Protein Leakage Assay Research Articles

Polymyxin combined with Ocimum gratissimum essential oil: one alternative strategy for combating polymyxin-resistant Klebsiella pneumoniae.

Introduction. Multidrug-resistant infections present a critical public health due to scarce treatment options and high mortality. Ocimum gratissimum L. essential oil (O.geo) is a natural resource rich in eugenol known for its antimicrobial activity.Hypothesis/Gap Statement. O.geo may exert effective antimicrobial activity against polymyxin-resistant Klebsiella pneumoniae and, when combined with Polymyxin B (PMB), may exhibit a synergistic effect, enhancing treatment efficacy and reducing antimicrobial resistance.Aim. This study aims to investigate the antimicrobial activity of O.geo against polymyxin-resistant K. pneumoniae using in vitro tests and an in vivo Caenorhabditis elegans model.Methodology. The O.geo was obtained by hydrodistillation followed by gas chromatography. The MIC and antibiofilm activity were determined using broth microdilution. Checkerboard and time-kill assays evaluated the combination of O.geo and polymyxin B (PMB), whereas a protein leakage assay verified its action.Results. Eugenol (39.67%) was a major constituent identified. The MIC of the O.geo alone ranged from 128 to 512 µg ml-1. The fractional inhibitory concentration index (0.28) and time-kill assay showed a synergism. In addition, O.geo and PMB inhibited biofilm formation and increased protein leakage in the plasma membrane. The treatment was tested in vivo using a Caenorhabditis elegans model, and significantly increased survival without toxicity was observed.Conclusion. O.geo could be used as a potential therapeutic alternative to combat infections caused by multidrug-resistant bacteria, especially in combination with PMB.

Inhibitory effect and mechanism of violacein on planktonic growth, spore germination, biofilm formation and toxin production of Bacillus cereus and its application in grass carp preservation

Bacillus cereus is a ubiquitous foodborne pathogen commonly found in various foods. Its ability to form spores, biofilms and diarrhoeal and/or emetic toxins further exacerbates the risk of food poisoning. Violacein is a tryptophan derivative with excellent antibacterial activity. However, the knowledge on the antibacterial action of violacein against B. cereus was lacking, and thus this study aimed to investigate the antibacterial activity and mechanism. The antibacterial results demonstrated that minimum inhibitory concentration and minimum bactericidal concentration of violacein were 3.125 mg/L and 12.50 mg/L, respectively. Violacein could effectively inhibit planktonic growth, spore germination and biofilm formation of B. cereus (P < 0.001). Meanwhile, violacein significantly downregulated the expression of toxin genes, including nheA (P < 0.05), nheB (P < 0.001), bceT (P < 0.01), cytK (P < 0.001), hblC (P < 0.001) and hblD (P < 0.001). Results of extracellular alkaline phosphatase, nucleotide and protein leakage assays and scanning and transmission electron microscopy observation tests showed violacein destroyed cell walls and membranes of B. cereus. In addition, 6.25 mg/kg of violacein could significantly inhibit B. cereus in grass carp fillets (P < 0.05). These results demonstrate that violacein has great potential as an effective natural antimicrobial preservative to control food contamination and poisoning events caused by B. cereus.

Investigating the synergistic antibacterial effects of chlorogenic and p-coumaric acids on Shigella dysenteriae

Chlorogenic acid (CGA) is a well-known plant secondary metabolite exhibiting multiple physiological functions. The present study focused on screening for synergistic antibacterial combinations containing CGA. The combination of CGA and p-coumaric acid (pCA) exhibited remarkably enhanced antibacterial activity compared to that when administering the treatment only. Scanning electron microscopy revealed that a low-dose combination treatment could disrupt the Shigella dysenteriae cell membrane. A comprehensive analysis using nucleic acid and protein leakage assay, conductivity measurements, and biofilm formation inhibition experiments revealed that co-treatment increased the cell permeability and inhibited the biofilm formation substantially. Further, the polyacrylamide protein- and agarose gel-electrophoresis indicated that the proteins and DNA genome of Shigella dysenteriae severely degraded. Finally, the synergistic bactericidal effect was established for fresh-cut tomato preservation. This study demonstrates the remarkable potential of strategically selecting antibacterial agents with maximum synergistic effect and minimum dosage exhibiting excellent antibacterial activity in food preservation.

Antioxidant, Anti-inflammatory, and Antimicrobial Activity of the Kalanchoe pinnata and Piper longum Formulation Against Oral Pathogens.

Background Dental caries stands out as a significant global infectious disease, with oral diseases posing substantial health concerns primarily due to bacterial, fungal, and yeast infections. Kalanchoe pinnata demonstrates antimicrobial, anticancer, antiparasitic, and hepatoprotective properties, with applications in various ailments. Piper longum exhibits potent antimicrobial effects against bacterial and viral pathogens due to the bioactive compounds within the plant. This study aims to assess the antimicrobial efficacy of P. longum and K. pinnata formulation against oral pathogens and evaluate its other biomedical potential. Methodology The agar well diffusion method was employed to assess the antimicrobial activity of the formulation containing P. longum and K. pinnata against oral pathogens. The protein leakage assay was employed to assess the ability of the prepared formulation to cause protein release from oral pathogens. The other biomedical potentials of the prepared formulation including cytotoxic effects, antioxidant, and anti-inflammatory properties were investigated using in vitro assays. Results The prepared P. longum and K. pinnata formulation demonstrated significant antimicrobial activity against tested oral pathogens, with inhibition zones observed for Staphylococcus aureus (32 mm), Streptococcus mutans (22 mm), and Candida albicans (12 mm). However, no inhibition was observed on Enterococcus faecalis at the highest concentration of 100 μL. Additionally, the formulation demonstrated significant antioxidant activity with percentages of 89.22%, 84.4%, and 86.93% in2,2-diphenyl-1-picrylhydrazyl (DPPH), hydrogen peroxide (H2O2), and ferric (Fe3+)-reducing antioxidant power assays, respectively, at the maximum concentration of 50 μL. Furthermore, the formulation exhibited potential anti-inflammatory activity, as evidenced by 79% inhibition in bovine serum albumin (BSA) denaturation assay and 77% inhibition in egg albumin (EA) denaturation assay at the highest concentration of 50 μL. Additionally, the formulation displayed low cytotoxic effects, even at the highest concentration of 80 μL. Conclusion K. pinnataandP. longumformulation demonstrated potential antimicrobial efficacy against oral pathogens and exhibited diverse therapeutic potentials. Thus, the developed formulation could be used as a potential alternative for pharmaceutical drugs against oral pathogens.

Cytoplasmic Leakage and Protein Leakage Analysis of Ocimum Gratissimum Stem Extract-Mediated Silver Nanoparticles Against Wound Pathogens

ABSTRACT Aim: The current work intends to examine the antibacterial activity of silver nanoparticles (AgNPs) mediated by Ocimum gratissimum stem extract against wound infections. Materials and Methods: To evaluate the membrane damage brought on by AgNPs, analyses of cytoplasmic leakage and protein leakage assays were performed. Results: The outcomes demonstrated that all of the tested bacterial strains were significantly resistant to the AgNPs’ antibacterial activity. AgNPs damaged membranes and caused cellular contents to leak in the target pathogens, according to an examination of protein and cytoplasmic leakage. Conclusion: According to the current investigation, AgNPs mediated by Ocimum gratissimum stem extract may be effective antibacterial agents against microorganisms that cause wounds.

Gamma Radiation-Induced Synthesis and Characterization of Decahedron-Like Silver Nanostructure and Their Antimicrobial Application

AbstractIn the current study, a decahedron-like silver nanostructure (D-AgNs) was successfully created in an aqueous solution in the presence of Polyvinylpyrrolidone (PVP) as a capping agent using the gamma-radiolysis approach without the use of a reducing agent. The synthesized D-AgNs were characterized using various analytical tools such as UV–Vis. spectroscopy, SEM, XRD, HRTEM, EDX and FTIR. UV–Vis. absorption spectra showed considerable surface Plasmon resonance (SPR) bands at 350–600 nm, indicating that colloidal D-AgNs had been successfully synthesized. HRTEM image demonstrates well-dispersed uniformly decahedral shapes that are well separated from each other. The produced nanoparticles were effectively stabilized by PVP through interactions, confirmed by the FTIR anlaysis. The synthesis of D-AgNs using gamma radiation was accomplished, in addition its antimicrobial potential, antibiofilm activity, and the effect of UV rays were assessed. In addition, protein leakage assays and SEM imaging were employed to analyze the antimicrobial reaction’s mechanism. A wide variety of bacteria, including S. aureus, P. aeruginosa, and C. albicans, were deactivated by D-AgNs. In the antibiofilm assay, D-AgNs inhibited the biofilm formation of S. aureus (89.58%), E. coli (80.35%), and P. aureginosa (78.45%). After investigating the effect of D-AgNs on the growth curve of S. aureus, we concluded that D-AgNs affect the growth curve of S. aureus, and the curve was reduced to be 0.125. The formation of holes in the S. aureus cell membrane is explained by the fact that the amount of cellular protein released from the bacteria is directly proportional to the concentration of D-AgNs, which was determined to be 259.25 µg/ml at concentration equal to 1.0 mg/mL.

Synthesis, Antimicrobial, and Antibiofilm Activities of Some Novel 7-Methoxyquinoline Derivatives Bearing Sulfonamide Moiety against Urinary Tract Infection-Causing Pathogenic Microbes.

A new series of 4-((7-methoxyquinolin-4-yl) amino)-N-(substituted) benzenesulfonamide 3(a-s) was synthesized via the reaction of 4-chloro-7-methoxyquinoline 1 with various sulfa drugs. The structural elucidation was verified based on spectroscopic data analysis. All the target compounds were screened for their antimicrobial activity against Gram-positive bacteria, Gram-negative bacteria, and unicellular fungi. The results revealed that compound 3l has the highest effect on most tested bacterial and unicellular fungal strains. The highest effect of compound 3l was observed against E. coli and C. albicans with MIC = 7.812 and 31.125 µg/mL, respectively. Compounds 3c and 3d showed broad-spectrum antimicrobial activity, but the activity was lower than that of 3l. The antibiofilm activity of compound 3l was measured against different pathogenic microbes isolated from the urinary tract. Compound 3l could achieve biofilm extension at its adhesion strength. After adding 10.0 µg/mL of compound 3l, the highest percentage was 94.60% for E. coli, 91.74% for P. aeruginosa, and 98.03% for C. neoformans. Moreover, in the protein leakage assay, the quantity of cellular protein discharged from E. coli was 180.25 µg/mL after treatment with 1.0 mg/mL of compound 3l, which explains the creation of holes in the cell membrane of E. coli and proves compound 3l's antibacterial and antibiofilm properties. Additionally, in silico ADME prediction analyses of compounds 3c, 3d, and 3l revealed promising results, indicating the presence of drug-like properties.

Separation of Bio-active Compounds and in vitro Antibacterial Potency of Callistemon linearis Floral Extract with Mechanism of Action

Abstract: Introduction: Infection caused by bacteria is treated with antibiotics which caused several side effects in human and animals. This problem enforced scientist to work out plant originated compounds for treatment of several disease caused by morbific bacteria. Objectives: Present work revealed isolation of bioactive phytocompounds from different fractions of Callistemon linearis flower ethanol extract by chromatographic technique and determination of their antibacterial potency against selected bacteria with mode of action in vitro. Materials and Methods: Antibacterial potency of four different fractions of ethanol extract were done quantitatively via Agar well diffusion method along with determination of Minimum Inhibitory Concentration, and Minimum Bactericidal Concentrations. Further, phytochemical analysis, Fourier Transform Infrared spectroscopic analysis, thin Layer Chromatography separation and Gas Chromatography Mass Spectroscopy analysis of bioactive fractions were done simultaneously to assess the presence of bioactive phytocompounds responsible for the antibacterial potency of the fractions. Time-kill assay, Nucleic acid and protein leakage assay, and FESEM study were employed to determine the mode of activity of the isolated active phytocompounds on the tested bacteria. Results: Maximum antibacterial activity was observed in NHEX of ethanol extract against Escherichia coli (MTCC 739). Chromatographic separation of NHEX detected several bioactive compounds. Assessment of Time-kill assay in treated and untreated bacterial strains determined that bioactive compound of NHEX was bactericidal in nature. Nucleic acid and protein leakage assay of bacterial cells with isolated active compound showed cell damages and FESEM images strongly ascertained this data. Conclusion: The C. linearis floral floral extract possesses antibacterial activities against selected pathogens and causes cellular damages. Keywords: Callistemon linearis, Antibacterial activity, FT-IR, GC-MS analysis, Bioactive compounds, Mechanism of action.

Nanomaterized zinc sulfide-meerschaum biomatrix efficiently suppressed Fusarium verticilloides with augmented rice seed quality benefits during storage.

The seed-borne mycopathogen Fusarium verticilliodes is a serious and deleterious pathogen causing substantial losses of rice seeds and grains. Rice seeds are prone to infestation at all points of the production chain and the fungal pathogen continues dormant devastation even during storage, adversely affecting the seed parameters. Its control is compromised due to the nonavailability of recommended fungicides during storage. Nanotechnological interventions can provide effective and ecofriendly alternative against mycopathogens during resting periods. Herein, the zinc sulfide-meerschaum nano bio-matrix (nZnS-MR) is presented to show this strategy, which worked well against F. verticilliodes when applied on freshly harvested rice seeds during 6 months of storage. The healthy, smooth and rounded girths of F. verticilloides mycelium were reduced with loss of turgidity, disrupting the hyphal exterior architecture, during in vitro treatment with nZnS-MR, endorsed by staining methodology, crystal violet and intracellular soluble protein leakage assays. In vivo application on rice seeds optimized 750 μg g-1 of nano zinc sulfide (nZnS) for 6 months of application during storage with maximum reduction of disease parameters [seedling blight (1.19%) and seed rot (5.43%)] and most augmented quality parameters [maximum germination (94.14%), seedling length (22.50 cm), dry weight (0.121 g) and vigor index (11.37)]. nZnS-MR acted as a slow release nanoformulation of nZnS for long-term antifungal activity. nZnS-MR is presented as an ecofriendly, biocompatible, bio-efficient, profertilization, cost-effective green material for the control of F. verticilliodes with rice seed invigorating effect, describing it as new a nano-generation material for efficient storage application.

Antibacterial activity of Chinese propolis and its synergy with β-lactams against methicillin-resistant Staphylococcus aureus.

Propolis has exhibited effective antibacterial activities in preventing the growth of multiple pathogenic bacteria. However, the antibacterial activity of Chinese propolis against methicillin-resistant Staphylococcus aureus (MRSA) is almost unknown. The present study aimed to explore the antibacterial activity and action mechanism of Chinese propolis ethanol extract (CPEE) against MRSA. Thirteen compounds of CPEE were identified using HPLC-DAD/Q-TOF-MS, and none of them showed better anti-MRSA activity than CPEE. The diameter of inhibition zone (DIZ) of CPEE was 20.1mm. The minimal inhibitory concentration (MIC) of CPEE was 32mg/L, while the minimal bactericidal concentration (MBC) against MRSA was 64mg/L. Moreover, CPEE showed significant synergistic effects with β-lactam antibiotics (ampicillin and oxacillin). Nucleic acid and protein leakage assays showed that CPEE can stimulate the release of intracellular macromolecules by damaging the cell membrane integrity of MRSA. Live/dead-staining and SDS-PAGE assays further confirmed that CPEE could inhibit bacterial activities by disrupting the membrane. The reduction in PBP2a expression and β-lactamase activity, as shown by western blot and β-lactamase detection assays, suggested that CPEE was able to reverse the drug resistance of MRSA. These results demonstrated the anti-MRSA activity of CPEE was mainly due to changing the cell membrane and reversing resistance, which indicates that CPEE could be an attractive candidate for use in future food and medical applications.

Development of 4-[4-(Anilinomethyl)-3-phenyl-pyrazol-1-yl] Benzoic Acid Derivatives as Potent Anti-Staphylococci and Anti-Enterococci Agents.

From a library of compounds, 11 hit antibacterial agents have been identified as potent anti-Gram-positive bacterial agents. These pyrazole derivatives are active against two groups of pathogens, staphylococci and enterococci, with minimum inhibitory concentration (MIC) values as low as 0.78 μg/mL. These potent compounds showed bactericidal action, and some were effective at inhibiting and eradicating Staphylococcus aureus and Enterococcus faecalis biofilms. Real-time biofilm inhibition by the potent compounds was studied, by using Bioscreen C. These lead compounds were also very potent against S. aureus persisters as compared to controls, gentamycin and vancomycin. In multiple passage studies, bacteria developed little resistance to these compounds (no more than 2 × MIC). The plausible mode of action of the lead compounds is the permeabilization of the cell membrane determined by flow cytometry and protein leakage assays. With the detailed antimicrobial studies, both in planktonic and biofilm contexts, some of these potent compounds have the potential for further antimicrobial drug development.

Synergistic Antibacterial Activity with Conventional Antibiotics and Mechanism of Action of Shikonin against Methicillin-Resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) is a troublesome pathogen that poses a global threat to public health. Shikonin (SKN) isolated from Lithospermum erythrorhizon (L. erythrorhizon) possesses a variety of biological activities. This study aims to explore the effect of the combined application of SKN and traditional antibiotics on the vitality of MRSA and the inherent antibacterial mechanism of SKN. The synergies between SKN and antibiotics against MRSA and its clinical strain have been demonstrated by the checkerboard assay and the time-kill assay. The effect of SKN on disrupting the integrity and permeability of bacterial cell membranes was verified by a nucleotide and protein leakage assay and a bacteriolysis assay. As determined by crystal violet staining, SKN inhibited the biofilm formation of clinical MRSA strains. The results of Western blot and qRT-PCR showed that SKN could inhibit the expression of proteins and genes related to drug resistance and S. aureus exotoxins. SKN inhibited the ability of RAW264.7 cells to release the pro-inflammatory cytokines TNF-α and IL-6, as measured by ELISA. Our findings suggest that SKN has the potential to be developed as a promising alternative for the treatment of MRSA infections.

Potential Impact of Reduced Graphene Oxide Incorporated Metal Oxide Nanocomposites as Antimicrobial, and Antibiofilm Agents Against Pathogenic Microbes: Bacterial Protein Leakage Reaction Mechanism

In the current study, nanocomposites-based reduced graphene oxide (RGO) and metal oxides (AgO, NiO, and ZnO) were fabricated. The starting precursor and RGO were characterized by XRD, Raman, SEM, and HRTEM, while SEM and EDX mapping validated the synthesized nanocomposites. In addition, ZOI, MIC, antibiofilm, and growth curve were tested. The antimicrobial reaction mechanism was investigated by protein leakage assay and SEM imaging. Results revealed that all synthesized nanocomposites (RGO-AgO, RGO-NiO, and RGO-ZnO) have outstanding antimicrobial activity against pathogenic bacteria and unicellular fungi. Moreover, RGO-AgO, RGO-NiO, and RGO-ZnO nanocomposites exhibited an antibiofilm activity percentage against Staphylococcus aureus (91.72%), Candida albicans (91.17%), and Escherichia coli (90.36%). The SEM analysis of S. aureus after RGO-AgO treatment indicated morphological differences, including the whole lysis of the outer surface supported by deformations of the bacterial cells. It was observed that the quantity of cellular protein leakage from S. aureus is directly proportional to the concentration of RGO-AgO, RGO-NiO, and RGO-ZnO nanocomposites and found to be 260.25 µg/mL, 110.55 µg/mL, and 99.90 µg/mL, respectively. The prepared nanocomposites promise to treat resistant microbes as a new strategy for managing infectious diseases.

Green materials (DL-methionine/abietic acid)-based epoxy acrylate as promising antimicrobial and antibiofilm agents, and corrosion inhibitors for electron beam curable steel coating in different corrosive media

In the current article, two natural molecules (DL-methionine (DLM) and abietic acid (AA)) were used as antimicrobial, and antibiofilm agents and novel corrosion inhibitors in solvent-free coating formulations using electron beam irradiation (EB). After then, all of the coating compositions were sonicated and applied as thin coating films on a variety of substrates; these coated films (epoxy acrylate-based formulations) were then polymerized under an electron beam at dose of 10 kGy. The homogeneity and distribution of AA and DLM in the EB-cured coating films were confirmed via FTIR, water contact angle (WCA), and SEM. Open circuit potential and different corrosion tests (degree of rust, blistering, and adhesion failure at the scribe) were studied for all cured coating mild steel in 3.5% and 0.5 M of NaCl and HCl, respectively. The antimicrobial, and antibiofilm activities, and Kinetics of S. aureus growth were evaluated, while the reaction mechanism was investigated through SEM, and protein leakage assay. The results showed that the coating films containing the two natural materials protect mild steel from corrosion, and the optimum concentration of them was 0.8 wt%. It was also found that the corrosion inhibition efficiency of both DLM and AA at 0.8% gave higher values in 0.5 M HCl with 73.70 and 70.03%, respectively, than those immersed in 3.5% NaCl which gave inhibition efficiencies of 55.00 and 50.50%, respectively. Antimicrobial results indicated that, D1.6/A1.6 possesses the most potent activity against S. aureus (11.0, and 13.0 mm), P. aeruginosa, (10.2, and 10.8 mm), P. mirabilis (13.4, and 14.2 mm), and C. albicans (11.0, and 13.0 mm), respectively. The maximum antibiofilm inhibition % of A1.6 and D1.6 sample was recorded for P. aeruginosa (84.43%, and 77.08%) followed by P. mirabilis (78.58%, and 58.74%), S. typhi (77.81%, and 75.52%), and S. aureus (75.30%, and 72.59%), respectively.

Cyclo(l-proline-l-serine) Dipeptide Suppresses Seed Borne Fungal Pathogens of Rice: Altered Cellular Membrane Integrity of Fungal Hyphae and Seed Quality Benefits.

Five proline-containing diketopiperazines (Pro-DKPs) produced by antagonistic microorganisms as secondary metabolites were selected and synthesized under laboratory conditions. Out of five synthesized Pro-DKPs, cyclo(l-Pro-l-Ser) (DKP-6) revealed the best inhibition of fungal pathogens (Fusarium verticillioides and Fusarium fujikuroi) of rice under in vitro conditions with effective doses lower than standard fungicide carbendazim. DKP-6 induced stress on the fungal cell membrane integrity, which was revealed by calcofluor white and propidium iodide assays, endorsed by ultra-microscopic details and soluble protein leakage assays. In vivo seed treatment of infested rice seeds with DKP-6 at 2000 μg/mL for 10 h of seed treatment inflicted best reduction in seed rot and seedling blight with respect to control and carbendazim. Significant enhancement in seedling quality parameters were also observed. The work presented the strong influence of cyclo(l-Pro-l-Ser) as a mycocidal seed treatment agent better than synthetic toxic fungicides for rice.

Bacteriostatic effect of Echeveria extracts on diarrheagenic E. coli pathotypes and non-cytotoxicity on human Caco-2 cells.

Diarrheagenic Escherichia coli pathotypes are important aetiological agents of diarrhoeal illness among children from less developed areas, worldwide. Diarrheagenic E. coli pathotypes strains are increasingly becoming drug resistant, thus effective and accessible therapeutic alternatives are required for their treatment; herbal extracts may be a potential alternative. to evaluate Echeveria craigiana, E. kimnachii, and E. subrigida methanol extracts antibacterial effect on six diarrheagenic E. coli reference strains and on human colorectal adenocarcinoma cells viability and cytokine production. Diarrheagenic E. coli pathotypes reference strains: typical enteropathogenic E2348/69, enterotoxigenic H10407, enterohaemorrhagic O157:H7/EDL933, enteroinvasive E11, diffusely adherent C18451-A, and enteroaggregative 042 E. coli. E craigiana, E. kimnachii, and E. subrigida leaves, collected at Sinaloa, Mexico, were freeze-dried and macerated in methanol solvent. Antibacterial activity was determined by a novel method developed in our laboratory, bacterial oxygen consumption by polarographic oxygen electrode technique and membrane integrity by two methods (live/dead and protein leakage assays). Colorectal adenocarcinoma cells viability by MTT assay and cytokine production using a Cytometric Bead Array kit. Extracts concentrations of 100 μg/mL and 5-hour incubation, reduced more than 93% the growth of all diarrheagenic E. coli pathotypes tested strains and significantly decreased bacterial oxygen consumption, like bacteriostatic antibiotics. After 24-hour incubation methanol extracts had a differential antibacterial effect on each diarrheagenic E. coli pathotypes strain. Echeveria extracts did not have any effect on viability and cytokine production of colorectal adenocarcinoma cells. Echeveria methanol extracts have a bacteriostatic effect on all diarrheagenic E. coli pathotypes strains, thus potentially they could be used as antibacterial agents on diarrheagenic E. coli pathotypes-contaminated products and on patients with diarrheagenic E. coli pathotypes infections.

Antibacterial Activity and Multi-Targeting Mechanism of Dehydrocorydaline From Corydalis turtschaninovii Bess. Against Listeria monocytogenes.

Listeria monocytogenes is a foodborne pathogen, with relatively low incidence but high case-fatality. Phytochemicals have been recognized as a promising antimicrobial agent as an alternative to synthetic chemicals due to their safety and high efficacy with multi-target sites. This study identified and characterized a novel antibacterial agent, dehydrocorydaline, in the Corydalis turschaninovii rhizome using HPLC-LTQ-Orbitrap-HRMS, and its antibacterial effect with lowest MIC (1 mg/mL) and MBC (2 mg/mL) values. In addition, an in vitro growth kinetic assay, cytoplasmic nucleic acid and protein leakage assay, and observation of morphological changes in bacterial cells supported the strong antibacterial activity. Dehydrocorydaline also displayed effective inhibitory effects on biofilm formation and bacterial motility. In order to investigate the potential antibacterial mechanism of action of dehydrocorydaline against L. monocytogenes, label-free quantitative proteomics was used, demonstrating that dehydrocorydaline has multiple targets for combating L. monocytogenes including dysregulation of carbohydrate metabolism, suppression of cell wall synthesis, and inhibition of bacterial motility. Overall, this study demonstrated that dehydrocorydaline has potential as a natural and effective antibacterial agent with multi-target sites in pathogenic bacteria, and provides the basis for development of a new class of antibacterial agent.

Biogenic silver nanoparticle (Bio‐AgNP) has an antibacterial effect against carbapenem‐resistant Acinetobacter baumannii with synergism and additivity when combined with polymyxin B

Carbapenem-resistant Acinetobacter baumannii represents a public health problem, and the search for new antibacterial drugs has become a priority. Here, we investigate the antibacterial activity of biogenic silver nanoparticles (Bio-AgNPs) synthesized by Fusarium oxysporum, used alone or in combination with polymyxin B against carbapenem-resistant A. baumannii. In this study, ATCC® 19606™ strain and four carbapenem-resistant A. baumannii strains were used. The antibacterial activity of Bio-AgNPs and its synergism with polymyxin B were determined using broth microdilution, checkboard methods and time-kill assays. The integrity of the bacterial cell membrane was monitored by protein leakage assay. In addition, the cytotoxicity in the VERO mammalian cell line was also evaluated, and the selectivity index was calculated. Bio-AgNPs have an antibacterial activity with MIC and MBC ranging from 0.460 to 1.870µg/ml. The combination of polymyxin B and Bio-AgNPs presents synergy against four of the five strains tested and additivity against one strain in the checkerboard assay. Considering the time of cell death, Bio-AgNPs killed all carbapenem-resistant isolates and ATCC® 19606™ within 1h. When combined, Bio-AgNPs presented 16-fold reduction of the polymyxin B MIC and showed a decrease in terms of viable A. baumannii cells in 4h of treatment, with synergic and additive effects. Protein leakage was observed with increasing concentrations for Bio-AgNPs treatments. Additionally, Bio-AgNP and polymyxin B showed dose-dependent cytotoxicity against mammalian VERO cells and combined the cytotoxicity which was significantly reduced and presented a greater pharmacological safety. The results presented here indicate that Bio-AgNPs in combination with polymyxin B could represent a good alternative in the treatment of carbapenem-resistant A. baumannii. This study demonstrates the synergic effect between Bio-AgNPs and polymyxin B on carbapenem-resistant A. baumannii strains.

Phenyl Substituted Thiazole Linked 1, 2, 4-triazole Derivatives: Synthesis and Their Biological Evaluation

Synthesize and evaluate some phenyl substituted thiazole linked 1, 2, 4-triazole derivatives as antimicrobial agents. Compounds containing 1, 2, 4-triazole moieties are widely used as antimicrobial and antifungal agents whereas thiazole is another heterocyclic ring exhibiting various pharmacological actions. It is interesting to incorporate different bioactive pharmacophores in the same molecular framework to examine cumulative effect exerted by the moiety. This hypothesis was applied in research work by having triazole and thiazole in the same molecular framework. The present work was mainly focused on synthesis of some 1, 2, 4-triazole derivatives linking with phenyl substituted thiazole nucleus and their evaluation for biological activity. The compounds (8a-8j) were synthesized as per design scheme and elucidated their structures using different spectroscopic data of IR, 1HNMR, 13CNMR &amp; mass spectroscopy. These synthesized derivatives were evaluated for their antibacterial activity using broth dilution assay. Further, mechanism of action of test compounds was examined using protein leakage assay. All the spectral data were confirmed the synthesis of phenyl substituted thiazole linked 1, 2, 4- triazole derivatives and some of them exhibited significant antimicrobial activity. Amongst all compound 8c showed most potent activity with lowest IC50 values 180 μg/ml and 120 μg/ml against S. aureus &amp; B. cereus respectively. Whereas compound 8j demonstrated strong inhibitory activities only against negative strains P. aeruginosa and E. coli with lowest IC50 values 240 μg/mL and 200μg/mL respectively.

Phyto-fabricated silver nanoparticles inducing microbial cell death via reactive oxygen species-mediated membrane damage.

Eco‐friendly synthesis of the silver nanoparticles (AgNPs) has a number of advantages like simplicity, biocompatibility, low toxicity in nature over their physical and chemical methods. In the present study, the authors report biosynthesized AgNPs using the root extract of the perennial plant ‘Spiny gourd’ (Momordica dioica) and investigated their anti‐bacterial application with mechanistic approaches. Different biophysical techniques such as UV‐Vis spectroscopy, FTIR, XRD, TEM, SAED, and DLS were employed for AgNPs characterization. The synthesized AgNPs were polydispersed, crystalline in nature, with anionic surface (−22.3 mV), spherical in shape with an average size of 13.2 nm. In addition, the AgNPs were stable in room temperature and in different biological buffers. The anti‐bacterial activities of AgNPs were studied with respect to the pathogens such as Bacillus subtilis, Staphylococcus aureus (Gram‐positive), Pseudomonas aeruginosa, Escherichia coli, Klebsiella planticola (Gram‐negative), and Candida albicans. Also, mechanistic studies of AgNPs such as protein leakage assay, nucleic acid leakage assay, ATP leakage assay, ROS accumulation, determination of biofilm degrading activity, measurement of potassium, showing that the synthesized AgNPs are capable of containing a potential application in the antimicrobial therapeutic agents and the pharmaceutical industry.