Antimicrobial activity of selected plant species of genera Arbutus L., Bruckenthalia Rchb., Calluna salisb. and Erica L. (Ericaceae)

Abstract

Uvae ursi folium (Arctostaphylos uva ursi, Ericaceae) is the best known and most widely used herbal urinary antiseptic. In traditional medicine, other Ericaceae species are also used for the treatment of urinary tract infections. The present study investigates antimicrobial activity of five species of Ericaceae family native to the Balkan Peninsula: Arbutus unedo, Bruckenthalia spiculifolia, Calluna vulgaris, Erica arborea and Erica carnea. Ethanolic extracts were tested against 10 different gram-positive and gram-negative bacteria by the disc diffusion technique, where standard tetracycline, streptomycin and penicillin discs and discs containing crystal violet (1 mg/ml) and solvent (70.0% v/v ethanol) were used as controls. The most prominent antibacterial effect was achieved on Staphylococcus aureus with extracts of Calluna vulgaris and Erica carnea. Tested samples showed no activity against the gram-negative strains Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae. Inhibitory effects on the growth of gram-positive bacteria were more potent. The exception is Arbutus unedo ethanol extract which exhibited certain activity against a laboratory strain of wild Escherichia coli. Antimicrobial activity of the ethanolic extracts against 10 tested strains of bacteria in disc diffusion assay was generally weak, even for sample in which HPLC determination confirmed the presence of arbutin (secondary metabolite responsible for most of the antibacterial activity of Uvaeursi folium).