| AIM: Ulcerative colitis, characterized with non-specific inflammatory response ulcer formation in colonic mucosa, is an autoimmune disease related with immune disorders, genetic susceptibility and flora disturbance. At present, there is still lack of effective treatment. Konjac is one of the common additives as an excipient in functional food and drugs. Konjac could regulate gastrointestinal function effectively and its active principle Konjac flour has mucosal protective effect and anti-tumor, immunity enhancer, blood lipids regulater. We used to treat the rats with konjac flour enema which leaded to swelling in the stomach and intestines and constipation, thus it is difficult to show the role of effective treatment. In this study, Konjac was degraded to acquire degraded amorphophallus konjac polysaccharides (DARP) with lower viscosity and molecular weigh. To establish the degradation method of Amorphophallus konjac polysaccharides and the effect of its product (degraded amorphophallus konjac polysaccharides,DAKP) on trinitro-benzene-sulfonic acid (TNBS)-induced colitis in rats.METHODS: The degraded amorphophallus konjac polysaccharides (DAKP) were acquired by dialysis, concentration, ethanol precipitation, freeze-drying after methanol saponifacation and acid-hydrolyzation from amorphophallus konjac polysaccharides. Rats with colitis were induced by TNBS enema and treated with DAKP or dexamethasone (DX) enema.All treatments (saline, DAKP and DX) were started 6 h after TNBS enema, and then once a day for 5 consecutive days. At the sixth day, all the rats were sacrificed to get peritoneal macrophage and colon tissue, the tumor necrosis factor-α(TNF-α) was detected by ELISA. Eight cm length of colon were excised, weighed, and fixed in 10 % of neutral buffered formalin for at least 24 hours for histopathological examinations. Ulcer area and colon index were measured. And thymus and spleen were weighed. Isolated colonic mucosa was frozed in liquid nitrogen and MPO activity was tested.RESULTS:1. DAKP was verified to be composed of glucose and mannose by thin layer chromatography, and its molecular weight is 5.8×104Da; Viscosity is 4.4 Pa.s; sugar content is 88.5%. 2. DAKP at middle or high dose significantly attenuated the colon index[(6.21±1.6),(6.13±2.1) vs (7.83±2.4); P<0.05] and the ulcer area [(31.8±8.1)%, (30.9±6.4)% vs (41.5±9.1)%; P<0.05]. DAKP at middle or high dose significantly attenuated colon edema and MPO activity in colon mucosa [(5.82±2.23), (5.12±1.02) vs (9.72±2.34); P<0.05] compared with the model group. The number of macrophage and the content of TNF-αin middle or high DAKP dose group were lower than that in the model group [(3.3±0.87), (2.9±0.85) vs (5.3±0.91); (215.1±7.2), (201.3±5.5) vs (306.9±8.1); P<0.05].3. As compared with dexamethasone, DAKP did not show significant difference therapeutic effect. DAKP Significantly reduced TNBS-induced thymic atrophy and splenomegaly; but dexamethasone significantly induced thymic atrophy which showed clear signs of immunity inhibition.CONCLUSION:1. Compared with Konjac Polysaccharide, the DAKP had small molecular weight, low viscosity, and high sugar content and improved water-solubility.2. DAKP had a good therapeutic effect on TNBS-induced experimental colitis but there was no significant difference between DAKP and dexamethasone treatment; while DAKP did not show signs of immune inhibition as that in dexamethasone group.3. DAKP showed significant therapeutic effects on TNBS-induced rat colitis by anti-inflammation. Low molecular weight DAKP might be the main component of konjac in regulation of gastrointestinal function. |
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