Solubilization of poorly soluble lichen metabolites for biological testing on cell lines.

The depside atranorin and depsidone fumarprotocetraric acid, isolated from the lichens Stereocaulon alpinum and Cetraria islandica, respectively, were chosen as prototypes for poorly soluble natural compounds in an effort to facilitate testing in pharmacological models. Solubilizing agents previously identified as being non-toxic towards a malignant leukemic (K-562) cell line and suitable for testing of anti-proliferative activity of the dibenzofuran lichen metabolite (+)-usnic acid were used in solubilization studies of the depside and depsidone. Cyclodextrin derivatives were found to be most suitable for solubilizing the lichen compounds, the greatest rise in solubility being witnessed for fumarprotocetraric acid, increasing almost 300-fold from 0.