Systemic absorption and metabolism of dietary procyanidin B4 in pigs

Scope: Procyanidins (PCs) are among the most abundant polyphenols in the human diet and they are reported to exhibit several beneficial health effects. However, the knowledge about their metabolic fate is rather limited. To investigate the systemic absorption and metabolism of dietary PC B4, a kinetic study using pigs as model system has been performed. Methods and results: After oral application of a single dose of 10 mg/kg body weight PC B4, urine and plasma were collected over a period of 48 h. PC B4 and its possible metabolites were analyzed in physiological samples using HPLC-MS/MS and GC-MS. PC B4 was detected as intact molecule in urine as well as in plasma. Maximum reached plasma concentration of PC B4 (c(max)) was 2.13 ng/mL (3.68 nM) and mean total urinary excretion related to the administered dose was 0.008 +/- 0.003%. In addition to that the monomeric structural units catechin and epicatechin were determined as degradation products. Furthermore, methylated and conjugated monomeric metabolites were identified. Monomeric metabolites were identified to be the major fraction occurring in the systemic circulation. The analysis of phenolic acids did not show an increase of these possible further metabolites. Conclusion: After oral administration, PC B4 is absorbed as intact molecule and it is excreted in urine. In addition, it is degraded to the monomeric subunits that are then further metabolized to methylated and glucuronidated conjugates in pigs.