Bioavailability and the mechanism of action of a grape extract rich in polyphenols in cholesterol homeostasis

• GE stimulates biomarkers of cholesterol metabolism in HepG2 and Caco2 cells.
• GE induces the expression of the membrane receptor for LDL.
• GE induces the expression of the intestinal cholesterol transporter.
• The bioaccessible fraction of the GE reduces the expression of the CYP7A1.
• The gastrointestinal digestion increases the GE's bioaccessibility.

The bioaccessibility of a grape extract rich in polyphenols (GE) was determined in order to shed light on the mechanism of action in cholesterol homeostasis. GE's bioaccessibility and the antioxidant capacity of the bioaccessible fraction (BF) of GE were determined using a dynamic gastrointestinal digester (DGD). BF and GE were used to elucidate GE's mechanism of action, using two cell lines (HepG2 and Caco2) and different biomarkers. It was demonstrated that gastrointestinal digestion increases GE's bioaccessibility, with the antioxidant capacity of BF being statistically superior to that of GE (p < 0.05). With GE, a statistically significant increase in the expression of the low density lipoprotein receptor (LDLr) was noted, as well as for the intestinal cholesterol transporter (NPC1.L1) (p < 0.05). Besides, a statistically significant reduction in the expression of the cholesterol 7 alpha-hydroxylase enzyme (CYP7A1) (p < 0.05) was noted in BF.