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Antivirulence activities of retinoic acids against Staphylococcus aureus.

ABSTRACT: Multidrug-resistant bacteria such as Staphylococcus aureus constitute a global health problem. Gram-positive S. aureus secretes various toxins associated with its pathogenesis, and its biofilm formation plays an important role in antibiotic tolerance and virulence. Hence, we investigated if the metabolites of vitamin A₁ might diminish S. aureus biofilm formation and toxin production. Of the three retinoic acids examined, 13-cis-retinoic acid at 10 μg/mL significantly decreased S. aureus biofilm formation without affecting its planktonic cell growth (MIC >400 μg/mL) and also inhibited biofilm formation by Staphylococcus epidermidis (MIC >400 μg/mL), but less affected biofilm formation by a uropathogenic Escherichia coli strain, a Vibrio strain, or a fungal Candida strain. Notably, 13-cis-retinoic acid and all-trans-retinoic acid significantly inhibited the hemolytic activity and staphyloxanthin production by S. aureus. Furthermore, transcriptional analysis disclosed that 13-cis-retinoic acid repressed the expressions of virulence- and biofilm-related genes, such as the two-component arlRS system, α-hemolysin hla, nuclease (nuc1 and nuc2), and psmα (phenol soluble modulins α) in S. aureus. In addition, plant and nematode toxicity assays showed that 13-cis-retinoic acid was only mildly toxic at concentrations many folds higher than its effective antibiofilm concentrations. These findings suggest that metabolites of vitamin A₁, particularly 13-cis-retinoic acid, might be useful for suppressing biofilm formation and the virulence characteristics of S. aureus.

SUBMITTER: Park I

PROVIDER: S-EPMC10525321 | biostudies-literature | 2023

REPOSITORIES: biostudies-literature

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Antivirulence activities of retinoic acids against Staphylococcus aureus.

Park Inji I Lee Jin-Hyung JH Ma Jin Yeul JY Tan Yulong Y Lee Jintae J

Frontiers in microbiology 20230913

Multidrug-resistant bacteria such as Staphylococcus aureus constitute a global health problem. Gram-positive S. aureus secretes various toxins associated with its pathogenesis, and its biofilm formation plays an important role in antibiotic tolerance and virulence. Hence, we investigated if the metabolites of vitamin A1 might diminish S. aureus biofilm formation and toxin production. Of the three retinoic acids examined, 13-cis-retinoic acid at 10 μg/mL sig ...[more]

PMID: 37771707

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Project description:Background/Objectives: Brown algae, particularly Eisenia bicyclis, produce various bioactive chemicals with significant application potential in the food, cosmetics, and pharmaceutical industries. This study aimed to evaluate the antibacterial, antibiofilm, and antivirulence properties of the ethyl acetate fraction (EA) of E. bicyclis and its synthesized gold nanoparticles (EA-AuNPs), with a focus on their potential applications against both Gram-positive and Gram-negative bacteria. Methods: The bioactive component in the ethyl acetate fraction was identified using a gas chromatography-mass spectroscopy (GC-MS) device and a liquid chromatography-mass spectrometer/mass spectrometry (LC-MS) system. The crystal violet method was utilized to evaluate the biofilm inhibition experiments. Several instruments, including dynamic light scattering, Fourier transform infrared, X-ray diffraction, field emission transmission electron microscopy, and energy-dispersive spectroscopy, were employed to completely characterize the produced EA-AuNPs. The cytotoxicity of the EA-AuNPs was determined using the MTT assay, and the expression of genes linked with biofilm and virulence in Pseudomonas aeruginosa and Staphylococcus aureus was investigated using real-time polymerase chain reaction (RT-PCR). Results: Various bioactive compounds were identified from the EA using GC-MS and LC-MS, including fatty acids and phlorotannins such as eckol, dieckol, 6,6'-bieckol, and phlorofucofuroeckol in high amounts, highlighting EA as a phlorotannin-rich fraction. The EA also demonstrated significant antibiofilm activity, with 79.86% inhibition at 512 μg/mL against P. aeruginosa and 87.00% at 64 μg/mL against S. aureus. EA was then used in the synthesis of gold nanoparticles (AuNPs) to improve their stability and safety. The synthesized EA-AuNPs were determined to have an average size of 165.04 nm, with a zeta potential of -29.86 mV, indicating good stability. In antibiofilm activity assays, EA-AuNPs demonstrated 45.76% inhibition against P. aeruginosa at 1024 μg/mL and 44.64% inhibition against S. aureus at 128 μg/mL. At sub-MIC levels, EA-AuNPs significantly inhibited biofilm formation and virulence factors, including the motility of P. aeruginosa and staphyloxanthin synthesis in S. aureus. The RT-PCR analysis revealed the downregulation of key genes involved in biofilm formation and virulence in P. aeruginosa and S. aureus. Conclusions: These findings highlight the potential of E. bicyclis solvent-soluble extracts and EA-AuNPs as effective antibacterial, antibiofilm, and antivirulence agents, with significant application potential in the pharmaceutical and food industries. To the best of our knowledge, this is the first report of antibiofilm activity against both Gram-positive and Gram-negative bacteria using EA-AuNPs.

Project description:An antivirulence approach targets bacterial virulence rather than cell viability in the antibiotic approach that can readily lead to drug resistance. Opportunistic human pathogen Pseudomonas aeruginosa produces a variety of virulence factors, and biofilm cells of this bacterium are much more resistant to antibiotics than planktonic cells. To identify novel inorganic antivirulence compounds, the dual screenings of thirty-six metal ions were performed to identify that zinc ions and ZnO nanoparticle inhibited the pyocyanin production and biofilm formation in P. aeruginosa without affecting the growth of planktonic cells. Moreover, zinc ion and ZnO nanoparticle markedly reduced the production of 2-heptyl-3-hydroxy-4(1H)-quinolone and siderophore pyochelin, while increased the production of another sideropore pyoverdine and swarming motility. Further, zinc ion and ZnO nanoparticle clearly suppressed hemolytic activity in P. aeruginosa. Transcriptome analyses showed that ZnO nanoparticle induced zinc cation efflux pump czc operon, porin genes (oprD and opdT), and Pseudomonas type III repressor A ptrA, while repressed pyocyanin-related phz operon, which partially explains the phenotypic changes. Overall, ZnO nanoparticle is a potential candidate for use in an antivirulence approach against persistent P. aeruginosa infection. P. aeruginosa Genechip Genome Array (Affymetrix, P/N 900339) was used in order to study the cells after the addition of ZnO nanoparticles. DNA microarray analysis with one biological replicate was performed with an Affymetrix system. P. aeruginosa was inoculated in 25 ml of LB medium in 250 ml shaker flasks with overnight cultures (1 : 100 dilution). Cells were cultured for 5 h with shaking at 250 rpm with and without ZnO nanoparticles (1 mM). Before sample collection, RNase inhibitor (RNAlater, Ambion, TX, USA) was added, and the cells were immediately chilled with dry ice and 95% ethanol (to prevent RNA degradation) for 30 s before centrifugation at 16,000 g for 2 min. The cell pellets were immediately frozen with dry ice and stored at –80°C. Total RNA was isolated using a Qiagen RNeasy mini Kit (Valencia, CA, USA).

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Antivirulence activities of retinoic acids against Staphylococcus aureus.

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Antivirulence activities of retinoic acids against <i>Staphylococcus aureus</i>.

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