| This dissertation aimed at investigating the stability and active groups of intestinal mucosal immunomodulating activity of orally administrated polysaccharide from Dendrobium huoshanense (DHP-2A). The obtained results were as follows:(1) DHP-2A-tyr-FITC was prepared using an indirect method, which is based on affinity reaction between fluorescein isothiocyanate (FITC) and amino groups. This method has many advantages including selectable labeling, stable structure and biological activity.(2) DHP-2A-tyr-FITC was employed to the absorption, metabolism and excretion of DHP-2A after oral administration using HPLC. Results showed that a new fluorescent signal occurred in mice stomach and intestine except DHP-2A fluorescent signal. The new substances also appeared in mice blood, but not in colon, urine and feces, although DHP-2A could be detected in mice colon and feces. These results indicated that the degradation fragment from DHP-2A was absorbed into the mice bloodstream and the degradation site of DHP-2A could be mouse gastrointestinal tract.(3) In vitro saliva, gastric and intestinal digestion experiments displayed that DHP-2A-tyr-FITC was stable saliva and intestinal fluid, but it was degraded gastric juice. This result demonstrated that the degradation site of DHP-2A-tyr-FITC could be in mice stomach. It was also found that the degradation of DHP-2A-tyr-FITC in the intestine is due to gastric acid, which was proved by stability analysis of DHP-2A in stomach acid and salt.(4) Compared with DHP-2A-tyr-FITC, its degradation fragment (DHP-2A-tyr-FITC-A) showed more significant effect on the intestinal mucosal immune system. DHP-2A-tyr-FITC-A could be detected in mice blood, gastric and intestinal fluid after oral administration. All results indicated that DHP-2A-tyr-FITC-A was functional group of DHP-2A-tyr-FITC to play a role in regulating intestinal mucosal immune system and its structure was relatively stable in gastrointestinal tract. |
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