Impact of in vitro simulated digestion on the potential health benefits of proanthocyanidins from Choerospondias axillaris peels

The influence of passage through a simulated gastrointestinal tract (GIT) on the stability and bioaccessibility of proanthocyanidins isolated from fruit (Choerospondias axillaris) peel was studied. In addition, the effects of the simulated GIT on the antioxidant and α-glucosidase inhibitory activities of proanthocyanidins extracts were evaluated. Gastric digestion had little effect on total polyphenol content (TPC) or mean degree of polymerization (mDP) of crude and purified extracts. However, intestinal digestion led to a significant decrease (about 26% and 19%) in TPC and (about 12% and 7%) in mDP for crude and purified extracts, respectively. The observed reduction in TPC and mDP levels was attributed to interactions of proanthocyanidins with pancreatic enzymes, rather than due to the chemical conditions during digestion. Only small flavan-3-ol molecules (monomers, dimers and trimers) could diffuse into the dialysis tubing used to simulate the intestinal wall. Changes in antioxidant activity during digestion were correlated to changes in TPC. After simulated GIT digestion, over 85% of α-glucosidase inhibitory activity of both extracts was preserved. These results indicate that the majority of the proanthocyanidins maintained their biological activities after passage through the simulated GIT, and were therefore still capable of providing valuable health benefits.