The Extraction,Derivatization And Packaging Materials Application Of Esculin

With the development of medical science and technology,the theory of traditional Chinese medicine with syndrome differentiation and overall concept has been paid more and more attention.Among them,the research on the monomer composition of traditional Chinese medicine has become one of the main ways to develop and apply traditional Chinese medicine resources.As the active ingredient of traditional Chinese medicine Qinpi,esculin has a wide range of pharmacological activities such as antibacterial,anti-oxidant,anti-inflammatory,anti-tumor and uric acid-lowering.At present,the extraction and purification of high purity esculin monomer is a difficult point in research,and because the structure of esculin contains multiple hydroxyl groups,the fat solubility is poor,and its derivatization modification has become a research focus.In addition,the fact that esculin is hydrolyzed by enterococci to detect bacteria has not been widely used.In view of the above situation,this topic uses Qinpi as raw material,adopts ethanol reflux extraction method,optimizes the extraction process of esculin by single factor and response surface optimization design,and structurally modifies the obtained esculin.At the same time,the characteristic of esculin detecting bacteria can be applied to packaging materials to develop a functional packaging film.The experimental research mainly draws the following conclusions:1.The esculin was extracted from the Qinpi by ethanol reflux extraction.The extraction rate was taken as the index.The effects of ethanol concentration,solid-liquid ratio,extraction time and frequency on the extraction rate of esculin were investigated by single factor experiment.The optimal extraction process was optimized by response surface methodology:ethanol concentration is 70%,the liquid ratio is 1:12,and the extraction time is 2h each time.Under this condition,the extraction rate of esculin can reach 1.223%.Then,it is purified by solvent extraction,macroporous resin adsorption,recrystallization,and the like to obtain a esculin monomer having a purity of 96.38%.It was confirmed by TLC and NMR to be esculin.2.The esterification reaction of esculin with sulfur-containing organic acids(lipoic acid and thiodipropionic acid)gives two derivatives with good fat solubility and strong antioxidant activity.According to the yield,the suitable conditions for synthesizing esculin lipoic acid ester and esculin thiodipropionic acid ester were obtained by single factor experiment.The structure of the derivative was characterized by NMR and confirmed to be the target compound of the subject.The antioxidant activity analysis showed that the newly synthesized derivative had better antioxidant activity,and the removal rate was more than 90%at a lower concentration,and the antioxidant activity was higher than that of the raw material monomer and the physical mixture.Estimation result of lipid-water partition coefficient proves that the synthesized ester derivatives are better in fat solubility than esculin,and they are expected to become a new type of antioxidant additive for use in foods and cosmetics to extend the shelf life.3.The esculin can be hydrolyzed by enterococci.Using this property,the extracted purified esculin is added to the sturgeon skin gelatin to prepare a biodegradable packaging film for Enterococcus detection.Taking mechanical properties as an indicator,the suitable dosages of ferric citrate,gelatin and glycerol for the preparation of films were obtained by single factor experiment and orthogonal experiment:ferric citrate concentration of 0.4 g/L,gelatin concentration of 50 g/L,glycerol concentration of 40 mL/L.Through a study on the performance of a batch of detecting film samples containing different concentrations of esculin(Control:0g/L,E1:2g/L,E2:3.5g/L,E3:5g/L),it has been found that esculin can effectively increase the tensile strength and airtightness of the film,improve the ultraviolet barrier property and antioxidant activity,and does not denature gelatin.Combined with the analysis of the effect of checking Enterococcus,it was found that the film sample E2(concentration of esculin is 3.5g/L,concentration of ferric citrate is 0.4 g/L,gelatin concentration is 50g/L,glycerol concentration is 40mL/L)in this study optimal.The packaging film prepared according to the prescription is beneficial to the preservation and storage of the product,and can prolong the shelf life of the product.When the content is contaminated by the bacteria,the preliminary judgment can be made through the color change of the packaging,and it is expected to become a new type of degradable green packaging material.4.To study the antibacterial activity of esculin on other foodborne pathogens(Salmonella)other than Enterococcus,the results showed that the MIC value of esculin to S.Enteritidis can reach 3.135mg/mL,MBC value 6.25mg/mL,the results of growth inhibition curve showed that esculin can shorten the retardation period of Salmonella,reduce the concentration of bacteria in log phase,and effectively inhibit the growth of Salmonella.