Quantitative variations of phenolic compounds related to thallus age in Umbilicaria antarctica in Antarctica

Densitometric analysis (HPTLC) was used to determine the concentrations of
phenolic metabolites in thalli of different ages in Umbilicaria antarctica Frey
et Lamb. Usnic acid and atranorin concentrations are highest in individuals of
the youngest age class and decrease towards the oldest age classes, whereas
gyrophoric acids is more abundant in intermediate age clases. Usnic acid and
atranorin are present in isolated rhizines. The importance of the spatial
distribution of atranorin and usnic acid in this species is discussed.