Separation of Flavonoids from Bamboo Leaves by Aqueous Two-Phase Extraction

The polyethylene glycol(PEG)/(NH4)2SO4 aqueous two-phase system was used to extract flavonoids from water extract of bamboo leaves.Effects of the molecular weight,mass fraction of PEG,mass fraction of(NH4)2 SO4,pH,mass fraction of NaCl,mass fraction of water extract solution and temperature on the aqueous two-phase system and extraction of flavonoids were studied.The optimal conditions were obtained by response surface methodology designed as: average molecular weight of PEG was 400,quality percentage of PEG was 31%,quality percentage of(NH4)2SO4 was 11%,pH was 3.9,quality percentage of NaCl was 0.7%,temperature was 20℃,quality percentage of water extract solution was 51.5%.Under these conditions,the extraction rate of flavonoids was 97.8%.The results indicate that aqueous two-phase system is simple and convenient,low cost,without causing inactivation and denaturation of biological materials.The method is suitable for extraction and separation of flavonoids.