ARS | Publication request: COMPLETE QUANTIFICATION OF GROUP A AND GROUP B SOYASAPONINS IN SOYBEANS

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 3, 2006
Publication Date: February 28, 2006
Citation: Berhow, M.A., Kong, Suk Bin, Vermillion, K.E., Duval, S.M. 2006. Complete quantification of group A and group B soyasaponins in soybeans. Journal of Agricultural and Food Chemistry. 54:2035-2044.

Interpretive Summary: Consumption of soy foods has been associated with the prevention or mitigation of a number of chronic diseases, such as heart disease and cancer. The identity and the exact nature of the mode of action of the compounds in soy which contribute to this effect are still not known. This paper outlines the procedure to identify and purify several phytochemical species from one group of compounds known as the saponins from soy germ, which was shown to be a rich source. These standards and methods will be used to accurately measure the levels of the saponins in soy and soy foods and to provide sufficient quantities of the purified soy saponins for evaluation of their biological effects in both cell culture and animal model systems.

Technical Abstract: A combination of high-pressure extraction and preparative HPLC was used to purify the group A and group B soyasaponins from soy germ for use as analytical standards and in biological assays. A standardized sample preparation and extraction method was developed for the analysis of the phytochemicals found in soy and processed soy products, which is reproducible in other labs as well as our own. The extracts can be analyzed with standard LC-MS and HPLC methods to identify and quantitate the group A and group B forms of the soy saponins, as well as the soy isoflavones. Complete saponin analysis of the extracts prepared from soy germ (hypocots), hulls, and cotyledons show that a significant portion of the saponins is concentrated in the germ. The germ contains nearly all the group A soyasaponins, while the group B soyasaponins are nearly equally distributed between the germ and cotyledons. The hulls contain little in the way of either isoflavones or saponins. Whole (full fat) 2003 central Illinois soybeans contain approximately 3-5% saponins on a weight basis, of which about one-sixth or less of the total saponin content is group A soyasaponins, the balance being group B soyasaponins.