Letteratura scientifica selezionata sul tema "Antibacterial mechanism"
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Articoli di riviste sul tema "Antibacterial mechanism":
1
Dong, Yingshan, e Xuesong Sun. "Antibacterial Mechanism of Nanosilvers". Current Pharmacology Reports 5, n. 6 (23 novembre 2019): 401–9. http://dx.doi.org/10.1007/s40495-019-00204-6.
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Dolla, Naveen K., Chao Chen, Jonah Larkins-Ford, Rajmohan Rajamuthiah, Sakthimala Jagadeesan, Annie L. Conery, Frederick M. Ausubel et al. "On the Mechanism of Berberine–INF55 (5-Nitro-2-phenylindole) Hybrid Antibacterials". Australian Journal of Chemistry 67, n. 10 (2014): 1471. http://dx.doi.org/10.1071/ch14426.
Abstract (sommario):
Berberine–INF55 hybrids are a promising class of antibacterials that combine berberine and the NorA multidrug resistance pump inhibitor INF55 (5-nitro-2-phenylindole) together in one molecule via a chemically stable linkage. Previous studies demonstrated the potential of these compounds for countering efflux-mediated antibacterial drug resistance but they didn’t establish whether the compounds function as originally intended, i.e. with the berberine moiety providing antibacterial activity and the attached INF55 component independently blocking multidrug resistance pumps, thereby enhancing the activity of berberine by reducing its efflux. We hypothesised that if the proposed mechanism is correct, then hybrids carrying more potent INF55 pump inhibitor structures should show enhanced antibacterial effects relative to those bearing weaker inhibitors. Two INF55 analogues showing graded reductions in NorA inhibitory activity compared with INF55 were identified and their corresponding berberine–INF55 hybrids carrying equivalent INF55 inhibitor structures synthesised. Multiple assays comparing the antibacterial effects of the hybrids and their corresponding berberine–INF55 analogue combinations showed that the three hybrids all show very similar activities, leading us to conclude that the antibacterial mechanism(s) of berberine–INF55 hybrids is different from berberine–INF55 combinations.
3
Pertiwi, Galuh Bela, I. Gusti Agung Ayu Kusuma Wardani e Ni Made Dwi Mara Widyani Nayaka. "A REVIEW OF ANTIBACTERIAL POTENTIAL OF BANANG-BANANG PLANT (Xylocarpus granatum J.Koenig) EXTRACT". Journal of Pharmaceutical Science and Application 5, n. 1 (1 giugno 2023): 19. http://dx.doi.org/10.24843/jpsa.2023.v05.i01.p03.
Abstract (sommario):
Background: Xylocarpus granatum has been used traditionally by coastal communities to treat various diseases. It is known that this plant contains secondary metabolites with various pharmacological activities, including as an antibacterial. Objective: This review article aims to provide information regarding the potential antibacterial activity of banang-banang plants and to summarize the content of compounds that have antibacterial properties and their mechanism of action. Methods: The preparation of this article is through literature studies from various international journals and national journals obtained online by taking into account predetermined inclusion and exclusion criteria. Then it was selected and studied further to obtain data related to the antibacterial activity of banang-banang plants and the content of secondary metabolites that have potential as antibacterials. Results: The banang-banang plant, especially the leaves, roots, fruit, seeds, fruit flesh, fruit peels, stems and bark with its secondary metabolites can inhibit several bacterial species such as Staphylococcus epidermidis, Pseudomonas aeruginosa, Escherichia coli, Vibrio alginolyticus, Staphylococcus aureus, Shigella boydii , Proteus spp., Streptococcus pyogenes, Ralstonia solanacaerum, Propionibacterium acnes, Agrobacterium tumefaciens, Aspergillus paraciticus, Bacillus subtilis, Candida albicans, Pseudomonas fluorescence, Micrococcus luteus, Saccharomyces ceresiviae, Salmonella typhi, Vibrio alginoliticus and Aeromonas hydrophilla. The secondary metabolites of this plant that have potential as antibacterial are tannins, saponins, steroids, phenols, triterpenoids, flavonoids, alkaloids, terpenoids and glycosides which have their respective mechanisms of action as antibacterial agents. Conclusion: Secondary metabolites contained in each part of the Xylocarpus granatum plant are thought to have a role in its antibacterial activity.Keywords: Antibacterial, Mechanism of action, Secondary metabolite, Xylocarpus granatum J.Koenig.
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Bremner, John B. "Some approaches to new antibacterial agents". Pure and Applied Chemistry 79, n. 12 (1 gennaio 2007): 2143–53. http://dx.doi.org/10.1351/pac200779122143.
Abstract (sommario):
Bacteria use a number of resistance mechanisms to counter the antibacterial challenge, and one of these is the expression of transmembrane protein-based efflux pumps which can pump out antibacterials from within the cells, thus lowering the antibacterial concentration to nonlethal levels. For example, in S. aureus, the NorA pump can pump out the antibacterial alkaloid berberine and ciprofloxacin. One general strategy to reduce the health threat of resistant bacteria is to block a major bacterial resistance mechanism at the same time as interfering with another bacterial pathway or target site. New developments of this approach in the context of dual-action prodrugs and dual-action (or hybrid) drugs in which one action is targeted at blocking the NorA efflux pump and the second action at an alternative bacterial target site (or sites) for the antibacterial action are discussed. The compounds are based on a combination of 2-aryl-5-nitro-1H-indole derivatives (as the NorA efflux pump blocking component) and derivatives of berberine. General design principles, syntheses, antibacterial testing, and preliminary work on modes of action studies are discussed.
5
Zhao, Lin, Yingying Zhao, Jinfeng Wei, Zhenhua Liu, Changqin Li e Wenyi Kang. "Antibacterial Mechanism of Dihydrotanshinone I". Natural Product Communications 16, n. 2 (febbraio 2021): 1934578X2199615. http://dx.doi.org/10.1177/1934578x21996158.
Abstract (sommario):
The antimicrobial activity and the underlying action mechanisms of dihydrotanshinone I against Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, extended-spectrum beta-lactamases Staphylococcus aureus were investigated with Kleihauer-Betke (K-B) test. The antibacterial mechanisms of dihydrotanshinone I were investigated by monitoring the changes in electric conductivity, concentration of AKP, protein content, and patterns of protein electrophoretic bands in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The antibacterial rings showed that antimicrobial activity of dihydrotanshinone I at 18 mM was stronger to Staphylococcus aureus than to methicillin-resistant Staphylococcus aureus and extended-spectrum beta-lactamases Staphylococcus aureus. The minimum inhibitory concentration (MIC) and IC50 values showed that dihydrotanshinone I had the strongest inhibitory activity against S. aureus (MIC = 280 µM, IC50 = 874 ± 0.01 µM, respectively). Dihydrotanshinone I could increase the electric conductivity, concentration of alkaline phosphatase (AKP) and protein content. The patterns of protein bands in SDS-PAGE were changed obviously. Dihydrotanshinone I also significantly inhibited S. aureus, methicillin-resistant S. aureus, and extended-spectrum beta-lactamases S. aureus, indicating that dihydrotanshinone I can damage the structures of cell wall and cell membrane to increase permeability of cell membrane and release of cell components. Dihydrotanshinone I could influence the synthesis of bacterial protein, destroy the protein, or reject the anabolism or expression of the protein, and finally lead to the loss of normal physiological function of bacteria.
6
Zhu, Hongtao, Xiaolu Zhang, Mengyao Lu, Haiqin Chen, Shiyi Chen, Jiaxuan Han, Yan Zhang, Ping Zhao e Zhaoming Dong. "Antibacterial Mechanism of Silkworm Seroins". Polymers 12, n. 12 (14 dicembre 2020): 2985. http://dx.doi.org/10.3390/polym12122985.
Abstract (sommario):
Seroin 1 and seroin 2 are abundant in silkworm cocoon silk and show strong antibacterial activities, and thus are thought to protect cocoon silk from damage by bacteria. In this study, we characterized the expression pattern of silkworm seroin 3, and found that seroin 3 is synthesized in the female ovary and secreted into egg to play its roles. After being infected, seroin 1, 2, and 3 were significantly up-regulated in the silkworm. We synthesized the full-length protein of seroin 1, 2, and 3 and their N/C-terminal domain (seroin-N/C), and compared the antimicrobial activities in vitro. All three seroins showed higher antibacterial activity against Gram-positive bacteria than against Gram-negative bacteria. Seroin 2 showed better antibacterial effect than seroin 1 and 3, whereas seroin 1/2/3-N was better than seroin 1/2/3-C. We found that seroin 2-C has stronger peptidoglycan binding ability than seroin 2-N per the ELISA test. The binding sites of seroin 2 with bacteria were blocked by peptidoglycan, which resulted in the loss of the antibacterial activity of seroin 2. Collectively, these findings suggest that seroin 1 and 2 play antibacterial roles in cocoon silk, whereas seroin 3 functions in the eggs. The three silkworm seroins have the same antibacterial mechanism, that is, binding to bacterial peptidoglycan by the C-terminal domain and inhibiting bacterial growth by the N-terminal domain.
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LIN, CHIA-MIN, JAMES F. PRESTON e CHENG-I. WEI. "Antibacterial Mechanism of Allyl Isothiocyanate†". Journal of Food Protection 63, n. 6 (1 giugno 2000): 727–34. http://dx.doi.org/10.4315/0362-028x-63.6.727.
Abstract (sommario):
Allyl isothiocyanate (AITC), a natural compound in plants belonging to the family Cruciferae, has been shown to have strong antimicrobial activity in liquid media as well as in its vapor form. To understand its antimicrobial mechanism, AITC was tested for bactericidal activities to Salmonella Montevideo, Escherichia coli O157:H7, and Listeria monocytogenes Scott A at different stages of growth and was compared with streptomycin, penicillin G, and polymyxin B, each of known antibacterial mechanisms. Bactericidal activities were determined by measuring bacterial viability and leakage of metabolites. To determine its effects on membrane permeability, β-galactosidase activity was examined after exposure of E. coli K-12 strain 3.300 to the three antibiotics and to AITC. The two gram-negative bacteria, Salmonella Montevideo and E. coli O157:H7, were more sensitive to AITC and to polymyxin B than the gram-positive L. monocytogenes. AITC and polymyxin B were effective bactericidal agents to bacteria at all growth stages, whereas penicillin G and streptomycin did not exhibit bactericidal activity to stationary cells. High A260 and A280 values of cellular filtrate and β-galactosidase activity were obtained after treatments of AITC and polymyxin B. These data indicated that AITC was most similar to polymyxin B with respect to its antibacterial effect on cell membranes and on leakage of cellular metabolites. Gaseous AITC caused metabolite leakages, measurable increases in β-galactosidase activity, and reduction of viable bacteria. The effectiveness of AITC in inhibiting bacteria at all growth stages and its strong activity in vapor phase support its application in food preservation.
8
Gao, Xin, Jinbao Liu, Bo Li e Jing Xie. "Antibacterial Activity and Antibacterial Mechanism of Lemon Verbena Essential Oil". Molecules 28, n. 7 (30 marzo 2023): 3102. http://dx.doi.org/10.3390/molecules28073102.
Abstract (sommario):
The destructive effect and mode of action of lemon verbena essential oil on cells were investigated, taking the isolated Pseudosciaena D4 as the research object. The extracellular absorbance of the Pseudosciaena D4 increased at OD260 and OD280 after being treated with lemon verbena essential oil, which destroyed the integrity of Pseudosciaena D4 cells, showing a significant effect on preventing biomembrane formation and destroying the formed biomembrane. With an increased concentration of lemon verbena essential oil, extracellular polysaccharide showed a significant decrease in content and a significant increase in inhibition rate, indicating that the secretion of extracellular polysaccharide by Pseudosciaena D4 cells could be inhibited by lemon verbena essential oil during the process of biomembrane formation. Cell introcession and shrinkage appeared after the treatment with essential oil, and a transparent cavity was formed by the out-flowed cell content. Lemon verbena essential oil destroyed the cell wall, resulting in an enhanced permeability of the cell membrane and leakage of the contents, thereby causing cell death.
9
Dandliker, Peter J., Steve D. Pratt, Angela M. Nilius, Candace Black-Schaefer, Xiaoan Ruan, Danli L. Towne, Richard F. Clark et al. "Novel Antibacterial Class". Antimicrobial Agents and Chemotherapy 47, n. 12 (dicembre 2003): 3831–39. http://dx.doi.org/10.1128/aac.47.12.3831-3839.2003.
Abstract (sommario):
ABSTRACT We report the discovery and characterization of a novel ribosome inhibitor (NRI) class that exhibits selective and broad-spectrum antibacterial activity. Compounds in this class inhibit growth of many gram-positive and gram-negative bacteria, including the common respiratory pathogens Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, and Moraxella catarrhalis, and are nontoxic to human cell lines. The first NRI was discovered in a high-throughput screen designed to identify inhibitors of cell-free translation in extracts from S. pneumoniae. The chemical structure of the NRI class is related to antibacterial quinolones, but, interestingly, the differences in structure are sufficient to completely alter the biochemical and intracellular mechanisms of action. Expression array studies and analysis of NRI-resistant mutants confirm this difference in intracellular mechanism and provide evidence that the NRIs inhibit bacterial protein synthesis by inhibiting ribosomes. Furthermore, compounds in the NRI series appear to inhibit bacterial ribosomes by a new mechanism, because NRI-resistant strains are not cross-resistant to other ribosome inhibitors, such as macrolides, chloramphenicol, tetracycline, aminoglycosides, or oxazolidinones. The NRIs are a promising new antibacterial class with activity against all major drug-resistant respiratory pathogens.
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Ulfah, Aida Julia, Muhammad Yulis Hamidy e Hilwan Yuda Teruna. "The mechanism of action underlying antibacterial activity of a diterpene quinone derivative against Staphylococcus aureus through the in vitro and in silico assays". Pharmacy Education 24, n. 2 (1 aprile 2024): 86–92. http://dx.doi.org/10.46542/pe.2024.242.8692.
Abstract (sommario):
Background: The need for new antibacterials to combat resistance is still constrained by the availability of antibacterials that are safe to use. Diterpene quinone-derived compounds are proven to have antibacterial activity. However, their mechanism of action is unknown. Objective: This study aims to determine the mechanism of antibacterial action of a diterpene quinone (6O7AR) on Staphylococcus aureus through in vitro and in silico assays. Method: MIC tests were performed using microdilution, and MBC determinations were carried out on MHA media. In vitro assays were conducted using membrane permeabilizing with Tris, Triton X-100, and ATPase-inhibiting agents with NaN3. Docking was performed on 2XCT proteins in S. aureus bacteria using AutoDock Vina. Result: The MIC and MBC results of 6O7AR were 300 μM and 2400 μM, respectively. The in vitro assay result suggested that the antimicrobial activities of 6O7AR were associated with the inhibition of ATPase function and disrupting membrane function. The docking results showed that the compound possessed good interactions with the 2XCT proteins of S. aureus. Conclusion: 6O7AR exhibited good antibacterial activity. Based on in vitro and in silico assays, the mechanism of action of this compound is related to the disruption of bacterial membrane function, and it has the potential to inhibit the ATPase enzyme and the S. aureus gyrase.
Tesi sul tema "Antibacterial mechanism":
1
Ooi, Nicola Chooi Twan. "Antibacterial activity and mechanism of action of lipophilic antioxidants". Thesis, University of Leeds, 2013. http://etheses.whiterose.ac.uk/5905/.
Abstract (sommario):
The emergence and spread of antibiotic resistance hampers effective treatment of bacterial infections. This is particularly the case for infections involving a biofilm component, as the activity of existing antibacterial drugs against these surface-attached communities is limited. The work presented in this thesis sought to identify and characterise compounds with antibacterial and antibiofilm activity against the important pathogen, Staphylococcus aureus. Antistaphylococcal activity was assessed for 16 antioxidants that are used in cosmetics, traditional medicines or as food additives, and which have been reported previously to have some antibacterial activity. Initial experiments with tert-butylhydroquinone (TBHQ) showed that activity that had previously been ascribed to the antioxidant, was a consequence of its conversion to tert-butylbenzoquinone (TBBQ) under culture conditions. TBBQ displayed innate bactericidal activity against S. aureus that was effected through perturbation of the bacterial membrane. The other antioxidants also inhibited staphylococcal growth through perturbation of the cytoplasmic membrane, and compounds that displayed selective action against bacterial membranes were identified. Of the agents with bacterial specificity, TBBQ, celastrol and nordihydroguaiaretic acid (NDGA) also eradicated staphylococcal biofilms; a rare property amongst antibacterial agents. Although these antioxidants exhibited a similar membrane-damaging mode of action, their mechanisms of antibiofilm activity differed. TBBQ eradicated preformed biofilms through sterilisation of slow-growing and persister cell populations, whilst celastrol and NDGA caused physical disruption of the biofilm. All three antioxidants acted synergistically with gentamicin against biofilms, eradicating surface attached populations at concentrations that did not cause irritation or visible damage to a human skin equivalent. The potent and selective antibacterial activity, and low resistance potential upon extended subculture, suggest that these compounds could be used topically in combination with gentamicin to treat infected wounds.
2
Martin, Constance Jean. "Efferocytosis is an Innate Antibacterial Mechanism of Mycobacterium tuberculosis Control". Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10094.
Abstract (sommario):
One third of the world’s population is infected with Mycobacterium tuberculosis, causing two million deaths annually. The bacteria avoid immune clearance by persisting within macrophages by subverting normal phagosome maturation and acidification. In order to spread, the bacteria induce necrotic death of its host macrophage, broadcasting the infection into neighboring cells. However, it has long been appreciated that the apoptotic, rather than necrotic death of an infected macrophage results in bacterial growth suppression, improved adaptive immune response and survival. The mechanism for apoptosis-mediated bacterial suppression has hitherto remained unknown. In this dissertation we report that apoptosis itself is not intrinsically bactericidal. We find that following apoptosis, the M. tuberculosis-infected macrophage is engulfed by bystander macrophages through the process of efferocytosis. Efferocytosis, or apoptotic cell clearance, is a critical function of macrophages; however, little is known regarding efferocytosis of infected apoptotic cells. We find that M. tuberculosis-infected macrophages die by apoptosis more commonly than found previously. By confocal microscopy we observed that apoptotic macrophages are rapidly engulfed by uninfected macrophages. Efferocytosis of M. tuberculosisinfected macrophages occurs in vitro with all macrophage types tested and in vivo- specifically in the lung, indicating that efferocytosis could play an important role during infection. We developed an uninfected macrophage co-culture system in which we observe efferocytosis and define conditions in which it occurs. Using this co-culture system we observe a suppression of bacterial growth. By blocking efferocytosis, we have found that the engulfment of infected cells is required for M. tuberculosis control in the macrophage co-culture system, demonstrating that efferocytosis is a novel antibacterial mechanism. We then demonstrated using transmission electron microscopy that the M. tuberculosis-containing efferocytic phagosome is structurally distinct from the traditional M. tuberculosis phagosome. Bacteria from within the efferocytic phagosome are unable to halt its maturation, and as such are delivered to lysosomes. Furthermore, we find that following efferocytosis, M. tuberculosis are killed. While efferocytosis is recognized as a constitutive housekeeping function of macrophages, our work indicates that is should also be viewed as an antimicrobial effector mechanism.
3
Adeyemi, Temitope. "Investigating the mechanism of action of potato extract against Helicobacter pylori". Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/investigating-the-mechanism-of-action-of-potato-extract-against-helicobacter-pylori(ddc5d0b6-6cbf-45aa-98ec-408de595e3f4).html.
Abstract (sommario):
Helicobacter pylori is a Gram-negative bacterium that is the major cause of many upper gastrointestinal diseases such as gastritis and peptic ulcer disease. It has the unique ability of colonising the human gastric mucosa. Failure in complete eradication of H. pylori in infected patients, mainly due to antibiotic resistance, has necessitated the development of better therapeutics, especially from natural sources. In this study, extract of Maris piper potatoes were obtained and evaluated for antibacterial activity against H. pylori in vitro. Antibacterial activity was carried out against antibiotic-sensitive and clinical antibiotic-resistant H. pylori strains, as well as a range of Gram-negative bacteria including Helicobacter and Campylobacter species, using the viable count method. Result of the antibacterial assays indicated that potato extract is bactericidal against H. pylori lab strain as well as clinical antibiotic-resistant strains, with minimum inhibitory concentration at 15.6 mg/ml. Potato extract also showed minimal antibacterial activity against other Gram- negative bacteria tested, with minimum inhibitory concentration at 250 mg/ml. The effect of the extract on the morphology of H. pylori was also observed by transmission electron microscopy (TEM). TEM analysis of potato extract-treated H. pylori cells showed disruption of the morphology of H. pylori, characterized by separation of the outer membrane from the inner membrane and loss of cell shape. Potato extract also caused hyperpolarisation of H. pylori plasma membrane; however it is unclear whether the membrane active pumping activity is affected. Mutants of H. pylori that are resistant to potato extract were generated as a means to identify the target of potato extract within the H. pylori genome. Genome sequence analysis led to the discovery of a hypothetical protein, encoded by HP0603 gene, which may be involved in inducing resistance to potato extract. The results obtained in this study provide great insights into the anti-H. pylori activity of potato extract. Overall, this study suggests the potential use of potato extract as a source of anti-H. pylori agents; and stimulates further studies into identifying its mechanism of action.
4
Silva, Fernanda Dias da. "Mecanismo de ação da microplusina, um peptídeo quelante de cobre com atividade antimicrobiana". Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/42/42135/tde-02122008-180144/.
Abstract (sommario):
Peptídeos antimicrobianos (PAMs) fazem parte de um dos mecanismos da imunidade inata contra infecções. A microplusina é um PAM de 10.204 Da, isolado da hemolinfa livre de células e dos ovos do carrapato Rhipicephalus (Boophilus) microplus. É um PAM aniônico em pH fisiológico, possui seis resíduos de cisteína, com formação de três pontes dissulfeto, além de sete resíduos de histidina concentrados principalmente na sua porção C-terminal. O presente trabalho teve como objetivo investigar o mecanismo de ação antimicrobiana da microplusina. A microplusina recombinante é ativa contra várias bactérias Gram-positivas e fungos, porém não apresenta atividade contra bactérias Gram-negativas. Para avaliar o seu mecanismo de ação, foram utilizados dois modelos: a bactéria Micrococcus luteus e o fungo Cryptococcus neoformans. A microplusina é bacteriostática contra M. luteus e apresenta localização intracelular na bactéria. Além disso, observamos que a microplusina liga cobre e que a adição deste metal ao meio de cultivo reduz sua atividade antibacteriana. Bactérias M. luteus pré-incubadas com microplusina retomam o seu crescimento quando cobre é adicionado ao meio. Estes dados indicam que a atividade da microplusina está relacionada à sua habilidade de depletar cobre do meio extra ou intracelular, sugerindo um efeito nutricional para o peptídeo. A microplusina apresenta estrutura terciária com cinco a-hélices e sua ligação ao cobre não induz mudanças conformacionais. Observou-se que as histidinas 1, 2 e 74 da microplusina podem estar envolvidas na formação de um sítio de ligação ao cobre. Quanto à C. neoformans, verificou-se que a microplusina inibe a melanização do fungo, um fator de virulência catalisado pela lacase, uma enzima cobre-dependente. Entretanto, a microplusina não afeta a atividade da lacase, nem sua expressão gênica. O peptídeo também não inibe a auto-polimerização de substratos fenólicos que levam à melanização. Sendo assim, mais estudos são necessários a fim de avaliar o mecanismo pelo qual a microplusina inibe a melanização. Adicionalmente, a microplusina afeta a viabilidade do fungo e reduz o tamanho de sua cápsula, outro importante fator de virulência. As atividades da microplusina sobre C. neoformans sugerem o seu potencial terapêutico. Experimentos in vivo com modelo murino, mostraram que a microplusina reduz o processo inflamatório e a viabilidade de C. neoformans nos pulmões, indicando que em condições otimizadas, o peptídeo pode atuar no controle de infecções.Antimicrobial peptides (AMPs) take part of innate immune mechanisms against infections. Microplusin is a 10,204 Da AMP, isolated from cell-free hemolymph and eggs of the tick Rhipicephalus (Boophilus) microplus. It is an anionic AMP at physiological pH, with six cysteine residues forming three disulfide bridges and seven histidine residues clustered mainly at the carboxy end portion. The goal of the present work was investigate the antimicrobial action mechanism of microplusin. Recombinant microplusin is active against Gram-positive bacteria and fungi, however, no activity is detected for Gram-negative bacteria. Two models were used to evaluate the action mechanism of microplusin: the bacteria Micrococcus luteus and the yeast Cryptococcus neoformans. Microplusin is bacteriostatic against M. luteus and its localization is intracellular for these bacteria. Moreover, microplusin binds copper and the addition of this metal into the medium reduces its antibacterial activity. M. luteus bacteria pre-treated with microplusin recover its growth when copper is added. These data indicate that microplusin activity is related to its ability to deplete copper present in the extracellular or intracellular environment, suggesting a nutritional effect. Microplusin presents a tertiary structure with five a-helix and the copper binding does not induce conformation changes. In addition, it was observed that histidines 1, 2 and 74 from microplusin may be involved in the formation of a copper binding site. About C. neoformans, it was verified microplusin inhibits its melanization, a virulence factor catalyzed by laccase, a copper dependent enzyme. However, microplusin does affect neither laccase activity nor its gene expression. The melanization caused by auto-polymerazation of phenolic substrates, is also not inhibited by microplusin. Hence, additional studies are required to evaluate the mechanism by which microplusin inhibits melanization. In addition, microplusin also affects the fungi viability and reduces the capsule size, another important virulence factor.The microplusin activities against C. neoformans suggest its therapeutic potential. In vivo experiments with murine model showed that microplusin reduces the inflammation and the viability of C. neoformans in the lungs, indicating that, in optimized conditions, the peptide may act in the infection control.
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Dannenberg, Guilherme da Silva. "Óleo essencial de pimenta rosa (Schinus terebinthifolius RADDI): atividade antimicrobiana e aplicação como componente ativo em filme para bioconservação de alimentos". Universidade Federal de Pelotas, 2017. http://repositorio.ufpel.edu.br:8080/handle/prefix/3666.
Abstract (sommario):
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
A utilização de conservantes naturais bem como de embalagens ativas vêm ganhando espaço na indústria de alimentos. Neste trabalho, objetivou-se avaliar as características antimicrobianas do óleo essencial de pimenta rosa (OEPR) e, utilizá- lo como componente ativo na elaboração de filmes para aplicação no desenvolvimento de embalagens bioconservantes para alimentos. Através da análise cromatográfica (CG/MS), detectou-se 18 compostos, 4 monoterpenos e 14 sesquiterpenos, dos quais β-mirceno (41%), β-cuvebeno (12%) e Limoneno (9%) foram os majoritários. Na atividade antimicrobiana do OEPR em ágar e caldo, verificou-se ação contra cinco bactérias patogênicas. A CIM (Concentração Inibitória Mínima) para S. aureus e L. monocytogenes foi de 0,68 e 1,36 mg/mL, respectivamente e a CBM (Concentração Bactericida Mínima) foi de 2,72 mg/mL, para ambas. Em micro-atmosfera a redução foi de 100% no desenvolvimento de S. aureus e L. monocytogenes e, 16 e 15% para E. coli e S. Typhimurium. O tempo de contato necessário para a CBM agir sobre bactérias Gram positivas foi inferior ao período de 12 h, e bactérias Gram negativas não foram inibidas. Além disso, foram verificadas alterações na permeabilidade e integridade da membrana citoplasmática de todas as bactérias avaliadas, indicando que o dano no envoltório celular é um dos seus mecanismos de ação. O OEPR foi aplicado como componente ativo em filmes de acetato de celulose, avaliados in vitro (ágar, caldo e micro-atmosfera) e in situ (queijo mozarela fatiado) contra bactérias patogênicas. Foi verificado que concentrações de 2, 4 e 6% de OEPR na matriz polimérica, conferiu atividade em todos os meios avaliados contra L. monocytogenes e S. aureus. Escherichia coli foi sensível em meio liquido e em micro-atmosfera, enquanto S. Typhimurium não demonstrou sensibilidade aos filmes antibacterianos. A inibição in situ, demonstrou que a afinidade entre as moléculas apolares do OEPR e os componentes lipídicos do queijo permite a migração do OE do interior do polímero para a superfície facilitando sua dispersão no alimento, indicando favorável sua aplicação como embalagem ativa.
The use of natural preservatives as well as active packaging has sparked interest in the food industry. The objective of this work was to evaluate the antimicrobial characteristics of the essential oil of pink pepper (PPEO) and to use it as an active component in the elaboration of films for application in the development of bioconservant packaging for food. Through the chromatographic analysis (GC/MS) 18 compounds, 4 monoterpenes and 14 sesquiterpenes were detected, of which β- myrcene (41%), β-cuvebene (12%) and Limonene (9%) were the majority. In the antimicrobial activity of PPEO in agar and broth, action was observed against five pathogenic bacteria. The MIC for S. aureus and L. monocytogenes was 0.68 and 1.36 mg/mL, and the MBC was 2.72 mg/mL for both. In micro-atmosphere the reduction was 100% in the development of S. aureus and L. monocytogenes, and 16 and 15% for E. coli and S. Typhimurium. The contact time required for MBC to act on Gram positive bacteria was lower than the 12 h period, and Gram negative bacteria were not inhibited. In addition, changes in the permeability and integrity of the cytoplasmic membrane of all evaluated bacteria were observed, indicating that damage in the cellular envelope is one of its mechanisms of action. PPEO was applied as an active component in cellulose acetate films evaluated in vitro (agar, broth and micro-atmosphere) and in situ (sliced mozzarella cheese) against pathogenic bacteria. It was found that concentrations of 2, 4 and 6% PPEO in the polymer matrix conferred activity on all média evaluated against L. monocytogenes and S. aureus. Escherichia coli was sensitive in liquid medium and in microatmosphere, while S. Typhimurium showed no sensitivity to antibacterial films. In situ inhibition has demonstrated that the affinity between the OEPR apolar molecules and the lipid components of the cheese allows migration of the OE from the interior of the polymer to the surface and facilitates its dispersion in the food, indicating its favorable application as an active packaging. Keywords: Essential oil; Antibacterial activity;
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Jacry, Cécile. "Découverte de nouvelles molécules antibiotiques et caractérisation de leurs modes d'action". Thesis, université Paris-Saclay, 2021. http://www.theses.fr/2021UPASL009.
Abstract (sommario):
Les flavonoïdes sont des métabolites secondaires largement répandus chez les plantes et appartiennent à une grande famille de composés chimiques d'intérêt industriel. Les flavonoïdes sont une source importante de nouveaux médicaments et nutraceutiques en raison de leurs activités anti-oxydantes, antivirales, antimicrobiennes, anticancéreuses, etc. Notre étude se concentre sur la caractérisation de l'activité antibactérienne des flavonoïdes ciblant spécifiquement les bactéries à Gram positif. Les objectifs de mon travail de recherche sont i) de mettre en place des méthodologies de cribles efficaces et rapides afin d’évaluer l’activité antibactérienne des flavonoïdes et ii) de déterminer les mécanismes d'action antibactérien des flavonoïdes. La caractérisation de l'activité antibactérienne des flavonoïdes a été réalisée avec des tests de toxicité des flavonoïdes envers la bactérie modèle à Gram positif B. subtilis par la méthode du Live Cell Array permettant d'enregistrer la cinétique de croissance bactérienne en temps réel. Différentes stratégies ont été employées pour décrypter le(s) mode(s) d'action des flavonoïdes ; telles que le crible d'une banque de flavonoïdes pour l'identification de nouveaux composés actifs contre B. subtilis, le crible d'une collection de mutants de B. subtilis pour l'identification de gènes impliqués dans la réponse de B. subtilis aux flavonoïdes, une évolution dirigée en laboratoire de B. subtilis en présence de flavonoïde pour l'obtention et la caractérisation de souches résistantes aux flavonoïdes, et enfin une analyse de la réponse transcriptionnelle de B. subtilis en présence de flavonoïdes. Deux flavonoïdes déjà identifiés dans la littérature pour inhiber la croissance de bactéries à Gram positif, la pinocembrine et la naringénine, ont une activité antibactérienne contre B. subtilis. Une diminution de 50 % du taux de croissance a été observée en présence de 93 mg.L ⁻¹ ou 32 mg.L ⁻¹ de naringénine ou pinocembrine respectivement.Pour décrypter les mécanismes d'action des flavonoïdes, une collection de 63 flavonoïdes a été criblée et les concentrations minimales inhibitrices (MICs) déterminées pour chaque flavonoïde en présence de B. subtilis. 17 flavonoïdes se sont avérés particulièrement actifs contre B. subtilis. La tentative d'établir un modèle QSAR (relation quantitative structure-activité) avec les 17 flavonoïdes actifs n'a malheureusement pas été concluante car malgré l'obtention d'une régression linéaire largement acceptable (R²≈ 0,9), la validation par exclusion systématique d'un composé ("leave one out") n'a pas été obtenue. La seule explication plausible de cet échec est que le nombre de modes d'action présents est trop élevé pour un set de 17 composés, rendant ainsi caduque la modélisation QSAR. Au cours d'un crible de 67 mutants de B. subtilis, huit gènes impliqués dans la réponse aux flavonoïdes (naringénine et pinocembrine) ont été identifiés, dont deux appartiennent au régulon LmrA/QdoR, déjà identifié dans la littérature pour répondre aux flavonoïdes. Les souches B. subtilis ∆lmrA et ∆qdoI sont respectivement plus sensibles et plus résistantes vis-à-vis de la naringénine et de la pinocembrine. Les 17 flavonoïdes précédemment identifiés et actifs envers B. subtilis induisent une réponse transcriptionnelle propre à chacun d'après notre analyse de l'activité de 10 promoteurs avec l'utilisation de fusions transcriptionnelles avec un gène rapporteur. Cette analyse est cohérente avec l'étude transcriptomique menée pour la caractérisation de la réponse de B. subtilis en présence de 5 flavonoïdes ; la 2’hydroxyflavanone, la bavachine, la naringénine, la pinocembrine et le résokaempférol. De ce travail ressort plusieurs modes d'action des flavonoïdes chez B. subtilis, impliquant l'induction de la réponse stringente, l'inhibition de voies métaboliques pour la synthèse des membranes et paroi cellulaires et l'inhibition du métabolisme carboné centralFlavonoids are secondary metabolites widespread in plants and belong to a large family of chemical compounds of industrial interest. Flavonoids are an important source of new drugs and nutraceuticals because of their antioxidant, antiviral, antimicrobial, anticancer activities. Our study focuses on the characterization of the antibacterial activity of flavonoids specifically targeting Gram-positive bacteria. The objectives of my research work are i) to establish efficient and rapid screening methodologies to evaluate the antibacterial activity of flavonoids and ii) to determine the mechanisms of action of antibacterial flavonoids. The characterization of the antibacterial activity of flavonoids was carried out with flavonoid toxicity tests against the Gram-positive model bacterium B. subtilis by Live Cell Array method, which measures the bacterial growth kinetics. Several strategies were used to decipher the mode(s) of action of the flavonoids, such as screening a flavonoid library for new compounds active against B. subtilis, screening a collection of B. subtilis mutants for the identification of genes involved in the flavonoid response of B. subtilis, an adaptive laboratory evolution of B. subtilis in presence of flavonoid to obtain and characterize flavonoid-resistant strains, and finally an analysis of the transcriptional response of B. subtilis in the presence of flavonoids. Two flavonoids already identified in the literature to inhibit the growth of Gram-positive bacteria, pinocembrin and naringenin, have antibacterial activity against B. subtilis. A 50% decrease in growth rate was observed in the presence of 93 mg.L ⁻¹ or 32 mg.L ⁻¹ of naringenin or pinocembrin respectively.To decipher the mechanisms of action of the flavonoids, a collection of 63 flavonoids was screened and minimal inhibitory concentrations (MICs) were determined for each flavonoid in the presence of B. subtilis. 17 flavonoids were found to be particularly active against B. subtilis. The attempt to establish a QSAR (quantitative structure activity relationship) model with the 17 active flavonoids was unfortunately not conclusive because, despite obtaining a high quality linear regression (R² ≈ 0.9), cross-validation by using leave-one-out basic method was not obtained. The only plausible explanation for this failure is that the number of modes of action present is too high for a set of 17 compounds, thus rendering the QSAR model obsolete. In a screen of 67 mutants of B. subtilis, eight genes involved in the response to flavonoids (naringenin and pinocembrin) were identified, two of which belong to the LmrA/QdoR regulon, already identified in the literature to respond to flavonoids. The B. subtilis strains ∆lmrA and ∆qdoI are respectively more sensitive and more resistant to naringenin and pinocembrin. The 17 flavonoids previously identified and active against B. subtilis induce a flavonoid-specific transcriptional response according to our analysis of the activity of 10 promoters with the use of transcriptional fusions with a reporter gene. This analysis is consistent with the transcriptomic study carried out for the characterization of the response of B. subtilis in the presence of 5 flavonoids; 2'hydroxyflavanone, bavachine, naringenin, pinocembrin and resokaempferol. Several modes of action of the flavonoids in B. subtilis were identified, involving induction of the stringent response, inhibition of metabolic pathways for cell membrane and cell wall synthesis, and inhibition of central carbon metabolism
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Bouhallab, Saïd. "Mecanisme d'action des facteurs i et ii des pristinamycines : etude de leur synergie et localisation du site de fixation de la pristinamycine ia". Paris 6, 1988. http://www.theses.fr/1988PA066095.
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Brunel, Frédéric. "Synthèse, conception et élaboration de nouveaux systèmes dérivés de liquides ioniques antibactériens à base de phosphonium". Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4087.
Abstract (sommario):
Un récent rapport de l’OMS met en garde les autorités de santé sur l’émergence de résistances chez les bactéries et le développement de souches bactériennes multi-résistantes aux traitements antibiotiques actuels. La progression de ces phénomènes est dû à différents facteurs. L’environnement hospitalier concentre un usage important de traitements antibiotiques et représente ainsi un terreau favorable au développement de résistances chez les bactéries. Le staphylocoque doré, ainsi que sa souche résistante (SARM), s’avèrent problématiques et entraînent un grand nombre de maladies nosocomiales. Dans ce contexte, il est primordial de mettre au point de nouveaux agents antibactériens permettant de lutter contre ces bactéries. Les liquides ioniques (sels à point de fusion bas) démontrent d’importantes propriétés antibactériennes. Néanmoins les mécanismes de cet effet bactéricide n’ont pas encore été établis. Ainsi nous nous proposons, dans un premier temps, de synthétiser des liquides ioniques di-cationiques afin d’étudier les différents facteurs structuraux qui régissent leur activité antibactérienne. Dans un second temps, nous concevrons des liquides ioniques à base de phosphoniums fonctionnalisés avec une sonde fluorescente. En exploitant les propriétés spectroscopiques, nous tenterons d’observer leurs interactions avec les cellules bactériennes. Enfin, nous nous proposons d'utiliser les phosphoniums comme agents de fonctionnalisation de surface dans le but de mettre au point des surfaces aux qualités bactéricides intrinsèques. Pour ce faire nous utiliserons différentes méthodes comme la conception de monocouches auto-assemblées ou l’électropolymérisationA recent WHO report warns the health authorities about the emergence of new bacterial resistances and the development of multi-resistant strains against current antibiotics treatments. The growth of those resistances is due to several factors. The hospital environment concentrates a significant use of antibiotics and disinfectant representing a favorable ground for bacterial resistance development. Among them the Staphylococcus aureus and its methicillin resistant strain (MRSA) represent a crucial issue in care environments and is a major cause of hospital acquired infections. In this context, it is essential to develop new antibacterial agents to fight against these bacteria. Ionic liquid are low melting point salts, they show significant antibacterial properties. However, the fact that the mechanisms of action of their bactericidal effect have not been established yet constitutes a major obstacle to their development as bactericidal agents. Thus, we propose to synthetize ammonium- and phosphonium-based di-cationic ionic liquids in order to study the different structural factors that govern their antibacterial activity. Then we will develop phosphonium based ionic liquids functionalized with a fluorescent probe. By taking advantage of their spectroscopic properties we will try to observe their interactions with bacterial cells. Finally, we propose to use the phosphonium salts as surface functionalization agents in order to design surfaces with intrinsic antibacterial properties. To do so, we will use innovative methods such as conception of self-assembled monolayers or electropolymerization technics
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Moore, Suzanne Louise. "The mechanisms of antibacterial action of some nonionic surfactants". Thesis, University of Brighton, 1997. https://research.brighton.ac.uk/en/studentTheses/35414631-9ae5-4dc4-afd4-6f724fe9a7f6.
Abstract (sommario):
Antibacterial agents are composed of a diverse group and many such agents have entered common usage through experience with little information on their mechanism of action. Study of the mechanism of action of an antimicrobial agent provides an insight into resistance mechanisms, toxicological problems and the design and development of new agents or combinations. The primary target of most antimicrobial agents (excluding antibiotics) is the cytoplasmic membrane and associated enzymes. Membrane-active agents can cause a change in the fluidity and/or permeability of the cytoplasmic membrane. Such changes can be determined by the leakage of cellular constituents such as potassium ions, nucleotides and their constituents and amino acids. The effect of an anti bacterial agent on the cytoplasmic membrane can also be determined by elucidating the effect of the antibacterial agent on the activity of membrane-bound enzymes and substrate uptake.
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Zhang, Huichun. "Metal oxide-facilitated oxidation of antibacterial agents". Diss., Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-07072004-152317/unrestricted/zhang%5Fhuichun%5F200407%5Fphd.pdf.
Abstract (sommario):
Thesis (Ph. D.)--School of Civil and Environmental Engineering, Georgia Institute of Technology, 2005. Directed by Ching-Hua Huang.Wine, Paul, Committee Member ; Pavlostathis, Spyros, Committee Member ; Mulholland, James, Committee Member ; Yiacoumi, Sotira, Committee Member ; Huang, Ching-Hua, Committee Chair. Includes bibliographical references.
Libri sul tema "Antibacterial mechanism":
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Anderson, Rosaleen J. Antibacterial agents: Chemistry, mode of action, mechanisms of resistance, and clinical applications. Chichester, West Sussex: John Wiley & Sons, 2012.
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Hahn, Fred E. Mechanism of Action of Antibacterial Agents. Springer, 2012.
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Hahn, Fred E. Mechanism of Action of Antibacterial Agents. Springer London, Limited, 2012.
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Cheung, Kam Sing. Antibacterial peptides containing mechanism-based enzyme inactivators: Design, synthesis and mechanism of action. 1985.
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Todd, Adam, Paul W. Groundwater, Rosaleen Anderson e Alan Worsley. Antibacterial Agents: Chemistry, Mode of Action, Mechanisms of Resistance and Clinical Applications. Wiley & Sons, Incorporated, John, 2012.
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Todd, Adam, Paul W. Groundwater, Rosaleen Anderson e Alan Worsley. Antibacterial Agents: Chemistry, Mode of Action, Mechanisms of Resistance and Clinical Applications. Wiley & Sons, Incorporated, John, 2012.
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Todd, Adam, Paul W. Groundwater, Rosaleen Anderson e Alan Worsley. Antibacterial Agents: Chemistry, Mode of Action, Mechanisms of Resistance and Clinical Applications. Wiley & Sons, Incorporated, John, 2012.
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Todd, Adam, Paul W. Groundwater, Rosaleen Anderson e Alan Worsley. Antibacterial Agents: Chemistry, Mode of Action, Mechanisms of Resistance and Clinical Applications. Wiley & Sons, Limited, John, 2012.
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Estes, Lynn L., e John W. Wilson. Antimicrobials. Oxford University Press, 2012. http://dx.doi.org/10.1093/med/9780199755691.003.0412.
Abstract (sommario):
This chapter approaches the field of infectious diseases from 3 perspectives. This third section reviews antimicrobial agents. The mechanisms of action, spectrums of activity, clinical uses, routes of excretion, and toxic effects of various antimicrobial agents are emphasized. Antibacterials such as penicillins, cephalosporins, carbapenems, aminoglycosides, tetracyclines, and fluoroquinolones are reviewed. Antifungals such as the azoles, polyenes, and echinocandins are also covered. Antivirals such as acyclovir, famciclovir, oseltamivir, and foscarnet are included as well.
Capitoli di libri sul tema "Antibacterial mechanism":
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Mei, Lin, e Xinge Zhang. "Polymer–Silver Nanocomposites: Preparation, Characterisation and Antibacterial Mechanism". In Silver Nanoparticles for Antibacterial Devices, 111–32. Boca Raton : CRC Press, [2017]: CRC Press, 2017. http://dx.doi.org/10.1201/9781315370569-5.
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Thakur, Neeraj S., Bharat P. Dwivedee, Uttam C. Banerjee e Jayeeta Bhaumik. "Bioinspired Synthesis of Silver Nanoparticles: Characterisation, Mechanism and Applications". In Silver Nanoparticles for Antibacterial Devices, 3–36. Boca Raton : CRC Press, [2017]: CRC Press, 2017. http://dx.doi.org/10.1201/9781315370569-1.
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Al-Harrasi, Ahmed, Saurabh Bhatia, Tapan Behl, Deepak Kaushik, Mohammed Muqtader Ahmed e Khalid Anwer. "Antibacterial Mechanism of Action of Essential Oils". In Role of Essential Oils in the Management of COVID-19, 227–37. Boca Raton: CRC Press, 2022. http://dx.doi.org/10.1201/9781003175933-17.
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Khan, Javed Ahamad, Hussein Hasan Abulreesh, Ramesh Kumar, Samreen e Iqbal Ahmad. "Antibiotic Resistance in Campylobacter jejuni: Mechanism, Status, and Public Health Significance". In Antibacterial Drug Discovery to Combat MDR, 95–114. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-9871-1_4.
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Yang, Xiaohui, Junlin Li e Ruiming Wang. "Antibacterial Mechanism of 10-HDA Against Bacillus subtilis". In Lecture Notes in Electrical Engineering, 317–24. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-45657-6_34.
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Johnson, Matthew D., Roger L. Nation e Jian Li. "Mechanism of the Antibacterial Activity and Resistance of Polymyxins". In Antimicrobial Drug Resistance, 333–44. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-46718-4_23.
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Suresh, Anil K. "Engineered Metal Oxide Nanocrystallites: Antibacterial Activity and Stress Mechanism". In SpringerBriefs in Molecular Science, 55–67. Dordrecht: Springer Netherlands, 2012. http://dx.doi.org/10.1007/978-94-007-4231-4_5.
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Tian, Lin, e Zhan Wang. "Study on Antibacterial Activity of Radix isatidis Extracts and Preliminary Investigation of Their Antibacterial Mechanism". In Proceedings of the 2012 International Conference on Applied Biotechnology (ICAB 2012), 1681–88. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-37925-3_180.
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Das, Asis, Joseph DeVito, Jason Sparkowski e Frederick Warren. "RNA Synthesis in Bacteria: Mechanism and Regulation of Discrete Biochemical Events at Initiation and Termination". In Emerging Targets in Antibacterial and Antifungal Chemotherapy, 68–116. Boston, MA: Springer US, 1992. http://dx.doi.org/10.1007/978-1-4615-3274-3_4.
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Yang, Xiaohui, Tengfei Wang e Ruiming Wang. "Antibacterial Activity and Mechanism of Action of 10-HDA Against Escherichia coli". In Proceedings of the 2012 International Conference on Applied Biotechnology (ICAB 2012), 585–95. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-37916-1_60.
Atti di convegni sul tema "Antibacterial mechanism":
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Cunha, Bernardo, Luis Fonseca e Cecilia Calado. "High-throughput bioassay for mechanism of action determination of antibacterial drugs". In 2017 IEEE 5th Portuguese Meeting on Bioengineering (ENBENG). IEEE, 2017. http://dx.doi.org/10.1109/enbeng.2017.7889478.
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Velkova, Lyudmila, Aleksandar Dolashki, Karina Marinova, Petar Petrov, Dimitar Kaynarov, Nevena Ilieva, Ventseslav Atanasov e Pavlina Dolashka. "Mechanism of antibacterial action of bioactive peptides from the Helix aspersa mucus". In RAD Conference. RAD Centre, 2023. http://dx.doi.org/10.21175/rad.abstr.book.2023.2.6.
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Prawatya, Ibnu Diptya, Daniel Winatakusuma, Ferdian Tanaka, Dwi Yuni Nur Hidayati e Hidayat Sujuti. "Antibacterial effect of Coffea canephora ethanolic extract through potassium and magnesium efflux mechanism". In THE 4TH INTERNATIONAL CONFERENCE ON LIFE SCIENCE AND TECHNOLOGY (ICoLiST). AIP Publishing, 2023. http://dx.doi.org/10.1063/5.0118070.
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Stanković, Marina M., Jelena Z. Pribojac, Jelena N. Terzić e Olgica D. Stefanović. "EFFECT OF PLANT EXTRACTS ON BACTERIAL GROWTH AND POTENTIAL MECHANISM OF ACTION". In 1st INTERNATIONAL Conference on Chemo and BioInformatics. Institute for Information Technologies, University of Kragujevac, 2021. http://dx.doi.org/10.46793/iccbi21.343s.
Abstract (sommario):
Mentha piperita and Melissa officinalis are both well-known medicinal plants that have applications in traditional medicine. In this research the antibacterial activity of the ethanol extracts of M. piperita and M. officinalis was examined against 14 bacterial strains via the microdilution method. Minimum inhibitory concentrations of ethanol extracts of both plant species ranged from 0.312 to 20 mg/mL. Standard strains of Staphylococcus aureus ATCC 25923 at a concentration of 0.312 mg/mL and Bacillus subtilis ATCC 6633 at a concentration of 1.25 mg/mL showed the highest sensitivity to the ethanol extract of M. piperita. Ethanol extract of M. officinalis showed antibacterial activity on standard strains of S. aureus ATCC 25923 and B. subtilis ATCC 6633 at a concentration of 0.625 mg/mL. In addition to the mentioned standard strains, it showed activity on the isolate from the food Proteus spp. at a concentration of 0.312 mg/mL and isolate from the wound Proteus mirabilis at a concentration of 0.625 mg/mL. Mechanism of action of the ethanol extract of M. officinalis was examined on the permeability of the bacterial cell membrane. The effect of the extract on the increased permeability of the cell membrane was measured based on the release of proteins and the percentage of crystal violet binding. Ethanol extract of M. officinalis has been shown to act at the level of the cell membrane in the following bacterial strains of Pseudomonas aeruginosa, S. aureus and Enterococcus spp.
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Adhayani, Layli, Suhartono Suhartono e Amalia Amalia. "Aceh patchouli oil (Pogostemon cablin Benth) as antibacterial and antibiofilm: Mechanism, challenges, and opportunities". In 2ND INTERNATIONAL CONFERENCE ON ADVANCED INFORMATION SCIENTIFIC DEVELOPMENT (ICAISD) 2021: Innovating Scientific Learning for Deep Communication. AIP Publishing, 2023. http://dx.doi.org/10.1063/5.0103567.
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Khair, Nedaa Kamalalden. "Activity of Antibiotic Producing Bacteria Isolated from Rhizosphere Soil Region of Different Medicinal Plants". In Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2020. http://dx.doi.org/10.29117/quarfe.2020.0093.
Abstract (sommario):
The rhizosphere soil of medicinal plants is rich in microorganisms that develop antibiotics as natural mechanism of protection against other microbes that live in their vicinity. The present study aims to explore the production of antibacterial agents from rhizosphere soil bacteria of 11 medicinal plants and determine their activity against Gram-negative (Pseudomonas aeruginosa, Escherichia coli) and Gram-positive (Bacillus cereus, Staphylococcus aureus) bacteria. Soil samples were collected and used to isolate antibiotic producing bacteria (APB). Those isolates (108) were first tested using Cross-streak method against test bacteria. Then, isolates that showed a positive antibacterial effect (12) were tested by antibiotic susceptibility test (AST) of their cell free supernatant (CFS) and their extracellular and intracellular secondary metabolites extraction which gave positive results. Staphylococcus aureus found to be the most sensitive test bacteria with inhibitory zones ranging from 13.5 - 19 mm. Moreover, combinatorial effect of isolates CFS with two organic acids (3% Acetic acid and 0.4 mg/ml Acetylsalicylic acid), two commercial antibiotics (0.016 mg/ml Augmentin and 0.128 mg/ml Doxycycline), and two pure antibiotics (10 mcg/disk Penicillin and 25mcg/disk Carbenicillin) was in vitro evaluated using AST. The combinations of CFS-carbenicillin showed a marked synergistic activity against all test bacteria. The presence of possible antibacterial agents as acetic acid, lactic acid and citric acid in CFS of APB was confirmed by HPLC analysis. Ultimately, in vitro antibacterial study for rhizosphere soil bacteria in this work suggests the possibility of using these bacterial metabolites in clinical infections caused by selected test bacteria, especially when they combine with antibiotics or organic acids.
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Zheng, Zhouyuan, Parth Bansal e Yumeng Li. "Numerical Study on Antibacterial Effects of Bio-Inspired Nanostructured Surface". In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-23594.
Abstract (sommario):
Abstract Natural bactericidal surfaces are found on the wings of cicada and dragonfly that compose of nanopatterns such as nanopillar arrays. Experimental studies have unveiled that the nanopillars can penetrate the bacterial walls or stretch them, resulting in the cell death. This offers an attractive “chemical-free” and wide-spectrum strategy to fight against bacteria-related infections and fouling, especially for implant-associated infections (IAIs). However, what is the fundamental mechanism and key factors governing the bactericidal performance of the nanostructured surface is the critical research questions need to be answered to realize its full potential. In this work, we developed mechanical single cell model of bacteria based on finite element analysis (FEA) to simulate the interactions between different strains of bacteria and the nanostructured surface. The nanostructured surface contains nanopillar arrays, which are made of polymer materials. Different strains of bacteria are simulated by adopting the corresponding geometry and material properties from experimental values. The mechanical responses of the bacteria cell on the nanopillar arrays with various configurations are studied based on estimated stress and strain distributions within the cell.
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Sharifullina, D. T., R. N. Nizamov, R. N. Nizamov, I. R. Yunusov e G. I. Rakhmatullina. "STUDYING THE POSSIBILITY OF JOINT CULTIVATION OF B.BIFIDUM AND E.COLI ON ADAPTED NUTRIENT MEDIA". In STATE AND DEVELOPMENT PROSPECTS OF AGRIBUSINESS Volume 2. DSTU-Print, 2020. http://dx.doi.org/10.23947/interagro.2020.2.423-426.
Abstract (sommario):
Microbial substances introduced into the body of animals increase radio stability and reduce the mortality rate. The greatest significance can be obtained by using vaccines based on bacteria of the intestinal-typhoid group, which in the process of life produce antibacterial substances, enzymes, antigens, entero-and exotoxins, and cytokines with radioprotective properties. The tests revealed a complex mechanism of interaction between bifidobacteria and Escherichia in their joint cultivation. The biomass accumulation of E.coli strain «PL-6» and B.bifidum 1 during co-cultivation depended on the ratio of live bacteria E.coli strain «PL-6» and B.bifidum 1. Microcopy of smears made on days 1-4 from monocultures showed that the grown microbes in morphology corresponded to these cultures. The concentration of microorganisms, determined by tenfold dilution by the above method, was 1x109 CFU/ml - E.coli and 1x107 CFU/ml B.bifidum, with a sowing dose of each type of microbe 1x108 CFU/ml. Microcopy of smears made from a mixture of cultures showed that a dilution of 0,9:1,1-1,0:1,0 is most optimal for co-growing bifidum and Escherichia coli, since with a relatively equal number of monocultures on the 1st day Escherichiae multiply intensely, splitting the components of the Blaurock medium and inhibiting the growth of bifidum, but from the 3rd day B.bifidum begins to prevail, splitting E.coli and assimilating substances cleaved by E.coli.
9
Yan, Xueting, Bin He, Ligang Hu e Guibin Jiang. "Antibacterial Mechanisms of Silver Nanoparticles on Pseudomonas aeruginosa". In Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.2971.
10
Graskova, I. A., A. I. Perfileva, I. V. Klimenkov e B. G. Sukhov. "ANTIBACTERIAL EFFECTS OF NANOCOMPOSITES". In The All-Russian Scientific Conference with International Participation and Schools of Young Scientists "Mechanisms of resistance of plants and microorganisms to unfavorable environmental". SIPPB SB RAS, 2018. http://dx.doi.org/10.31255/978-5-94797-319-8-1225-1228.
Rapporti di organizzazioni sul tema "Antibacterial mechanism":
1
Pound, B. G. GRI-99-0000 Gap Analysis of the GRI Research Program on Internal Corrosion. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), dicembre 1999. http://dx.doi.org/10.55274/r0010720.
Abstract (sommario):
Extensive information on the corrosion of steel in aqueous CO2 systems is now available from this program and numerous other sources. This information was reviewed to identify what research has been performed and what research remains to be undertaken to develop a expert system/risk management program. Four areas were examined: corrosion mechanisms, mitigation strategies, monitoring techniques, and models/risk assessment. There were five gaps in mechanisms (two for bacteria and one each for flow rate/chloride concentration, hydrocarbons, and organic acids) and four gaps in mitigation (antibiofilm additives, antibacterial corrosion inhibitors, antibiofilm coatings, and UV light). Monitoring techniques have one principal gap, which is the lack of a single sensor that can indicate the type of corrosion and whether bacteria are involved. Various gaps were found in the approaches used for modeling and risk assessment: semiempirical and mechanistic models (deficient in their ability to treat films, H2S, and bacteria); thermodynamic models (incomplete range of key chemical species); statistical models (limited testing); probabilistic risk assessment (lack of usable data); and ranking risk assessment (lack of appropriate algorithms for internal corrosion).
2
Evans, Donald L., Avigdor Eldar, Liliana Jaso-Friedmann e Herve Bercovier. Streptococcus Iniae Infection in Trout and Tilapia: Host-Pathogen Interactions, the Immune Response Towards the Pathogen and Vaccine Formulation. United States Department of Agriculture, febbraio 2005. http://dx.doi.org/10.32747/2005.7586538.bard.
Abstract (sommario):
The objectives of the BARD proposal were to determine the mechanisms of nonspecific cytotoxic cells (NCC) that are necessary to provide heightened innate resistance to infection and to identify the antigenic determinants in Streptococcus iniae that are best suited for vaccine development. Our central hypothesis was that anti-bacterial immunity in trout and tilapia can only be acquired by combining "innate" NCC responses with antibody responses to polysaccharide antigens. These Objectives were accomplished by experiments delineated by the following Specific Aims: Specific aim (SA) #1 (USA) "Clone and Identify the Apoptosis Regulatory Genes in NCC"; Specific aim #2 (USA)"Identify Regulatory Factors that Control NCC Responses to S. iniae"; Specific aim #3 (Israel) "Characterize the Biological Properties of the S. iniae Capsular Polysaccharide"; and Specific aim #4 (Israel) "Development of an Acellular Vaccine". Our model of S. iniae pathogenesis encompassed two approaches, identify apoptosis regulatory genes and proteins in tilapia that affected NCC activities (USA group) and determine the participation of S.iniae capsular polysaccharides as potential immunogens for the development of an acellular vaccine (Israel group). We previously established that it was possible to immunize tilapia and trout against experimental S. difficile/iniaeinfections. However these studies indicated that antibody responses in protected fish were short lived (3-4 months). Thus available vaccines were useful for short-term protection only. To address the issues of regulation of pathogenesis and immunogens of S. iniae, we have emphasized the role of the innate immune response regarding activation of NCC and mechanisms of invasiveness. Considerable progress was made toward accomplishing SA #1. We have cloned the cDNA of the following tilapia genes: cellular apoptosis susceptibility (CAS/AF547173»; tumor necrosis factor alpha (TNF / A Y 428948); and nascent polypeptide-associated complex alpha polypeptide (NACA/ A Y168640). Similar attempts were made to sequence the tilapia FasLgene/cDNA, however these experiments were not successful. Aim #2 was to "Identify Regulatory Factors that Control NCC Responses to S. iniae." To accomplish this, a new membrane receptor has been identified that may control innate responses (including apoptosis) of NCC to S. iniae. The receptor is a membrane protein on teleost NCC. This protein (NCC cationic antimicrobial protein-1/ncamp-1/AAQ99138) has been sequenced and the cDNA cloned (A Y324398). In recombinant form, ncamp-l kills S. iniae in vitro. Specific aim 3 ("Characterize the Biological Properties of the S.iniae Capsular Polysaccharide") utilized an in- vitro model using rainbow trout primary skin epithelial cell mono layers. These experiments demonstrated colonization into epithelial cells followed by a rapid decline of viable intracellular bacteria and translocation out of the cell. This pathogenesis model suggested that the bacterium escapes the endosome and translocates through the rainbow trout skin barrier to further invade and infect the host. Specific aim #4 ("Development of an Acellular Vaccine") was not specifically addressed. These studies demonstrated that several different apoptotic regulatory genes/proteins are expressed by tilapia NCC. These are the first studies demonstrating that such factors exist in tilapia. Because tilapia NCC bind to and are activated by S. iniae bacterial DNA, we predict that the apoptotic regulatory activity of S. iniae previously demonstrated by our group may be associated with innate antibacterial responses in tilapia.