Upgrading of byproducts from the holothurian Cucumaria frondosa by the study of bioactive extracts and ecotoxicological approach of the secondary metabolites released under stress conditions

• Main Author: Tripoteau, Ludovic
• Other Authors: Laboratoire de Biotechnologie et Chimie Marines (LBCM), Université de Bretagne Sud (UBS)-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 de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Bretagne Sud, Nathalie Bourgougnon, Jacques Gagnon
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2015
• Subjects: Holothurian; Upgrading of marine byproducts; Anti-HSV activity; Enzymatic hydrolysis; Secondary metabolites; Triterpene glycosides; Holothurie; Valorisation de coproduits marins; Activité anti-VHS; Hydrolyse enzymatique; Métabolites secondaires; Glycosides triterpéniques; [SDV.BIO]Life Sciences [q-bio]/Biotechnology; Cucumaria frondosa
• Online Access: https://theses.hal.science/tel-01297042; https://theses.hal.science/tel-01297042/document; https://theses.hal.science/tel-01297042/file/2015theseTripoteauL.pdf

The transformation of marine products generates huge quantities of rejects. The majority of these rejects is used for an upgrading of products with low added value. In New Brunswick, 85 000 tons of marine products are transformed annually, the half is little or not upgraded, that is the case of the holothurian Cucumaria frondosa. Confronted with environmental pressures, and especially predation, the marine invertebrates have evolved and developed various metabolites of different chemical classes. Thus, these metabolites represent ideal candidates for the development of new natural bioactive substances. The objectives of this study was first based on the upgrading of the major byproducts from Cucumaria frondosa by creating a wide library of extracts obtained by different type of extractions (solvent extractions and enzymatic hydrolysis) and then, by bioguided fractionation, evaluating the in vitro anti-HSV-1 (Herpes Simplex Virus, type 1) activities of the fractions. We showed the presence of potent antiherpetic fractions without cytotoxicity on mammalian cells. The enzymatic hydrolysis has been demonstrated to be efficient for the generation of high molecular weight active substances regarding HSV-1. The aquapharyngeal bulb, considered to be less used industrially, represents a real potential for the extraction of anti-HSV-1 compounds, and especially when hydrolyzed by papain under controlled conditions. Secondly, we have searched to understand the mechanism of defense of the holothurian under stress conditions. The secondary metabolites involved were evaluated on different ecotoxicological models. This work has confirmed the existence and the production of toxic compounds released under stress conditions. These secondary metabolites have shown a strong toxicity on acute and chronic ecotoxicological models. The bioguided fractionation assisted by analytical evaluation led to the identification of several triterpene glycosides, and especially the Frondoside A into the cytotoxic fraction. This study has permitted ...