In vitro susceptibility of Helicobacter pylori to protolichesterinic acid from the lichen Cetraria islandica

Abstract

With reference to the traditional rise of Cetraria islandica (Iceland moss) for relief of gastric and duodenal ulcer, plant extracts were screened for in vitro activity against Helicobacter pylori. (+)-Protolichesterinic acid, an aliphatic α-methylene-γ-lactone, was identified as an active component. The MIC range of protolichesterinic acid, in free as well as in salt form, was 16 to 64 μg/ml.