Isolation and characterisation of 13 pterosins and pterosides from bracken (Pteridium aquilinum (L.) Kuhn) rhizome

Authors Organisations
  • Rizgar Hassan Mohammad(Author)
    Prifysgol Bangor | Bangor University
  • Mohammad Nur e-Alam(Author)
    Prifysgol Bangor | Bangor University
    King Saud University
  • Martina Lahman(Author)
    Prifysgol Bangor | Bangor University
  • Ifat Shah(Author)
  • Graham J. Tizzard(Author)
    University of Southampton
  • Simon J. Coles(Author)
    University of Southampton
  • Mark Fowler(Author)
    Unilever R&D Centre
  • Alex F. Drake(Author)
    King's College London
  • Derren Heyes(Author)
    The University of Manchester
  • Vera Thoss(Author)
    Prifysgol Bangor | Bangor University
Type Article
Original languageEnglish
Pages (from-to)82-94
JournalPhytochemistry
Volume128
Early online date10 May 2016
DOI
Publication statusPublished - 01 Aug 2016
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Abstract

Systematic phytochemical investigations of the underground rhizome of Pteridium aquilinum (L.) Kuhn (Dennstaedtiaceae) afforded thirty-five pterosins and pterosides. By detailed analysis of one- and two-dimensional nuclear magnetic resonance spectroscopy, circular dichroism (CD) and high-resolution mass spectrometric data, thirteen previously undescribed pterosins and pterosides have been identified. Interestingly, for the first time 12-O-β-D-glucopyranoside substituted pterosins, rhedynosides C and D, and the sulfate-containing pterosin, rhedynosin H, alongside the two known compounds, histiopterosin A and (2S)-pteroside A2, were isolated from the rhizomes of subsp. aquilinum of bracken. In addition, six-membered cyclic ether pterosins and pterosides, rhedynosin A and rhedynoside A, are the first examples of this type of pterosin-sesquiterpenoid. Additionally, the three previously reported compounds (rhedynosin I, (2S)-2-hydroxymethylpterosin E and (2S)-12-hydroxypterosin A) were obtained for the first time from plants as opposed to mammalian metabolic products. Single crystal X-ray diffraction analysis was applied to the previously undescribed compounds (2R)-rhedynoside B, (2R)-pteroside B and (2S)-pteroside K, yielding the first crystal structures for pterosides, and three known pterosins, (2S)-pterosin A, trans-pterosin C and cis-pterosin C. Rhedynosin C is the only example of the cyclic lactone pterosins with a keto group at position C-14. Six selected pterosins ((2S)-pterosin A, (2R)-pterosin B and trans-pterosin C) and associated glycosides ((2S)-pteroside A, (2R)-pteroside B and pteroside Z) were assessed for their anti-diabetic activity using an intestinal glucose uptake assay; all were found to be inactive at 300 μM

Keywords

  • Pteridium aquilinum, Dennstaedtiaceae, Bracken pterosins, Pterosides, Norsesquiterpenes, Sesquiterpenoids, Pterosins A and B, Circular dichroism, SGLT1 and GLUT2 transporters