Evaluation of antimicrobial activity of the lichens Lasallia pustulata, Parmelia sulcata, Umbilicaria crustulosa, and Umbilicaria cylindrica.

The antimicrobial properties of acetone, methanol, and aqueous extracts of the lichens Lasallia pustulata, Parmelia sulcata, Umbilicaria crustulosa, and Umbilicaria cylindrica were studied comparatively in vitro. Antimicrobial activities of the extracts of different lichens were estimated by the disk diffusion test for Gram-positive bacteria, Gram-negative bacteria, and fungal organisms, as well as by determining the MIC (minimal inhibitory concentration). The obtained results showed that the acetone and methanol extracts of Lasallia pustulata, Parmelia sulcata, and Umbilicaria crustulosa manifest antibacterial activity against the majority of species of bacteria tested, in addition to selective antifungal activity. The MIC of lichen extracts was lowest (0.78 mg/ml) for the acetone extract of Lasallia pustulata against Bacillus mycoides. Aqueous extracts of all of the tested lichens were inactive. Extracts of the lichen Umbilicaria cylindrica manifested the weakest activity, inhibiting only three of the tested organisms.

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.

Antifungal activity of Rubia tinctorum, Rhamnus frangula and Caloplaca cerina.

The results of a preliminary antifungal screening of the methanol extracts and the major anthraquinone aglycones, alizarin and emodin, of Rubia tinctorum and Rhamnus frangula in comparison with the antifungal activity of the anthraquinone-containing lichen Caloplaca cerina and its main secondary metabolite parietin are reported.