Phytochemical and biological characterization of acetone extracts from the lichen Cladonia coniocraea and Cladonia ramulosa growing in Serbia

A comparative study of aromatic secondary metabolites and antioxidant, antimicrobial, and anticancer potential of two lichen species Cladonia coniocraea and Cladonia ramulosa is presented in this paper. HPLC-UV analysis revealed the presence of depsidone fumarprotocetraric acid and depside sekikaic acid as major aromatic metabolites in both tested species but in different amounts. The antioxidant activity was evaluated by free radical scavenging and reducing power assays. In both assays the extracts showed weak activity (IC50>1000 mu g/ml, while absorbances for reducing power were from 0.0118 to 0.1675). The total content of phenol and flavonoid in extracts was examined using Folin-Ciocalteu reagent and aluminium chloride method and the obtained values were expressed as pyrocatechol equivalents, and as rutin equivalents, respectively. Further, the antimicrobial activity was estimated by determination of the minimal inhibitory concentration by the broth microdilution method against five bacterial and 10 fungal species. Tested extracts showed similar antimicrobial activity with minimum inhibitory concentration values ranging from 0.156 to 20 mg/ml. Finally, the cytotoxic activity was tested using MTT method on the human epithelial carcinoma (Hela), human lung carcinoma (A549) and human colon carcinoma (LS174) cells. The strongest cytotoxic activity with IC50 value of 185.59 mu g/ml expressed extract of C. ramulosa toward Hela cells. Obtained results indicate that these lichens showed the potential for further investigation and possible biopharmaceutical application.