Studies On The Anti-Diabetic Cataract Of Polysaccharides From Dendrobium Huoshanense

The functionary approach and molecular mechanism of polysaccharides from Dendrobium huoshanense C. Z. Tang et S. J. Cheng (Orchidaceae) on anti-cataract activity were assessed. Rats with intraperitoneal injection of streptozotocin (STZ, 45 mg kg^-1) were set as the animal model of diabetic cataract. Administration of polysaccharides from Dendrobium huoshanense (HPS) caused a significant weight increase at all dosage of 50 mg kg^-1day^-1, 100 mg kg^-1day^-1 and 200 mg kg^-1day^-1, while the blood sugar was decreased. Compared to the rats without therapy, the opacity of lenses was abated in the groups treated with HPS. Taken into account of NO and NOS levels in lenses, 70.2μmol mg^-1 pro of NO and 23.4 U mg^-1 pro of NOS were obtained with a dosage of HPS at 200 mg kg^-1day^-1, which all decreased over 33% compared to those in the rats without therapy. Real time PCR analysis also showed that the inhibition response of iNOS gene expression was in a dose-dependent manner with HPS treatment. Compared to the rats without therapy, the 100 mg kg^-1day^-1 and 200 mg kg^-1day^-1 treatments could bring a gain of GSH over 137%and 148%. The GSH-PX do not showed a distinct difference between 200 mg kg^-1day^-1 treatments and normal control group. The GR at 100 mg kg^-1day^-1 treatment and 200 mg kg^-1day^-1 treatment was 4.65 U mg^-1 prot and 4.70 U mg^-1 prot respectively, between which there was also no distinct difference. GST activity of 1.69 U mg^-1 prot was obtained with a dosage of HPS at 200 mg kg^-1day^-1. The SOD was adjacent between 200 mg kg^-1day^-1 treatments and normal control group, implying that the HPS may protect the SOD consumingly. At the same time, the CAT activity was protected at a certain extent when the dosage of HPS was at 200 mg kg^-1day^-1. As a result, the production of MDA and damnification of protein oxidation were inhibited by HPS. Compared to the rats in normal control group, 187% and 141% of MDA were obtained in the diabetic group and 200 mg kg^-1day^-1 treatment respectively, and MDA was reduced 46% by HPS treatment. The damnifications of protein oxidation were 2.97 nmol mg^-1 prot and 1.91 nmol mg^-1 prot in the diabetic group and 200 mg kg^-1day^-1 treatment respectively, which was decreased 75% in comparison with the control of 1.39 nmol mg^-1 prot. To restrain advanced glycation end productions (AGEs) synthesis by HPS was another phenomenon in this experiment and the suppression ratio reached 40.2% at 200 mg kg^-1day^-1 treatment as compared with the rats without therapy. These results indicated that polysaccharides of D. huoshanense would be a new pharmaceutical reagent for prevention and cure of diabetic cataract.