Study On Prebiotic Activity And Immunomodulatory Activity Of Wheat Arabinoxylans

Wheat arabinoxylan(AX) is a kind of non-starch polysaccharides. It has immunomodulatory activity and prebiotic activity, which are related to the structure and composition of AX. Research on immunomodulatory activity of AX is relatively less, so it is difficult to find the connection between prebiotic and immunomodulatory activity of AX. In this study, immunomodulatory activity and prebiotic activity of wheat AXs with different structures were evaluated, in order to find AX samples with good functional activity. At the same time, the connection between immunomodulatory activity and intestinal metabolite was explored, in order to provide some theoretical basis for the utilization of wheat byproducts.1. Preparation and Characterization Analysis of AX samples: six kinds of AX samples with different structure and components were prepared with wheat bran or flour, which were named AX1, AX2, AX3, AX4, AX5 and AX6, respectively. Pentosan content of AX was greater than 75% except AX6. Besides, protein content and ferulic acid content of AX from wheat flour were more than that of samples from wheat bran. Molecular weight of AX samples were between 6.67 × 103 ~ 2.73× 105. AX samples extracted with alkaline had higher substitution degree of arabinose than AX extrated with water.2. Study on the prebiotic activity of AX: p H controlled in vitro fermentation method was used to evaluate the prebiotic activity of AX samples by inoculated with human feces. The results showed that fermentation of wheat AX can promote the proliferation of bifidobacteria. AX1, AX5 and AX6 showed a better effect on the proliferation of bifidobacteria. Moreover, the contents of short-chain fatty acids(SCFA) also increased during fermentation of AX. AX3, AX5 and AX6 showed better effect on the production of SCFA, especially butyrate. According to the number of probiotic and short chain fatty acids production, the prebiotic activity of AX5 and AX6 were better.3. Immunomodulatory activity of AX: immunosuppressed mice model and OVA- immunized mice model were selected to evaluate immunomodulatory activity of AX samples. The results showed that AX1, AX4 and AX6 can enhance the immune activity of immunosuppressed mice. AX4 and AX6 can enhance the immune response of OVA- immunized mice. Both of them can not only promote the lymphocyte proliferation induced by Con A, LPS or OVA, but also improved the Ig G level(P < 0.01, P < 0.05). In general, AX4 and AX6 showed better immunomodulatory activity.4. Effect of AX on immune activity and intestinal metabolites of tumor-bearing mice : on the basis of fermentation test in vitro and immune test in vivo,we studied the effects of wheat AX on the immune activity and SCFA content of S180 tumor-bearing mice. The results showed that AX4 and AX5 had better anti-tumor and immune activity. Meanwhile AX, especially AX4 and AX5 can improve SCFA contents in colon and cecum of mice. In conclusion, AX4 and AX5 showed better effect not only on anti-tumor and immune activity, but also on SCFA production in colon and cecum. It suggests that the immunomodulatory effects of AX may be related to SCFA in the intestinal.