title: Diterpene glycosides from Stevia phlebophylla A. Gray.
abstract: The rare Mexican species Stevia phlebophylla A. Gray was long considered to be the only known Stevia species, beside the well-known S. rebaudiana, containing the highly sweet diterpenoid steviol glycosides. We report a re-evaluation of this claim after phytochemically screening leaves obtained from two herbarium specimens of S. phlebophylla for the presence of steviol glycosides. Despite extensive MS analyses, no steviol glycosides could be unambiguously verified. Instead, the main chromatographic peak eluting at retention times similar to those of steviol glycosides was identified as a new compound, namely 16β-hydroxy-17-acetoxy-ent-kauran-19-oic acid-(6-O-β-D-xylopyranosyl-β-D-glucopyranosyl) ester (1) on the basis of extensive NMR and MS data as well as the characterization of its acid hydrolysate. Seven more compounds were detected by ESIMS which are possibly structurally related to 1. It can therefore be concluded that S. phlebophylla is unlikely to contain significant amounts of steviol glycosides, if any.
authors.affiliation: Laboratory of Functional Biology, Kasteelpark Arenberg 31, Heverlee, Belgium. stijn.ceunen@bio.kuleuven.be
authors.forename: Stijn
authors.initials: S
authors.lastname: Ceunen
authors.forename: De Borggraeve
authors.initials: de B
authors.lastname: Wim
authors.forename: Frans
authors.initials: F
authors.lastname: Compernolle
authors.forename: Anh Hung
authors.initials: AH
authors.lastname: Mai
authors.forename: Jan M C
authors.initials: JM
authors.lastname: Geuns
mesh_terms: D002236:Carbohydrate Conformation; D004224:Diterpenes / Q000737:chemistry* / Q000302:isolation & purification; D006027:Glycosides / Q000737:chemistry* / Q000302:isolation & purification; D009682:Magnetic Resonance Spectroscopy / Q000592:standards; D018515:Plant Leaves / Q000737:chemistry*; D012015:Reference Standards; D036625:Stevia / Q000737:chemistry*
chemical_list: D004224:Diterpenes; D006027:Glycosides
keywords: Asteraceae; Diterpene glycosides; MS; NMR; Stevia phlebophylla; Steviol glycosides