Isolation and structure elucidation of highly antioxidative 3,8″-linked biflavanones and flavanone-C-glycosides from garcinia buchananii bark

Timo D. Stark, Toshiaki Matsutomo, Sofie Lösch, Paul A. Boakye, Onesmo B. Balemba, Sofie P. Pasilis, Thomas Hofmann

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28 Scopus citations

Abstract

The aim of this study was to identify antioxidants from Garcinia buchananii bark extract using hydrogen peroxide scavenging and oxygen radical absorbance capacity (ORAC) assays. LC-MS/MS analysis, 1D- and 2D-NMR, and circular dichroism (CD) spectroscopy led to the unequivocal identification of the major antioxidative molecules as a series of three 3,8″-linked biflavanones and two flavanone-C-glycosides. Besides the previously reported (2R,3R,2″R, 3″R)-naringenin-C-3/C-8″ dihydroquercetin linked biflavanone (GB-2; 4) and (2R,3S,2″R,3″R)-manniflavanone (3), whose stereochemistry has been revised, the antioxidants identified for the first time in Garcinia buchananii were (2R,3R)-taxifolin-6-C-β-D-glucopyranoside (1), (2R,3R)-aromadendrin-6-C-β-D-glucopyranoside (2), and the new compound (2R,3S,2″S)-buchananiflavanone (5). The H 2O 2 scavenging and the ORAC assays demonstrated that these natural products have an extraordinarily high antioxidative power, especially (2R,3S,2″R,3″R) -manniflavanone (3) and GB-2 (4), with EC 50 values of 2.8 and 2.2 μM, respectively, and 13.73 and 12.10 μmol TE/ μmol. These findings demonstrate that G. buchananii bark extract is a rich natural source of antioxidants.

Original languageEnglish
Pages (from-to)2053-2062
Number of pages10
JournalJournal of agricultural and food chemistry
Volume60
Issue number8
DOIs
StatePublished - 29 Feb 2012

Keywords

  • (2R,3S,2″R)-3″ R)-manniflavanone
  • (2R,3S,2″S)- buchananiflavanone
  • 3,8″-linked biflavanones
  • Antioxidants
  • Flavanone-6-C-glycosides
  • GARCINIA buchananii

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