Provide an overview of the different bioactivities that have been attributed to lichen secondary metabolites, and outline potential issues associated with exploiting lichens as a source of bioactive compounds
The different bioactivities exhibited by lichen secondary metabolites include antioxidant, antimicrobial, anti-inflammatory antiviral properties. Usnic acid, a secondary metabolite produced by Usnea species is known to have tumor inhibitory and analgesic properties. It is also found as a hepatotoxic agent against monogastric murine hepatocytes because of its ability to inhibit the electron transport chain in the mitochondria and induce oxidative stress in cells. Usnic acid also reduced human breast cancer cells and human lung cancer cell proliferation without any DNA damage. Usnic acid may represent a novel source of a chemotherapeutic agent. Some other secondary metabolites of lichen include depsidones, physodic and physodalic acids which are found to prevent the formation of reactive metabolites by blocking the oxidation systems present in the hepatic microsomal fraction. Ursolic acid, another metabolite was found to inhibit the growth of human epidermoid carcinoma cells and also it has been patented to use ursolic acid for manufacturing anticancer agent for suppressing metastasis. Antioxidant activities of some despides have also been reported. Norstictic acid, physodic acid, evernic acid, usnic acid, salazinic acid, fumar protocetraric acid, protocetraric acid, atranorin and zeorin isolated from different lichen species are relatively strong antioxidant, antimicrobial and anticancer agents. Lichen phenolic compounds are secondary metabolites have several potential pharmaceutical applications based on antibiotic, anticancer, antioxidant, and anti-viral properties. In addition, some lichen phenolics serve as “sunscreen” effectively regulating the quality and quantity of light available to the algal partner (photobiont).
One of the main potential issues of exploiting lichens as a source of bioactive compounds is them being severely impacted to the point of disappearance.
Provide an overview of the different bioactivities that have been attributed to lichen secondary metabolites, and outline potential issues associated with exploiting lichens as a source of bioactive c...