Cyto- and genotoxic effects of usnic-acid (+)- and (–)-enantiomers have been studied in human peripheral-blood lymphocytes. It has been shown that usnic-acid enantiomers in concentrations of 0.04–0.30 mM have pronounced cytotoxic action. Usnic-acid enantiomers in concentrations of 0.04–0.30 mM have exhibited a genotoxic effect; moreover, the genotoxicity of usnic-acid (–)-enantiomer in concentrations of 0.15 and 0.30 mM was twice as high as that of (+)-enantiomer. The effect of usnic-acid (+)- and (–)-stereoisomers has been accompanied by the formation of atypical DNA comets. Furthermore, (–)-usnic acid has induced 2.5–3.5 times more atypical comets than its (+)-stereoisomer.

The composition and contents of secondary metabolites in Flavocetraria lichens from Eastern Siberia were analyzed using herbarium specimens. Based on the composition of identified metabolites, three ...