FIG. 19.

Proposed pathways for the conversion of cyanidin-based red raspberry anthocyanins to phenolic acids and aromatic compounds. After consumption of 300 g of raspberries ∼40% of the ingested anthocyanins, principally cyanidin-O-glycosides, pass into the large intestine. When raspberry anthocyanins are incubated with fecal suspensions under anaerobic conditions, the cyanidin aglycone is released and catabolized by the colonic microflora undergoing C-ring fission, releasing phenolic acids, originating from both the A- and B-rings, which are metabolized via the pathways illustrated. Analysis of urine collected after raspberry consumption indicates that some of the colonic catabolites enter the circulatory and undergo further metabolism before being excreted in urine. These catabolites are thus detected in urine, but not fecal suspensions. F, catabolites detected in fecal suspensions; U, catabolites detected in urine (also highlighted in gray); *potential intermediates that did not accumulate in detectable quantities. Adapted from Gonzalez-Barrio et al. (159).