Water soluble phenolic compounds of the marine phanerogam Posidonia oceanica in a Mediterranean area colonised by the introduced chlorophyte Caulerpa taxifolia

Abstract Unbound phenolic compounds of leaves of the marine phanerogam Posidonia oceanica (L.) Delile from an area colonised by the introduced chlorophyte Caulerpa taxifolia (Vahl) C. Ag. have been investigated and their concentration assessed using high performance liquid chromatography (HPLC). Leaves of the colonised area exhibited high maximum values of phenolic contents in comparison with a reference area. Nonetheless, because of the high variability of the values, further studies will be needed to confirm that P. oceanica plants are producing unbound phenolic compounds in reaction to growth of C. taxifolia . Ferulic acid, phloridzin, phloroglucinol, p -anisic acid, acetosyringone, sinapic acid, phenol, p -hydroxybenzoic acid, p -coumaric acid and cinnamic acid represent more than 95% of the mean relative concentration of phenolic compounds measured. Several of these compounds had not hitherto been reported in P. oceanica .