Antimicrobial activity of extracts of the lichens Cladonia furcata, Parmelia caperata, Parmelia pertusa, Hypogymnia physodes and Umbilicaria polyphylla.

The antimicrobial activity of acetone, methanol and aqueous extracts of the lichens Cladonia furcata, Parmelia caperata, Parmelia pertusa, Hypogymnia physodes and Umbilicaria polyphylla is assessed. The extracts are tested on six species of bacteria and 10 species of fungi using the disk-diffusion method, and broth tube dilution is used to determine minimal inhibitory concentration (MIC). The tested bacteria were more sensitive than the tested fungi. Aqueous extracts of the investigated lichens showed no antimicrobial activity against any of the test organisms, whereas the acetone and methanol extracts showed antimicrobial activity. In general, methanol extracts had stronger activity than did acetone extracts. The strongest activity was recorded for the methanol extract of Parmelia pertusa, which had the lowest measured MIC value (0.78 mg/mL). The least active species was Parmelia caperata (highest MIC value: 50 mg/mL). Bacillus mycoides was the most sensitive of the tested bacterial species, while Candida albicans was the most sensitive fungal species.