Extraction and gastro-intestinal digestion of phytosteryl ferulates and phytosteryl glycosides

Abstract

Phytosterols are known to decrease the atherogenic LDL-cholesterol. In earlier studies, free phytosterols and their fatty acid esters have been extensively studied for their cholesterollowering properties. However, the metabolic fate of phytosterols still need investigations. This dissertation focused on phytosteryl ferulates and phytosteryl glycosides. The aim was to study the digestion of phytosteryl ferulates and phytosteryl glycosides under stomach and small intestinal conditions. Two methods were tested for phytosteryl ferulates and phytosteryl glycosides extraction. Secondly, stigmasterol, phytosteryl ferulates and phytosteryl glycosides were digested under stomach and small intestinal conditions. Soxhlet extraction, followed by fractionation by NP-SPE was found to be suitable for phytosteryl ferulates and phytosteryl glycosides extraction. The pH was found to have an effect on phytosteryl ferulates. Phytosteryl ferulates and phytosteryl glycosides fractions and stigmasterol were tested for their stability under stomach and small intestinal conditions. The amounts of stigmasterol recovered and the RP-HPLC chromatograms showed that stigmasterol was stable under stomach and small intestinal conditions. No new peaks were detected when phytosteryl ferulates and phytosteryl glycosides samples were digested under stomach conditions. The disappearance of peaks and formation of new peaks, as showed by the RP-HPLC chromatograms, gave an indication that phytosteryl ferulates and phytosteryl glycosides samples contained compounds which were unstable under small intestinal conditions.