title: Isolation and structure elucidation of a highly haemolytic saponin from the Merck saponin extract using high-field gradient-enhanced NMR techniques.
abstract: Saponins SAPO50 and SAPO30, of which SAPO50 is highly haemolytic, have been isolated from the commercial Merck Saponin. Their structures have been determined exclusively by high-field gradient-enhanced NMR methods. The 1H and 13C NMR spectra of these saponins in pyridine-deuterium oxide have been assigned by homonuclear and heteronuclear correlation experiments. Anomeric configurations were obtained by combined use of 1JCH, 3JH-1.H-2, and 1D-NOESY data. Sugar residues were identified by use of 3JHH values obtained from their subspectra recorded using an optimized 1D-zeta-TOCSY sequence. Linkage assignments were made using the ge-HMBC and 1D-NOESY spectra. This study shows that SAPO50 represents a hitherto undescribed saponin with the following structure: 3-O-beta-D-xylopyranosyl-(1-->3)-[beta-D-galactopyranosyl- (1-->2)]-beta-D-glucuronopyranosyl gypsogenin 28-O-(6-deoxy-beta-D-glucopyranosyl)-(1-->4)-[beta-D-xylopyranosyl-(1--> 3)- beta-D-xylopyranosyl-(1-->4)]-alpha-L-rhamnopyranosyl-(1-->2)-beta-D- fucopyranoside. SAPO30, however, corresponds to a saponin previously described [D. Frechet, B. Christ, B. Monegier du Sorbier, H. Fischer, and M. Vuilhorgne, Phytochemistry, 30 (1991) 927-931].
authors.affiliation: Centre de Biochimie Structurale, CNRS-UMR 9955, Université de Montpellier I, Faculté de Pharmacie, France.
authors.forename: C
authors.initials: C
authors.lastname: Delay
authors.forename: J A
authors.initials: JA
authors.lastname: Gavin
authors.forename: A
authors.initials: A
authors.lastname: Aumelas
authors.forename: P A
authors.initials: PA
authors.lastname: Bonnet
authors.forename: C
authors.initials: C
authors.lastname: Roumestand
mesh_terms: D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009828:Oleanolic Acid / Q000031:analogs & derivatives*; D009844:Oligosaccharides / Q000737:chemistry; D012503:Saponins / Q000737:chemistry* / Q000302:isolation & purification*
chemical_list: D009844:Oligosaccharides; D012503:Saponins; C107576:saponin SAPO50; D009828:Oleanolic Acid