Isoflavone-aglycone fraction from Glycine max : a promising raw material for isoflavone-based pharmaceutical or nutraceutical products

Abstract

he present work was designed to obtain a fraction containing high concentration of isoflavone-aglycones from Glycine max (L.) Merr., Fabaceae, named isoflavone enriched-fraction, from a dry extractcontaining isoflavones-glycosides. A simple and low cost method was proposed: extraction of isoflavoneglycosides from the G. max dry extract with a proper solvent, hydrolysis of the glycosides, recovery ofthe aglycones, and purification of the fraction containing high isoflavone-aglycones concentration. Allthe extraction and purification parameters were optimized based on the isoflavones yields, which wereanalyzed by liquid chromatography and expressed as total isoflavone aglycones. The optimization of theprocess conditions was accomplished using the classical one-variable-at-a-time method. The identity andpurity of the isoflavones contained in this enriched fraction were determined by LC/UV/ESI/MS analysis,Fourier transformed-infrared spectroscopy, and1H and13C nuclear magnetic resonance spectroscopy.The physicochemical properties of the isoflavone enriched-fraction were evaluated by scanning elec-tron microscopy, X-ray diffraction and differential scanning calorimetry. The moisture content, particlesize, equilibrium solubility and thermal and photostability were also determined. The high isoflavone-aglycone content (daidzein, 489.35 mg/g; glycitein, 251.02 mg/g and genistein, 158.96 mg/g) as well asthe high purity obtained (90% of total isoflavones) make this fraction a promising novel raw material forthe production of isoflavone-aglycones based pharmaceuticals or functional foods.