Basic Research on Materialization of Apple Polyphenol as Functional Food

以未成熟苹果为原料，研究苹果多酚低聚物的生物活性。苹果多酚低聚物对低密度脂蛋白过氧化有较强的抑制作用，其抑制作用与儿茶素相当。膳食苹果多酚低聚物以剂量依赖性方式降低大鼠肝脏磷脂过氧化氢水平。苹果多酚低聚物还降低了大鼠肝脏HMG-CoA还原酶和Δ6去饱和酶的活性。另一方面，苹果多酚低聚物可提高肝脏胆固醇7α-羟化酶的活性。反映这些酶活性的调节，肝脏胆固醇水平和组织脂质的Δ6去饱和指数降低，酸性类固醇的粪便排泄水平增加，在喂食苹果多酚低聚物的大鼠。苹果多酚低聚物可使HDL-胆固醇/总胆固醇比值升高。此外，在喂食苹果多酚的大鼠血清中发现了许多来自苹果多酚低聚物的未鉴定化合物，尽管在喂食无多酚饮食的大鼠血清中未鉴定出这些化合物。因此，从苹果多酚低聚物中吸收和分解的化合物可能具有多种生物功能，如抗氧化作用和调节脂质代谢。

Biological activities of apple polyphenol oligomer derived from unripe apple in this study. Peroxidation of low density lipoprotein was strongly inhibited by apple polyphenol oligomer in in vitro assay and its potency was equal to that of tea catechin. Dietary apple polyphenol oligomer lowered the levels of liver phospholipids hydroperoxides in rats in the dose-dependent manner. Dietary apple polyphenol oligomer also lowered the activities of hepatic HMG-CoA reductase and Δ6 desaturase in rats. On the other hand, the activity of hepatic cholesterol 7α-hydroxylase was increased by dietary apple polyphenol oligomer. Reflecting these modulations of enzyme activities, liver cholesterol level and Δ6 desaturation indices of tissue lipids were lowered and fecal excretion level of acidic steroids was increased in rats fed apple polyphenol oligomer. The ratio of HDL-cholesterol/total cholesterol was increased by intake of apple polyphenol oligomer The dimer and trimer of apple polyphenol oligomer were identified in serum in rats fed apple polyphenol oligomer. Moreover, many unidentified compounds derived from apple polyphenol oligomer were found in serum in rats fed apple polyphenol, although these compounds were not identified in serum in rats fed polyphenol-free diet. Therefore, absorbed and decomposed compounds derived from apple polyphenol oligomer may exhibit various biological functions such as antioxidative action and regulation of lipid metabolism.