Soyasapogenol A and B Distribution in Soybean (Glycine max L. Merr.) in Relation to Seed Physiology, Genetic Variability, and Growing Location H. P. VASANTHA RUPASINGHE,* ,† CHUNG-JA C. JACKSON, † VAINO POYSA, ‡ CHRISTINA DI BERARDO, § J. DEREK BEWLEY, § AND JONATHAN JENKINSON | Guelph Center for Functional Foods, Laboratory Services, University of Guelph, Guelph, Ontario, N1H 8J7, Canada, Greenhouse and Processing Crops Research Center, Agriculture and Agri-Food Canada, Harrow, Ontario, N0R 1G0, Canada, Department of Botany, University of Guelph, Guelph, Ontario, N1G 2W1, Canada, and First Line Seeds Ltd., Guelph, Ontario, N1H 6H8, Canada An efficient analytical method utilizing high-performance liquid chromatography (HPLC)/evaporative light scattering detector (ELSD) was developed to isolate and quantify the two major soyasaponin aglycones or precursors in soybeans, triterpene soyasapogenol A and B. Soaking of seeds in water up to 15 h did not change the content of soyasapogenols. Seed germination had no influence on soyasapogenol A content but increased the accumulation of soyasapogenol B. Soyasapogenols were mainly concentrated in the axis of the seeds as compared with the cotyledons and seed coat. In the seedling, the root (radicle) contained the highest concentration of soyasapogenol A, while the plumule had the greatest amounts of soyasapogenol B. In 10 advanced food-grade soybean cultivars grown in four locations in Ontario, total soyasapogenol content in soybeans was 2 ( 0.3 mg/g. Soyasapogenol B content (1.5 ( 0.27 mg/g) was 2.5-4.5-fold higher than soyasapogenol A content (0.49 ( 0.1 mg/g). A significant variation in soyasapogenol content was observed among cultivars and growing locations. There was no significant correlation between the content of soyasapogenols and the total isoflavone aglycones. KEYWORDS: Soybean; Glycine max; soyasaponin; soyasapogenol; triterpene aglycones; HPLC/ELSD; isoflavones; germination; soaking INTRODUCTION The presence of saponins in soybean has attracted consider- able interest because of both their health benefits and adverse sensory characteristics. Soybean saponins are triterpenoid gly- cosides and comprise a hydrophobic aglycone (triterpenoid soyasapogenol) linked to one or more hydrophilic mono- or oligosaccharide moieties (1). Soyasaponins are classified into two major groups, soyasaponin A and B (Figure 1)(2). Group A acetylated saponins, present in soybean, are implicated as the phytochemicals mostly responsible for undesirable bitter and astringent taste (3, 4). However, group B saponins, including 2,3-dihydro-2,5-dihydroxy-6-methyl-4H-pyran-4-one (DDMP)- conjugated saponins, possess several health benefits (5, 6). They appear to possess inhibitory activity against infection by human immunodeficiency virus (HIV) (7) and the activation of Ep- stein-Barr virus early antigen (8). Soyasaponin B 1 in particular is a potent inhibitor of HIV infection in vitro and offers great potential in the treatment of retroviral infections (7). Recent in vitro studies suggest that group B saponins also possess hypocholesterolemic, immunostimulatory, anticarcinogenic, an- tioxidative, antitumor, antivirus, antihepatitic, antidiabetic, and hepatoprotective properties (9). Dietary saponins of soybean are beneficial in preventing hypercholesterolemia and aortic ath- erosclerosis in rats (10). Group A saponins appear to be a naturally occurring form, and Shiraiwa et al. (11) identified six different group A saponins, designated as Aa, Ab, Ac, Ad, Ae, and Af, according to their * To whom correspondence should be addressed. Tel: +1 519-823-1268. Fax: +1 519-767-6240. E-mail: vrupasin@lsd.uoguelph.ca. † Guelph Center for Functional Foods, University of Guelph. ‡ Agriculture and Agri-Food Canada. § Department of Botany, University of Guelph. | First Line Seeds Ltd.. Figure 1. Chemical structures of soyasaponin precursors soyasapogenol A and B. 5888 J. Agric. Food Chem. 2003, 51, 5888-5894 10.1021/jf0343736 CCC: $25.00 © 2003 American Chemical Society Published on Web 08/30/2003