1 Institut des Molécules et Matériaux du Mans, Le Mans Université, Avenue Olivier Messiaen, 72085, Le Mans, France
2 Laboratoire Biologie des Organismes, Santé, Environnement, Le Mans Université, Avenue Olivier Messiaen, 72085, Le Mans, France
Contact: amina.latigui(@)univ-lemans.fr
The genus Haslea (pinnate diatoms, Naviculaceae) includes more than twenty species. This genus is known for the existence of Haslea ostrearia, which produces the marennine, a unique blue-green pigment responsible for the natural greening of oysters in the French Atlantic coast. Marennine structure is very complex and recent studies have shown that it is probably an association of polysaccharide chains with a small organic molecule responsible of the color. New “blue diatoms” have recently been identified in different geographic locations, and no structural characterization had been done yet concerning the nature of their chromophore and the comparison with marennine. Therefore, preliminary studies were carried out in order to compare the structures of the “marennine-like” pigments of different strains with that of the marennine of H.ostrearia. The first results obtained in 1H-NMR and in vibrational spectroscopy seem consistent with the hypothesis according to which marennine consists of a polysaccharide structure carrying one or more aromatic chromophores. Different times of acid hydrolysis were set up in order to release sugars and recover the chromophore. Furthermore, spectral characterization shows that different strains of Haslea absorb at different wavelengths and do not react in the same way depending on pH variation, suggesting that the chromophore is slightly different. These results seem promising for elucidating the chemical structure of this original family of natural blue pigments, which are extremely interesting for many applications.
Keywords: Diatom; Haslea ostrearia; Marennine; Microalgae; natural blue pigment
