Antioxidant and free radical scavenging activity of isoflavone metabolites

Abstract

1. Soy isoflavones have been extensively studied because of their possible health-promoting effects. Genistein and daidzein, the major isoflavone aglycones, have received most attention; however, they undergo extensive metabolism in the gut and liver, which might affect their biological properties. 2. The antioxidant activity, free radical-scavenging properties and selected cellular effects of the isoflavone metabolites equol, 8-hydroxydaidzein, O-desmethylangiolensin, and 1,3,5 trihydroxybenzene were investigated in comparison with their parent aglycones, genistein and daidzein. 3. Electron spin resonance spectroscopy indicated that 8-hydroxydaidzein was the most potent scavenger of hydroxyl and superoxide anion radicals. Isoflavone metabolites also exhibited higher antioxidant activity than parent compounds in standard antioxidant (FRAP and TEAC) assays. However, for the suppression of nitric oxide production by activated macrophages, genistein showed the highest potency, followed by equol and daidzein. 4. The metabolism of isoflavones affects their free radical scavenging and antioxidant properties, and their cellular activity, but the effects are complex

Daidzein enhances intramuscular fat deposition and improves meat quality in finishing steers

“…These results may be related to the intrinsic antioxidant activity of daidzein and equol. 31 Daidzein has been shown to have a direct effect on lipid metabolism in our study. Concentrations of lipid metabolites in serum including non-esterified fatty acid, triglyceride, total cholesterol, HDL-C, and LDL-C were reduced by supplemental daidzein.…”

Nutritional flavonoids impact on nuclear and extranuclear estrogen receptor activities

“…Consequently, their physiologic behavior is likely to be different from that of the native compounds. It has been shown that glucuronidation reduces the biological activities of daidzein and genistein and the genistein sulfation decreases its antioxidant activity as well as its effect on platelet aggregation, inflammation, cell adhesion, and chemotaxis (Rimbach et al, 2003;Turner et al, 2004).…”

Structural Elucidation of Hydroxylated Metabolites of the Isoflavan Equol by Gas Chromatography-Mass Spectrometry and High-Performance Liquid Chromatography-Mass Spectrometry

“…The activities were comparable to that of genistein; however, cis-and trans-4-hydroxy-equol were less cytotoxic. Regarding the antioxidant activity, it has been shown that equol is more potent than genistein or daidzein and that the hydroxylated metabolites of genistein and daidzein exert an even higher antioxidant efficacy than equol (Arora et al, 1998;Rimbach et al, 2003;Turner et al, 2004). Therefore, studies on the antioxidant capacity of the hydroxylated equol metabolites seem to be interesting.…”