Parmelia sulcata Taylor and Usnea filipendula Stirt induce apoptosis-like cell death and DNA damage in cancer cells

ObjectivesSuccessful cancer treatments still require more compounds to be isolated from natural sources. Thus, we have investigated anti-proliferative/apoptotic effects of methanolic extracts of lichen species Parmelia sulcata Taylor and Usnea filipendula Stirt on human lung cancer (A549, PC3), liver cancer (Hep3B) and rat glioma (C6) cells. Materials and methodsAnti-proliferative effects were monitored by MTT and adenosine triphosphate viability assays, while genotoxic activity was studied using the comet assay. Additionally, cell death mode and apoptosis assays (fluorescence staining, caspase-cleaved cytokeratin 18, caspase-3 activity and PARP cleavage) were performed. ResultsExtracts produced anti-population growth effects in a dose-dependent manner (1.56-100g/ml) by inducing apoptosis-like cell death. This resulted in the lines having the presence of pyknotic cell nuclei. In addition, significant increase in genetic damage in the cell lines was seen, indicating that DNA damage may have been responsible for apoptotic cell death. ConclusionIn this study, methanolic extracts of Parmelia sulcata and Usnea filipendula induced apoptosis-like cell death by causing DNA damage, to cancer cells.