ISOLATION AND PURIFICATION OF SOY ISOFLAVONES FROM SOYBEAN EXTRACTS BY ADSORPTION CHROMATOGRAPHY ON 12% CROSS-LINKED AGAROSE GEL MEDIA

Abstract

A chromatographic method for isolation and purification of soy isoflavones from soybean extracts was established by using 12% cross-linked agarose gel, Superose 12, as the separation media. 30% and 65% methanol in gradient elution mode was employed for separation. Soybean extracts were separated by the proposed method and six soy isoflavones, including glycitin, daidzin, genistin, glycitein, daidzein, and genistein, were obtained. The purity of these compounds was 97.8%, 98.5%, 99.4%, 99.0%, 98.8%, 99.2%, respectively, which was determined by HPLC area normalization method. The retention behavior of soy isoflavones on Superose 12 was also discussed. The retention is based on a mixture of hydrogen bonding and hydrophobic interactions between the hydroxyl groups of soy isoflavones and the residues of the cross-linking reagents used in the manufacturing process of Superose 12.

Keywords:

• adsorption
• chromatography
• cross-linked agarose gel
• isoflavones
• purification

ACKNOWLEDGMENT

This work was supported by Natural Science Foundation of China (No 31170110), Natural Science Foundation of Shandong Province (No 2009ZRB01753), Key National Science & Technology Specific Projects of China (2010ZX09401-302-5-12), Key Technologies R&D Program of Shandong Province (No 2010GWZ20243), and The Project of Taishan Scholarship of Shandong Province.

Notes

*Retention factor k is calculated as follows: ; where t _R is the retention time for retained species and t _M the time for unretained species (dead time).