Analytical Sciences

Simple and Rapid Separation of Soyasaponin Bb from a Soy Extract

Hajime KATANO,* Nobuhiro OKAMOTO,* Masahiro TAKAKUWA,* Shu TAIRA,* Taiho KAMBE,** and Masakazu TAKAHASHI*

*Department of Bioscience, Fukui Prefectural University, Eiheiji, Fukui 910-1195, Japan
**Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan

A simple method to separate soyasaponin Bb from a soy extract is presented. This method is based on the difference in the solubility of soyasaponin Bb and Ba and other components into 3:7 and 1:1 (v/v) acetone–water mixed solvents. The crude soyasaponin consisting of soyasaponins Aa, Ab, Ba, and Bb at the 10 wt% level and other components was examined as the soy extract. A 10 mg quantity of the crude soyasaponin was mixed with 1 mL of the 3:7 acetone–water containing 0.1 mol/L HCl, and the supernatant was removed to obtain a precipitate, which was found to contain mainly soyasaponins Bb and Ba. The precipitate was mixed with 0.4 mL of the 1:1 acetone–water containing 0.1 mol/L HCl; the supernatant was transferred, and was mixed with 0.6 mL of water to obtain a precipitate, which was found to contain mainly soyasaponin Bb. The yield was ca. 30%, which may be much higher than that by the conventional preparative chromatographic approach. The separation method is rapid and easy to carry out, and is useful for the preparation of a soyasaponin Bb sample.

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