Nolwenn Kergosien1,2, Stéphane Cérantola3, Gaëlle Simon3, Solène Connan1, Jérémy Brébion2, Franck Hennequart2, Valérie Stiger-Pouvreau1
1Univ Brest, CNRS, IRD, Ifremer, LEMAR, F-29280, Plouzané, France
2ALGAIA, R&D center, Saint-Lô, France
3Service RMN-RPE, Université de Bretagne Occidentale, UFR Sciences et Techniques, Brest, France
Phlorotannins are highly hydroxylated polymeric metabolites produced by brown seaweeds, and known for their wide array of bioactivities, which makes them interesting for many fields of applications. It is strongly suspected that the strength of their bioactivities is directly related to their chemical structure. The present study aims to characterize the phlorotannin’s chemical structure of six abundant brown macroalgae, known to produce different types of phlorotannins: two species were collected in the tropical Atlantic Ocean (Sargassum natans, Sargassum fluitans), while the others were exploited by French companies (Sargassum muticum, Laminaria digitata, Laminaria hyperborea and Ascophyllum nodosum), sampled either on the coasts of Brittany or Normandy (France). Phlorotannins were extracted and extensively purified to obtain phlorotannin-rich fractions. The chemical structure was then elucidated through 2-Dimensions Nuclear Magnetic Resonance spectroscopy (2D-NMR) and Mass-Spectroscopy (MS). In parallel, the fractions were tested for their antioxidant activity as well as their antibacterial activity against several bacterial strains of interest for human health and cosmetics. Results of activities are linked with the structure of phlorotannins and highlight the interest to propose phlorotannins as promising metabolites for human well-being.