Query: antibacterial activity

title: Facile green synthesis of silver nanoparticles using Berberis vulgaris leaf and root aqueous extract and its antibacterial activity.
abstract: Most recently, silver nanoparticles due to antibacterial properties have been considered in medical science. So the aim of the study was green synthesis of silver nanoparticles using Berberis vulgaris leaf and root aqueous extract and its antibacterial activity. After collection, identification and extraction of Berberis vulgaris was performed production of silver nanoparticles. In the study effect of parameters such as AgNO3 concentration (0.5, 1, 3, 10 mM) aqueous extract (3, 5, 10, 15, 30 mL) and contact time (1, 2, 6, 12, 24 h) were investigated in the synthesis of nanoparticles and also the antibacterial effect of these nanoparticles was studied on Escherichia coli and Staphylococcus aureus bacteria by Disk diffusion test and Minimum Inhibitory Concentration test (MIC) According to XRD results and analysis of TEM, nanoparticles have spherical shapes and size of 30 to 70 nm. On the other hand antibacterial tests showed these nanoparticles have more antibacterial activity more than other extracts. Result showed the biosynthesis of silver nanoparticles using aqueous extract of Berberis vulgaris is a clean, inexpensive and safe method that has not been used any toxic substance and consequently does not side effects and this nanoparticles has a high antibacterial activity.

title: Antibacterial activity of flavonoids and their structure activity relationship: An update review
abstract: Based on World Health Organization reports, resistance of bacteria to well known antibiotics is a major global health challenge now and in the future. Different strategies have been proposed to tackle this problem including inhibition of multidrug resistance pumps and biofilm formation in bacteria and development of new antibiotics with novel mechanism of action. Flavonoids are a large class of natural compounds, have been extensively studied for their antibacterial activity, and more than 150 articles have been published on this topic since 2005. Over the past decade, some promising results were obtained with the antibacterial activity of flavonoids. In some cases, flavonoids (especially chalcones) showed up to sixfold stronger antibacterial activities than standard drugs in the market. Some synthetic derivatives of flavonoids also exhibited remarkable antibacterial activities with 20 to 80 fold more potent activity than the standard drug against multidrug resistant Gram negative and Gram positive bacteria (including Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus) This review summarizes the ever changing information on antibacterial activity of flavonoids since 2005, with a special focus on the structure activity relationship and mechanisms of actions of this broad class of natural compounds.

title: Review on Zinc Oxide Nanoparticles: Antibacterial Activity and Toxicity Mechanism
abstract: Antibacterial activity of zinc oxide nanoparticles (ZnO NPs) has received significant interest worldwide particularly by the implementation of nanotechnology to synthesize particles in the nanometer region. Many microorganisms exist in the range from hundreds of nanometers to tens of micrometers. ZnO NPs exhibit attractive antibacterial properties due to increased specific surface area as the reduced particle size leading to enhanced particle surface reactivity. ZnO is a bio safe material that possesses photo oxidizing and photocatalysis impacts on chemical and biological species. This review covered ZnO NPs antibacterial activity including testing methods, impact of UV illumination, ZnO particle properties (size, concentration, morphology, and defects) particle surface modification, and minimum inhibitory concentration. Particular emphasize was given to bactericidal and bacteriostatic mechanisms with focus on generation of reactive oxygen species (ROS) including hydrogen peroxide (H2O2) OH (hydroxyl radicals) and O2 2 (peroxide) ROS has been a major factor for several mechanisms including cell wall damage due to ZnO localized interaction, enhanced membrane permeability, internalization of NPs due to loss of proton motive force and uptake of toxic dissolved zinc ions. These have led to mitochondria weakness, intracellular outflow, and release in gene expression of oxidative stress which caused eventual cell growth inhibition and cell death. In some cases, enhanced antibacterial activity can be attributed to surface defects on ZnO abrasive surface texture. One functional application of the ZnO antibacterial bioactivity was discussed in food packaging industry where ZnO NPs are used as an antibacterial agent toward foodborne diseases. Proper incorporation of ZnO NPs into packaging materials can cause interaction with foodborne pathogens, thereby releasing NPs onto food surface where they come in contact with bad bacteria and cause the bacterial death and/or inhibition.

title: Antibacterial Activity of Silver Nanoparticles: Structural Effects
abstract: The increase of antibiotic resistance in bacteria has become a major concern for successful diagnosis and treatment of infectious diseases. Over the past few decades, significant progress has been achieved on the development of nanotechnology based medicines for combating multidrug resistance in microorganisms. Among this, silver nanoparticles (AgNPs) hold great promise in addressing this challenge due to their broad spectrum and robust antimicrobial properties. This review illustrates the antibacterial mechanisms of silver nanoparticles and further elucidates how different structural factors including surface chemistry, size, and shape, impact their antibacterial activities, which are expected to promote the future development of more potent silver nanoparticle based antibacterial agents.

title: Polymyxins: Antibacterial Activity, Susceptibility Testing, and Resistance Mechanisms Encoded by Plasmids or Chromosomes
abstract: Polymyxins are well established antibiotics that have recently regained significant interest as a consequence of the increasing incidence of infections due to multidrug resistant Gram negative bacteria. Colistin and polymyxin B are being seriously reconsidered as last resort antibiotics in many areas where multidrug resistance is observed in clinical medicine. In parallel, the heavy use of polymyxins in veterinary medicine is currently being reconsidered due to increased reports of polymyxin resistant bacteria. Susceptibility testing is challenging with polymyxins, and currently available techniques are presented here. Genotypic and phenotypic methods that provide relevant information for diagnostic laboratories are presented. This review also presents recent works in relation to recently identified mechanisms of polymyxin resistance, including chromosomally encoded resistance traits as well as the recently identified plasmid encoded polymyxin resistance determinant MCR 1. Epidemiological features summarizing the current knowledge in that field are presented.

title: Metal nanoparticles: understanding the mechanisms behind antibacterial activity
abstract: As the field of nanomedicine emerges, there is a lag in research surrounding the topic of nanoparticle (NP) toxicity, particularly concerned with mechanisms of action. The continuous emergence of bacterial resistance has challenged the research community to develop novel antibiotic agents. Metal NPs are among the most promising of these because show strong antibacterial activity. This review summarizes and discusses proposed mechanisms of antibacterial action of different metal NPs. These mechanisms of bacterial killing include the production of reactive oxygen species, cation release, biomolecule damages, ATP depletion, and membrane interaction. Finally, a comprehensive analysis of the effects of NPs on the regulation of genes and proteins (transcriptomic and proteomic) profiles is discussed.

title: Phytochemicals for human disease: An update on plant derived compounds antibacterial activity.
abstract: In recent years, many studies have shown that phytochemicals exert their antibacterial activity through different mechanisms of action, such as damage to the bacterial membrane and suppression of virulence factors, including inhibition of the activity of enzymes and toxins, and bacterial biofilm formation. In this review, we summarise data from the available literature regarding the antibacterial effects of the main phytochemicals belonging to different chemical classes, alkaloids, sulfur containing phytochemicals, terpenoids, and polyphenols. Some phytochemicals, besides having direct antimicrobial activity, showed an in vitro synergistic effect when tested in combination with conventional antibiotics, modifying antibiotic resistance. Review of the literature showed that phytochemicals represent a possible source of effective, cheap and safe antimicrobial agents, though much work must still be carried out, especially in in vivo conditions to ensure the selection of effective antimicrobial substances with low side and adverse effects.

title: Antibacterial activity of silver nanoparticles: A surface science insight
abstract: Silver nanoparticles constitute a very promising approach for the development of new antimicrobial systems. Nanoparticulate objects can bring significant improvements in the antibacterial activity of this element, through specific effect such as an adsorption at bacterial surfaces. However, the mechanism of action is essentially driven by the oxidative dissolution of the nanoparticles, as indicated by recent direct observations. The role of Ag+ release in the action mechanism was also indirectly observed in numerous studies, and explains the sensitivity of the antimicrobial activity to the presence of some chemical species, notably halides and sulfides which form insoluble salts with Ag+ As such, surface properties of Ag nanoparticles have a crucial impact on their potency, as they influence both physical (aggregation, affinity for bacterial membrane, etc. and chemical (dissolution, passivation, etc. phenomena. Here, we review the main parameters that will affect the surface state of Ag NPs and their influence on antimicrobial efficacy. We also provide an analysis of several works on Ag NPs activity, observed through the scope of an oxidative Ag+ release.

title: Differential Pd nanocrystal facets demonstrate distinct antibacterial activity against Gram positive and Gram negative bacteria
abstract: Noble metal based nanomaterials have shown promise as potential enzyme mimetics, but the facet effect and underlying molecular mechanisms are largely unknown. Herein, with a combined experimental and theoretical approach, we unveil that palladium (Pd) nanocrystals exhibit facet dependent oxidase and peroxidase like activities that endow them with excellent antibacterial properties via generation of reactive oxygen species. The antibacterial efficiency of Pd nanocrystals against Gram positive bacteria is consistent with the extent of their enzyme like activity, that is {100} faceted Pd cubes with higher activities kill bacteria more effectively than {111} faceted Pd octahedrons. Surprisingly, a reverse trend of antibacterial activity is observed against Gram negative bacteria, with Pd octahedrons displaying stronger penetration into bacterial membranes than Pd nanocubes, thereby exerting higher antibacterial activity than the latter. Our findings provide a deeper understanding of facet dependent enzyme like activities and might advance the development of noble metal based nanomaterials with both enhanced and targeted antibacterial activities.Noble metal nanoparticles are potential antibacterial agents, perhaps owing to their enzyme like activities. Here, the authors find that the exposed facets of palladium nanocrystals demonstrate their specific antibacterial behavior against both Gram positive and Gram negative bacteria.

title: Antibacterial Activity and Synergistic Antibacterial Potential of Biosynthesized Silver Nanoparticles against Foodborne Pathogenic Bacteria along with its Anticandidal and Antioxidant Effects
abstract: Silver nanoparticles plays a vital role in the development of new antimicrobial substances against a number of pathogenic microorganisms. These nanoparticles due to their smaller size could be very effective as they can improve the antibacterial activity through lysis of bacterial cell wall. Green synthesis of metal nanoparticles using various plants and plant products has recently been successfully accomplished. However, few studies have investigated the use of industrial waste materials in nanoparticle synthesis. In the present investigation, synthesis of silver nanoparticles (AgNPs) was attempted using the aqueous extract of corn leaf waste of Zea mays, which is a waste material from the corn industry. The synthesized AgNPs were evaluated for their antibacterial activity against foodborne pathogenic bacteria (Bacillus cereus ATCC 13061, Listeria monocytogenes ATCC 19115, Staphylococcus aureus ATCC 49444, Escherichia coli ATCC 43890, and Salmonella Typhimurium ATCC 43174) along with the study of its synergistic antibacterial activity. The anticandidal activity of AgNPs were evaluated against Candida species (C. albicans KACC 30003 and KACC 30062, C. glabrata KBNO6P00368, C. geochares KACC 30061, and C. saitoana KACC 41238) together with the antioxidant potential. The biosynthesized AgNPs were characterized by UV Vis spectrophotometry with surface plasmon resonance at 450 nm followed by the analysis using scanning electron microscope, X ray diffraction, Fourier transform infrared spectroscopy and thermogravimetric analysis. The AgNPs displayed moderate antibacterial activity (9.26 11.57 mm inhibition zone) against all five foodborne pathogenic bacteria. When AgNPs were mixed with standard antibacterial or anticandidal agent, they displayed strong synergistic antibacterial (10.62 12.80 mm inhibition zones) and anticandidal activity (11.43 14.33 mm inhibition zones) In addition, the AgNPs exhibited strong antioxidant potential. The overall results highlighted the potential use of maize industrial waste materials in the synthesis of AgNPs and their utilization in various applications particularly as antibacterial substance in food packaging, food preservation to protect against various dreadful foodborne pathogenic bacteria together with its biomedical, pharmaceutical based activities.