Screening Study On The α-Glucosidase Inhibitors From Diospyros Kaki Leaves

Diospyros kaki Leaves can be used as an experimental material. We can use an Enzyme-inhibitor as the screening model, of which the active site can make the activity of a-glucosidase inhibition screening, we can select the high activity of a-glucosidase inhibition site, from which separating and purifying the inhibition of enzymatic activity monomer compounds and we can study it in vitro activity dynamics, searching for the inhibition mechanism in the high activity of the a-glucosidase activity inhibition monomer, appraising the structure of the inhibitory activity monomer. The main researching contents and results can be presented here as the below:1. Polar solvents as Petroleum ether, N-butanol, Ethyl acetate, Distilled water can orderly be used and isolated from Persimmon leaf meal extraction, so we can gain four different extract fractions. And then through dry milling, we separately get the extraction rate of Petroleum ether, N-butanol, Ethyl acetate and the remaining water portion as3.59%,5.80%,3.20%,8.15%.2. We can use the a-glucosidase inhibition as the screening model, selecting the inhibitory activity from the four different fractions. As a consequence, the inhibitory activity rate of Petroleum ether, N-butanol, Ethyl acetate and the remaining water portion can be separately as4.30%,89.83%,55.19%%5.21%.3. We can select the extracts from the high activity of Ethyl acetate, taking the measure of the inhibitory activity, researching the extracts in vitro enzymatic kinetics, the result is:the density between0.1-1.2mg-mL-1, the inhibition rate of the enzyme rises accompanying its density increasing, Density1.2mg-mL-1, inhibition rate89.3%, which means a high activity of non-competitive reversible enzyme inhibitor.4. We can use high-speed countercurrent chromatography(HSCCC) to separate and the preparation of secondary separation preparative of high performance liquid chromatography from the ethyl acetate extract persimmon leaf can make the enzyme inhibitory activity monomers. The points in each group can be checked by high performance liquid chromatography (HPLC), by mass spectrometry and by Nuclear magnetic resonance spectroscopy, their structures are evaluated. The results shows: the four different compounds obtained (belongs to which substance).The purity separately as99.5%、90.1%、94.0%.91.7%.97.2%.94.1%、95.7%. We conclude the structure of the4different compounds are Hyperin,Isoquercetin,Trifolin and Astragalin.5. Taking the measure of inhibitory activity, we can separately measure the inhibitory activity of monomeric and study in the enzyme kinetics. The result shows:Reaction type rendering of compounds Ⅰ,Ⅱ,Ⅲ,Ⅳ,Ⅴ shows as noncompetitive inhibition type;compounds Ⅵ,Ⅶshows as competitive inhibition type.