Extraction Of Platycodn D And Lobetyolin From Platycodon Grandifloras And Catalytic Conversion Processes

Focusing on the needs of national economic and social development,the study of Platycodon grandiflorus（Jacq.）A.DC.),a medicinal plant characteristic of northeastern China,was conducted.The immunologically active monomeric compounds platycodin D and lobetyolin were obtained by efficient isolation and transformation using high yield,green and clean modern technology.In order to provide basic support for the preparation of high-end and high-value products of platycodin D,lobetyolin or their mixture components,we seek to improve the multiple value-added of the characteristic Chinese herbal products by extending the industrial chain.The results of the study are as follows:The extraction experiments in this thesis used polyethylene glycol 200（PEG 200）and polyethylene glycol 400（PEG 400）as extraction solvents and ultrasonic extraction technique for the synergistic extraction of platycodin D and lobetyolin;the optimal extraction conditions for the synergistic extraction of platycodin D and lobetyolin were obtained by Box-Behnken response surface optimization after single factor screening:concentration was 10%polyethylene glycol（PEG200+PEG400,v:v=1:1）as extraction solvent,ultrasonic irradiation power was280 W,liquid to material ratio was 23 m L/g,ultrasonic irradiation time was 43 min,ultrasonic system temperature was 30℃,cavitation time was 1.0 s,and buffer time was 1.5 s.Under these experimental conditions,the yield of platycodin D was 5.12±0.13 mg/g,and the yield of lobetyolin was 0.14±0.01 mg/g.Various enzymes such as cellulase,hemicellulase and pectinase were screened for their catalytic conversion efficiency of platycodin in P.grandiflorus extracts using the yield of platycodin D as an index.The experimental results showed that the hemicellulase catalyzed conversion of platycodin into platycodin D was the most efficient in the hydrolysis system under the same catalytic conditions.On this basis,Mg Al hydrotalcite immobilized hemicellulase（Mg Al-HC-LDH）catalysts were prepared by co-precipitation method with a solid loading capacity of 72.54 mg/g.Analysis of the SEM results showed that the synthesized Mg Al-HC-LDH had an irregular lamellar structure.The corresponding energy spectrum analysis showed that the synthesized Mg Al-HC-LDH contained N elements,indicating that the hemicellulase had been immobilized on Mg-Al hydrotalcite.The characteristic peaks of the-NH₂ group appeared near 2840 cm^-1 and 2750 cm^-1 in the infrared spectrum,which proved that hemicellulase was successfully embedded in the interlayer of Mg-Al hydrotalcite.X-ray diffraction results show that the synthesized ones have a crystalline structure and the crystalline forms are all hexagonal.The results of thermogravimetric analysis showed that the synthesized Mg Al-HC-LDH all had good heat resistance properties.The optimal process conditions for Mg Al-HC-LDH catalysis of platycodin were determined experimentally:the immobilized hemicellulase was added at an activity of 5 U in 10 m L of P.grandiflorus extract,the reaction temperature was 60℃,the p H of the hydrolysis system was5.0,and the reaction time was 60 min.The platycodin D in the extract catalyzed by Mg Al-HC-LDH increased from 0.65 mg/m L to 0.86 mg/m L,an increase of 32.31%.The Mg Al-HC-LDH catalyst maintained a fair catalytic effect after four repeated uses.In this paper,an innovative attempt was made to use non-volatile polyethylene glycol solution as an alternative to traditional ethanol and methanol solutions as extraction solvents,which resulted in high yields of platycodin D and lobetyolin,with less environmental impact and safer operation.An attempt was made to prepare platycodin D by using Mg Al-HC-LDH catalyzed transformation of platycodin,which resulted in a significant increase in the yield of platycodin D.