Effect of the A-Type Linkage on the Pharmacokinetics and Intestinal Metabolism of Litchi Pericarp Oligomeric Procyanidins

The bioavailability of A-type procyanidins in vivo has been rarely investigated; as such, this study discusses the effect of A-type linkage and degree of polymerization on the metabolism of procyanidins extracted from litchi pericarp (LPOPC). Sprague–Dawley rats were gavaged with (−)-epicatechin (EC) and LPOPC and sacrificed at different time points after ingestion. A-type linkage procyanidin oligomers inhibited the absorption of EC. Analysis of urinary contents from rats administered with EC, A-type procyanidin dimer (A-2), and A-type procyanidin trimer (A-3) showed distinct native and metabolite profiles for each rat. Rats fed with A-2 and A-3 presented significantly higher levels of shikimic acid and less amount of m(p)-coumaric acid metabolites in vivo and provide insight into the quantitative structure–activity relationship of procyanidin oligomers during metabolism, indicating that procyanidins with A-type linkage could induce an altered metabolic pathway of oligomers in the gastrointestinal system.