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Yi Z, Xu X, Meng X, Liu C, Zhou Q, Gong D, Zha Z. Emerging markers for antimicrobial resistance monitoring. CHINESE CHEM LETT 2023. [DOI: 10.1016/j.cclet.2023.108238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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Haile F, G/Medhin MT, Kifle ZD, Dejenie TA, Berhane N. Synergetic antibacterial activity of Vernonia auriculifera Hiern and Buddleja polystachya Fresen on selected human pathogenic bacteria. Metabol Open 2022; 16:100210. [PMID: 36148018 PMCID: PMC9486573 DOI: 10.1016/j.metop.2022.100210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 09/13/2022] [Accepted: 09/14/2022] [Indexed: 12/03/2022] Open
Abstract
Background Medicinal plants have been used as traditional treatments for various human diseases for many years and they are still widely practiced throughout the world. Due to the long history of the practice, medicinal plants have become an integral part of the Ethiopian culture. This study aimed to evaluate the antibacterial activities of Vernonia auriculifera Hiern and Buddleja polystachya Fresen leaf extracts and their synergistic effect against some selected human pathogenic bacteria. Methods Ethanol, methanol, and n-hexane crude extracts of Vernonia auriculifera, Buddleja polystachya, and a mixture of the two-plant respective of each solvent were evaluated against tested pathogenic bacteria using the agar well diffusion method; the inhibition zones were recorded in millimeters. Gentamycin was used as a positive control, while dimethyl sulfoxide served as a negative control. The minimum inhibitory concentration of the plant extracts against test bacteria was evaluated using two-fold broth dilution methods and then Minimum bactericidal concentration was determined by sub-culturing the test dilutions from minimum inhibitory concentration tubes onto fresh Muller Hinton Agar plates incubated at 37 °C for 24 h. Results Maximum antibacterial inhibition zone was observed on methanol extracts of synergism against S. Typhimurium (ATCC 1333) (31.00 ± 1.73 mm) while, a minimum inhibition zone was observed on methanol extract of Buddleja polystachya, against E. coli (ATCC 35218) (5.67 ± 0.57). Minimum inhibitory concentration and minimum bactericidal concentration values of the crude extracts of Vernonia auriculifera, Buddleja polystachya, and their mixture lies between (3.125%–12.5%) and (6.25%–25%) respectively. The data were analyzed using the SPSS software package version 20 for windows. Conclusion The present study revealed that ethanol and methanol extracts of Vernonia auriculifera and Buddleja polystachya possess significant inhibitory effects against tested pathogens and the antibacterial activity of both plants leaf extracts was greater than the activity of currently used antibiotics (Gentamycin) against some selected organisms.
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Salcedo-Sora JE, Jindal S, O'Hagan S, Kell DB. A palette of fluorophores that are differentially accumulated by wild-type and mutant strains of Escherichia coli: surrogate ligands for profiling bacterial membrane transporters. MICROBIOLOGY (READING, ENGLAND) 2021; 167:001016. [PMID: 33406033 PMCID: PMC8131027 DOI: 10.1099/mic.0.001016] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 12/15/2020] [Indexed: 12/12/2022]
Abstract
Our previous work demonstrated that two commonly used fluorescent dyes that were accumulated by wild-type Escherichia coli MG1655 were differentially transported in single-gene knockout strains, and also that they might be used as surrogates in flow cytometric transporter assays. We summarize the desirable properties of such stains, and here survey 143 candidate dyes. We eventually triage them (on the basis of signal, accumulation levels and cost) to a palette of 39 commercially available and affordable fluorophores that are accumulated significantly by wild-type cells of the 'Keio' strain BW25113, as measured flow cytometrically. Cheminformatic analyses indicate both their similarities and their (much more considerable) structural differences. We describe the effects of pH and of the efflux pump inhibitor chlorpromazine on the accumulation of the dyes. Even the 'wild-type' MG1655 and BW25113 strains can differ significantly in their ability to take up such dyes. We illustrate the highly differential uptake of our dyes into strains with particular lesions in, or overexpressed levels of, three particular transporters or transporter components (yhjV, yihN and tolC). The relatively small collection of dyes described offers a rapid, inexpensive, convenient and informative approach to the assessment of microbial physiology and phenotyping of membrane transporter function.
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Affiliation(s)
- Jesus Enrique Salcedo-Sora
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Crown St, Liverpool L69 7ZB, UK
| | - Srijan Jindal
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Crown St, Liverpool L69 7ZB, UK
| | - Steve O'Hagan
- Department of Chemistry and Manchester Institute of Biotechnology, The University of Manchester, 131 Princess St, Manchester M1 7DN, UK
| | - Douglas B. Kell
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Crown St, Liverpool L69 7ZB, UK
- Novo Nordisk Foundation Centre for Biosustainability, Technical University of Denmark, Building 220, Kemitorvet, 2800 Kgs Lyngby, Denmark
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Lu WJ, Lin HJ, Hsu PH, Lin HTV. Determination of Drug Efflux Pump Efficiency in Drug-Resistant Bacteria Using MALDI-TOF MS. Antibiotics (Basel) 2020; 9:antibiotics9100639. [PMID: 32987695 PMCID: PMC7598683 DOI: 10.3390/antibiotics9100639] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 09/18/2020] [Accepted: 09/22/2020] [Indexed: 12/26/2022] Open
Abstract
Multidrug efflux pumps play an essential role in antibiotic resistance. The conventional methods, including minimum inhibitory concentration and fluorescent assays, to monitor transporter efflux activity might have some drawbacks, such as indirect evidence or interference from color molecules. In this study, MALDI-TOF MS use was explored for monitoring drug efflux by a multidrug transporter, and the results were compared for validation with the data from conventional methods. Minimum inhibitory concentration was used first to evaluate the activity of Escherichia coli drug transporter AcrB, and this analysis showed that the E. coli overexpressing AcrB exhibited elevated resistance to various antibiotics and dyes. Fluorescence-based studies indicated that AcrB in E. coli could decrease the accumulation of intracellular dyes and display various efflux rate constants for different dyes, suggesting AcrB’s efflux activity. The MALDI-TOF MS analysis parameters were optimized to maintain a detection accuracy for AcrB’s substrates; furthermore, the MS data showed that E. coli overexpressing AcrB led to increased ions abundancy of various dyes and drugs in the extracellular space at different rates over time, illustrating continuous substrate efflux by AcrB. This study concluded that MALDI-TOF MS is a reliable method that can rapidly determine the drug pump efflux activity for various substrates.
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Affiliation(s)
- Wen-Jung Lu
- Department of Food Science, National Taiwan Ocean University, No. 2, Pei-Ning Road, Keelung 202, Taiwan; (W.-J.L.); (H.-J.L.)
| | - Hsuan-Ju Lin
- Department of Food Science, National Taiwan Ocean University, No. 2, Pei-Ning Road, Keelung 202, Taiwan; (W.-J.L.); (H.-J.L.)
| | - Pang-Hung Hsu
- Department of Bioscience and Biotechnology, National Taiwan Ocean University, No. 2, Pei-Ning Road, Keelung 202, Taiwan
- Center of Excellence for the Oceans, National Taiwan Ocean University, No. 2, Pei-Ning Road, Keelung 202, Taiwan
- Institute of Biochemistry and Molecular Biology, National Yang Ming University, No. 155, Sec. 2, Linong Street, Taipei 112, Taiwan
- Correspondence: (P.-H.H.); (H.-T.V.L.); Tel.: +886-2-2462-2192 (ext. 5567) (P.-H.H.); +886-2-2462-2192 (ext. 5121) (H.-T.V.L.); Fax: +886-2-2463-4203 (H.-T.V.L.)
| | - Hong-Ting Victor Lin
- Department of Food Science, National Taiwan Ocean University, No. 2, Pei-Ning Road, Keelung 202, Taiwan; (W.-J.L.); (H.-J.L.)
- Center of Excellence for the Oceans, National Taiwan Ocean University, No. 2, Pei-Ning Road, Keelung 202, Taiwan
- Correspondence: (P.-H.H.); (H.-T.V.L.); Tel.: +886-2-2462-2192 (ext. 5567) (P.-H.H.); +886-2-2462-2192 (ext. 5121) (H.-T.V.L.); Fax: +886-2-2463-4203 (H.-T.V.L.)
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Sisay M, Bussa N, Gashaw T, Mengistu G. Investigating In Vitro Antibacterial Activities of Medicinal Plants Having Folkloric Repute in Ethiopian Traditional Medicine. J Evid Based Integr Med 2020; 24:2515690X19886276. [PMID: 31707813 PMCID: PMC6851602 DOI: 10.1177/2515690x19886276] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Medicinal plants are targeted in the search for new antimicrobial agents. Nowadays, there
is an alarmingly increasing antimicrobial resistance to available agents with a very slow
development of new antimicrobials. It is, therefore, necessary to extensively search for
new agents based on the traditional use of herbal medicines as potential source. The
antibacterial activity of 80% methanol extracts of the leaves of Verbena
officinalis (Vo-80ME), Myrtus communis (Mc-80ME), and
Melilotus elegans (Me-80ME) was tested against 6 bacterial isolates
using agar well diffusion technique. In each extract, 3 concentrations of 10, 20, and 40
mg/well were tested for each bacterium. The minimum inhibitory concentration (MIC) and
minimum bactericidal concentration (MBC) were also determined. Vo-80ME and Mc-80ME
exhibited promising antibacterial activity against Staphylococcus aureus
with the highest zone of inhibition being 18.67 and 26.16 mm, respectively at
concentration of 40 mg/well. Regarding gram-negative bacteria, Vo-80ME exhibited an
appreciable activity against Escherichia coli and Salmonella
typhi. Mc-80ME displayed remarkable activity against all isolates including
Pseudomonas aeruginosa with the maximum zone of inhibition being 22.83
mm. Me-80ME exhibited better antibacterial activity against E coli, but
its secondary metabolites had little or no activity against other gram-negative isolates.
The MIC values of Vo-80ME ranged from 0.16 to 4.00 mg/mL. The lowest MIC was observed in
Mc-80ME, with the value being 0.032 mg/mL. Mc-80ME had bactericidal activity against all
tested bacterial isolates. Mc-80ME showed remarkable zone of inhibitions in all tested
bacterial isolates. Besides, Vo-80ME showed good antibacterial activity against S
aureus, E coli, and S typhi. Conversely,
Me-80ME has shown good activity against E coli only. Generally, M
communis L and V officinalis have good MIC and MBC
results.
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Affiliation(s)
- Mekonnen Sisay
- School of Pharmacy, Haramaya University, Harar, Ethiopia
| | - Negussie Bussa
- Food Science and Post-harvest Technology, Haramaya University, Dire Dawa, Ethiopia
| | - Tigist Gashaw
- School of Pharmacy, Haramaya University, Harar, Ethiopia
| | - Getnet Mengistu
- Department of Pharmacy, Wollo University, Dessie, Amhara, Ethiopia
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Atzori A, Malloci G, Cardamone F, Bosin A, Vargiu AV, Ruggerone P. Molecular Interactions of Carbapenem Antibiotics with the Multidrug Efflux Transporter AcrB of Escherichia coli. Int J Mol Sci 2020; 21:E860. [PMID: 32013182 PMCID: PMC7037162 DOI: 10.3390/ijms21030860] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 01/26/2020] [Indexed: 12/22/2022] Open
Abstract
The drug/proton antiporter AcrB, engine of the major efflux pump AcrAB(Z)-TolC of Escherichia coli and other bacteria, is characterized by its impressive ability to transport chemically diverse compounds, conferring a multi-drug resistance (MDR) phenotype. Although hundreds of small molecules are known to be AcrB substrates, only a few co-crystal structures are available to date. Computational methods have been therefore intensively employed to provide structural and dynamical fingerprints related to transport and inhibition of AcrB. In this work, we performed a systematic computational investigation to study the interaction between representative carbapenem antibiotics and AcrB. We focused on the interaction of carbapenems with the so-called distal pocket, a region known for its importance in binding inhibitors and substrates of AcrB. Our findings reveal how the different physico-chemical nature of these antibiotics is reflected on their binding preference for AcrB. The molecular-level information provided here could help design new antibiotics less susceptible to the efflux mechanism.
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Affiliation(s)
| | - Giuliano Malloci
- Department of Physics, University of Cagliari, 09042 Monserrato (CA), Italy; (A.A.); (F.C.); (A.B.); (P.R.)
| | | | | | - Attilio Vittorio Vargiu
- Department of Physics, University of Cagliari, 09042 Monserrato (CA), Italy; (A.A.); (F.C.); (A.B.); (P.R.)
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Defects in Efflux ( oprM), β-Lactamase ( ampC), and Lipopolysaccharide Transport ( lptE) Genes Mediate Antibiotic Hypersusceptibility of Pseudomonas aeruginosa Strain Z61. Antimicrob Agents Chemother 2019; 63:AAC.00784-19. [PMID: 31036686 DOI: 10.1128/aac.00784-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 04/15/2019] [Indexed: 02/08/2023] Open
Abstract
Antibiotic hypersensitive bacterial mutants (e.g., Escherichia coli imp) are used to investigate intrinsic resistance and are exploited in antibacterial discovery to track weak antibacterial activity of novel inhibitor compounds. Pseudomonas aeruginosa Z61 is one such drug-hypersusceptible strain generated by chemical mutagenesis, although the genetic basis for hypersusceptibility is not fully understood. Genome sequencing of Z61 revealed nonsynonymous single-nucleotide polymorphisms in 153 genes relative to its parent strain, and three candidate mutations (in oprM, ampC, and lptE) predicted to mediate hypersusceptibility were characterized. The contribution of these mutations was confirmed by genomic restoration of the wild-type sequences, individually or in combination, in the Z61 background. Introduction of the lptE mutation or genetic inactivation of oprM and ampC genes alone or together in the parent strain recapitulated drug sensitivities. This showed that disruption of oprM (which encodes a major outer membrane efflux pump channel) increased susceptibility to pump substrate antibiotics, that inactivation of the inducible β-lactamase gene ampC contributed to β-lactam susceptibility, and that mutation of the lipopolysaccharide transporter gene lptE strongly altered the outer membrane permeability barrier, causing susceptibility to large antibiotics such as rifampin and also to β-lactams.
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Mikalayeva V, Sakalauskaitė S, Daugelavičius R. Interaction of ethidium and tetraphenylphosphonium cations with Salmonella enterica cells. MEDICINA-LITHUANIA 2017; 53:122-130. [PMID: 28462872 DOI: 10.1016/j.medici.2017.04.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 03/01/2017] [Accepted: 04/04/2017] [Indexed: 10/19/2022]
Abstract
BACKGROUND AND OBJECTIVE One of the main causes of bacterial resistance to antimicrobials is multidrug resistance induced by the increased efficiency of the efflux pumps. In this study we analyzed how the conditions of assay affect the efflux of indicator substrates ethidium (Et+) and tetraphenylphosphonium (TPP+) in Salmonella enterica ser. Typhimurium cells. Impact of the outer membrane permeability barrier, composition and temperature of the medium on accumulation of the indicator compounds also was analyzed. MATERIALS AND METHODS The fluorescence of Et+ and Nile Red was measured using 96-well plates and a plate reader. In parallel to traditional studies of fluorescence we applied a constructed selective electrode to follow the accumulation of Et+ in S. enterica cells. Simultaneously with monitoring of Et+ concentration in the cell incubation medium, electrochemical measurements of TPP+ accumulation were performed. Furthermore, Et+ and TPP+ were used within the same sample as agents competing for the interaction with the efflux pumps. An inhibitor phenylalanyl-arginyl-β-naphtylamide (PAβN) was applied to evaluate the input of RND-family pumps in the total efflux of these indicator compounds. RESULTS S. enterica cells with the intact outer membrane (OM) bound very low amounts of Et+ or TPP+. Cells with the permeabilized OM accumulate considerably higher amounts of the indicator compounds at pH 8.0, but only Et+ was considerably accumulated at pH 6.5. At conditions of electrochemical monitoring accumulation of Et+ by the permeabilized cells at 37°C was considerably faster than at 23°C, but at the higher temperature most of the cell-accumulated Et+ was extruded back to the medium. The fluorescence of Et+ in suspension of cells incubated in 400mmol/L Tris buffer was about twice higher compared to 100mmol/L one. The inhibitory action of TPP+ on Et+ efflux was evident only in 400mmol/L Tris although PAβN effectively increased Et+ fluorescence at both buffer concentrations. CONCLUSIONS Results of our experiments indicate that ionic strength of the incubation medium influence the selectivity, the medium temperature and the assay conditions impact the kinetics of efflux. The lower accumulated amount and the weaker fluorescence of Et+ registered in slightly acidic medium indicate that ΔΨ plays a role in the accumulation of this indicator cation. The bound amount of Et+ to the de-energized or permeabilized cells considerably varies depending on the conditions and methods of de-energization or permeabilization of cells. Tris/EDTA permeabilization of the cells does not inhibit the efflux.
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Affiliation(s)
- Valeryia Mikalayeva
- Department of Biochemistry, Faculty of Natural Sciences, Vytautas Magnus University, Kaunas, Lithuania; Institute of Cardiology, Medical Academy, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Sandra Sakalauskaitė
- Department of Biochemistry, Faculty of Natural Sciences, Vytautas Magnus University, Kaunas, Lithuania
| | - Rimantas Daugelavičius
- Department of Biochemistry, Faculty of Natural Sciences, Vytautas Magnus University, Kaunas, Lithuania.
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Chalhoub H, Pletzer D, Weingart H, Braun Y, Tunney MM, Elborn JS, Rodriguez-Villalobos H, Plésiat P, Kahl BC, Denis O, Winterhalter M, Tulkens PM, Van Bambeke F. Mechanisms of intrinsic resistance and acquired susceptibility of Pseudomonas aeruginosa isolated from cystic fibrosis patients to temocillin, a revived antibiotic. Sci Rep 2017; 7:40208. [PMID: 28091521 PMCID: PMC5238406 DOI: 10.1038/srep40208] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 12/01/2016] [Indexed: 12/29/2022] Open
Abstract
The β-lactam antibiotic temocillin (6-α-methoxy-ticarcillin) shows stability to most extended spectrum β-lactamases, but is considered inactive against Pseudomonas aeruginosa. Mutations in the MexAB-OprM efflux system, naturally occurring in cystic fibrosis (CF) isolates, have been previously shown to reverse this intrinsic resistance. In the present study, we measured temocillin activity in a large collection (n = 333) of P. aeruginosa CF isolates. 29% of the isolates had MICs ≤ 16 mg/L (proposed clinical breakpoint for temocillin). Mutations were observed in mexA or mexB in isolates for which temocillin MIC was ≤512 mg/L (nucleotide insertions or deletions, premature termination, tandem repeat, nonstop, and missense mutations). A correlation was observed between temocillin MICs and efflux rate of N-phenyl-1-naphthylamine (MexAB-OprM fluorescent substrate) and extracellular exopolysaccharide abundance (contributing to a mucoid phenotype). OpdK or OpdF anion-specific porins expression decreased temocillin MIC by ~1 two-fold dilution only. Contrarily to the common assumption that temocillin is inactive on P. aeruginosa, we show here clinically-exploitable MICs on a non-negligible proportion of CF isolates, explained by a wide diversity of mutations in mexA and/or mexB. In a broader context, this work contributes to increase our understanding of MexAB-OprM functionality and help delineating how antibiotics interact with MexA and MexB.
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Affiliation(s)
- Hussein Chalhoub
- Pharmacologie cellulaire et moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
| | - Daniel Pletzer
- Life Sciences, School of Engineering and Science, Jacobs University, Bremen, Germany
| | - Helge Weingart
- Life Sciences, School of Engineering and Science, Jacobs University, Bremen, Germany
| | - Yvonne Braun
- Life Sciences, School of Engineering and Science, Jacobs University, Bremen, Germany
| | - Michael M Tunney
- CF &Airways Microbiology Research Group, Queen's University Belfast, Belfast, UK
| | - J Stuart Elborn
- CF &Airways Microbiology Research Group, Queen's University Belfast, Belfast, UK
| | - Hector Rodriguez-Villalobos
- Laboratoire de microbiologie, Cliniques Universitaires Saint-Luc, Université catholique de Louvain, Brussels, Belgium
| | - Patrick Plésiat
- Laboratoire de bactériologie, Hôpital Jean Minjoz, Besançon, France
| | | | - Olivier Denis
- Laboratoire de microbiologie, Hôpital Erasme, Université libre de Bruxelles, Brussels, Belgium
| | - Mathias Winterhalter
- Life Sciences, School of Engineering and Science, Jacobs University, Bremen, Germany
| | - Paul M Tulkens
- Pharmacologie cellulaire et moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
| | - Françoise Van Bambeke
- Pharmacologie cellulaire et moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
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Molla Y, Nedi T, Tadesse G, Alemayehu H, Shibeshi W. Evaluation of the in vitro antibacterial activity of the solvent fractions of the leaves of Rhamnus prinoides L'Herit (Rhamnaceae) against pathogenic bacteria. Altern Ther Health Med 2016; 16:287. [PMID: 27527076 PMCID: PMC4986379 DOI: 10.1186/s12906-016-1279-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 08/11/2016] [Indexed: 11/20/2022]
Abstract
Background Medicinal plants play great roles in the treatment of various infectious diseases. Rhamnus prinoides is one of the medicinal plants used traditionally for treatment of bacterial diseases. The antibacterial activity of the crude extract of the plant had been shown by a previous study, but this study was undertaken to further the claimed medicinal use of the plant by screening its solvent fractions for the said activity so that it could serve as a basis for subsequent studies. Methods The solvent fractions of the plant were obtained by successive soxhlet extraction with solvents of increasing polarity, with chloroform and methanol, followed by maceration of the marc of methanol fraction with water. The antibacterial activity of the solvent fractions was evaluated on seven bacterial species using agar well diffusion method at different concentrations (78 mg/well, 39 mg/well and 19.5 mg/well) in the presence of positive and negative controls. The minimum inhibitory concentration of the solvent fractions was determined by micro-broth dilution method using resazurin as indicator. Result Methanol and chloroform fractions revealed antibacterial activities against the growth of test bacterial strains with varying antibacterial spectrum and the susceptible bacterial species were Staphylococcus aureus, Streptococcus pyogen, Streptococcus pneumoniae and Salmonella typhi. The average minimum inhibitory concentration value of the methanol and chloroform fractions ranged from 8.13 mg/ml to 32.5 mg/ml and from 8.13 mg/ml to 16.25 mg/ml, respectively. Conclusion The methanol and chloroform fractions demonstrated significant antibacterial activities against the growth of pathogenic bacteria but the aqueous fraction did not reveal antibacterial activity against any of the test bacteria.
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Abstract
Bacterial multidrug resistance (MDR) efflux pumps are an important mechanism of antibiotic resistance and are required for many pathogens to cause infection. They are also being harnessed to improve microbial biotechnological processes, including biofuel production. Therefore, scientists of many specialties must be able to accurately measure efflux activity. However, myriad methodologies have been described and the most appropriate method is not always clear. Within the scientific literature, many methods are misused or data arising are misinterpreted. The methods for measuring efflux activity can be split into two groups, (i) those that directly measure efflux and (ii) those that measure the intracellular accumulation of a substrate, which is then used to infer efflux activity. Here, we review the methods for measuring efflux and explore the most recent advances in this field, including single-cell or cell-free technologies and mass spectrometry, that are being used to provide more detailed information about efflux pump activity.
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