Potential of Silver Nanoparticles in Overcoming the Intrinsic Resistance of Pseudomonas aeruginosa to Secondary Metabolites from Carnivorous Plants

Abstract

Carnivorous plants are exemplary natural sources of secondary metabolites with biological activity. However, the therapeutic antimicrobial potential of these compounds is limited due to intrinsic resistance of selected bacterial pathogens, among which Pseudomonas aeruginosa represents an extreme example. The objective of the study was to overcome the intrinsic resistance of P. aeruginosa by combining silver nanoparticles (AgNPs) with secondary metabolites from selected carnivorous plant species. We employed the broth microdilution method, the checkerboard titration technique and comprehensive phytochemical analyses to define interactions between nanoparticles and active compounds from carnivorous plants. It has been confirmed that P. aeruginosa is resistant to a broad range of secondary metabolites from carnivorous plants, i.e., naphthoquinones, flavonoids, phenolic acids (MBC = 512 µg mL−1) and only weakly sensitive to their mixtures, i.e., extracts and extracts’ fractions. However, it was shown that the antimicrobial activity of extracts and fractions with a significant level of naphthoquinone (plumbagin) was significantly enhanced by AgNPs. Our studies clearly demonstrated a crucial role of naphthoquinones in AgNPs and extract interaction, as well as depicted the potential of AgNPs to restore the bactericidal activity of naphthoquinones towards P. aeruginosa. Our findings indicate the significant potential of nanoparticles to modulate the activity of selected secondary metabolites and revisit their antimicrobial potential towards human pathogenic bacteria.

Polish Achievements in Bioactive Compound Production From In Vitro Plant Cultures

“…Synergistic interactions with AgNPs increased the efficacy of reduced 3ChPL concentrations, at which they are non-toxic to human keratinocytes (Krychowiak et al, 2018). Further studies have shown that AgNPs overcome intrinsic microbial resistance to NQs (Krychowiak-Maśnicka et al, 2021). 3ChPL also has high activity toward cancer cells, particularly breast cancer cells (IC 50 = 0.6-2 μM).…”

Diversity of biofilm-specific antimicrobial resistance genes in Pseudomonas aeruginosa recovered from various clinical isolates

“…The rapid increase in the number of drug-resistant P. aeruginosa isolates in clinical settings poses a severe therapeutic challenge and has resulted in a higher mortality rate among patients with the infection ( 1 ). P. aeruginosa is characterized by intrinsic resistance to a broad range of antimicrobial drugs ( 2 , 3 ). Biofilm-producing P. aeruginosa is the reason for a wide variety of serious infections such as post-surgical infections, otitis media, periodontitis, thermal burns, trauma, and cystic fibrosis ( 4 ).…”