Résumé:
Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, are chronic immune-mediated inflammatory diseases of the intestinal tract. Under low vitamin B conditions, homocysteine accumulates and leads to hyperhomocysteinemia and the association between hyperhomocysteinemia and the risk of IBD has been widely studied. The objective of our work is to study the preventive effect of Rosa canina and Citrus sinensis fruits on intestinal inflammation induced by hyperhomocysteinemia in mice. In the first part of this study we determinate two compounds, the polyphenol and flavonoid in fruit extracts of Rosa canina and Citrus sinensis, followed by an evaluation of the antioxidant activity of these fruit extracts by different methods: DPPH, ABTS, GOR, reducing power and CUPRAC. The extracts were then tested in vitro for their anti-inflammatory effect via the bovine serum albumin (BSA) denaturation test. The chemical composition, ascorbic acid content, electrochemical characterization and antioxidant capacity of Rosa canina fruit extract were determined. In addition, the in vitro antioxidant activity of R. canina fruit extract and its protective effect on hydrogen peroxide (H2O2)-stressed human fibroblast cells were evaluated using MTT assay.
In the second part, we studied the protective, anti-inflammatory and anti-homocysteinemic effect of the fruits: Citrus sinensis, Rosa canina and vitamin C on the intestinal inflammation induced by high doses of L-methionine during the 21 days in vivo experimental procedure. The levels of plasma inflammatory markers (hs-CRP, homocysteine), reduced glutathione (GSH) and catalase (CAT) in liver tissue were measured, and histological sections of intestinal tissue were examined. The results show that both extracts are rich in polyphenols and have significant antioxidant power. Both extracts prevented the denaturation of BSA in a dose-dependent manner indicating that both extracts have anti-inflammatory activity, which was confirmed by the in vivo anti-inflammatory study. The extract of Rosa.canina fruit indicates the presence of n-hexadecanoic acid, oleic acid and stearic acid, which were identified as the main compounds of this fruit. This fruit is rich in ascorbic acid and has an important antioxidant capacity. Moreover, the results show that Rosa canina fruit extract has a non-toxic effect on the viability of human fibroblasts with a protective effect against oxidative stress induced by hydrogen peroxide on fibroblasts. In addition, treatment with fruits and vitamin C led to a decrease in the level of plasma homocysteine, an increase in the levels of GSH and CAT. This was confirmed by the histological study of the restoration of the integrity of the intestinal epithelium. This study revealed that the fruits of Citrus sinensis and Rosa canina have antioxidant and antiinflammatory powers and can be considered as a natural source to prevent and treat IBD.
