Complex flavonoids in cocoa: synthesis and degradation by intestinal microbiota.

Rarely occurring flavan-3-ol derivatives such as C-glycosides can be generated during food processing, for example, by cocoa production. These astringent taste compounds may also exert interesting behavior toward microbial metabolism, as other C-glycosides have been shown to be quite stable. Oligomeric flavan-3-ols, the procyanidins, bear also a C-C bond between the main moieties and are suspected to resist microbial metabolism for a prolonged time compared to other flavonoids. This paper describes a semisynthetic approach for the generation of flavan-3-ol C-glycosides. Results of incubation experiments studying five flavan-3-ol C-glycosides bearing different sugars, linkage positions, and stereochemistries are presented as well as the behavior of di- and trimeric B-type procyanidins toward intestinal microbiota. Low molecular weight degradation products are considered as well as concentration-time courses of degraded and liberated compounds. All metabolic studies were performed with the well-proven pig cecum model.