RESUMEN
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.
Asunto(s)
Líquenes/química , Triterpenos/química , Triterpenos/aislamiento & purificación , Argentina , Estructura Molecular , Resonancia Magnética Nuclear Biomolecular , Relación Estructura-ActividadRESUMEN
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.
Asunto(s)
Antivirales/aislamiento & purificación , Benzofuranos/aislamiento & purificación , Emodina/análogos & derivados , Líquenes/química , Líquenes/crecimiento & desarrollo , Animales , Antivirales/farmacología , Benzofuranos/farmacología , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Chlorocebus aethiops , Cromatografía Líquida de Alta Presión , Emodina/aislamiento & purificación , Emodina/farmacología , Haplorrinos , Esporas/fisiología , Células VeroRESUMEN
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. Mycelia grown on BMRM did not produce the lichen secondary metabolite and rendered triacylglycerides (8.5%) instead. Analysis by GC-MS of the fatty acid methyl esters revealed the presence of oleic, palmitic and stearic acids as the main triacylglyceride constituents. The present results highlight the impact of the culture conditions on the lichen mycobiont secondary metabolism and confirm that MY10 is a useful medium to obtain usnic acid from mycobionts in the laboratory.