As a processing by-product, green pea hull (GPH) was found to be rich in phenolic components in our previous studies. In this study, UHPLC-LTQ-OrbiTrap-MS (Ultra performance liquid chromatography-linear ion trap orbitrap tandem mass spectrometry) technique was used to quantify polyphenols, and DSS (sodium dextran sulfate)-induced colitis mouse model was established to explore the effect of GPH extracts on colitis. The results showed that quercetin and its derivatives, kaempferol trihexanside and catechin and its derivatives were the main phenolic substances in the extract, reaching 2836.57, 1482.00 and 1339.91 µg quercetin/g GPH extract, respectively; GPH extracts can improved inflammatory status, repaired colonic function, regulated inflammatory factors, and restored oxidative balance in mice. Further, GPH extracts can activate Keap1-Nrf2-ARE signaling pathway, regulate downstream antioxidant protease and gut microbiota by increasing F/B value and promoting the growth of Lactobacillaceae and Lachnospiraceae, and improve the level of SCFAs (short-chain fatty acids) to relieve DSS-induced colitis in mice. Therefore, GPH may be a promising dietary resource for the treatment of ulcerative colitis.

Green pea hulls are a byproduct of the processing of green pea and are rich in phenolic substances. In the present study, in vitro digestion, human colonic adenocarcinoma cell line (Caco-2) monolayer, and the Caco-2/macrophage cell lines of the murine origin (Raw264.7) coculture model were established to investigate the release of polyphenols, absorption, and transport of digestive products and their effects on inflammation and intestinal barrier. During the digestive process, polyphenols were constantly released from the pea hulls, reaching the maximum amount in the small intestine (total phenolic content (TPC): 5.41 ± 0.04 mg gallic acid (GAE)/g dry weight (DW)), and the digestive products (800 μg/mL) could reduce the secretion of NO (50.9%), IL-6 (50.6%), and TNF-α (24.6%) and inhibit the mRNA expression of cyclooxygenase-2 (COX-2) (37.2%) and inducible nitric oxide synthase (iNOS) (91.1%) compared with the lipopolysaccharide (LPS) group. A total of 12 phenolic components were quantified by ultraperformance liquid chromatography-linear ion trap orbitrap tandem mass spectrometry (UHPLC-LTQ-OrbiTrap-MS) technology. Kaempferol trihexoside in digestive products could be absorbed and transported (1.25 ± 0.13 ng quercetin/mL). The digestive products could promote the expression of claudin-1 (210.8%), occludin (64.9%), and zonulin occludin-1 (ZO-1) (52.0%) compared with the LPS group and exert anti-inflammatory effects after being absorbed. The results indicated that pea hull polyphenols could be continuously released and absorbed to play a positive role in protecting the intestinal barrier and antiinflammatory activity.