Countercurrent Chromatographic Separation of Soybean Isoflavones by Two Different Types of Coil Planet Centrifuges with Various Two‐Phase Solvent Systems

Abstract

The countercurrent chromatographic separation of isoflavones from a crude soybean extract was performed with various two‐phase solvent systems, using two different types of the coil planet centrifuge (CPC) of the cross‐axis CPC and the type‐J multilayer CPC. The overall results indicated that the type‐J multilayer CPC separates daidzin and genistin with an ethyl acetate/ethanol/water (4:2:7) system at the purity of over 97 and near 100%, respectively, while the cross‐axis CPC resolves these compounds in a much longer elution time with an ethyl acetate/1‐butanol/water (2:1:3) system. The type‐J multilayer CPC further resolves daidzein and genistein with an n‐hexane/ethyl acetate/1‐butanol/methanol/water (5:5:0:5:5) system, and also, simultaneously, all four isoflavones under a linear gradient elution, using the solvent system composed of n‐hexane/ethyl acetate/1‐butanol/methanol/acetic acid/water by shifting the volume ratio from 1:2:1:1:1:5 to 1:2:1:3:0.5:5. The present methods may be useful for the separation of isoflavones from other plant extracts.

Keywords:

• Countercurrent chromatography
• Isoflavones
• Coil plant centrifuge
• Two‐phase solvent system

Acknowledgments

The authors would like to thank Misses Makiko Yanagi, Yuka Yakou and Sayaka Kato for their technical assistance. The authors are also indebted to Ms. Etsu Katori and Prof. Susumu Kitanaka (College of Pharmacy, Nihon University, Chiba, Japan) for their helpful advice.