Antimicrobial activity of a grape marc polyphenolic extract on antibiotic resistant clinical isolates

The problem of bacterial resistance is a global public threat, difficult to solve due to the lack of development of new antibiotics, which highlights the importance of the search for new alternatives to treat infections caused by resistant pathogens. The bioactive compounds of plants, such as polyphenols, could be a solution to this relevant problem as these molecules have antimicrobial properties. In this work we have studied the antimicrobial activity of a polyphenolic-rich extract from Galician white grapes against clinical strains, some of them presenting antibiotic resistance. For the polyphenolic extraction, a Medium-Scale Ambient Temperature (MSAT) system was employed, based on the principles of Green Chemistry, being respectful of the environment, as mild process conditions and solvents recognised as safe (GRAS) were used. As selected extracting mixture, ethyl lactate:water 50% is used. To estimate the polyphenol content of extract, total polyphenol index (TPI) was determined, while liquid chromatography with tandem mass spectrometry (LC- MS/MS) was used for detailed analytical characterisation of these compounds, obtaining their individualised polyphenol profile and their quantitative composition. The antimicrobial capacity of the extract was determined by calculating the minimum bactericidal concentration (MBC) and half the maximum inhibitory concentration (IC₅₀), using a range of concentrations of the extract between 0 and 20% (v/v). The bacterial strains used were collected from clinical samples. The values of IC₅₀ obtained ranged from about 0.4 to 8% (v/v). Our results showed that this grape extract is effective against the majority of the pathogenic bacteria studied.

Publication History

Article published online:
16 November 2023