Extraction, Determination And Hypoglycemic Effect Of Polysaccharides And Flavonoids From Gynura Divaricata (L.) DC

In this thesis,the extraction,isolation,purification and determination of PGD were extensively studied. Extraction of TFGD and their hypoglycemic effects in rats were investigated.Optimum technical process of extracting TFGD was obtained by single factor and orthogonal tests as follows:70% ethanol, 12-fold solvent, two times extraction, 1.5 hours each time. Under the optimum extracting conditions,the content of total flavonoids in Gynura divaricata(L.)DC was determined as 3.0%. Under conditions that:9-fold water, temperature 90℃,two times extraction,2.5 hours each time,the highest content of water-soluble polysaccharide in Gynura divaricata(L.)DC.(PGD) was obtained as 1.49%. By studying the process of ethanol precipitation and decolorizing, an optimal polysaccharide purification method was established. It showed that a favorable yield of polysaccharide was obtained: precipitated by 75% ethanol; temperature 80℃, decoloring 45 min, active-carbon concentration 15%,repeated once, the optimum decoloring effect was achieved and that 60℃temperature, 120 min decoloring time, 70% hydrogen peroxide,the optimum decoloring effect of hydrogen peroxide was obtained. After purified polysaccharides were separated by DEAE-52 column chromatography, PGD-1,PGD-2,PGD-3 were collected. PGD-2 was further isolated by Sephadex G-100 column chromatography.HPGFC-ELSD method was applied for the first time to determine weight-average molecular weight (M_W) of polysaccharide. Using dextran T₅, T₁₀, T₂₀, T₄₀, T₇₀ to establish standard curve based on logarithm of M_W to the retention time(t_R). The experimental results showed that the method's linear range was between Mw 5 000 and 70 000. Standard curve equation was gained as lgM_W=-0.2805t_R+3.2924, r=-0.9804. Mw of the sample polysaccharide was 26242. It is practical, reliable, accurate to determine Mw with HPGFC-ELSD method.In this thesis, diabetes model establishing conditions was optimized and male mice was adopted as subject animals. Uing the method of high fat diet combined with alloxan saline solution injected in intragastric forms to establish diabetic model, hypoglycemic effects of polysaccharides and flavonoids in Gynura divaricata(L.)DC were observed. Results showed that compared with the model control group, PGD and TFGD could decrease the fasting glucose and increase the blood insulin level in ALX diabetic mice. They could lengthen the anti-anoxia time as compared to normal mice. It exhibited that PGD and TFGD were effective in hypoglycemic and anti-anoxia.Gynura divaricata(L.)DC was used by many diabetics from Yueyang city in Hunan province. It showed significant hypoglycemic effect. There was few study on its constituent analysis and pharmacological activity. This research provided scientific reference for further study and development of Gynura divaricata(L.)DC as a natural plant resources.