The aim of the present study is to investigate the antioxidant properties of the lichen Cetraria aculeata. Antioxidant activity of the methanol and ethyl acetate extracts of lichen was tested by different methods including determination of total phenolics content, determination of total antioxidant capacity, DPPH free radical scavenging activity, inhibitory activity towards lipid peroxidation, ferrous ion chelating ability and hydroxyl radical scavenging activity. The extracts of the lichen C. aculeata showed significant antioxidant activity. The methanol extract showed higher values for total phenolics and total antioxidant capacity compared to the ethyl acetate extract, while the ethyl acetate extract demonstrated better results for DPPH radical scavenging, inhibitory activity towards lipid peroxidation, chelating ability and hydroxyl radical scavenging than the methanol extract. This is the first report of the antioxidant properties of Cetraria aculeata growing in Serbia. The results of antioxidant activity indicate the application of this lichen as source of natural antioxidants that could be used as a possible food supplement, in the pharmaceutical industry and in the treatment of various diseases.

The aim of this study was to investigate the antimicrobial activity and HPLC analysis of the methanol and chloroform extracts of leaves and twigs of endemic species Daphne blagayana collected from the area of Suva Mountain, Serbia. The antimicrobial activity, expressed as the values of MIC, were investigated on the 6 standardized bacterial strains and two strains of fungi. Amracin and ketoconazole are used as standard antibiotics. MIC values of the tested extracts were ranged from 15.62 to 125μg/ml. The strongest effect of the extracts exhibited against Klebsiella pneumoniae, Staphylococcus aureus and Proteus mirabilis. Results of the HPLC analysis showed the presence of a variety of secondary metabolites, one of which is 7,8-dihydroxycoumarin (daphnetin), which was identified in all the extracts tested. Daphnetin, as biologically active substance, is most responsible for the antimicrobial activity of the tested extracts, but its role can not exclude the influence of other secondary metabolites (phenols and flavonoids) present in the extracts, which may have a synergistic effect.