Novel algal polyphenolic biomacromolecules as significant contributors to resistant fractions of marine dissolved and particulate organic matter

To investigate whether novel polyphenolic constituents, that have been reported to contribute considerably to dissolved organic matter (DOM) and particulate organic matter (POM), are of algal origin, a number of algae, i.e. the brown macroalgae Nereocystis luetkeana, Fucus gardneri, Costaria costata, Sargassum muticum, a green macroalga Ulva fenestrata, a red macroalga Opuntiella californica and a microalga Rhodomonas sp., were subjected to analytical pyrolysis. The freeze-dried algae were extracted and saponified. In the case of N. luetkeana and U. fenestrata proteins and carbohydrates were removed by acid treatments with HCl and H2SO4. All fractions were analysed by Curie-point pyrolysis-gas chromatography-mass spectroscopy (CuPy-GC-MS). Alkylphenols were encountered in the pyrolysates of all algae, and in the residues obtained after acid treatment of N. luetkeana and U. fenestrata. It is thought that these alkylphenols are generated from possibly alkylated phlorotannin-type compounds. Though non-alkylated phlorotannins are known to occur almost exclusively in brown macroalgae, these postulated alkylated counterparts occur in both brown macroalgae and other algae. Their selective preservation during water column transport causes a significant enrichment of these substances in DOM and POM.