Abstract

Antibacterial and antifungal activity of the acetone, methanol and aqueous extracts of the lichen Lecanora frustulosa and Parmeliopsis hyperopta and their divaricatic acid and zeorin constituents has been screened in vitro against the following species of  microorganisms: Bacillus mycoides, Bacillus subtilis,Staphylococcus aureus, Enterobacter cloaceae, Escerichia coli, Klebsiella pneumoniae, Aspergillus flavus, Aspergillus fumigatus, Botrytis cinerea, Candida albicans, Fusarium oxysporum, Mucor mucedo, Paecilomyces variotii, Penicillium purpurescens, Penicillium verrucosum and Trichoderma harsianum. The antimicrobal activity was estimated by the disc-difusion method and determination of the minimal inhibitory concentration (MIC) by the Broth tube Dilution method. The bacteria were more sensitive related to the tested fungi. The smallest MIC values were 0.39 mg/mL against bacteria and 1.56 mg/mL against fungi. Acetone and methanol extracts of the investigated lichens showed relatively strong antimicrobial activity, whereas aqueous extracts were inactive.Divaricatic acid and zeorin also showed strong activity against bacteria and fungi. There was no antimicrobial activity against E. coli species. The lichen extracts maximum activity showed in the concentrations of 0.78 mg/mL and the lichen components demonstrated maximum activity in the concetrations of 0.39 mg/mL. Generally, the tested lichen extracts and lichen compounds demostrated a strong antimicrobial effect against the tested microorganisms. That suggest a possibility of their use in the treatment of various diseases caused by these and similar microorganisms.

Key words: Antimicrobial activity, lichen extracts, lichen components.