Extraction,purification And Application Of Total Flavones In Aboveground Parts Of Licorice And Their Application In The Preparation Of Nanometer Zinc Oxide

Liquorice,as a medicinal herb,contains more than 30 species and has a wide distribution range.At present,the use of liquorice is limited to its roots,and the above ground part of liquorice is mostly used for the feed of farm animals and the fuel of farmers,which is a great waste of resources.To alleviate the shortage of liquorice resources,we should give full play to the rational use of the effective components of liquorice.In this thesis,on the basis of exploring the influence of various influencing factors on the yield of total flavonoids,a response surface scheme was designed to optimize the extraction process,improve the yield of total flavonoids,and make full use of liquorice resources.The macroporous resin purification method was used to improve the content of total flavonoids in the extracts.Resins with different polarity models were selected for screening.The adsorption kinetics model and thermodynamic model were combined to explore the adsorption characteristics.The influence factors of the resin in the adsorption process were optimized,the purification process was optimized,and the antioxidant activity of the total flavonoids was evaluated.Nano-sized zinc oxide was prepared from the aboveground extract of licorice by coordination and calcination with zinc source.Then the photocatalytic and antibacterial activities of nano-sized zinc oxide were studied.The research contents mainly include:?.The response surface method to optimize the extraction of total flavones in the above ground parts of licorice technology researchBased on the experimental analysis of various factors affecting the yield of total flavonoids,a response surface scheme was designed to optimize the extraction process.The optimal extraction conditions were as follows: ethanol concentration is 83 wt%,extraction time is 2.6 h,extraction temperature is 80?,and the material-to-liquid ratio is 1:17.The yield of total flavonoids under this process is 1.51%,and the theoretical error(RSD)is small,indicating that the experimental process is stable and feasible.?.Macroporous resin purification technology research of total flavones in the above ground parts of licorice and its antioxidant activityThe static adsorption and desorption method was used for different polarity macroporous resins,and the results of adsorption and desorption rate were investigated.Combined with the kinetic model,the optimal adsorption resin was selected.The purification process optimization was investigated by taking each influencing factor in the purification process as the single factor condition,and the purification scheme was further optimized by calculating adsorption thermodynamic parameters.The optimal purification process for HPD-100 macroporous resin was as follows: the concentration of sample solution was 1.62 mg/m L,the pH of sample solution was 5,the loading speed was 1 BV/h,and the loading volume was 3.0BV.The desorption process was 70 wt% ethanol elution,eluent velocity was 2 BV/h,and elution volume was 2 BV.The content of total flavonoids in the above ground part of licorice was increased from(6.8±0.37)% to(36.5±0.48)%,an increase of about 5.4 times.It was proved that the experimental conditions were low cost and good purification.The antioxidant activity of total flavonoids in vitro showed that DPPH free radical scavenging rate was 81%and hydroxyl free radical scavenging rate was 82.3% at the concentration of 1.2 mg/m L.When the concentration was higher than 0.75 mg/m L,the reducing power of total flavonoids in the above ground part of licorice was greater than that of ascorbic acid(VC).?.Green synthesis of nanometer zinc oxide particles from the above ground parts of licorice extract and its photocatalytic degradation and antibacterial activityNanometer zinc oxide particles(ZnONPs)were prepared by coordination synthesis and calcination with licorice extract as a template.The green products were analyzed and identified by basic characterization methods.The catalytic degradation and antibacterial activity of ZnONPs were investigated by photocatalysis,inhibition zone method,and minimum inhibition concentration.The results show that the ZnONPs are hexagonal wurtzite structures with the size of 52.3 nm,and the distribution is uniform.Under the light,the degradation rate of pollutants was 98% within 120 min,which indicated that the green ZnONPs had good catalytic degradation properties.The antimicrobial properties of ZnONPs were tested with Staphylococcus aureus and Escherichia coli as research objects.The results showed that the diameters of the inhibition zone against the two strains were 11 mm and 14 mm,respectively,which were similar to those of ceftazidime.The minimum inhibitory concentration(MIC)values of ZnONPs were 2 mg/m L and 1 mg/m L,respectively,indicating that ZnONPs also had good antibacterial effect.