Exploring the Antibacterial, Antioxidant, and Anticancer Properties of Lichen Metabolites

摘要: Antibiotic screening of crude extracts of 36 lichen species demonstrated inhibitory effects against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Methicillin-resistant S. aureus (MRSA). Generally, acetone extractions were found to be more effective than methanol extractions. It has also been shown that L. vulpina extract was bacteriocidal against MRSA with a relatively slow kill rate that disrupts cell membrane integrity and cell division as possible modes of action. Antioxidant screening of extracts from 11 lichen species, using the Oxygen Radical Absorbance Capacity (ORAC) assay, showed that lichen extracts inhibited the oxidative degradation of the fluorescent molecule (fluorescein-sodium salt) by the oxygen free radical initiator AAPH (2,2'-azobis(2-aminidopropane) dihydrochloride Acetone extracts as well as pure compounds from lichen species showed cytotoxic effects against Burkitt's lymphoma (Raji) cells and a colon cancer cell line (HT29 and SW620). They decreased proliferation, arrested cell cycle at various stages and force the cell to undergo apoptosis. The tested extracts or pure compounds were not toxic to normal cells. In colon cancer apoptosis took place independent of casapase-3.