Countercurrent chromatography isolation of 11′‐γ‐tocomonoenol from pumpkin seed oil with detection of novel minor tocochromanols

Abstract

AbstractA 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 PSO. Saponification of ~2 L of PSO, followed by repeated countercurrent chromatography (CCC) with the solvent system n‐hexane/benzotrifluoride/acetonitrile (v/v/v) and silica gel column chromatography enabled the isolation of 6.8 mg γ‐T1 with a purity of 96.0% according to gas chromatography with mass spectrometry (GC/MS) analysis. Structural analysis by 1H nuclear magnetic resonance (NMR) spectroscopy and GC/MS of the γ‐T1 isolate confirmed the presence of a double bond in C‐11′‐position (11′‐γ‐tocomonoenol). In addition, CCC fractionation enabled the detection of 18 different tocochromanols, many of which were reported for the first time in PSO. This unmatched variety included 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.