Absorption, Excretion, and Transformation of Individual Anthocyanins in Rats

Abstract

Anthocyanins are polyphenolics responsible for most red to purple colors in plants. Human consumption is increasing because of their potential health benefits and use as natural colorants. However, their absorption and metabolism are not well characterized. We compared anthocyanin absorption and excretion in rats receiving chokeberry, bilberry or grape enriched diet (4g anthocyanin/kg) for 13 weeks. Traces of anthocyanins and metabolites were detected in plasma. In urine, intact anthocyanins and methylated derivatives (~ 24, 8, 15 mg cy-3-gla equivalent/L urine for chokeberry, bilberry, grape) were found. High metabolite concentration suggested accumulation of methylated anthocyanins in tissue. Fecal anthocyanin extraction was maximized with aqueous methanol (60%). Anthocyanin concentration in feces ranged from 0.7 to 2g anthocyanin/kg, similar to cecal content. In the gut, anthocyanin degradation was high for glucosides, moderate for galactosides and negligible for arabinosides and xylosides. Both, glycosylation and acylation seemed to affect the bioavailability of anthocyanins in vivo.