Chemical investigation of the lichen Cetraria islandica has led to the isolation of four compounds identified as
protolichesterinic acid, lichesterinic acid, protocetraric acid and fumarprotocetraric acid. Their structures were characterized
using their physical and spectroscopic data. Using an Alamarblue™ 96 well microplate assay, these compounds were
tested to evaluate their trypanocidal activity against Trypanosoma brucei brucei. Protolichesterinic acid (MIC = 6.30 µM)
and lichesterinic acid (MIC = 12.5 µM) showed very significant activity against the test organism. Docking studies (GRIP
technique) of these molecules revealed their strong affinity towards possible targets of Trypanosoma brucei such as riboflavin
kinase, sterol-14α-demethylase (CYP51), rohedsain and glutathione synthetase. Hydrophobicity played a significant
role in their antitrypanosomal activity.