Protective Effects of Grape Seed Proanthocyanidin Extract in Preventing DSSInduced Ulcerative Colitis Based on Pharmacodynamic, Pharmacokinetic and TissueDistribution

Background: Based on pharmacodynamic, pharmacokinetic and tissue distribution studies, we explored the potential effect of grape seed proanthocyanidin extract (GSPE) on dextran sodium sulfate (DSS) -induced ulcerative colitis in mice and its underlying mechanism. Methods: A liquid chromatography-mass spectrometry method was developed to measure the content of five components of GSPE in rat plasma and tissue. After oral administration of GSPE, correlative index levels of interleukin- 1β (IL-1β), interleukin-6 (IL-6), factor-α (TNF-α), Nitric Oxide (NO), malonaldehyde (MDA), and superoxide dismutase (SOD) were detected in the serum and colon tissues. The protein expression levels of HO-1, Nrf2 and NF-κB in the mouse colonic mucosa were analysed using immunohistochemistry. Results: Pharmacodynamic tests showed substantially reduced mice body weight, diarrhea, and bloody stool in the model group. The pathological damage to the colonic mucosa of mice in the GSPE groups was remarkably reduced in a dose-dependent manner. The histopathological score of the colon in the model group was significantly higher than that of the control group (P <0.05), suggesting that DSS caused severe damage to the colon. After oral administration of GSPE, the serum and colonic tissue levels of IL-1β, IL-6, TNF-α, NO, and MDA decreased, whereas SOD content increased. Moreover, the protein levels of NF-κB and Keap-1 were significantly decreased, whereas the expression levels of Nrf2 and HO-1 proteins increased (P＜0.01) based on the results of the microwaveimmunohistochemical assay. The pharmacokinetic results showed that catechin, epicatechin, and procyanidins B1, B2, and B4 are widely distributed in the tissues and blood of rats and may accumulate in some tissues. Catechin and epicatechin peaked at 0.25 and 1.5 h for the first and second time, respectively. Procyanidin B1, B2, and B4 peaked at 0.5 and 1.5 h for the first and second time, respectively, owing to the effect of the hepato-enteric circulation. The active components of GSPE can reach the colon of the lesion site, and hepatoenteric circulation can increase the residence time of the active components in the body, further increasing the anti-ulcer activity. Conclusion: Our findings suggest that GSPE has a potential protective effect against DSS-induced ulcerative colitis in mice.