Regulative Actions of Dietary Soy Isoflavone on Biological Antioxidative System and Lipid Metabolism in Rats

Yuki Kawakami, Wakako Tsurugasaki, Yu Yoshida, Yasuo Igarashi, Shingo Nakamura, Kyoichi Osada

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)

Abstract

Male Sprague-Dawley rats, 4 weeks of age, were fed purified diets either with or without 0.2% soy isoflavones rich powder for 5 weeks to elucidate their direct functions such as antioxidative action and regulation of lipid metabolism. Dietary soy isoflavones decreased serum lipid peroxide level in rats. Levels of liver and serum α-tocopherol were higher in the rats fed isoflavone than in those fed isoflavones-free diet. Thus, dietary soy isoflavones exhibited mild antioxidative function in this animal experiment. Isoflavone metabolites from diet may act as scavengers of reactive oxygen species. Dietary soy isoflavones lowered hepatic 3-hydroxy-3-methylglutaryl CoA reductase activity, although liver cholesterol level was not modulated. However, the levels of serum cholesterol and triglyceride decreased by consumption of soy isoflavones. Therefore, dietary soy isoflavones may exhibit hypocholesterolemic and hypolipidemic functions. Moreover, dietary soy isoflavones lowered hepatic Δ6 desaturase activity. Reflecting this observation, Δ6 desaturation indices ((18:2(n = 6) + 18:3(n = 6))/20:4(n = 6)) of tissue lipids tended to be lower in rats fed isoflavones than in those fed isoflavones-free diet. This action may contribute to the prevention of inflammatory response by imbalance of eicosanoids. These observations suggest that the positive intake of soy isoflavones may reduce the risk of some cardiovasucular diseases through their radical scavenging function and hypocholesterolemic action.

Original languageEnglish
Pages (from-to)1764-1768
Number of pages5
JournalJournal of agricultural and food chemistry
Volume52
Issue number6
DOIs
Publication statusPublished - 24 Mar 2004

Keywords

  • Antioxidation
  • Diet
  • Lipid metabolism
  • Rats
  • Soy isoflavones

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