Acetification And Anti-α-glucosidase Activity Of Eucommia Ulmoides Leaves

This paper studied the fermentation conditions of Eucommia Ulmoides vinegar and effects of fermentation on anti-a-glucosidase activity (AGA) of Eucommia Ulmoides Leaves. To elucidate the active compounds in Eucommia Ulmoides Leaves, the a-glucosidase inhibitors were separated, purifiied and identified. The main results were as follows:(1) To make Eucommia Ulmoides Leaves into vinegar, the fermentation conditions of Eucommia Ulmoides Leaves were studied. It was found that the optimal parameters of enzymolysis were0.8%(w/w) cellulase in20%(w/v) substrate concentration,at45℃for4h. After the sugar content of the was adjusted to204g/L with glucose, the hydrolyzed solution was inoculate5%yeast and ferment for11d at28℃. At the end of alcoholization, the alcohol content was adjusted to4%(V/V), Eucommia ulmoides leaf wine was then inoculated with acetic acid bacteria for11d at32℃.40-45g/L (acetic) the final vinegar was of40-45g/L of acetic acid and less than0.5%of alcohol content. Sensory evaluation showed that100mL diluted vinegar containing0.050g citric acid,0.015g malic acid,4.5g glucose is acceptable. AGA was found to decrease with the fermentation processings.(2) Eucommia Ulmoides Leave was extracted and the inhibitor of a-glucosidase was purificated. The optimum water extraction conditions for a-glucosidase inhibitor were determined by the orthogonal experiment. Results indicated that the substrate concentration10%(w/v), extraction temperature90℃and extraction time40min were the optimal conditions for the extactraction of the inhibitors from Eucommia Ulmoides Leaves. Under these conditions, the IC50of crude extract from duzhong leaves was66.2g/L. The crude extract was then separated by ultrafiltration and the component with molecular weight between5000-30000Da had the highest AGA. This filtrate was further isolated by sephadex gels. Finally a component was obtained with IC50at8.29g/L。(3) Eucommia ulmoies leaves were extracted with several solvents with different polarities and their AGA ranks were as follows:flavonoids (57.37%)> iridoids (36.94%)> Lignans (34.51%)> chlorogenic acid (32.63%)> polyphenol (32.17%)> Eucommiol (30.16%)> polysaccharides (10.43%). The flavonoids content of the crude extract was3.069mg/mL, and its extraction ratio was3.836%. AB-8resin was employed to purify flavonoids crude extract with dynamic adsorption and eluted with five different ethanol-aqueous solutions. The eluent were collected and their AGAs were measured which were in the following order:20%ethanol aqueous solution (43.08%)>40%ethanol aqueous solution (26.74%)> aqueous solution (25.60%)>80%ethanol aqueous solution (17.07%)>60%ethanol aqueous solution (13.87%). (4) The components from eluents by20%and40%ethanol aqueous solution (3) were further identified with GC-MS owing to their higher AGA. GC-MS preprocessed with silylation showed that there were54and82components in component A and component B, respectively, accounting for64.84%and73.35%of the total compounds in component A and component B. The two eluents have18kinds of compounds in common, such as catechin, which had been determined as the major glucosidase inhibitor. In addition, component A also contained the amino acid VB6, and thymol. While composition B is possessed Danshensu, gallic acid, coumarins, and so on. These compounds could be the major contributors of the glucosidase inhibitors in Duzhong.