of the studied complexes showed that compounds 2b, 3a, and 3b exhibited moderate activity at 100 µg/mL and product 2b is the most active.


Subject(s)
Boronic Acids/chemical synthesis , Boronic Acids/pharmacology , Bromides/chemistry , Chlorides/chemistry , Palladium/chemistry , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Antioxidants/chemistry , Antioxidants/pharmacology , Carbon-13 Magnetic Resonance Spectroscopy , Catalysis , Cholinesterase Inhibitors/chemistry , Cholinesterase Inhibitors/pharmacology , Microbial Sensitivity Tests , Proton Magnetic Resonance Spectroscopy , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
16.
Anaerobe ; 27: 1-6, 2014 Jun.
Article in English | MEDLINE | ID: mdl-24583094

ABSTRACT

A new bacterium called FL31, which was selected for its antimicrobial activity against the pathogenic bacterium Listeria monocytogenes, was identified as Enterococcus faecium and noted to produce an antibacterial proteinaceous substance (BacFL31). The active peptide from the cell-free supernatant of E. faecium FL31 was purified in four steps and the results revealed a single band with an estimated molecular mass of approximately 3.5 kDa. The N-terminal amino acid sequence of the purified BacFL31 "GLEESXGHXGQXGPXGPXGAXGP" (X = hydroxyproline) showed the presence of six hydroxyproline residues. It displayed a bactericidal mode of action against L. monocytogenes. Its application at 400 AU/g was also noted to constitute an effective approach for preventing the contamination and growth of the pathogenic bacterium L. monocytogenes during the storage of minced beef meat at 4 °C.


Subject(s)
Bacteriocins/chemistry , Bacteriocins/pharmacology , Enterococcus faecium/metabolism , Hydroxyproline/analysis , Listeria monocytogenes/drug effects , Peptides/chemistry , Peptides/pharmacology , Amino Acid Sequence , Bacteriocins/isolation & purification , Bacteriocins/metabolism , Food Preservation/methods , Listeria monocytogenes/growth & development , Microbial Viability/drug effects , Molecular Weight , Peptides/isolation & purification , Peptides/metabolism
17.
Food Chem ; 152: 566-72, 2014.
Article in English | MEDLINE | ID: mdl-24444976

ABSTRACT

During a screening programme for bacteriocin producers, a new lactic acid bacterium called J1, isolated from chicken gizzard, was noted to produce a bacteriocin (BacJ1) that inhibited Gram-positive and Gram-negative food-borne pathogens, especially Salmonella typhimurium, and it was, therefore, selected for identification and further study. The results, from 16S rRNA gene nucleotide sequencing (1583 pb accession no HE861352) and phylogenetic analysis, suggested that the new isolate be assigned as Weissella paramesenteroides J1. BacJ1 was purified from the culture supernatant of the J1 strain using heat treatment (15 min at 90 °C), 80% ammonium sulfate precipitation, and gel filtration (Sephadex G25). MALDI-TOF analyses revealed that BacJ1 had an exact molecular mass of 1881.036 Da. The analysis of the N-terminal sequence (GPAGPFGKLY) of this active peptide revealed no significant similarity to currently available antimicrobial peptides. The addition of pre-purified BacJ1, at a final concentration of 400 AU per gramme, may open new promising opportunities for the prevention of contamination from and growth of pathogenic bacteria, particularly S. typhimurium, during turkey escalope storage at 4 °C.


Subject(s)
Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Bacteriocins/chemistry , Bacteriocins/pharmacology , Meat/microbiology , Salmonella typhimurium/drug effects , Weissella/metabolism , Animals , Anti-Bacterial Agents/metabolism , Bacteriocins/genetics , Bacteriocins/metabolism , Chickens , Food Contamination/prevention & control , Food Storage , Gizzard, Avian/microbiology , Microbial Sensitivity Tests , Microbial Viability/drug effects , Molecular Sequence Data , Molecular Weight , Salmonella typhimurium/growth & development , Turkeys , Weissella/chemistry , Weissella/genetics , Weissella/isolation & purification
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