Antibacterial compounds from Vaccinium myrtillus (bilberry)

Bilberries have been used in herbal medicine against various diseases [1]. The aim of the study was to determine the antibacterial activity of three different (petroleum ether (PB), acetone (A) and methanol (M)) extracts of Icelandic bilberries, using broth microdilution assay. Bioguided fractionation was used to isolate active compounds. The PB extract exhibited potent antibacterial activity against antibiotic sensitive and resistant Gram-positive bacteria (Staphylococcus aureus, Enterococcus faecalis and E. faecium) where minimum inhibitory concentration (MIC) was shown to be from 8 to125µg/mL. The extracts showed no significant activity against Gram-negative bacteria and C. albicans.

A fraction composed of three pentacyclic triterpenoids was isolated from the PB extract using LC and HPLC. These triterpenoids were tested against seven resistant Gram-positive bacteria. The MIC value for the triterpenoids was determined to be: 8µg/mL against coagulase-negative staphylococci and ampicillin resistant E. faecium; 16µg/mL against ampicillin-and vancomycin resistant E. faecium and 31µg/mL against methicillin-resistant S. aureus, gentamicin resistant E. faecalis and vancomycin resistant E.faecalis, respectively. Aqueous extract of bilberries has previously been shown to exhibit some antibacterial activity (2). However, the MIC value was ranging from 15–31mg/mL [2].

Acknowledgements: Icelandic Council of Science, University of Iceland Research Fund

References: 1. Morazzoni, P., Bombardelli, E. (1996), Fitoterapia 66: 3–29. 2. Brantner, A., Grein, E. (1994), J. Ethnophamacol. 44: 35–40.