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

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

  • Phytochemistry. 2016 Aug:128:82-94. doi: 10.1016/j.phytochem.2016.05.001.
Rizgar Hassan Mohammad 1,  Mohammad Nur-E-Alam 2,  Martina Lahmann 1,  Ifat Parveen 3,  Graham J Tizzard 4,  Simon J Coles 4,  Mark Fowler 5,  Alex F Drake 6,  Derren Heyes 7,  Vera Thoss 8
Affiliations

Affiliations

  • 1 School of Chemistry, Bangor University, Bangor LL57 2UW, UK.
  • 2 School of Chemistry, Bangor University, Bangor LL57 2UW, UK; Department of Pharmacognosy, College of Pharmacy, King Saud University, P.O. Box 2457, Riyadh 11451, Saudi Arabia.
  • 3 IBERS, Aberystwyth University, Penglais, Aberystwyth SY23 3DA, UK.
  • 4 UK National Crystallography Service, School of Chemistry, University of Southampton, University Road, Southampton SO17 1BJ, UK.
  • 5 Strategic Science Group, Unilever R&D, Colworth Science Park, Bedford MK44 1LQ, UK.
  • 6 Biomolecular Spectroscopy Centre, Pharmaceutical Optical & Chiroptical Spectroscopy Facility, King's College London, The Wolfson Wing, WWB10 Hodgkin Building, Guy's Campus, London SE1 1UL, UK.
  • 7 Manchester Institute of Biotechnology, University of Manchester, 131 Princess St, Manchester M1 7DN, UK.
  • 8 School of Chemistry, Bangor University, Bangor LL57 2UW, UK. Electronic address: vera.thoss@bangor.ac.uk.
PMID: 27177933 DOI: 10.1016/j.phytochem.2016.05.001
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

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

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