title: Molecular diversity and body distribution of saponins in the sea star Asterias rubens by mass spectrometry.
abstract: Saponins are natural molecules that the common sea star Asterias rubens produces in the form of steroid glycosides bearing a sulfate group attached on the aglycone part. In order to highlight the inter-organ and inter-individual variability, the saponin contents of five distinct body components, namely the aboral body wall, the oral body wall, the stomach, the pyloric caeca and the gonads, from different individuals were separately analyzed by mass spectrometry. MALDI-ToF experiments were selected as the primary tool for a rapid screening of the saponin mixtures, whereas LC-MS and LC-MS/MS techniques were used to achieve chromatographic separation of isomers. First of all, our analyses demonstrated that the diversity of saponins is higher than previously reported. Indeed, nine new congeners were observed in addition to the 17 saponins already described in this species. On the basis of all the collected MS/MS data, we also identified collision-induced key-fragmentations that could be used to reconstruct the molecular structure of both known and unknown saponin ions. Secondly, the comparison of the saponin contents from the five different body components revealed that each organ is characterized by a specific mixture of saponins and that between animals there are also qualitative and quantitative variability of the saponin contents which could be linked to the sex or to the collecting season. Therefore, the observed high variability unambiguously confirms that saponins probably fulfill several biological functions in A. rubens. The current results will pave the way for our future studies that will be devoted to the clarification of the biological roles of saponins in A. rubens at a molecular level.
authors.affiliation: Mass Spectrometry Research Group, Interdisciplinary Center for Mass Spectrometry, University of Mons - UMONS, 23 Place du Parc, B-7000 Mons, Belgium; Biology of Marine Organisms and Biomimetics, University of Mons - UMONS, 23 Place du Parc, B-7000 Mons, Belgium.
authors.forename: Marie
authors.initials: M
authors.lastname: Demeyer
authors.affiliation: Mass Spectrometry Research Group, Interdisciplinary Center for Mass Spectrometry, University of Mons - UMONS, 23 Place du Parc, B-7000 Mons, Belgium.
authors.forename: Julien
authors.initials: J
authors.lastname: De Winter
authors.affiliation: Biology of Marine Organisms and Biomimetics, University of Mons - UMONS, 23 Place du Parc, B-7000 Mons, Belgium.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Caulier
authors.affiliation: Biology of Marine Organisms and Biomimetics, University of Mons - UMONS, 23 Place du Parc, B-7000 Mons, Belgium.
authors.forename: Igor
authors.initials: I
authors.lastname: Eeckhaut
authors.affiliation: Biology of Marine Organisms and Biomimetics, University of Mons - UMONS, 23 Place du Parc, B-7000 Mons, Belgium. Electronic address: Patrick.Flammang@umons.ac.be.
authors.forename: Patrick
authors.initials: P
authors.lastname: Flammang
authors.affiliation: Mass Spectrometry Research Group, Interdisciplinary Center for Mass Spectrometry, University of Mons - UMONS, 23 Place du Parc, B-7000 Mons, Belgium. Electronic address: Pascal.Gerbaux@umons.ac.be.
authors.forename: Pascal
authors.initials: P
authors.lastname: Gerbaux
mesh_terms: D000818:Animals; D047271:Asterias / Q000378:metabolism*; D002417:Cattle; D002853:Chromatography, Liquid; D006461:Hemolysis; D007536:Isomerism; D013058:Mass Spectrometry; D015394:Molecular Structure; D012503:Saponins / Q000737:chemistry / Q000378:metabolism*; D014018:Tissue Distribution
chemical_list: D012503:Saponins
keywords: Echinoderms; LC-MS; Mass spectrometry; Natural products; Saponins; Structure elucidation