Bioavailability and metabolism of hydroxycinnamates in rats fed with durum wheat aleurone fractions†
The consumption of wholemeal cereals has been associated with the reduced risk of several chronic diseases, and the mechanisms behind these protective effects may be linked, besides dietary fiber and micronutrients, to an increased intake of hydroxycinnamates contained in the bran. Among bran fractions, aleurone usually contains the highest concentration of ferulic acid and diferulic acid esters linked to arabinoxylans representing the most relevant subclasses. The aim of the present study was to evaluate the absorption of hydroxycinnamates by measuring the urinary metabolite profiles of rats fed with the two different aleurone fractions (the inner part of the aleurone, named wheat aleurone A, WA-A, and the outer part, named wheat aleurone B, WA-B). An acute feeding experiment with two rat groups consuming equivalent amounts of total ferulic acid from the different aleurone fractions was carried out to evaluate ferulic acid bioavailability as affected by different sources. A chronic feeding experiment was also conducted with two rat groups consuming the same amount of the two different aleurone fractions, carried out to investigate the short-term metabolism and absorption of aleurone phenolics. The results revealed higher increases in the 24 h-excretion of phenolic metabolites/catabolites in aleurone fed rats compared to rats fed with a regular diet. Specifically, in the chronic feeding, ferulic acid was more bioavailable when WA-A was ingested. Based on previous observations, demonstrating various positive physiological responses to ferulic acid and aleurone fractions characterized by higher phenolic bioavailability, our results indicate that the WA-A fraction has potentially interesting nutritional characteristics that might be used for the formulation of new wheat based products.