Comparative Study on Two Extraction Methods of Total Flavonoids from Lotus Leaf

The optimum extraction method of total flavonoids with the ultrasound-assisted ethanol extraction and two-aqueous phase system from lotus leaf was investigated,respectively,through single factor experiments. The extraction efficiency of the two methods was compared. The result showed that the optimum condition of ultrasound extraction was62% ethanol by extracting 31 min under 45 ℃ with 40∶1 solid-Liquid ratio. The optimum condition of two-aqueous phase system extraction was 20% PEG600 and 25%( NH4)2SO4system by extracting at pH 11 and temperature 25 ℃.The average yield of total flavonoids reached 14. 7% by ultrasound-assisted ethanol extraction,and the average yield of total flavonoids was 23% by two-aqueous phase system extraction. The two-aqueous phase system extraction had better efficiency than ultrasound-assisted ethanol extraction in the both yield and concentration of total flavonoids from lotus leaf.