title: Artefact formation during acid hydrolysis of saponins from Medicago spp.
abstract: Artefact compounds obtained during acid hydrolysis of saponins from Medicago spp. (Fabaceae), have been monitored and evaluated by GC-FID. Their identification has been performed by GC-MS and1H and13C NMR. Saponins with different substituents on the triterpenic pentacyclic aglycones were considered, and their hydrolysis products were detected and quantified during 10 h of time course reaction. From soyasapogenol B glycoside the well known soyasapogenols B, C, D and F were obtained together with a previously undescribed sapogenol artefact identified as 3β,22β,24-trihydroxyolean-18(19)-en and named soyasapogenol H. From a zanhic acid saponin two major artefact compounds identified as 2β,3β,16α-trihydroxyolean-13(18)-en-23,28-dioic acid and 2β,3β,16α-trihydroxyolean-28,13β-olide-23-oic acid were obtained, together with some zanhic acid. Other compounds, detected in very small amount in the reaction mixture, were also tentatively identified based on their GC-MS and UV spectra. The other most characteristic saponins in Medicago spp., hederagenin, bayogenin and medicagenic acid glycosides, under acidic condition of hydrolysis, released instead the correspondent aglycones and generated a negligible amount of artefacts. Nature of artefacts and mechanism of their formation, involving a stable tertiary carbocation, is here proposed and discussed for the first time.
authors.affiliation: Consiglio per la Ricerca in Agricoltura e l'Analisi dell'Economia Agraria - Centro di Ricerca per le Produzioni Foraggere e Lattiero Casearie, CREA-FLC, v.le Piacenza 29, 26900 Lodi, Italy. Electronic address: aldo.tava@crea.gov.it.
authors.forename: Aldo
authors.initials: A
authors.lastname: Tava
authors.affiliation: Consiglio per la Ricerca in Agricoltura e l'Analisi dell'Economia Agraria - Centro di Ricerca per le Produzioni Foraggere e Lattiero Casearie, CREA-FLC, v.le Piacenza 29, 26900 Lodi, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Biazzi
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Pavia, v.le Taramelli 12, 27100 Pavia, Italy.
authors.forename: Mariella
authors.initials: M
authors.lastname: Mella
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Pavia, v.le Taramelli 12, 27100 Pavia, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Quadrelli
authors.affiliation: Dipartimento di Farmacia-Scienze del Farmaco, Università degli Studi di Bari Aldo Moro, via Orabona 4, 70125 Bari, Italy.
authors.forename: Pinarosa
authors.initials: P
authors.lastname: Avato
mesh_terms: D016477:Artifacts; D008401:Gas Chromatography-Mass Spectrometry; D006027:Glycosides / Q000737:chemistry; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D029902:Medicago / Q000737:chemistry*; D015394:Molecular Structure; D009828:Oleanolic Acid / Q000031:analogs & derivatives / Q000737:chemistry; D012503:Saponins / Q000737:chemistry*; D014315:Triterpenes / Q000737:chemistry
chemical_list: D006027:Glycosides; D012503:Saponins; D014315:Triterpenes; C407096:soyasapogenol B; D009828:Oleanolic Acid; C005982:medicagenic acid; C025763:hederagenin
keywords: Acid hydrolysis; Artefact formation; Chemical structure; Fabaceae; GC-MS; Medicago spp.; NMR; Soyasapogenol H; Triterpenic pentacyclic saponins