Efficient enzymatic hydrolysis of Protogracillin for clean preparation of Prosapogenin A by response surface methodology optimization

Abstract

Prosapogenin A (also known as Progenin III and polyphyllin V), a secondary steroidal saponin in Dioscorea zingiberensis tubers, has more superior pharmacological activities than its primary form Protogracillin. Conventional preparation methods, such as column chromatography, and acidic hydrolysis, are of very low efficiency and limited scale due to tedious procedures and large consumption of organic solvent. This study aims to establish a convenient method for efficiently obtaining Prosapogenin A by enzymatic hydrolysis of abundant Protogracillin in the raw material. In light of the highest hydrolysis performance, β-dextranase was selected from four commercial enzymes in this application. After optimization of the conditions by the response surface methodology using Box–Behnken design, the enzymatic hydrolysis was carried out in 0.20 M HAc-NaAc buffer (pH 4.81) containing β-dextranase/Protogracillin (5.0:1, w/w), and the system was constantly kept at 56.7°C water bath for 4 h. Consequently, Protogracillin has been almost completely hydrolyzed to be Prosapogenin A and the highest yield was 96.4 ± 1.4%. The newly proposed approach is efficient and promising for conveniently obtaining Prosapogenin A and aimed to provide a laboratory-scale experimental foundation for the preparation of Prosapogenin A in industrial applications.