NMR and LC‐MS ⁿ characterisation of two minor saponins from 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 → 3)‐α‐L‐arabinopyranosyl}‐(28 → 1)‐β‐D‐glucopyranosyl ester (guaiacin B) and ­oleanolic acid‐3‐O‐{β‐D‐glucopyranosyl‐(1 → 3)‐{α‐L‐rhamnopyranosyl‐(1 → 2)}‐α‐L‐arabinopyranosyl}‐(28 → 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‐MS n experiments. Copyright © 2001 John Wiley & Sons, Ltd.

Triterpenes and triterpenoidal glycosides from the fruits of Ilex paraguariensis (Maté)

“…If the plant material is collected in the period from December to February, a significant amount of fruits will be processed together. Considering that its saponins differ from those found in its leaves 2,3 and considering the pronounced bitter taste of ilexoside II, one of the major saponins, the added amount of fruits can produce chemical variation on the final product that has unknown physiological and pharmacological consequences. Further biological investigation on the fruit of Ilex paraguariensis are required to clear this question.…”

“…Previously, we described the structure of 11 saponins isolated from the leaves of I. paraguariensis and established that all saponins were glycosides derived from the ursolic and oleanolic acids 2 and more recently two other minor saponins were described. 3 We investigated also the structures of the saponins of other Ilex species reported as adulterant of genuine Maté. 4 The present work deals with the structural elucidation of triterpenes and triterpenoidal glycosides isolated from fruits of I. paraguariensis, compounds 1-6.…”

Recent advances on Ilex paraguariensis research: Minireview

“…Ilex paraguariensis green (non-roasted) extracts contain purine alkaloids (methyl xanthines), flavonoids, vitamins such as vitamin A, B complex, C and E, tannins, chlorogenic acid and its derivatives, and numerous triterpenic saponins derived from ursolic acid, known as matesaponins (Bastos et al, 2007;Heck and de Mejia, 2007;Menini et al, 2007;Martinet et al, 2001). Though the presence of methyl xanthines account for many of the pharmacological activities of yerba mate, many other very interesting and important properties have been found to be independent of the presence of these compounds.…”

Modern Screening Techniques for Plant Extracts

“…For larger polar molecules such as saponins (MW > 800 Da), CF-FAB or ES are the methods of choice. All these LC/MS interfaces produce soft ionization and the generation of useful fragment information is obtained by tandem mass spectrometry (MS/MS) or by multiple stage MS/MS experiments (MS n ) on ion trap systems (Perret et al, 1999;Martinet et al, 2001). Very recently, high-resolution mass spectrometers such as Q-TOF instruments have also been used for the LC/MS analysis of crude plant extracts allowing the determination of accurate masses on-line.…”