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1.
Antibiotics (Basel) ; 9(6)2020 Jun 20.
Article in English | MEDLINE | ID: mdl-32575738

ABSTRACT

Bacterial resistance to antibiotics has become a public health issue around the world. The present study aimed to evaluate the antibacterial activity of chalcones isolated from flowers of Arrabidaea brachypoda, and their potential as efflux pump inhibitors of Staphylococcus aureus efflux pumps. Microdilution assays were performed with natural products from A. brachypoda. Chalcones 1, 3, 4, and 5 did not show intrinsic antimicrobial activity against all S. aureus strains tested, but they were able to potentiate the Norfloxacin action against the SA1199-B (norA) strain, with a better modulating action for the 4 trimethoxylated chalcone. All chalcones were also able to potentiate the action of EtBr against SA1199-B strain, suggesting a potential NorA inhibition. Moreover, chalcone 4 was able to interfere in the activity of MepA, and interfered weakly in the QacA/B activity. Molecular docking analyzes showed that tested chalcones are capable of binding in the hydrophobic cavity of NorA and MepA, in the same Norfloxacin binding site, indicating that chalcone 4 compete with the antibiotic for the same NorA and MepA binding sites. Association of chalcone 4 with Norfloxacin could be an alternative against multidrug resistant S. aureus over-productive of NorA or MepA.

2.
Microb Pathog ; 140: 103935, 2020 Mar.
Article in English | MEDLINE | ID: mdl-31857236

ABSTRACT

Arrabidaea brachypoda is a native shrub of the Brazilian Cerrado widely used in the folk medicine for treatment of renal diseases and articular pains. This study aimed to, first, evaluate the antimicrobial activity of both extracts and isolated molecules Brachydins BR-A and BR-B obtained from the flowers of A. brachypoda against Staphylococcus aureus, Escherchia coli and Candida albicans species. A second objective was to investigate if these natural products were able to potentiate the Norfloxacin activity against the strain Staphylococcus aureus SA1199-B that overexpress the norA gene encoding the NorA efflux pump. Extracts and isolated compounds were analyzed by HPLC-PDA and LC-ESI-MS respectively. Minimal inhibitory concentrations of Norfloxacin or Ethidium Bromide (EtBr) were determined in the presence or absence of ethanolic extract, dichloromethane fraction, as well as BR-A or BR-B by microdilution method. Only BR-B showed activity against Candida albicans. Addition of ethanolic extract, dichloromethane fraction or BR-B to the growth media at sub-inhibitory concentrations enhanced the activity of both Norfloxacin and EtBr against S. aureus SA1199-B, indicating that these natural products and its isolated compound BR-B were able to modulate the fluoroquinolone-resistance possibly by inhibition of NorA. Moreover, BR-B inhibited the EtBr efflux in the SA1199-B strain confirming that it is a NorA inhibitor. Isolated BR-B was able to inhibit an important mechanism of multidrug-resistance very prevalent in S. aureus strains, thus its use in combination with Norfloxacin could be considered as an alternative for the treatment of infections caused by S. aureus strains overexpressing norA.


Subject(s)
Bacterial Proteins/drug effects , Bignoniaceae/metabolism , Flavonoids/pharmacology , Multidrug Resistance-Associated Proteins/drug effects , Anti-Bacterial Agents/isolation & purification , Anti-Bacterial Agents/pharmacology , Bacterial Proteins/metabolism , Candida albicans/drug effects , Ciprofloxacin/pharmacology , Drug Resistance, Multiple, Bacterial/drug effects , Ethidium/pharmacology , Flavonoids/isolation & purification , Fluoroquinolones/pharmacology , Multidrug Resistance-Associated Proteins/metabolism , Plant Extracts/pharmacology , Staphylococcus aureus/drug effects , Staphylococcus aureus/metabolism
3.
Microb Pathog ; 130: 242-246, 2019 May.
Article in English | MEDLINE | ID: mdl-30876871

ABSTRACT

The aim of this study was to evaluate the antimicrobial activity of ethanoic extract of P. amarus (PAEE) and its compound Phyllanthin, as well as, investigate if these natural products could modulate the fluoroquinolone-resistance in S. aureus SA1199-B by way of overexpression of the NorA efflux pump. Microdilution tests were carried out to determine the minimal inhibitory concentration (MIC) of the PAEE or Phyllanthin against several bacterial and yeast strains. To evaluate if PAEE or Phyllanthin were able to act as modulators of the fluoroquinolone-resistance, MICs for Norfloxacin and ethidium bromide were determined in the presence or absence of PAEE or Phyllanthin against S. aureus SA1199-B. PAEE showed antimicrobial activity against Gram-negative strains, meanwhile Phyllanthin was inactive against all strains tested. Addition of PAEE or Phyllanthin, to the growth media at sub-inhibitory concentrations enhanced the activity of the Norfloxacin as well as, Ethidium Bromide, against S. aureus SA1199-B. These results indicate that Phyllanthin is able to modulate the fluoroquinolone-resistance possibly by inhibition of NorA. This hypothesis was supported by in silico docking analysis which confirmed that Phyllantin is a NorA ligand. Thus, this compound could be used as a potentiating agent of the Norfloxacin activity in the treatment of infections caused by fluoroquinolone-resistant S. aureus.


Subject(s)
Anti-Bacterial Agents/pharmacology , Bacterial Proteins/antagonists & inhibitors , Enzyme Inhibitors/pharmacology , Lignans/pharmacology , Multidrug Resistance-Associated Proteins/antagonists & inhibitors , Phyllanthus/chemistry , Plant Extracts/pharmacology , Staphylococcus aureus/drug effects , Anti-Bacterial Agents/isolation & purification , Drug Resistance, Bacterial/drug effects , Drug Synergism , Enzyme Inhibitors/isolation & purification , Ethidium/pharmacology , Lignans/isolation & purification , Microbial Sensitivity Tests , Norfloxacin/pharmacology , Plant Extracts/isolation & purification , Staphylococcus aureus/enzymology
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