Human bioavailability and metabolism of phenolic compounds from red wine enriched with free or nano-encapsulated phenolic extract

The impact of nano-encapsulation of a phenol extract from grape pomace on human plasma pharmacokinetic parameters and urine clearance of phenolic metabolites was examined. A dealcoholised red wine was used as the vehicle for enrichment with both non-encapsulated and nano-encapsulated phenol extracts in a randomised cross-over pharmacokinetic study. The analysis of plasma only showed an increase in the concentration of syringic acid sulphate, catechin sulphate and catechin glucuronide, whereas urine data, especially at interval of 0-6 hours, showed an increase in most of the metabolites from stilbenes, flavan-3-ols, phenolic acids and anthocyanins after the intake of phenol-enriched wines compared with the control wine. The nano-encapsulation of the extract slightly enhanced the bioavailability of malvidin-3-O-glucoside, as observed in the higher urine excretion of its native form and its microbial metabolites syringic and gallic acids. Metabolic pathways of different phenolic groups were proposed, with special emphasis on novel pathways of hydroxytyrosol generation.