Optimization Of Extraction Technology And Activity Determination Of Total Alkaloids From Astragalus

Astragalus adsurgens,as an excellent pasture containing alkaloids,has broad adaptability,high yield and abundant resources.The active substances of Astragalus adsurgens have the important development and utilization values.In this study,the extraction and purification process of the total alkaloids of Astragalus adsurgens was optimized,and its activity was determined.The results of the study would improve the utilization of the total alkaloids of Astragalus adsurgens as a green feed additive,Furthermore,the results could provide technical guarantee for healthy breeding without antibiotics.Firstly,a single-factor experimental design were carried out in this study,with five ethanol concentration of 75%,80%,85%,90% and 95%,five gradients of material-to-liquid ratio of 1:15,1:20,1:25,1:30 and 1:35,5 extraction time of 2h,2.5h,3h,3.5h and 4h.The relationship between the different levels of the above three factors and the total alkaloid yield was analyzed to obtain 3 suitable levels for each factor;Based on the above results,the Box-Behnken response surface method was used to design a three-factor and three-level central combination experiment to optimize the extraction process of Astragalus adsurgens total alkaloids.During the purification process,the sample concentration(2mg/ml,4mg/ ml,6mg/ml),sample solution p H(4,5,6),ethanol concentration(70%,80%,90%),flow rate(1Bv/h,2Bv/h,3Bv/h)were used in orthogonal test design,macroporous resin was used as the chromatography carrier.The antioxidant activity and antibacterial activity of the purified total alkaloids were determined.The results showed that the total alkaloid yield of Astragalus adsurgens is the highest when the ethanol concentration is 80%,the material-to-liquid ratio is 1:20,and the extraction time is 2.5h.The response surface experiment indicated that the optimal extraction conditions for the total alkaloids of Astragalus adsurgens were 80.93% ethanol,the ratio of material to liquid equal to 1:21.36,and 2.75 h extraction time.which could obtain 1.4243%,the predicted maximum yield of the total alkaloids of Astragalus adsurgens.The optimized purification conditions are: the sample concentration(6mg/m L),the p H of the sample solution(5),the ethanol concentration of elution(70%),and the elution flow rate(3BV/h).In this condition,the purity of the total alkaloids increased by 3.36 times.The results of antioxidant activity and antibacterial activity confirmed the strong antioxidant capacity of total alkaloids,and the removal rate gradually increased with the increase of the concentration of total alkaloids of Astragalus adsurgens.The MIC for Staphylococcus aureus and Escherichia coli are 100mg/ml and 50mg/ml,respectively.