Study Of The Neutral Tea Polysaccharide Of Antidiabetic Activity And Mechanism On KK-A～y Ⅱ Diabetes Mellitus Mice

Objective:To establish the optimal procedure for extraction and separation of tea polysaccharides.and to observe its hypoglycemic effects in type 2 diabetes mellitus mice The mechanism of its hypoglycemic effect were investigated and discussed.. Methods:The different levels of temperature, heating time and ratio of tea to water on extraction rate of TPS were studied with L9(3~4)orthogonal experimental design.Proteins were removed from the extract of tea by Sevag method.The crude polysaccharides obtained were subjected to stepwise alcohol precipitation and CTAB precipitation,and several fractions were obtained. Then the fractions were successively purified with DEAE and Sephadex exchange column.The TPS extract was given to KK-A~y mice with character of human type 2 diabetes mellitus to observe its effects on plasma glucose,serum insulin,and some indeces related to type 2 diabetes Morphological changes were evaluated by professional pathological method. The expression of TNF α ,leptin and GLUT4 correlated with insulin resistance during the therapeutic process of diabetes mellitus were detected by RT-PCR,Western-Blot and immunohistochemistry methods. Results:The optimal procedure for preparation of tea polysaccharide with water extraction included the ratio of material:dissolvent is 1 : 6,extracting temperature 60 ℃, extracting time 6h.6 times repeatedly removing proteins by sevag method.There were polysaccharide Ah A2, A3 and A2A,A2N were obtained by stepwise alcohol precipitation and CTAB precipitation apart. The purified polysaccharides was obtained from DEAE and Sephadex seperation.A2 was in a great measure,and A2N was more than A2A.So A2N TPS A2N was selected to next experiment. TPS A2N had antidiabetetic activity and could ameliorate glycometabolism and fat metabolism,and increase insulin sensitivity. And liver glycogen were increased.Also the TPS A2N could increase the expression of GLUT4 mRNA and decrease the expression of TNF...