Occurrence of sulphated flavones and caffeic acid esters in members of the fluviales

A survey of 50 species of the Fluviales showed that over 50% have either flavone or caffeic acid sulphates present. Flavone sulphates were detected in 16% of the sample and the 7-sulphates of luteolin, apigenin, diosmetin and chrysoeriol and the 7,3′-disulphate of luteolin were identified variously in Thalassia, Zannichellia and Zostera species. Anionic caffeic esters were found in 46% of the sample; preliminary studies indicate the presence of sulphated caffeylquinic acids in these plants. In confirmation of earlier studies, glycoflavones were found to be widespread and flavonols and proanthocyanidins to be rare. The taxonomic and ecological significance of these results are discussed.