Chemical composition of new varietal honeys and they antimicrobial activities

Abstract Nowadays, there is an urgent need to look for antimicrobial substances due to a widespread occurrence of multidrug resistant bacterial and fungal strains. Honey with its antimicrobial properties is a very promising substance with many valuable properties. In this study we examined for the first time antimicrobial properties of novel varietal honeys. The experiments were carried out with 11 honey samples, i.e.: Plum, Rapeseed, Lime, Phacelia, Honeydew, Sunflower, Willow, and Multifloral-P (Prunus spinosa L.), Multifloral-AP (Acer negundo L., Prunus spinosa L.), Multifloral-Sa (Salix sp.), Multifloral-Br (Brassica napus L.). Their antimicrobial activity was tested against bacteria (such as Escherichia coli, Bacillus circulans, Staphylococcus aureus, Pseudomonas aeruginosa), yeasts (such as Saccharomyces cerevisiae and Candida albicans) and mold fungi (such as Aspergillus niger). In tested honeys, phenolic acids were one of the most important group of compounds with antimicrobial activity. In our study, the highest amount of phenolic acids was found in honeydew honey (808.05 µg GAE/g) with the highest antifungal activity aiming A. niger. Among the tested phenolic acids, caffeic acid was in the greatest amount, which was found in the highest amounts in honeys as: phacelia − 356.72 µg/g, multifloral (MSa) and multifloral (MBr) − 318.9 µg/g. The highest bactericidal activity against S. aures was found in multifloral honeys MSa and MBr. Additionally, the highest amounts of syringic acid and cinnamic acid were identified in rapeseed honey. Multifloral honey (MAP) showed the highest bactericidal activity against E. coli, and multifloral honey (MSa) against S. aureus. Additionally, multifloral honey (MBr) was effective against both bacteria: E. coli and S. aureus. Novel varietal honeys tested in our study show various levels of antibacterial and antifungal activity and alhough they had some limitations, they can still enhance drug treatment against multidrug resistant bacterial and fungal strains.