Activité antimicrobienne d'antioxydants phénoliques

1978 ◽  
Vol 24 (11) ◽  
pp. 1306-1320 ◽  
Author(s):  
Pierre Turcotte ◽  
Samir A. Saheb
Keyword(s):  
Culture Media ◽  
Osmotic Shock ◽  
Bacterial Species ◽  
Butylated Hydroxytoluene ◽  
In Vitro Assays ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
The Family ◽  
Increased Sensitivity

The antimicrobial activity of three antioxydants, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA) and ethoxyquin (ETO) was studied. In vitro assays showed that when these antioxydants are added to the culture media at concentrations lower or equal to that used in nutrition, they inhibit or decrease the growth of certain microorganisms. BHT showed the most marked effect, affecting Gram-positive bacteria at a higher degree than the Gram-negative bacteria belonging to the family Enterobacteriaceae. Inactivation study of different bacterial species by BHT revealed differences in sensitivity among a single genus and between strains of the same species. The association of ETO with BHT results in an increase of the inhibitory activity. The increased sensitivity to BHT resulting from the osmotic shock of Escherichia coli cells suggests that the resistance to BHT of the Gram-negative bacteria belonging to the family Enterobacteriaceae might be due in part to the structure of their cell wall.

scholarly journals Structural insights into a novel family of integral membrane siderophore reductases

2021 ◽  
Vol 118 (34) ◽  
pp. e2101952118
Author(s):  
Inokentijs Josts ◽  
Katharina Veith ◽  
Vincent Normant ◽  
Isabelle J. Schalk ◽  
Henning Tidow
Keyword(s):  
Iron Uptake ◽  
Bacterial Species ◽  
Gram Negative Bacteria ◽  
Inner Membrane ◽  
Gram Negative ◽  
Inner Membrane Protein ◽  
Uptake Studies ◽  
Structural Insights

Gram-negative bacteria take up the essential ion Fe3+ as ferric-siderophore complexes through their outer membrane using TonB-dependent transporters. However, the subsequent route through the inner membrane differs across many bacterial species and siderophore chemistries and is not understood in detail. Here, we report the crystal structure of the inner membrane protein FoxB (from Pseudomonas aeruginosa) that is involved in Fe-siderophore uptake. The structure revealed a fold with two tightly bound heme molecules. In combination with in vitro reduction assays and in vivo iron uptake studies, these results establish FoxB as an inner membrane reductase involved in the release of iron from ferrioxamine during Fe-siderophore uptake.

scholarly journals Antibacterial and Antibiotic Modifying Potential of Crude Extracts, Fractions, and Compounds from Acacia polyacantha Willd. against MDR Gram-Negative Bacteria

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Flora T. Mambe ◽  
Jean Na-Iya ◽  
Ghislain W. Fotso ◽  
Fred Ashu ◽  
Bathélémy Ngameni ◽  
...  
Keyword(s):  
Oleanolic Acid ◽  
Bacterial Infections ◽  
Efflux Pump ◽  
Synergistic Effects ◽  
Bacterial Species ◽  
Gram Negative Bacteria ◽  
Efflux Pump Inhibitor ◽  
Gram Negative ◽  
Acacia Polyacantha

The present study aimed to assess the in vitro antibacterial and antibiotic modifying activities of methanol extracts prepared from the leaf (APL) and bark (APB) of Acacia polyacantha, fractions (APLa-d) and compounds isolated from APL against a panel of multidrug resistant (MDR) Gram-negative bacteria. Leaf extract was subjected to column chromatography for compounds isolation; antibacterial assays were performed on samples alone and with an efflux pump inhibitor (EPI), respectively, and several antibiotics on the tested bacteria. The phytochemical investigation of APL led to the isolation of stigmasterol (1), β-amyrin (2), 3-O-β-D-glucopyranosylstigmasterol (3), 3-O-methyl-D-chiro-inositol (4), epicatechin (5), quercetin-3-O-glucoside (6), 3-O-[β-D-xylopyranosyl-(1→4)-β-D-galactopyranosyl]-oleanolic acid (7), and 3-O-[β-galactopyranosyl-(1→4)-β-D-galactopyranosyl]-oleanolic acid (8). APL and APB had minimal inhibitory concentration (MIC) values ≤ 1024 μg/mL on 73.3% and 46.7% of the tested bacteria, respectively. APLb and APLd were effective against 88.9% of tested bacterial species with compound 8 showing the highest activity inhibiting 88.9% of tested bacteria. The EPI, phenylalanine-arginine-β-naphthylamide (PAßN), strongly improved the activity of APL, APLb, APLd, and compound 8 on all tested bacteria. Synergistic effects were obtained when APL and compounds 7 and 8 were combined with erythromycin (ERY), gentamycin (GEN), ciprofloxacin (CIP), and norfloxacin (NOR). The present study demonstrates the antibacterial potential of Acacia polyacantha and its constituents to combat bacterial infections alone or in combination with EPI.

scholarly journals Boar Semen Contamination: Identification of Gram-Negative Bacteria and Antimicrobial Resistance Profile

Animals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 43
Author(s):  
Luminita Costinar ◽  
Viorel Herman ◽  
Elena Pitoiu ◽  
Ionica Iancu ◽  
Janos Degi ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Artificial Insemination ◽  
Bacterial Contamination ◽  
Bacterial Species ◽  
Reproductive Capacity ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
The Family ◽  
Boar Semen

Bacterial contamination of boar semen occurs with some frequency in artificial insemination centers and may have a negative effect on the quality of the semen as well as on the sows’ reproductive capacity. Normally, the source of bacterial contamination in pig seminal doses is the own boar. However, distilled water or laboratory equipment used to elaborate the seminal doses can be an important source of bacterial contamination. This study focused on the identification of gram-negative bacteria in boar semen, and impact on the quality of ejaculates obtained from boar, as well as on the establishment of antimicrobial resistance patterns of isolated gram-negative bacteria. Semen samples were collected from 96 boars, ranging in age from 12–36 month, from three artificial insemination centers from the North-West of Romania. Bacterial species were identified by two methods: matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry and API 20 E (BioMerieux, France). The main bacteria isolated from the doses diluted semen were gram-negative bacteria (47.91%), with a majority of the contaminant bacteria belonging to the family Enterobacteriaceae: Seratia marcescens 19.56%, Proteus mirabilis 15.21% and Escherichia coli 10.86% and to the family Pseudomonaceae: Ralstonia picketii 17.39%, Burkholderia cepacia 10.86%, Pseudomonas aeruginosa 8.69%, and Pseudomonas fluorescens 4.34%, respectively. More than half of these isolates (56.52%) were resistant to gentamycin and 58.69% were resistant to penicillin. These antibiotics are very frequently added in sperm diluent in the centers for the processing of sperm from boars in Romania. Regular monitoring for bacterial contamination is an important aspect of a control program.

scholarly journals Fixation of microorganisms with paraformaldehyde for TLR stimulation.

2021 ◽  
Author(s):  
Ana Neves-Costa
Keyword(s):  
Immune Responses ◽  
Cytokine Production ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Tlr Agonists ◽  
E Coli ◽  
The Family ◽  
Molecular Patterns ◽  
Stimulation Of

Abstract Toll-like receptors (TLRs) are part of the family of pattern recognition receptors (PRRs) that evolved to recognize pathogen-associated molecular patterns (PAMPs). A variety of PAMPs have been identified, from various microbial components to viral molecules. E.coli (Escherichia coli) has been widely used as a prototype Gram-negative bacteria with the capacity to stimulate TLRs, in particular to elicit TLR4-dependent immune responses. This receptor mainly recognizes an essential component of the outer membrane of Gram-negative bacteria: lipopolysaccharide (LPS). In vitro stimulation of immune cells for cytokine production can be achieved with the use of commercially-available purified TLR agonists, including LPS. Here we show how to prepare an alternative stimulator of TLR4 in a very fast an inexpensive way, paraformaldehyde-fixed preparations of E. coli. This reagent is a powerful tool for the in vitro activation of TLR4 that can be quantified and therefore used in defined amounts. Moreover, it is a safe reagent (the E.coli cells are fixed) and it is easy to prepare in large quantities and to store. Other microorganisms such as yeasts can also be fixed in this way.

scholarly journals Human Pre-Elafin Inhibits a Pseudomonas aeruginosa-Secreted Peptidase and Prevents Its Proliferation in Complex Media

2007 ◽  
Vol 52 (2) ◽  
pp. 483-490 ◽  
Author(s):  
Audrey Bellemare ◽  
Nathalie Vernoux ◽  
Dany Morisset ◽  
Yves Bourbonnais
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Neutrophil Elastase ◽  
Inflammatory Diseases ◽  
Bacterial Species ◽  
Antimicrobial Activities ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Innate Defense ◽  
Protease Iv

ABSTRACT Pseudomonas aeruginosa is a life-threatening opportunist human pathogen frequently associated with lung inflammatory diseases, namely, cystic fibrosis. Like other species, this gram-negative bacteria is increasingly drug resistant. During the past decade, intensive research efforts have been focused on the identification of natural innate defense molecules with broad antimicrobial activities, collectively known as antimicrobial peptides. Human pre-elafin, best characterized as a potent inhibitor of neutrophil elastase with anti-inflammatory properties, was also shown to possess antimicrobial activity against both gram-positive and gram-negative bacteria, including P. aeruginosa. Its mode of action was, however, not known. Using full-length pre-elafin, each domain separately, and mutated variants of pre-elafin with attenuated antipeptidase activity toward neutrophil elastase, we report here that both pre-elafin domains contribute, through distinct mechanisms, to its antibacterial activity against Pseudomonas aeruginosa. Most importantly, we demonstrate that the whey acidic protein (WAP) domain specifically inhibits a secreted peptidase with the characteristics of arginyl peptidase (protease IV). This is the first demonstration that a human WAP-motif protein inhibits a secreted peptidase to prevent bacterial growth in vitro. Since several WAP-motif proteins from various species demonstrate antimicrobial function with variable activities toward bacterial species, we suggest that this mechanism may be more common than initially anticipated.

Synthesis, In Vitro and In Silico Studies of Indolequinone Derivatives against Clinically Relevant Bacterial Pathogens

2020 ◽  
Vol 20 (3) ◽  
pp. 192-208 ◽  
Author(s):  
Talita Odriane Custodio Leite ◽  
Juliana Silva Novais ◽  
Beatriz Lima Cosenza de Carvalho ◽  
Vitor Francisco Ferreira ◽  
Leonardo Alves Miceli ◽  
...  
Keyword(s):  
In Silico ◽  
Bacterial Infections ◽  
Antimicrobial Agents ◽  
Mass Spectrometry Analysis ◽  
World Health ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Dione Derivative ◽  
In Silico Studies

Background: According to the World Health Organization, antimicrobial resistance is one of the most important public health threats of the 21st century. Therefore, there is an urgent need for the development of antimicrobial agents with new mechanism of action, especially those capable of evading known resistance mechanisms. Objective: We described the synthesis, in vitro antimicrobial evaluation, and in silico analysis of a series of 1H-indole-4,7-dione derivatives. Methods: The new series of 1H-indole-4,7-diones was prepared with good yield by using a copper(II)- mediated reaction between bromoquinone and β-enamino ketones bearing alkyl or phenyl groups attached to the nitrogen atom. The antimicrobial potential of indole derivatives was assessed. Molecular docking studies were also performed using AutoDock 4.2 for Windows. Characterization of all compounds was confirmed by one- and two-dimensional NMR techniques 1H and 13C NMR spectra [1H, 13C – APT, 1H x 1H – COSY, HSQC and HMBC], IR and mass spectrometry analysis. Results: Several indolequinone compounds showed effective antimicrobial profile against Grampositive (MIC = 16 µg.mL-1) and Gram-negative bacteria (MIC = 8 µg.mL-1) similar to antimicrobials current on the market. The 3-acetyl-1-(2,5-dimethylphenyl)-1H-indole-4,7-dione derivative exhibited an important effect against different biofilm stages formed by a serious hospital life-threatening resistant strain of Methicillin-Resistant Staphylococcus aureus (MRSA). A hemocompatibility profile analysis based on in vitro hemolysis assays revealed the low toxicity effects of this new series. Indeed, in silico studies showed a good pharmacokinetics and toxicological profiles for all indolequinone derivatives, reinforcing their feasibility to display a promising oral bioavailability. An elucidation of the promising indolequinone derivatives binding mode was achieved, showing interactions with important sites to biological activity of S. aureus DNA gyrase. These results highlighted 3-acetyl-1-(2-hydroxyethyl)-1Hindole- 4,7-dione derivative as broad-spectrum antimicrobial prototype to be further explored for treating bacterial infections. Conclusion: The highly substituted indolequinones were obtained in moderate to good yields. The pharmacological study indicated that these compounds should be exploited in the search for a leading substance in a project aimed at obtaining new antimicrobials effective against Gram-negative bacteria.

scholarly journals Coumarin Exhibits Broad-Spectrum Antibiofilm and Antiquorum Sensing Activity against Gram-Negative Bacteria: In Vitro and In Silico Investigation

ACS Omega ◽  
2021 ◽  
Author(s):  
Faizan Abul Qais ◽  
Mohammad Shavez Khan ◽  
Iqbal Ahmad ◽  
Fohad Mabood Husain ◽  
Rais Ahmad Khan ◽  
...  
Keyword(s):  
Broad Spectrum ◽  
In Silico ◽  
Gram Negative Bacteria ◽  
Gram Negative

scholarly journals Targeting SARS-CoV-2 Polymerase with New Nucleoside Analogues

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3461
Author(s):  
Vasiliki Daikopoulou ◽  
Panagiotis Apostolou ◽  
Sofia Mourati ◽  
Ioanna Vlachou ◽  
Maria Gougousi ◽  
...  
Keyword(s):  
Inhibitory Activity ◽  
Drug Repositioning ◽  
Nucleoside Analogues ◽  
In Vitro Assays ◽  
Rna Dependent Rna Polymerase ◽  
Sugar Moiety ◽  
The Family ◽  
Approved Drugs ◽  
Fda Approved Drugs

Despite the fact that COVID-19 vaccines are already available on the market, there have not been any effective FDA-approved drugs to treat this disease. There are several already known drugs that through drug repositioning have shown an inhibitory activity against SARS-CoV-2 RNA-dependent RNA polymerase. These drugs are included in the family of nucleoside analogues. In our efforts, we synthesized a group of new nucleoside analogues, which are modified at the sugar moiety that is replaced by a quinazoline entity. Different nucleobase derivatives are used in order to increase the inhibition. Five new nucleoside analogues were evaluated with in vitro assays for targeting polymerase of SARS-CoV-2.

scholarly journals In Vitro and In Vivo Antibacterial Activities of DW-224a, a New Fluoronaphthyridone

2006 ◽  
Vol 50 (6) ◽  
pp. 2261-2264 ◽  
Author(s):  
Hee-Soo Park ◽  
Hyun-Joo Kim ◽  
Min-Jung Seol ◽  
Dong-Rack Choi ◽  
Eung-Chil Choi ◽  
...  
Keyword(s):  
Antibacterial Activities ◽  
The Other ◽  
Vitro Activity ◽  
Gram Negative Bacteria ◽  
In Vitro Activity ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria

ABSTRACT DW-224a showed the most potent in vitro activity among the quinolone compounds tested against clinical isolates of gram-positive bacteria. Against gram-negative bacteria, DW-224a was slightly less active than the other fluoroquinolones. The in vivo activities of DW-224a against gram-positive bacteria were more potent than those of other quinolones.

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