Isoflavones antioxidant activity

Arora A, Nair NG, Strasburg GM. Antioxidant activities of isoflavones and their biological metabolites in a liposomal system. Arch. Biochem. Biophys. 356, 133-141, 1998. 

The value of antioxidant protection by way of natural food sources has been pointed out in the literature with considerable frequency. Among the components of soy flour known to have some antioxidant properties are isoflavones and phospholipids. Amino acids and peptides in soybean flour also possess some antioxidant activity. There also may be some antioxidant impact from aromatic amines and sulfhydryl compounds. 

Sato et a2- (34) demonstrated that a variety of common meat additives, inclucnrTg cottonseed flour, nonfat dry milk, spray-dried whey, wheat germ, and textured soy flour, inhibited WOF in the meat system. These products may have exerted their inhibitory effect on WOF through the Maillard reaction, since most of them contain some reducing sugars. Pratt (40) reported soybeans and soy protein concentrate had an inhibitory effect upon development of WOF and was able to demonstrate that the active components are water soluble. Fractionation and analysis of the water-soluble fraction showed the antioxidant activity was due to the presence of isoflavones and hydroxylated cinnamic acids (40). This confirms earlier work showing that the flavonoTcis present in plant extracts inhibit oxidation in sliced roast beef (41 ). 

Meng, Q.H. Lewis, P. Wahala, W. Adlercreutz, H. Tikkanen, M.J. 1999. Incorporation of esterified soybean isoflavones with antioxidant activity into low density lipoprotein. Biochim. Biophys. Acta. 1438 369 376. 

Isoflavones are found in Glycine max (soybean). Clinical research has demonstrated soy isoflavones to be effective in menstrual diseases. They have antioxidant activity also. Isoflavones belong to a group of compounds known as phyto-estrogens. The isoflavone content of soybean is 10 tO 20 times more than other plants. Genistein is a potent tyrosine inhibitor, whereas daidezein has antioxidant activity. Recently isoflavones have been investigated for hypolipidemic activity. 

As indicated in Table XIII, human exposure to soybean isoflavones, measured in DES equivalents, is considerably more likely than exposure to coumestrol in soybeans. Several fold Increases in Isoflavone content during germination is a definite possibility. The Importance of soybean estrogens, particularly in germinated soybeans, in the etiology of deleterious reactions in humans needs more study. Soybean isoflavones and phenolic acids probably account for the antioxidant activity of soybeans, defatted soy flour, protein concentrates, and Isolates (89). 

Third, these flavonoids reveal anti-protozoal, anti-inflammatory and antioxidant activities. Additionally, some isoflavones were also known to have their insecticidal, antifungal and antibacterial activities [43]. 

Flavonoids interact with the major enzymatic scavengers of ROS within the cytosol such as catalase, superoxide dismutase (SOD), ascorbate peroxidase (APX), and with several enzymes involved in maintaining reduced antioxidant pool such as glutathione reductase (GR) (Fig. 6.8). Depending on their structure, some flavones and flavonols activate CAT from bovine liver. Isoflavones and flavanones exhibit weak antioxidative activities against... 

---