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Keywords:

  • In-mixture NMR;
  • liquid chromatography-mass spectrometry;
  • saponins;
  • guaiacin B;
  • nudicaucin C;
  • Ilex paraguariensis

Abstract

Two minor saponins obtained from the methanolic extract of the leaves of Ilex paraguariensis have ­been characterised by 13C-NMR, 1H-NMR, API-MS and chemical hydrolysis as oleanolic acid-3-O-­{β-D-glucopyranosyl-(1 [RIGHTWARDS ARROW] 3)-α-L-arabinopyranosyl}-(28 [RIGHTWARDS ARROW] 1)-β-D-glucopyranosyl ester (guaiacin B) and ­oleanolic acid-3-O-{β-D-glucopyranosyl-(1 [RIGHTWARDS ARROW] 3)-{α-L-rhamnopyranosyl-(1 [RIGHTWARDS ARROW] 2)}-α-L-arabinopyranosyl}-(28 [RIGHTWARDS ARROW] 1)-β-D-glucopyranosyl ester (nudicaucin C). Both are isomeric forms of the known matesaponins 1 (MSP 1) and 2 (MSP 2) and differ only by the nature of the aglycone: they have oleanolic acid instead of ursolic acid, as found in the matesaponins. These minor saponins have not been fully separated from their major isomers MSP 1 and 2 and were characterised by in-mixture NMR analysis, LC-MS and LC-MSn experiments. Copyright © 2001 John Wiley & Sons, Ltd.