Antioxidant oligomeric proanthocyanidins from sea buckthorn (Hippophae rhamnoides) Pomace

Daniel Rösch, Clemens Mügge, Vincenzo Fogliano, Lothar W. Kroh*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

35 Citations (Scopus)

Abstract

After flavonol glycosides, monomeric flavan-3-ols, and dimeric and trimeric proanthocyanidins were fractionated from an extract of sea buckthorn (Hippophaë rhamnoides) pomace by Sephadex LH-20 gel chromatography, oligomeric proanthocyanidins were eluted. The oligomeric fraction accounted for 84% of the total proanthocyanidins and 75% of the total antioxidant activity of the sea buckthorn pomace extract. To elucidate the structure of the oligomeric fraction, it was depolymerized by acid catalysis in the presence of phloroglucinol. The structure of the resulting flavan-3-ol monomers and flavan-3-ol-phloroglucinol adducts was determined by electrospray ionization mass spectrometry (ESI-MS) and 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. Quantitative high-performance liquid chromatography investigations demonstrated (+)-gallocatechin as the predominating subunit in the oligomeric fraction. This observation was confirmed by ESI-MS, matrix-assisted laser desorption/ ionization mass spectrometry, and 13C NMR spectroscopy. The results showed that the majority of the flavan-3-ol subunits possessed a 2,3-trans configuration. The oligomers consisted mainly of prodelphinidin subunits whereas procyanidins were present in smaller amounts, indicating a very uncommon composition of the sea buckthorn proanthocyanidins. The mean degree of polymerization of the oligomeric proanthocyanidins was between 6 and 9.

Original languageEnglish
Pages (from-to)6712-6718
Number of pages7
JournalJournal of Agricultural and Food Chemistry
Volume52
Issue number22
DOIs
Publication statusPublished - 3 Nov 2004
Externally publishedYes

Keywords

  • C NMR
  • Acid catalysis
  • ESI-MS
  • ESR
  • Fremy's salt
  • Hippophaë rhamnoides
  • MALDI-TOF-MS
  • Polyphenols
  • Pomace
  • Proanthocyanidins
  • Sea buckthorn

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