In vivo bioavailability of polyphenols from grape by-product extracts, and effect on lipemia of normocholesterolemic Wistar rats

Abstract

BACKGROUND The direct use of phenolic extracts from grape by‐products can be useful to formulate functional food to improve consumers’ health. The use of phenolic extracts instead of pure polyphenols as an ingredient is relevant in this context. The current work studied the bioavailability and absorption of polyphenols from grape by‐product extracts and their health effect on cholesterolemia, by adding the extract (GE) to Wistar rats diet (50 g/kg) in vivo.

RESULTS GE caused the appearance of (+)‐catechin, myricetin and quercetic acid in plasma and liver. (+)‐Catechin was the most abundant compound, with 6 μg/mL in plasma and 0.7 μg/mg protein in liver, while no phenolic compounds were detected in plasma or liver in the control group. Similarly, 3,4‐hydroxyphenylacetic (DOPAC), a major product of polyphenol digestion, was detected in the plasma, liver and urine of the GE‐group only. GE‐group had significantly lower cholesterol level and lower total cholesterol/HDL ratio in plasma. Total bile acid (TBA) content significantly increased in faecal matter after 24 h administration of the GE‐enriched diet.

CONCLUSION Grape extract polyphenols are partially bioavailable and showed improvement in lipid metabolism. Thus, the results suggest that GE is promising as a functional ingredient in the prevention of hypercholesterolemia.