Extraction Of Oligosaccharides From Rehmannia Glutinosa Libosch. And Its Pharmacological Effects In Experimental Diabetic Rats By Oral Administration

It is well known that diabetes mellitus(DM) is a common disease with the main phenotypes of metabolism disorder in sugar, protein, lipid and electrolures caused by insulin deficiency and a number of severe complications could frequently happen in the late process. The DM have been a threaten to the health of human beings since its mortality was only behind the cancer and cardiovascular disorder in non-infectious diseases. The incidence of DM in worldwide including China increased year by year and more than 90% of diabetic patients contribute to type 2 diabetes which is lack of efficient treatment and prevention.The treatment of DM by Traditional Chinese Drugs (TCD) has been for thousands of years, and one of the cures for this is Rehmannia glutinosa Libosch.. Recent researches revealed that oligosaccharides from Rehmannia glutinosa Libosch. (ROS) exerted a hypoglycemic effect in diabetic rats by intraperitoneal administration, but no reports about its pharmacological effects and mechanism on glucose metabolism by oral administration.The study included three parts:1. Extraction, separation of oligosaccharides from Rehmannia glutinosa Libosch. and determination of stachyose by HPLC.2. Pharmacological effect and mechanism of water extraction and oligosaccharides from Rehmannia glutinosa Libosch. on normal, hyperglycemic and diabetic rats by oral administration, and screening of its antidiabetic effective components.3. Pharmacological mechanism of antidiabetic components from Rehmannia glutinosa Libosch.Methods:1. Orthogonal method was used to inspect the factors such as water volume, times and time for extraction by water from Rehmannia glutinosa Libosch. And the content of stachyose, main component of Rehmannia glutinosa Libosch. was determined by HPLC.2. The oligosaccharide rudiment was obtained by using ion exchange resin and activated charcoal chromatography.3. The hypoglycemic effects of different components from Rehmannia glutinosa Libosch. was screened in Glucose- or adrenaline- hyperglycemic rat model which were induced by glucose (2g·kg-1) or adrenaline (300μg·kg-1), respectively.4. The effects of active extraction from Rehmannia glutinosa Libosch. were studied in diabetic rat model induced by alloxan at a dose of 150 mg·kg-1, ip.. And the plasma glucose level, body weight and the morphologly of pancreas in rat were observed. The blood insulin level, hepatic glycogen and the intestinal flora in rats were also determined so as to explored primarily the pharmacological mechanism of the active extraction component.Results:1. Oligosaccharides extraction by water from Rehmannia glutinosa Libosch. According to the weight of the extraction, the influence factors was extraction times (B) > water volume (A) > time for extraction (C) in turn. The best extraction condition was found to be A2B2C3, that is, with 10volume of water for 1.5 hour, 2 times. Under the same factors, the content of stachyose in the extraction was not coincided with the weight of the extraction.2. Analysis of stachyose in Oligosaccharides by HPLC The results showed that the HPLC analysis was stable and reliable under the conditions used in this study. The correlation (r) of standard curve was 0.997 and the variation coefficients of intra-day and inter-day were 0.16% and 0.12%. Recoveries of stachyose were 99.67±2.29%. 3. Primary purification of Oligosaccharides from Rehmannia glutinosa Libosch. By using ion exchange resin and activated charcoal chromatography, partⅠ,Ⅱ,Ⅲ and Ⅳ components were obtained with the elution of water and ethanol of 5%, 10% and 20% (V/V), respectively. In all four elution components, the most weight and the highest content of stachyose were found in part Ⅲ by HPLC analysis.4. Hypoglycemic effects of different components from Rehmannia glutinosa Libosch. Part Ⅲ that mainly consist of stachyose by oral administration exerted a significant hypoglycemic effect in glucose- and adrenaline- induced hyperglycemic rats, compared with that of the water extract and...