Abstract
An extraction method was designed and scaled up to produce multicomponent polyphenolic extracts from blueberries (Vaccinium corymbosum) of three different varieties. The process was specifically drawn up to comply with green chemistry principles. Extracts were obtained for the direct assessment of their antimicrobial and antiadhesive activities, and their direct use in the control of infections caused by concerning multidrug-resistant nosocomial pathogens. Analytical characterization was performed by liquid chromatography–tandem mass spectrometry (LC–MS/MS). Similar qualitative profiles were obtained in the three studied varieties with some significant quantitative differences. Up to 22 different polyphenols were identified with a clear predominance of anthocyani(di)ns followed by flavanols, non-flavonoids, and far behind by flavan-3-ols and procyanidins. The individual content of the main polyphenols was also discussed. A pilot scale extract has been also produced as a proof-of-concept, showing that scaling-up triples the content of bioactive phytochemicals. The effect of the polyphenolic extracts was analyzed against seven multidrug-resistance bacterial species by performing biofilm formation and growth and killing curves assays. All the studied varieties showed antibacterial and antiadhesive activities, being the extract containing the highest concentration of bioactive polyphenols, the most active with a high bactericidal effect.
Highlights
Nowadays, the rapid emergence of multidrug-resistant pathogens represents one of the major medical challenges
The antimicrobial resistance of these pathogens can even increase when they grow in biofilms, which are organized communities of bacteria encased in a self-produced matrix made of extracellular polymeric substances [4]
The total polyphenol content (TPC) of the extract was evaluated, which highlighted the content of the Ventura (VcV) blueberries (343 ± 10 mg GAE L−1) compared to the Emerald (VcE) (128 ± 5 mg GAE L−1) and Star (VcS) (163 ± 12 mg GAE L−1) ones
Summary
The rapid emergence of multidrug-resistant pathogens represents one of the major medical challenges. Effective drugs for infections caused by tough-to-treat pathogens, that are less prone to causing resistance are required. Carbapenems have been considered as last-line antibiotics for the treatment of infections caused by multidrug-resistant (MDR) Gram-negative pathogens. Several carbapenem resistant (CR) pathogens are increasing, representing a great threat to human health [1,2,3]. The antimicrobial resistance of these pathogens can even increase when they grow in biofilms, which are organized communities of bacteria encased in a self-produced matrix made of extracellular polymeric substances [4]. Due to the high resistance to antimicrobials shown by biofilmassociated bacteria, these device-related infections are difficult to treat, being responsible for recurrence of infections [4,5]
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