Usnic acid and triacylglycerides production by the cultured lichen mycobiont of Ramalina celastri.

A strain of the lichen mycobiont of Ramalina celastri, isolated from ascospores, was cultured axenically on two solid media containing high amounts of the carbon source: sucrose in MY10 and mannitol in BMRM. Usnic acid, the major cortical lichen metabolite, was produced by the colonies grown on MY10, with a very high yield (7.9%) in comparison with that in the lichen thallus.

Fernene triterpenoids from the lichen Pyxine berteriana.

Two new fernene triterpenoids, fern-9(11)-en-3,19-dione (1) and 3beta-acetoxyfern-9(11)-en-19-one (2), together with the known 3beta-acetoxyfern-9(11)-en-19beta-ol (3) and lichexanthone (4), have been isolated from the acetone extract of the lichen Pyxine berteriana. The structures of the new compounds were established on the basis of IR, extensive 1D and 2D NMR, and MS analyses. Although several fern-9(11)-enes have been isolated from lichens, compounds 1 and 2 are the first examples of naturally occurring fernene triterpenoids with a carbonyl function at C-19.

Lichen secondary metabolites from the cultured lichen mycobionts of Teloschistes chrysophthalmus and Ramalina celastri and their antiviral activities.

Lichens and spore-derived cultured mycobionts of Teloschistes chrysophthalmus and Ramalina celastri were studied chemically, and results indicated that they produced, respectively, parietin and usnic acid as major secondary metabolites, which were purified and identified. Identification of the compounds was performed by high performance liquid chromatography and structural elucidation by nuclear magnetic resonance (1H) and electron impact mass spectrometry. Usnic acid exhibited antiviral activity whereas parietin had a virucidal effect against the arenaviruses Junin and Tacaribe.