Chemical composition and biological activities of the extracts and secondary metabolites of lichens belonging to the genus Usnea, Parmeliaceae

Abstract

Lichens represent a promising source of antimicrobial, cytotoxic and antioxidant agents. Their great pharmacological potential lies in the fact that they represent specific symbiotic organisms and thus possess natural roles allowing them to be highly adaptable to different environmental conditions. On the other hand, stated biological activities of lichens with prospective medicinal significance may be connected to their long-term use in the traditional treatment of various ailments. Genus Usnea from the Parmeliaceae family is certainly one of the best studied in terms of chemical composition and biological properties of its extracts and/or isolated compounds. In the first part of the study, a detailed review of the literature has been performed yielding a detailed report on the investigations of biological activities of the lichens belonging to this genus. In the second part of the study, the chemical composition of the lichens from the genus was described and, additionally, a survey of the biological properties of the most representative secondary metabolites in these lichens has been reported. It could be concluded that the extracts and/or isolated compounds from the lichens belonging to the genus Usnea may be considered a valuable source of prospective drug candidates with potential clinical relevance.

Assessment of the Antibacterial Potency of Usnea sp. against Foodborne Pathogens

“…Phytochemical researches revealed the presence of various many chemicals in different Usnea species such as usnic acid, zeorin, ergosterol peroxide, psoromic acid, methyl-β-orcinolcarboxylate, atranorin, barbatic acid, usnic acid, diffractaic acid, usneaceratin A and B, evernic acid, constictic acid, sekikaic acid, squamatic acid, stictic acid, thamnolic acid, norstictic acid, β-orcinol, salazinic acid, protocetraric acid, chloroatranorin, barbatolic acid, lobaric acid, etc. [30,38,39]. In particular, usnic acid, a yellowish pigment of Usnea sp., has been studied for its potential biological activities.…”

Fungi and Algae as Sources of Medicinal and Other Biologically Active Compounds: A Review

“…Another example of use for the production of therapeutic agents are lichenized fungi (lichens), due to the properties of their secondary metabolites such as an anticancer, antimicrobial, and antioxidant activity [ 80 , 81 , 82 , 83 , 84 ].…”

“…For example, lichen extracts of the genus Usnea showed good antioxidant potential, such as a protective role in human lymphocytes by regulating enzymatic activity. This is especially evident in usnic acid (dibenzofuran) isolated from Usnea species and other lichens have demonstrated various biological activities, antitumor, antimicrobial and cytoprotective [ 84 ]. Additionally, other certain lichen species such as B. fuscescens , P. tiliacea , and U. decussata were potential natural antioxidant resources due to their free radical scavenging activities [ 85 ].…”