| Ergothioneine(EGT),named trimethylbetaineof 2-thiol-L-histidineis,is a kind of secondary metabolites synthesized by a handful of microorganisms,such as edible fungi.EGThas a high application value in the food,cosmetics and biomedical industries because of its unique multifunctional cellular physiological functions.The content of EGT in common edible fungi is significantly higher than that of other types of microorganisms,and edible fungi are readily available,which can be a good resource for the preparation of EGT.The extraction process,separation and purification process of EGT from Flammulina velutipes were optimized in this study.The embedding process of the purified EGT and its effect on the antioxidant activity of EGT were alsoinvestigated.The results could provide the theoretical basis for the explorationand utilization of the EGT from Flammulina velutipes.The main contents and results are as follows:(1)Effects of different extraction methods on EGT yield of Flammulina velutipes were studied.The results showed that the different extraction methods could significantly(P < 0.05)affect the yield of EGT in Flammulina velutipes,in which secondary extraction(3.23mg/gDW)> solvent extraction(2.87mg/gDW)> microwave ultrasonic extraction(2.82 mg/gDW)> ultrasonic extraction(2.35 mg/gDW).In order to save reagents and time,the method of solvent extraction was used to extract the EGT in Flammulina velutipes.(2)The conditions of extracting the EGT were optimized by the single factor experiment and the response surface method.The results showed that in the factors selected,three factors which had a significant effect on the extract were the solid-liquid ratio,ethanol concentration and extraction temperature.The optimized final extraction condition is ethanol concentration 62%,the liquid material ratio 58:1,the temperature 53 ?,the substitute for the fitting equation obtains the extract quantity is 3.48(mg/g dry weight),and the extraction amount under the condition may be due to the different production period and the batch changes,generally around 3.5(mg / g dry weight).(3)The optimization of purification conditions of EGT extraction were studied.The results showed that Sephadex G-10 had the optimum effect on the purification of EGT using three kinds of dextran gels and five macroporous resins.The above sample quantity,column height and elution speed were used to design the orthogonal experiment to optimized the purification condition,andthe optimum purification conditions are gel column height is 20 cm,loading quantity of sample is 2mL,the elution speed is 0.5mL/min.Three repeated trials with this condition were made,the yield of EGT were 92.4%,95.31% and 94.22%,and the purity were 52.51%,55.01% and 56.98%,respectively.(4)The embedding conditions of purified EGT were studied.The results showed that EGT was onlydetected in atype of capsule of the four selected microencapsulation methods,which wasdried by spray drying method,using the non-emulsified EGT purification solution as the core material and sodium alginate: gelatin =2:3 as a wall material(core: wall =1:5).However,the yield of capsule was only 11.34%,and the embedding rate was only 5.4%.While for enteric capsule of purifiedEGT liquid.The acid dissolution of enteric capsule was less than 10%,andthe dissolution were average of83.56%(>70%)in buffer solution,which in line with the requirements of the Chinese Pharmacopoeia.By detecting the DPPH clearance under the same ergot concentration,showed that the purified EGT solution(96.9%)> EGT enteric capsules treated by acid(85.3%)> the purified EGT solution treated with acid(44.7%),indicatedt he enteric capsules could effectively protect the EGT in low pH environment from the damage to its antioxidant activity. |
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