Study on Plant Polyphenol Extraction from Mulberry Leaves by Propyl Alcohol-Ammonium Sulfate Aqueous Two-phase System Coupling with Ultrasonic

[Objective] The study was to provide the theoretical basis for the application of aqueous two-phase technique and the development of mulberry leaves. [Method] The mulberry leaves were extracted and filtered with petroleum ether ultrasonic for 30 min after comminution,and 60 ml mixed solution of water and propyl and 13.2 g alcohol-ammonium sulfate were added into filter residue to form the aqueous two-phase system.The plant polyphenol was extracted with ultrasonic and the polyphenol content was detected and its extraction rate was calculated.[Result] In propyl alcohol-ammonium sulfate aqueous two-phase system,the stable aqueous two-phase system and higher extraction rate of plant polyphenol were obtained when the dosage of(NH4)2SO4 was 0.30 g/ml and the ratio of alcohol and water was 0.6.The extraction rate of plant polyphenol from mulberry leaves was highest when the ultrasonic time was 20 min.By using this extraction method the extraction rate of plant polyphenol from mulberry leaves was 1.83%,and the polyphenol content in plant extraction was 24.1%,which were obviously higher than that by reflux extraction.[Conclusion] With the method of ultrasonic coupling with Propyl-alcohol ammonium sulfate aqueous two-phase system to extract plant polyphenol from mulberry leaves,the extraction time could be shorten and the extraction rate was increased.Decreasing the extraction temperature was beneficial to separate the heat-sensitive ingredients,and got bioactive substances with high purity and high activity.