High performance liquid chromatography of phenolics in recent and subfossil lichens

Subfossils of the lichens Umbilicaria krascheninnikovii (Sav.) Zahlbr. and Umbilicaria hyperborea (Ach.) Hoffm. were discovered after they were exposed by ice melt in Greenland. Extracellular phenolic substances of emerging lichens were analyzed by high performance liquid chromatography and compared with those found in lichens of the same species that escaped glaciation. All major and minor phenolics of living lichens were present in subfossils. although significantly lower amounts of the major constituent, gyrophoric acid, were documented. After being subjected to experimental pressure treatments in a hydraulic press, Umbilicaria nammulata (Ach) Tuck. thalli showed highly significant reductions in the levels of both gyrophoric acid and lecanoric acid, and the decrease was more pronounced under the more severe of two pressure treatments. The decrease in mean phenolic content following immersion in water for 5 days was not statistically significant. There was a considerable range of phenolic concentrations among thalli of modern arctic specimens of Umbilicaria as well as among thalli recently released from ice, and the variance in subfossils was not significantly different from that in living populations.