Full Length Research Paper

Adsorption separation of 3b-D-monoglucuronyl-18b-glycyrrhetinic acid from directional biotransformation products of glycyrrhizin

Dingqiang Lu^{1, 2}*, Shumin Zhang¹, Jun Wang¹, Hui Li¹ and Yan Dai¹

¹College of Life Science and Pharmaceutical Engineering, Nanjing University of Technology, Nanjing 210009, P.R. China.

²Jiangsu Provincial Institute of Materia Medica, Nanjing 210009, P.R. China.

*Corresponding author. E-mail: ludingqiang@njut.edu.cn. Tel: 86-25- 8328-5202.

Accepted 22 September, 2008

3β-D-monoglucuronyl-18b-glycyrrhetinic acid (GAMG) can be obtained on a large scale by directional hydrolysis of glycyrrhizin (GL) with b-glucuronidases, which has more physiologically potential application than GL in a wide range of biological activities. In this study, the preparative separation of GAMG in hydrolysates of GL by macroporous resins (NKA-9, D4020, HZ-803, 1300, HP-20 and X-5) were studied systematically, and the column packed with selected resin was used to perform dynamic adsorption and desorption tests to optimize the separation process. The results shown that NKA-9 resins was the appropriate resin for the separation of GAMG and GL under pH 5, which adsorption data fitted to the Freundlich isotherm equation and pseudo-second-order kinetic model at 25ºC. While with desorption of 70-90% ethanol-water solution, GAMG with the purity of 85.02% was obtained on a NKA-9 resins packed column. Comparing with conventional methods, the developed method can successfully improve product yield and reduce the consumption of raw materials in the biotransformation process of GL. The structure identification of each pure fraction was carried out by ¹H and ¹³C NMR.

Key words: 3b-D-monoglucuronyl-18b-glycyrrhetinic acid (GAMG), glycyrrhizin (GL), adsorption separation, macroporous resin, directional bio-transformation.