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Countercurrent chromatographic isolation of 11´-γ-tocomonoenol from and detection of novel minor tocochromanols in pumpkin seed oil
  • Alexander Kröpfl,
  • Walter Vetter
Alexander Kröpfl
University of Hohenheim
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Walter Vetter
University of Hohenheim
Author Profile

Abstract

A non-refined, organic pumpkin seed oil (PSO) was chosen for the isolation and structure verification of the rare vitamin E compound γ-tocomonoenol (γ-T1). Initial measurements indicated the presence of ~0.4 mg γ-T1 per 100 g pumpkin seed oil. Saponification of ~2 L pumpkin seed oil, followed by repeated countercurrent chromatography (CCC) with the solvent system n-hexane/benzotrifluoride/acetonitrile (10:3.5:6.5, v/v/v) and silica gel column chromatography enabled the isolation of 6.8 mg γ-T1 with a purity of 96.0%. Structural analysis by 1H NMR spectroscopy and gas chromatography with mass spectrometry (GC/MS) of the γ-T1 isolate confirmed the presence of a double bond in C-11´-position (11´-γ-tocomonoenol). Next to γ-T1, CCC fractionation enabled the detection of 18 different tocochromanols, many of which were reported for the first time in pumpkin seed oil. This unmatched variety covered among others α-/γ-tocopherol, α-/γ-tocomonoenol, two α- and two γ-tocodienol isomers, α-/γ-tocotrienol as well as the rare 11´-β-tocomonoenol (β-T1) and δ-T1. Three uncommon tocochromanols were also detected whose origins and structure remained unclear.

Peer review status:IN REVISION

26 Feb 2021Submitted to Journal of the American Oil Chemists' Society
01 Mar 2021Submission Checks Completed
01 Mar 2021Assigned to Editor
04 Mar 2021Reviewer(s) Assigned
11 Apr 2021Review(s) Completed, Editorial Evaluation Pending
09 May 2021Editorial Decision: Revise Major
14 Jun 20211st Revision Received
14 Jun 2021Assigned to Editor
14 Jun 2021Submission Checks Completed