ISHS Acta Horticulturae 629: XXVI International Horticultural Congress: The Future for Medicinal and Aromatic Plants
A RAPID METHOD TO ANALYZE SAPONIN PRECURSORS IN SOYBEAN (GLYCINE MAX (L.) MERRILL) |
| Authors: | H.P.V. Rupasinghe, C.C. Jackson, V. Poysa, J. Kinjo |
| Keywords: | Soyasapogenol, triterpene aglycones, histochemical analysis, HPLC/ELSD, acid hydrolysis |
| Abstract:
A rapid and efficient analytical method was developed to distinguish and to quantify two major saponin precursors in soybeans; soyasapogenol A, contributing to the undesirable sensory characteristics, and soyasapogenol B, representing group B and E saponins, which have chemoprotective properties. Aqueous ethanolic extraction (80 % v/v) yielded the highest recovery of saponin from finely ground soybean powder. Acid hydrolysis of extracted saponin in 8 % HCl in anhydrous methanol at 75 C° for 3 hrs cleaved the attached sugar moietie(s) completely from the triterpene aglycones and produced no artifacts. Resultant soyasapogenols were isolated using solid phase extraction and chromatograms of high resolution were obtained by HPLC equipped with evaporative light scattering detector (ELSD). Histochemical analysis revealed that soyasapogenols are mainly concentrated in the axis of seed compared with cotyledon and seed coat. To determine the distribution of soyasapogenol A and B in soybean, 10 advanced food-grade soybean lines were grown in 1999 at four locations in Ontario. In general, total soyasapogenol content in soybeans was 0.2±0.02 %. Soyasapogenol B content (1480±200 µg/g) was 2.5 to 4.5-fold higher than soyasapogenol A content (479±72 µg/g). A significant variation in soyasapogenol content was observed among the cultivars tested. | |
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