INVESTIGATION OF SELECTED SERBIAN LICHENS FOR ANTIOXIDANT, ANTIMICROBIAL AND ANTICANCER PROPERTIES

The acetone extracts of the lichens Parmeliopsis ambigua, Parmelia pertusa and Hypogymnia physodes were tested for antioxidant, antimicrobial and anticancer potential. Antioxidant activity was evaluated by measuring free radical and superoxide anion scavenging activity and reducing power. These results revealed that the extract from Parmeliopsis ambigua had highest free radical scavenging activity (62.12% inhibition). Moreover, the tested extracts have strong reducing power and superoxide anion radical scavenging. Content of phenols and flavonoids in extracts was estimated as pyrocatechol equivalent, and as rutin equivalent, respectively. Between total phenolic and flavonoid contents and the antioxidant effect of tested extracts, the strong relationships were found. The antimicrobial activity was determined by measuring the minimal inhibitory concentration by the broth microdilution method against Bacillus mycoides, Bacillus subtilis, Staphylococcus aureus, Enterobacter cloaceae, Escherichia coli, Klebsiella pneumonia, Aspergillus flavus, Aspergillus fumigatus, Botrytis cinerea, Candida albicans, Fusarium oxysporum, Mucor mucedo, Paecilomyces variotii, Penicillium purpurescens, Penicillium verrucosum and Trichoderma harsianum. The extract of Parmelia pertusa was found to be the most active with lowest MIC values (0.78 to 12.5 mg/ml). Anticancer activity was tested by using the microculture tetrazolium test on FemX (human melanoma) and LS174 (human colon carcinoma) cell lines. The extracts tested has strong anticancer activity against both cell lines with IC50 values ranging from 6.84 to 43.45 mu g/ml.