Dragendorff-positive compounds in some Mediterranean red algae

The distribution of Dragendorff-positive compounds in more than 20 species of Mediterranean red algae has been investigated. In addition to several new occurrences of known metabolites, two previously unreported compounds, N-acetyllaminine; and N,N-dimethyl-methionine sulphoxide, have been isolated and their structures have been assigned mainly on the basis of spectral data. The possible taxonomic significance of onium salts is discussed