Short Lecture “Unique Molecules from a Bioactive Irish Bog Lichen, Cladonia portentosa”

Cladonia portentosa, commonly known as Reindeer lichen, is widely distributed on the diverse Irish boglands. A lichen is a unique symbiotic blend of photobiont (eukaryotic alga and/or cyanobacterium) and mycobiont (filamentous fungus) partners. The former undergoes primary production to fuel the latter, which in return biosynthesise secondary metabolites called lichenic acids, to protect the two against harsh environment, thereby prolonging their sustainability. Lichenic acids include diverse metabolites including depsides, depsidones, dibenzofurans, diphenylether, xanthones, pulvinic acid derivatives etc [1]. To date, two lichenic acids usnic acid (dibenzofuran) and perlatolic acid (depside) have been reported from C. portentosa [2]. In present study, methanol extracts were prepared from C. portentosa, harvested from six Irish bogland ecosystems and their cytotoxicity and anti-inflammatory activity were measured using an in vitro model of immortalised bone marrow derived macrophages (iBMDM) cell line ([Fig. 1]). Resazurin assay and ELISA techniques were used to investigate cell viability and to measure cytokine production including IFN-β, IL-6, TNF-α and Rantes, respectively. The extracts showed a clear inhibition of IFN-β and IL-6 while stimulation of Rantes production. HPLC, LC-ESI-MSn and column chromatography were used to separate and identify the active main components of the extracts. The metabolites, olivetolic acid, 4-O-Me-olivetolic acid and 2-O-Me-perlatolic acid were identified for the first time in C. portentosa along with previously reported usnic and perlatolic acids, and their structures were confirmed with 2D-NMR. These components may act as a precursor in biosynthesis of perlatolic acid. The cytotoxicity and anti-inflammatory screening of individual components of methanol extract is in progress.

Fig. 1 

Publication History

Article published online:
12 December 2022

• References

• 1 Ranković B. Lichen Secondary Metabolites, Bioactive Properties and Pharmaceutical Potential. Cham, Switzerland: Springer; 2019: 1-30
• 2 Le Pogam P, Schinkovitz A, Legouin B. et al. Matrix-free UV-laser desorption ionization mass spectrometry as a versatile approach for accelerating dereplication studies on lichens. Analytical chemistry 2015; 87: 10421-10428