The genus Cystoseira from the coasts of Brittany: taxonomy, ecology and naturalproducts

• Main Author: Jégou, C.
• Other Authors: Laboratoire d'Écophysiologie et de Biotechnologie des Halophytes et des Algues Marines (LEBHAM), Université de Brest (UBO), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Ministère de l'Enseignement Supérieur et de la Recherche, Université de Bretagne Occidentale, Valérie-Stiger-Pouvreau
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2011
• Subjects: terpene; chemotaxonomy; NMR; LC-MS; population; ecologie; ecology; Cystoseira; baccata; foeniculaceae; humilis; nodicaulis; tamariscifolia; phlorotannin; phloroglucinol; polyphénol; chimiotaxonomie; RMN; [SDV]Life Sciences [q-bio]; [CHIM.ANAL]Chemical Sciences/Analytical chemistry; North East Atlantic
• Online Access: https://tel.archives-ouvertes.fr/tel-01167228; https://tel.archives-ouvertes.fr/tel-01167228/document; https://tel.archives-ouvertes.fr/tel-01167228/file/Manuscrit_these_camille_jegou.pdf

Along the North-East Atlantic, the genus Cystoseira (brown algae, family Sargassaceae) is composed of five species, and their populations settle in rock pools from the intertidal zone. Beyond the ecological value of these organisms, they are now more and more studied as a source of natural products. However, taxonomical issues within this genus must be solved first. So, we investigated the taxonomy of the five species occurring in Brittany using two strategies: phylogenetic analyses (thanks to molecular markers) and chemical analyses (using NMR and LC-MS). Usingrecent phylogenetic data, our results highlighted the relevancy of the use of chemical criteria to illustrate the phylogenetic relationships. This way, we were able to associate a “chemical ID card” to each species. We also isolated a meroditerpene from Cystoseira nodicaulis. The second part of our work was an ecological study of several populations settled in Brittany. Concerning the emerged substrata of the intertidal zone, the available data about zonation patterns are plethoric; conversely, few authors have investigated the distribution of macroalgae in tide pools. We highlighted a singular distribution pattern for the Cystoseira species that must be under the dependency of biotic and abiotic factors. We also demonstrated the spatio-temporal variability of several variables of the populations. Additionally, we showed through the quantification of the main pigments by HPLC that different photo-adaptive behaviors exist within and between populations. Finally, we investigated the phlorotannins of the Cystoseira species. These molecules are known to exhibit several biological activities and many ecological roles have been demonstrated in the literature. We develop a new protocol for the purification and quantification of the compounds, and we also determined their radical-scavenging activity. This way, we revealed specific differences and seasonal patterns in phlorotannin production. We also purified phenolics and identified the main kind of compounds in ...