Antimicrobial activity of methanol extracts of four Parmeliaceae lichen species

The methanol extracts of four Parmeliaceae lichens: Hypogymnia physodes, Evernia prunastri, Flavoparmelia caperata and Parmelia sulcata, were screened for their in vitro antimicrobial activity using a disk diffusion assay against 11 bacteria, fungi A. niger and yeast C. albicans. Aglomerative cluster analysis (AHC) of obtained activity showed that  H. physodes and E. prunastri extracts manifested stronger activity (diameter of inhibition zones ranged from 17 to 26 mm) than F. caperata and  P. sulcata extracts (diameter of inhibition zones ranged from 15 to 22 mm). Based on microorganisms´ susceptibility towards extracts two groups were distinguished: the first consisting of Gram negative bacteria (P. vulgaris and K. pneumoniae) and fungi (A. niger and C. albicans) and the second group including all Gram positive bacteria and three Gram negative bacteria (E. coli, S. enteritidis and  P. aeruginosa). F. caperata and E. prunastri extracts inhibited A. niger and C. albicans slightly more than Nystatin standard which suggests their possible use as active ingredients in phyto-therapeutics.