Resin glycosides from the herbal drug jalap (Ipomoea purga)

J Nat Prod. 2011 May 27;74(5):1148-53. doi: 10.1021/np200080k. Epub 2011 Mar 29.

Abstract

Three new resin glycosides, purginosides I and II (1 and 2) and purgin I (3), were isolated from the aerial parts of Ipomoea purga and purified by preparative-scale recycling HPLC from a chloroform-soluble extract. Their structures were established through NMR spectroscopy and mass spectrometry. Purginosides I and II (1 and 2) are partially acylated branched pentasaccharides derived from operculinic acid A, which is composed of one D-fucose, one D-glucose, and three l-rhamnose units. The site of the aglycon macrolactonization is at C-2 of the second saccharide (rhamnose). In both compounds 1 and 2, three different esterifying residues were located at C-2 of the second rhamnose unit and at C-2 (or C-3) and C-4 on the third rhamnose moiety. The acylating residues were characterized as trans-cinnamic, n-decanoic, and either (+)-(2S)-2-methylbutanoic or n-hexanoic acid. Purgin I (3) was found to be an ester-type dimer of operculinic acid A, acylated by n-dodecanoic, (+)-(2S)-2-methylbutanoic, and trans-cinnamic acids at the same oligosaccharide core positions found in compounds 1 and 2. The site of lactonization by the aglycon in unit A was placed at C-2 of the second saccharide. The position for the ester linkage for the monomeric unit B on the macrocyclic unit A was identified as C-4 of the terminal glucose. This is the first report on the isolation, purification, and structure elucidation of intact individual resin glycoside constituents from the herbal drug jalap.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chromatography, High Pressure Liquid
  • Glucose / chemistry
  • Glycosides / chemistry
  • Glycosides / isolation & purification*
  • Ipomoea / chemistry*
  • Mexico
  • Molecular Structure
  • Nuclear Magnetic Resonance, Biomolecular
  • Resins, Plant / chemistry*
  • Stereoisomerism

Substances

  • Glycosides
  • Resins, Plant
  • purgin I
  • purginoside I
  • purginoside II
  • Glucose