ABSTRACT
ABSTRACT The 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 extract containing isoflavones-glycosides. A simple and low cost method was proposed: extraction of isoflavone glycosides from the G. max dry extract with a proper solvent, hydrolysis of the glycosides, recovery of the aglycones, and purification of the fraction containing high isoflavone-aglycones concentration. All the extraction and purification parameters were optimized based on the isoflavones yields, which were analyzed by liquid chromatography and expressed as total isoflavone aglycones. The optimization of the process conditions was accomplished using the classical one-variable-at-a-time method. The identity and purity of the isoflavones contained in this enriched fraction were determined by LC/UV/ESI/MS analysis, Fourier transformed-infrared spectroscopy, and 1H and 13C nuclear magnetic resonance spectroscopy. The physicochemical properties of the isoflavone enriched-fraction were evaluated by scanning electron microscopy, X-ray diffraction and differential scanning calorimetry. The moisture content, particle size, 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 as the high purity obtained (90% of total isoflavones) make this fraction a promising novel raw material for the production of isoflavone-aglycones based pharmaceuticals or functional foods.
ABSTRACT
BACKGROUND/OBJECTIVES: Fermentation can increase functional compounds in fermented soybean products, thereby improving antioxidant and/or anti-inflammatory activities. We investigated the changes in the contents of phenolics and isoflavones, antioxidant activity and anti-inflammatory activity of Doenjang during fermentation and aging. MATERIALS/METHODS: Doenjang was made by inoculating Aspergillus oryzae and Bacillus licheniformis in soybeans, fermenting and aging for 1, 3, 6, 8, and 12 months (D1, D3, D6, D8, and D12). Doenjang was extracted using ethanol, and sequentially fractioned by hexane, dichloromethane (DM), ethylacetate (EA), n-butanol, and water. The contents of total phenolics, flavonoids and isoflavones, 2,2-diphenyl-1 picryl hydrazyl (DPPH) radical scavenging activity, and ferric reducing antioxidant power (FRAP) were measured. Anti-inflammatory effects in terms of nitric oxide (NO), prostaglandin (PG) E2 and pro-inflammatory cytokine production and inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 expressions were also measured using LPS-treated RAW 264.7 macrophages. RESULTS: Total phenolic and flavonoid contents showed a gradual increase during fermentation and 6 months of aging and were sustained thereafter. DPPH radical scavenging activity and FRAP were increased by fermentation. FRAP was further increased by aging, but DPPH radical scavenging activity was not. Total isoflavone and glycoside contents decreased during fermentation and the aging process, while aglycone content and its proportion increased up to 3 or 6 months of aging and then showed a slow decrease. DM and EA fractions of Doenjang showed much higher total phenolic and flavonoid contents, and DPPH radical scavenging activity than the others. At 100 microg/mL, DM and EA fractions of D12 showed strongly suppressed NO production to 55.6% and 52.5% of control, respectively, and PGE2 production to 25.0% and 28.3% of control with inhibition of iNOS or COX-2 protein expression in macrophages. CONCLUSIONS: Twelve month-aged Doenjang has potent antioxidant and anti-inflammatory activities with high levels of phenolics and isoflavone aglycones, and can be used as a beneficial food for human health.