Study On Extraction And Purification Process,Antioxidant And Antibacterial Activity Of Polyphenols From Loquat Leaves

In this experiment, the extraction of polyphenols by solvent treatment, the extraction process optimized to increase the extraction rate of polyphenols from loquat leaves, polyphenols purified thorough macro-porous resin, the composition of polyphenols identified by high performance liquid chromatography (HPLC) and the antioxidant activity of polyphenols were researched in this paper. The results were as follows:(1) The response surface methodology analysis was used to optimize the polyphenol extraction in order to improve the extraction rate of polyphenols from loquat leaves. The solid-liquid ratio, extraction temperature and extraction time were the most important factors in extracting polyphenols. The optimal extraction process, polyphenol extraction rate is 3.40%, was:solid-liquid ratio 1:21,48.5% ethanol concentration, temperature 60 ℃, time 2.6 h.(2) Compared the adsorption and desorption of six macro-porous resin, the measure of purification of D101 macro-porous resin, the polyphenol solution 2.0 mg/mL, flow rate 2.0 mL/min, desorption agent ethanol solution 60%, elution flow rate of 1.0mL/min, eluent volume of 250 mL were selected to purify polyphenols from loquat leaves. Finally, polyphenols powder of loquat leaves were obtained successfully through the eluate merge of 100-200 mL being concentrated and lyophilized. The content of polyphenol from loquat leaves content was up to 68.48% from the percentage of 13.23 in the raw power.(3) The components of polyphenols of loquat leaves were identified by high performance liquid chromatography. In the raw sample powder, the contents of gallic acid, vanillic acid,syringic acid,ferulic acid and quercertin were respectively 1.057 mg/g,1.197 mg/g, 1.439 mg/g,2.234 mg/g and 1.068 mg/g. moreover, in the purified powder, there are respectively 12.731 mg/g,8.433 mg/g,8.651 mg/g,9.477 mg/g and 18.554 mg/g.(4) The antioxidant capacity of raw powder and purified powder of polyphenols of loquat leaves was detected through the controls of antioxidants ascorbic acid and Tea Polyphenols. The data suggested that the important roles of polyphenols clearing DPPH, ABTS+, hydroxyl radicals, nitroso and significantly oxidation reduction were revealed. Hereby, we infer that the polyphenols of loquat leaves will be used to the natural antioxidants source from above effect.(5) The significantly antibacterial effect on the bacteria of Escherichia coli and Staphylococcus aureus inhibited by the purified polyphenols of loquat leaves was assayed in the filter paper experiments, and the poor effect on the Bacillus subtilis and Pseudomonas aeruginosa. The results of the minimal inhibitory concentration and minimum bactericidal concentration by broth microdilution method showed that, E. coli MIC and MBC are 2.5 mg/mL, Staphylococcus aureus MIC was 2.5 mg/mL, MBC of 5.0 mg/mL, Bacillus subtilis MIC and MBC of 5 mg/mL, for the worst Pseudomonas aeruginosa, which MBC reached 40 mg/mL, MIC of 20 mg/mL.