Anti-inflammatory properties of fruit juices enriched with pine bark extract in an in vitro model of inflamed human intestinal epithelium: The effect of gastrointestinal digestion

Enrichment of fruit juices with pine bark extract (PBE) could be a strategy to compensate for phenolic losses during the gastrointestinal digestion. A coculture system with Caco-2 cells and RAW 264.7 macrophages was established as an in vitro model of inflamed human intestinal epithelium for evaluating the anti-inflammatory capacity of fruit juices enriched with PBE (0.5 g L−1) before and after in vitro digestion. The digestion of both PBE-enriched pineapple and red fruit juice led to significant changes in most of the analysed phenolic compounds. The in vitro inflammatory state showed cell barrier dysfunction and overproduction of IL-8, nitric oxide (NO) and reactive oxygen species (ROS). In the inflamed cells, incubation with nondigested samples reduced (P < 0.05) the production of IL-8 and NO compared with digested samples. ROS production increased in the inflamed cells exposed to digested commercial red fruit juice (86.8 ± 1.3%) compared with fresh juice (77.4 ± 0.8%) and increased in the inflamed cells exposed to digested enriched red fruit juice (82.6 ± 1.6%) compared with the fresh enriched juice (55.8 ± 6%). The anti-inflammatory properties of PBE-enriched fruit juices decreased after digestion; further research on the bioavailability of the assayed compounds is needed to properly assess their usefulness for the treatment of gut inflammation.

► Anti-inflammatory effect of fruit juices enriched with pine bark extract. ► IL-8, nitric oxide, TEER and ROS production by Caco-2 cells were used as inflammatory markers. ► In vitro gastrointestinal digestion process reduces the anti-inflammatory properties of enriched fruit juices.