Ultrasonic-microwave Synergistic Extraction Of Flavonoids From Sea Buckthorn Leaves And Studies On Their Constituents And Activities

Hippophae rhamnoides is a deciduous shrub native to European and Asian,which is a collective name for plants and their fruits.The branches of the Hippophae rhamnoides are gray-black,with more spines,and the fruits are spherical,orange or orange-red.As a medicinal and edible plant,Hippophae rhamnoides is rich in multiple biologically active substances,and has the effects of promoting blood circulation,removing blood stasis,relieving cough and expectorant,and strengthening the spleen and stomach.Flavonoids are an important bioactive component in Hippophae rhamnoides,mainly distributed in the leaves and fruits of Hippophae rhamnoides.Studies showed that Hippophae rhamnoides flavonoids have functions such as anti-oxidation,lowering blood sugar and lipids,and regulating metabolism,but Hippophae rhamnoides leaves are often discarded as waste.In order to make full use of flavonoids from Hippophae rhamnoides leaves,the extraction of flavonoids,microstructure,composition,antioxidant activity and processing of flavonoid tablets were studied.(1)Extracting Flavonoids with four different treatments,and comparing flavonoid yields.Scanning electron microscope to observe and analyze Hippophae rhamnoides leaves under different treatments.The results show that the surface of the sample treated with conventional solvent extraction has a complete thin-walled structure;The structure of the powder after the ultrasonic and microwave synergistic treatment was most severely damaged.(2)Extraction of flavonoids from Hippophae rhamnoides leaves by ultrasonic and microwave collaborative extraction method,with ethanol volume fraction,microwave power,ultrasonic microwave extraction time,and liquid-material ratio as factors.The optimal process parameters are:61%ethanol volume fraction,collaborative extraction time 18 min,and microwave power 446 W.Under these conditions,the extraction rate of flavonoids is high,which is 42.09 mg/g,and the model had extremely good fitting degree.(3)The structure and content of flavonoids in the extraction from Hippophae rhamnoides leaves were analyzed by HPLC.The results showed that six flavonoids were identified in the extraction,including catechin,syringic acid,kaempferol,quercetin,isorhamnetin,and myricetin.Among them,the catechin content was the highest,with 1.4748 mg/g,the other five species were between 0.1-0.3,and kaempferol was the least,with 0.1252 mg/g.(4)The anti-oxidative ability of flavonoids extraction from Hippophae rhamnoides leaves was evaluated by DPPH+,ABTS+,·OH free radical,and FRAP+.The results showed that Hippophae rhamnoides leaves flavonoids have higher antioxidant activity.(5)Blend Hippophae rhamnoides leaves flavones and ?-cyclodextrin,freeze freeze-dried in vacuum,then add corn starch,magnesium stearate,and L-HPC to make tablets.The best raw materials and auxiliary materials are:30%of the extraction from Hippophae rhamnoides leaves,and 30%of ?-cyclodextrin,20%of corn starch,1%of magnesium stearate,15%of glucose,and 4%of L-HPC.(6)Hippophae rhamnoides leaf flavonoids extract was prepared by blending,filling,sealing,sterilization and cooling to make flavonoids oral liquid.The content of flavonoid extract in oral liquid is 30%,sucrose is 15%,citric acid is 0.1%.