Antimicrobial activity of methanol extracts of four Parmeliaceae lichen species

Abstract

Antimicrobial activity of methanol extracts of four Parmeliaceae lichens (Hypogymnia physodes (L.) Nyl., Evernia prunastri (L.) Ach., Flavoparmelia caperata (L.) Hale and Parmelia sulcata Taylor) against a panel of microbial strains (11 Gram-positive (Enterococus sp., Bacillus subtilllis, Sarcina lutea, Micrococus luteus, Staphylococcus aureus, Clostridium sporogenes) and Gram-negative bacteria (Escherichia coli, Proteus vulgaris, Salmonela enteritidis, Pseudomonas aeruginosa, Klebsiella pneumoniae), the filamentous fungus A. niger and the yeast C. albicans) was assayed using a disk diffusion method (1 mg of the extract per disc; extracts were dissolved in methanol, 25 mg/mL). All tested extracts showed moderate antimicrobial activity. Multivariate statistical treatment (agglomerative hierarchical clustering analysis, AHC) of the obtained results allowed grouping of the samples according to their antimicrobial potential against different strains: antimicrobial profile of H. physodes and E. prunastri extracts were comparable; the similar is true for F. caperata and P. sulcata samples. In addition, based on the similarities/ dissimilarities in their susceptibility toward the tested extracts, two groups of microorganisms could be distinguished: Group I - P. vulgaris, K. pneumoniae (Gram-negative bacteria), A. niger and C. albicans; Group II - E. coli, S. enteritidis, P. aeruginosa (Gram-negative bacteria) and all of the assayed Gram-positive strains.