Phytosterols esterified with conjugated linoleic acid. in vitro intestinal digestion and interaction on cholesterol bioaccessibility

Abstract

Intestinal in vitro digestion of phytosterols esterified with conjugated linoleic acid (PS-CLA) was performed to study (1) the potential bioaccessibility of the released bioactive-lipid products and (2) the interference with cholesterol bioaccessibility. Commercial food-grade PS ester (PS-C) was assayed as reference. Hydrolysis of PS-CLA by digestive enzymes was similar to that of PS-C (51 and 47%, respectively), most lipids products being mainly included in the bioaccessible fraction, namely, the micellar phase (MP). Control assays in the absence of PS esters showed most cholesterol solubilized within the MP, whereas a displacement of total cholesterol was caused from MP after digestion of PS esters (14 and 36% displacement for PS-CLA and PS-C, respectively), cholesterol being partially precipitated. Precipitated cholesterol was linearly related to a parallel precipitation of saturated-chain PS, mainly determined by sitosterol (R 2 = 0.936). The higher composition in sitosteryl esters of PS-C with respect to PS-CLA might explain their different effects on cholesterol. Therefore, besides being a lipid delivery form of PS similar to other commercial esterified PS, the PS-CLA might have the additional advantage of being a lipid delivery form of CLA. Moreover, PS-CLA might hinder the bioaccessibility of cholesterol. Furthermore, the qualitative/quantitative profile in esterified PS forms might determine the magnitude of cholesterol interaction. © 2012 American Chemical Society.