Functional Components in Soybean Cake and Their Effects on Antioxidant Activity

Abstract

The antioxidant activities of four fractions of isoflavones from soybean cake were evaluated and compared with those of ISO-1 and ISO-2 fractions, five isoflavone standards, and mixtures of two or four isoflavone standards, as well as four commercial antioxidants, using DPPH, TEAC, reducing power, metal ion chelating, conjugated diene, and TBARS assays. Both malonylglucoside and glucoside fractions were isolated using preparative chromatography with Diaion HP-20 as adsorbent, whereas acetylglucoside and aglycone fractions were separated with silica gel as adsorbent. The other two fractions, ISO-1 and ISO-2, were soybean cake extracts containing 12 isoflavones for the former and a combination of 4 fractions for the latter. Both acetylglucoside and ISO-1 fractions exhibited the highest efficiency in scavenging DPPH free radicals, whereas all six fractions were effective in inhibiting conjugated diene formation. However, a low reducing power was observed for all six fractions and isoflavone standards. The aglycone fraction and genistein standard showed a pronounced increase of TEAC value and a moderate decrease of TBARs value. For chelating metal ions, both ISO-1 and ISO-2 fractions were the most efficient. Overall, the isoflavone fractions showed a better antioxidant activity than the isoflavone standards, probably caused by the presence of some other functional components such as saponin, flavonoid, and phenolic compounds in soybean cake.

Probiotic properties of lactic acid bacteria isolated from traditionally fermented Xinjiang cheese

“…The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity was measured by the method of Kao and Chen (2006) with modifications. Reaction mixtures containing 1.0 ml of 10 8 CFU/ml bacterial cells and 1.0 ml of 50 μmol/L DPPH (Aladdin Industrial Corporation, Aladdin, Reagent Company, China) in ethanol (SCRC, Shanghai, China) were incubated at 37 °C in the dark for 30 min.…”

Chromatographic Determination of Phenolic Acids and Flavonoids in Lycium barbarum L. and Evaluation of Antioxidant Activity

“…The method of Kao and Chen (2006) was used. One mL of L. barbarum L. fruit extract was mixed with a 0.2 mL of 1 mM DPPH • solution (in methanol), and next the solution was mixed and then stood in the dark for 30 min, and the absorbance was measured at 517 nm.…”

“…One mL of L. barbarum L. fruit extract was mixed with a 0.2 mL of 1 mM DPPH • solution (in methanol), and next the solution was mixed and then stood in the dark for 30 min, and the absorbance was measured at 517 nm. The scavenging effect (percent) was determined using the formula described by Kao and Chen (2006). …”

Soy and Soy-Based Foods: Role in Health and Nutrition

“…About 80-90% of total seed isoflavones are located in the cotyledons (Tsukamoto et al 1995). Isoflavones have attracted a great deal of attention due to their antioxidant (Kao and Chen 2006;Chung et al 2008), antiinflammatory García-Lafuente et al 2009), and antiallergic (Chang et al 2000) properties. These compounds have shown to reduce the risk of cardiovascular disease (Jackman et al 2007), and promote the inhibition of cancer cell growth (Sarkar and Li 2003;Kao et al 2007;Davis et al 2008).…”