Comprehensive Extraction Of Active Substances From Lycium Barbarum L.leaves And Screening Of Their Biological Activities In Vitro

Lycium barbarum L.leaves are plants of the Lycium genus in the Solanaceae family.The nutritional components and active ingredient types are basically the same as those of Lycium barbarum L.leaves,with polyphenols,polysaccharides,alkaloids,and proteins as the main active ingredients.This project uses Lycium barbarum L.leaves as raw materials to systematically study the extraction process of effective components such as polyphenols,polysaccharides,proteins,and alkaloids from Lycium barbarum L.leaves.The physicochemical properties,structural characterization,and functional evaluation of these components were also conducted.Finally,the antioxidant,hypoglycemic,and lipid-lowering effects of the extract were evaluated through in vitro antioxidant experiments and in vitro enzyme inhibition experiments.This study has certain theoretical significance for the deep processing and utilization of Lycium barbarum L.leaves,and has important significance in the food industry.The specific research content and results are as follows:(1)This chapter takes Lycium barbarum L.leaves as the research object to study the optimal process for extracting polysaccharides and alkaloids from Lycium barbarum L.leaves.Based on single factor analysis,the optimal extraction process of polysaccharides was analyzed by Box-Behnken design:extraction temperature 55℃,material liquid ratio 1:25 g/mL,alkali concentration 0.8%,precipitation pH3.5.The yield of Lycium barbarum L.leaves polysaccharides were 4.40±0.18%;The optimal extraction process for alkaloids is as follows:extraction temperature:70℃,ethanol volume fraction 70%,solid-liquid ratio 30 g/mL,ultrasonic power 150 W,and the yield of alkaloids from Lycium barbarum L.leaves were 3.02±0.09%.(2)This chapter takes four extracts of Lycium barbarum L.leaves as the research object,and studies the physicochemical properties,structural characterization,and functional characteristics of the four extracts through basic composition,SDS-PAGE,infrared spectroscopy,monosaccharide composition,scanning electron microscopy,and thermal stability.The results showed that the contents of polyphenols,polysaccharides,proteins,and alkaloids in the extracted leaves of Lycium arbarum were 82.09 ±1.23%,43.47±0.22%,52.39±0.45%,and 45±0.6%,respectively;UV and IR spectra showed that the four extracts had corresponding characteristic peaks;Through LC-MS analysis,12 polyphenolic substances were identified,including chlorogenic acid,rutin,caffeic acid,para coumaric acid,ferulic acid,and kaempferol;X-ray diffraction analysis showed that the alkaloids from Lycium barbarum L.leaves had two absorption peaks;The contents of uronic acid and protein in polysaccharides were 19.26±0.14%and 12.25±0.25%,respectively;In thermal stability,the mass of polysaccharides decreased by 70%with the increase of temperature;The polysaccharides from Lycium barbarum L.leaves exhibit fibrous and irregular reticular structures in microscopic state;Lycium barbarum L.leaves polysaccharides is composed of eight monosaccharides:Rha,Ara,GalN,Gal,Glc,Xyl,GalA,GulA;The molecular weight of Lycium barbarum L.leaves protein determined by SDS-PAGE was mainly 55 kDa;When pH5.0,the solubility of Lycium barbarum L.leaves protein was the lowest;The water holding capacity of Lycium barbarum L.leaves protein is 2.70 g/g,and the oil holding capacity is 3.43 g/g;With pH ranging from 5.0～9.0,the foaming stability of Lycium barbarum L.leaves protein ranges from 64.67%～88.97%,and with pH ranging from 5.0～9.0,the foaming stability ranges from 71.77%～84.75%;The emulsifying stability of Lycium barbarum L.leaves protein was the lowest at pH5.0,and reached the maximum at pH7.0;After heating the Lycium barbarum L.leaves protein,its advanced structure changes when the temperature reaches 85.73℃,that is,the deformation temperature of Lycium barbarum L.leaves protein is 85.73℃.The study on the chemical properties and fine structure of the four extracts from Lycium barbarum L.leaves will provide extensive feasibility for further research on the structure-activity relationship of Lycium barbarum L.leaves.(3)The biological activity of the extract from Lycium barbarum L.leaves was screened through antioxidant and enzyme inhibition experiments in vitro.In vitro antioxidant experiments,four extracts showed significant dose-effect relationships,among which the antioxidant capacity of Lycium barbarum L.leaves polyphenols was the best,while the antioxidant capacity of Lycium barbarum L.leaves protein was the worst;In vitro enzyme activity inhibition experiments,it was found that the inhibitory effects of Lycium barbarum L.leaves polyphenols,alkaloids,polysaccharides,and proteins on the four enzymes were proportional to the mass concentration of the sample.Therefore,the polyphenols,polysaccharides,proteins,and alkaloids in the Lycium barbarum L.leaves have antioxidant,hypoglycemic,and hypolipidemic effects.