Depolymerization Optimization of Cranberry Procyanidins and Transport of Resultant Oligomers on Monolayers of Human Intestinal Epithelial Caco‐2 cells

Abstract

Procyanidins in cranberries are predominantly polymers (>;85%). The objective of this study was to optimize the depolymerization of polymers and to investigate the absorption of resultant oligomers on Caco‐2 cell monolayers. Depolymerization conditions with or without added epicatechin were optimized using a response surface methodology. Depolymerization without added epicatechin yielded 202 μg oligomers (monomer through tetramers) per mg partially purified polymers (PP). Depolymerization with added epicatechin resulted in a higher yield of 644 μg oligomers per mg PP. Procyanidin oligomers yielded from both methods transported through Caco‐2 cell monolayer with transport ratios less than 2%. These results suggested that these newly generated oligomers are bioavailable albeit the aborption rates were low. With the aid of response surface methodology, the optimum depolymerization conditions were determined to be 60°C, 0.1 M HCl in methanol and 3 h without added epicatechin. The calculated maximum theoretical yield was 364 μg oligomers per mg PP. The optimum depolymerization condition with added epicatechin shared the same temperature, acid concentration and reaction time in addition to an epicatechin/PP mass ratio of 2.19. Its theoretical maximum oligomer yield was 1089 μg/mg. These conditions were verified by experimental data. Therefore, procyanidins depolymerization produced bioavailable oligomers on Caco‐2 monolayers with a good yield.