Purification,Composition Analysis And Antioxidant Activity Of Fermented Dandelion Flavonoids

Dandelion(Taraxacum mongolicum Hand Mazz)is a member of the composite family,is a kind of medicine and food plant.Flavonoids are one of the main active components of dandelion,can effectively eliminate free radicals,prevent lipid peroxidation,has strong antioxidant activity.The separation and purification process of fermented dandelion flavonoids(FDF)was established.The composition of purified fermented dandelion flavonoids(PFDF)was analyzed by UPLC-MS/MS technique,Its antioxidant activity was evaluated in vitro and in vivo.The thesis mainly includes the following parts:1.Separation and purification of FDF(1)Separation of FDFThe separation technology of flavonoids from dandelion was established by hot water extraction and ethanol extraction.The best water extraction process is:The ratio of material to water was 1:20,the extraction temperature was 80,the extraction time was 30min;The best alcohol extraction process is:The ethanol concentration was 40%,the ratio of material to liquid was 1:35,the extraction temperature was 70.and the extraction time was 30min.Under these conditions,the content of flavonoids was 144.28 mg/g.(2)Purification of FDFThe FDF was further purified by static dynamic adsorption and desorption experiments.AB-8 macroporous resin had the best purification effect on FDF.The optimal adsorption condition is:The concentration of the sample solution was 2 mg/mL,the pH of the sample solution was 2,and the product of the sample solution was 120 mL;The optimal desorption condition is:The concentration of ethanol was 70%,the pH was 5,and the elution liquid volume was 90 mL.The PFDF were purified under these conditions,and the content of flavonoids was 356.08 mg/mL.2.Composition and structure of PFDFThe composition of PFDF was analyzed by UPLC-MS/MS method.The results showed that PFDF was mainly composed of flavonoid,flavonols,isoflavones and flavanols,etc,a total of 135 flavonoids were identified.The main flavonoids aglycone in PFDF include Luteolin,Hispidulin,Diosmetin,Taxifolin,Tricin,etc.The main flavonoglycosides are contained Luteolin 7-O-glucoside,Kaempferol 3-O-rutinoside,Quercetin-3-O-α-L-rhamnop yranoside,Kaempferol-3-O-neohesperidoside,Luteolin-7-O-rutinoside,Kaempferol 3-O-robinobioside(Biorobin),Kaempferol-3-O-glucoside-7-O-rhamnoside,Lonicerin,Avicularin,Astragalin,etc.These relatively high content substances have special structural characteristics and have antioxidant activity.3.Antioxidant activity of PFDF(1)In vitro antioxidant activity of PFDFIn vitro antioxidant activity of PFDF was evaluated by measuring DPPH free radicals,hydroxyl radical scavenging ability and reducing power.The results showed that PFDF had strong reducing power and hydroxyl radical scavenging ability.At the same concentration,the DPPH radical scavenging rate of PFDF was similar to Vitamin c.The purified fermented dandelion flavonoids had strong in vitro antioxidant capacity.(2)In vivo antioxidant activity of PFDFTaking zebrafish embryos as the research object,the mitigation effects of PFDF on AAPH-induced oxidative stress in zebrafish embryos was evaluated by fluorescence analysis and enzyme detection methods.The results of fluorescence analysis showed that PFDF reduced the reactive oxygen species(ROS)production rate and the degree of lipid peroxidation of zebrafish under AAPH-induced oxidative stress.Antioxidant enzyme activity analysis showed that the superoxide dismutase(SOD)and catalase(CAT)activities in zebrafish embryos were significantly reduced after AAPH exp osure.The co-exposure of PFDF and AAPH can significantly increase the activities of SOD and CAT in zebrafish embryos.The above research results show that the PFDF have strong antioxidant activity in vivo.The above experiments showed that the dandelion flavonoids could be enriched effectively by the purification of AB-8 macroporous resin by hot water extraction combined with ethanol,and it was composed of 135 kinds of flavonoids.Dandelion flavone had certain antioxidant activity,which significantly alleviated the oxidative stress induced by AAPH in zebrafish embryos.