Sterols Analysis


Sterols, or Steroidal Alcohols, are members of the steroid family of organic molecules. Theses compounds fulfill essential roles in eukaryotic cell membrane structure and dynamics, and as precursors to steroid hormones and fat-soluble vitamins. This class of organic molecules is further sub-divided into phytosterols (plant sterols), zoosterols (animal sterols) and mycosterols (fungal sterols).

Zoosterols – The main zoosterol of interest is cholesterol. Cholesterol forms part of the cellular membrane in animals, and as such serves an important role in the cell membrane's fluidity and as a signaling molecule. Corticosteroids, such as cortisol, act as signaling compounds in cellular communication and metabolism of mammalian cells. Human skin oils are often enriched in sterols.

Phytosterols – Sterols in plants commonly occur as mixtures with β-sitosterol, campesterol, and stigmasterol representing three of the major phytosterols. These plant sterols have been documented to help reduce cholesterol absorption in humans by inhibiting absorption site in the intestine. They are thus used as a food supplement to reduce risk for cardiovascular diseases and are approved by the U.S. Food and Drug Administration for use as such. Preliminary research has shown that phytosterols may have anticancer effects.

Mycosterols – Ergosterol is the main mycosterols of interest. Isolated from fungal species, ergosterol has been shown to have inhibitory effects on the absorption and biosynthesis of cholesterol in humans. Additional health benefits have been associated with mycosterols, such as anti-cancer, antiproliferative, anti-inflammatory and antimicrobial effects. Ergosterol is also a precursor of Vitamin D2 and as such may improve bone metabolism, immunity and mood.

Analytical Targets – Cholesterol, cortisol (and other corticosteroids), ergosterol, campesterol, sitosterol, and stigmasterol.

Sterol Sources - Common sources of sterols include biological material (e.g. blood), nutraceutical oils, industrially-produced food products, etc.

Analysis Platform – GC-FID

Method Summary

Gas chromatography offers qualitative and quantitative analysis of sterols. The aim of sample preparation is to isolate the sterol fraction and to convert all conjugated or esterified sterols into free phytosterols for GC analysis. Lipids (containing sterols) are extracted following a modified Folch method, in the presence of an internal standard. The sterols are then concentrated in the unsaponifiables fraction. After saponification, the unsaponifiable material (sterols) is extracted using a nonpolar solvent. Lastly, derivatization of sterols is performed using a basic silylation procedure. The resulting sterols are then analyzed on a Varian 3400 gas-liquid chromatograph against their internal standard. Data is reported in mg/100g or mmol/L.

Sample Requirement

  • Liquid Medium – Oils, Biological Cells (RBC / WBC / Serum)– minimum 2.5g equivalency per analysis.
  • Tissues/foods/powders – Grains, powders, foods – minimum of 2.5g per analysis.
  • Please contact with regards to your specific medium.

Data Reporting

  • CoA (pdf.) provided for sample analysis.
  • Data reported as: mg/100g or mmol/L for individual sterols.
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