Characterization of sterols in refined borage oil by GC-MS

Borage oil sterols were isolated by TLC and characterized using GC and GC-MS. Several diunsaturated Δ⁵-sterols, some of them not previously recorded in vegetable oils, were found. Of these, 24-methylcholesta-5,23-dienol and 24-ethylcholesta-5,23-dienol could be useful markers for borage oil. Two other diunsaturated Δ⁵-sterols that are rarely found in vegetable oils, 24-methylcholesta-5,24(25)-dienol and 24-ethylcholesta-5,24(25)-dienol, were identified. The diunsaturated C-24(28)-sterol, isofucosterol, was also found, as well as the monounsaturated Δ⁵-sterols campesterol and sitosterol. These are normally present in vegetable oils, which makes them unsuitable as markers for borage oil.