Simultaneous quantification of serum phytosterols and cholesterol precursors using a simple gas chromatographic method

Determination of the main phytosterols (Ps, beta-sitosterol and campesterol) and cholesterol precursors (desmosterol and lathosterol) in human serum using a simple GC-FID method has been validated. Direct saponification, without lipid extraction, sterols extraction, and further derivatization was applied to samples prior to GC analysis. To evaluate the method, a pool of serum samples from eight healthy women was used. Good linearity (r>0.99) was found in the assay range: beta-sitosterol (0.9917.82 mu g/mL), campesterol (0.1410.8 mu g/mL), desmosterol (0.172.6 mu g/mL), and lathosterol (0.65.97 mu g/mL). Limits of detection (ng/mL) were: 86 (beta-sitosterol), 42 (campesterol), 4 (desmosterol), and 44 (lathosterol). Accuracy, estimated by recovery assays (%), were: 113 (beta-sitosterol), 114 (campesterol), 111 (desmosterol), and 102 (lathosterol). Within and between precision values (%), expressed as the relative SD (RSD), were: 2.6 and 8.1 (beta-sitosterol), 1.6 and 7.2 (campesterol), 2.1 and 7.9 (desmosterol), and 4.1 and 5.8 (lathosterol), respectively. The developed methodology allowed fast (1-day analysis) and reliable quantification of sterols in serum, required a small volume of sample and reduced use of solvents. It therefore could be used in clinical assays for the determination of serum sterols, as in evaluating the pharmacological response to lipid-lowering agents, and in assessing biological responses to Ps-enriched diets. Practical applications: This methodology allows fast and reliable quantification of sterols in serum, requiring a small volume of sample and reduced use of solvents. It can be used as a routine method for the quantification of phytosterols and cholesterol precursors in clinical assays, and it is also suitable for monitoring biological responses to health-promoting phytosterol-enriched diets.