Soy and Alfalfa Phytoestrogen Extracts Become Potent Low-Density Lipoprotein Antioxidants in the Presence of Acerola Cherry Extract

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• 作者：Juliana Hwang ; Howard N. Hodis ; and Alex Sevanian
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2001
• 出版时间：January 2001
• 年：2001
• 卷：49
• 期：1
• 页码：308 - 314
• 全文大小：95K
• 年卷期：v.49,no.1(January 2001)
• ISSN：1520-5118

文摘

Postmenopausal women have an increased risk of coronary heart disease. Oxidation of low-densitylipoprotein (LDL) has been implicated in atherogenesis, and the presence of modified LDL (LDL^-)in plasma appears to represent LDL oxidation in vivo. Because previous studies have demonstrateda strong antiatherogenic effect of estrogen due to its antioxidant activity and similar antioxidantactivity was found for specific isoflavones derived from soy extract, the antioxidant activity of aphytoestrogen extract derived from soy and alfalfa was studied. Copper-mediated LDL oxidationwas inhibited in the presence of soy and alfalfa extracts, and this effect was further enhanced inthe presence of acerola cherry extract, which is rich in ascorbic acid. Male rabbit aortic endothelialcells pretreated with soy extract were resistant to the toxic effects of high levels of LDL and LDL^-,and a lesser, but significant protection, was also afforded by alfalfa extract. Cell-mediated oxidationof LDL, measured by LDL^- formation, was inhibited in the presence of soy extract but not alfalfaextract. However, in the presence of acerola cherry extract, both soy and alfalfa extracts potentlyinhibited the formation of LDL^-. These findings show that acerola cherry extract can enhance theantioxidant activity of soy and alfalfa extracts in a variety of LDL oxidation systems. The protectiveeffect of these extracts is attributed to the presence of flavonoids in soy and alfalfa extracts andascorbic acid in acerola cherry extract, which may act synergistically as antioxidants. It is postulatedthat this synergistic interaction among phytoestrogens, flavonoids, and ascorbic acid is due to the"peroxidolitic" action of ascorbic acid, which facilitates the copper-dependent decomposition of LDLperoxides to nonradical products; this synergy is complemented by a mechanism in whichphytoestrogens stabilize the LDL structure and suppress the propagation of radical chain reactions.The combination of these extracts markedly lowers the concentrations of phytoestrogens requiredto achieve significant antioxidant activity toward LDL.Keywords: Antioxidant; low-density lipoprotein; soy extract; alfalfa extract; acerola extract