Sterol synthesis. High-pressure liquid chromatography of C27 sterol precursors of cholesterol

Chromatographic analysis of plant sterols in foods and vegetable oils

This paper reviews recently published chromatographic methods for the analysis of plant sterols in various sample matrices with emphasis on vegetable oils. An overview of structural complexities and biological/nutritional aspects including hypocholesterolemic activities of phytosterols is provided in the Section 1. The principal themes of the review highlight the development and application of chromatographic techniques for the isolation, purification, separation and detection of the title compounds. Pertinent gas chromatographic and high-performance liquid chromatographic methods from the literature are tabulated to illustrate common trends and methodological variability. The review also covers specific analyses of natural/synthetic standard mixtures to shed light on potential applicability in plant sample assays. Examples of combined chromatographic techniques linked in tandem for the analysis of complex samples are included. Elution characteristics of sterol components are discussed in the context of analyte substituent effects, structural factors and stationary/mobile phase considerations.

High-performance liquid chromatography of sterols: yeast sterols

It is evident that the high-pressure liquid chromatograph is an excellent tool for studying sterol metabolism. As noted in the text, the individual effects of unsaturations and alkyl groups on reverse phase elution volumes cannot be extrapolated to predict quantitative effects of multiple functional groups. The mechanism(s) of retention seems more complex than can be explained simply by polarity or hydrophobicity. Since the molecular location of these functional moieties seems critical, retention and separation of sterols may involve specific structural configurations and hence specific interactions with the stationary phase material. The association we have drawn between polarity and HPLC elution may indeed be a secondary effect of another phenomenon. Future studies may unveil the true mechanism(s) of HPLC retention and separation, and allow for the construction of HPLC systems which will separate all isomeric combinations of sterols at the analytical level. The simplicity, rapidity, and reproducibility of these methods make the coupled technique very useful for investigating sterol metabolism. Application of this technique to analyzing putative sterol mutants, purifying sterols for auxotrophic feeding, and analyzing the metabolism of supplemented sterols in auxotrophs provides for significant advances in membrane physiology.