Study On Purification Of Flavonoids And Polysaccharides In Lycium Barbarum L. By Foam Separation

Lycium barbarum L. is a special kind of plant resources widely distributed in northwest plateau, as well as an important economic crop in the farm and pastoral area in Qinghai province. Flavonoids and Lycium barbarum polysaccharides(LBPs)are natural active components in Lycium barbarum L., which possess many useful physiological functions. Fundamental study on their extraction, isolation and purification is of high importance for the development and utilization of Lycium barbarum L. resources.This paper selected Lycium barbarum from nuomuhong as sample, and ethanol extraction assisted by ultrasound method was conducted to gain the total flavonoids,followed by basic separation using solvent sublation. Furthermore, anti-oxidation activity of the product was evaluated by the capacity of eliminating free radical. First of all, through orthogonal design, effect of ethanol concentration, p H value,temperature and extraction time on the yield of flavonoids was optimized, and under the existed conditions, when regulate p H value to 8.00 and temperature 70 ℃, 70%ethanol used as solvent to extract for 60 min, content of total flavonoids reached highest to 0.253%. Secondly, solvent sublation was selected to purify flavonoids in the extract after hydrolysis, and influence of single factors p H value, sublation time,temperature and ion strength on enrichment ratio and recovery was optimized by orthogonal experiment. Results showed that butanol saturated by water as solvent, ion strength was 0.06 mol/kg, p H value 6.00, temperature 20 ℃ and floated for 75 min,enrichment ratio and recovery can be ideal and content of flavonoids in the solvent layer can reached 0.371%; thirdly, according to HPLC, content of quercetin,kaempferol and isorhamnetin in the solvent layer were 0.574 μg/m L, 0.439 μg/m L and 0.355 μg/m L. Finally, by scavenging DPPH free radical trials, half removals value(EC50) of the purified product is 1.392 μg/m L, drawing a conclusion that the elimination capacity is 3.06 times compared with the same concentration of Vc. On the other hand, LBPs was obtained from the residue by hot water extraction, and content of total LBPs and uronic acid were detected by phenol-sulfuric and hydroxy-biphenyl method, which were 3.49% and 1.05%, respectively. Then effect ofdilution ratio, initial p H value and gas velocity on foam separation was inspected and response surface methodology was used to obtain the optimal technological parameters: when diluted 7.6 times, regulate p H to 3.42, bubbling under a gas velocity of 295 m L/min, theory value of enrichment ratio and recovery were 2.57 and 57.31%,and relative errors are 6.6% and 6.5%, compared with validation value(2.41 and61.28%). As for the dynamics process, simulated model showed that the foam separation process of LBPs belongs to first-order kinetics model and equivalent rate constant is 0.00602 min-1.In this text, the study established a novel method for the separation and purification of flavonoids and polysaccharides in Lycium barbarum L., which provides basic theoretic support and technological guidance for the development and utilization of Lycium barbarum L..