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Inhibitory Effects of Foodstuffs on Sugar-Protein Condensation Reaction Related to Aging

食品对与衰老相关的糖蛋白缩合反应的抑制作用

基本信息

批准号：
01580068
负责人：
KINAE Naohide
金额：
$ 0.96万
依托单位：
University of Shizuoka
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

项目摘要

It is well known that crosslinking mediated by nonenzymatic glycosylation occur in human serum albumin, collagen and lens protein. The fluorescent substances formed in the reaction increase as a function of age and diabetes.Our interest was focused to know whether several tea leaf extracts show an inhibitory effect on the formation of the advanced glycosylation end products (AGEs). Furthermore, an attempt was made to identify compounds which inhibit AGEs formation.A mixture of D-glucose and human serum albumin or casein was incubated under physiological conditions with or without tea leaf extract. From the determination of relative fluorescence intensity, it was found that all tea leaf extracts (Japanese green tea, Chinese tea, black tea, Oolong tea) showed high inhibitory activity (10-60%) on AGEs formation. When 3-deoxy-D-glucosone or 5-hydroxymethy1-2-furaldehyde, which are key intermediates of the Maillard reaction, was used as carbonyl component, the inhibitory effects of tea leaf extracts were extremely low (5-15%). By applying solvent extraction method for isolation of the specific inhibitory compounds of AGEs formation, four catechins containing (-) epigallocatechin gallate were isolated and identified from Japanese green tea. SDS-polyacrylamide electrophoresis showed disappearance of a major high molecular weight protein aggregate in samples incubated with tea leaf extracts or catechins. From the chemical structure of catechins, it is believed that catechins can act as antioxidative agents or free radical scavengers at early stage of nonenzymatic glycosylation.

众所周知，非酶糖基化介导的交联发生在人血清白蛋白、胶原蛋白和晶状体蛋白中。反应中形成的荧光物质随着年龄和糖尿病的增加而增加。我们的兴趣集中于了解几种茶叶提取物是否对高级糖基化终产物 (AGE) 的形成表现出抑制作用。此外，还尝试鉴定抑制AGEs形成的化合物。将D-葡萄糖和人血清白蛋白或酪蛋白的混合物在有或没有茶叶提取物的生理条件下温育。通过相对荧光强度的测定，发现所有茶叶提取物（日本绿茶、中国茶、红茶、乌龙茶）对AGEs形成均表现出较高的抑制活性（10-60%）。当使用美拉德反应的关键中间体3-脱氧-D-葡萄糖酮或5-羟甲基1-2-糠醛作为羰基成分时，茶叶提取物的抑制效果极低(5-15%)。采用溶剂萃取法分离AGEs形成的特异性抑制化合物，从日本绿茶中分离鉴定出4种含有(-)表没食子儿茶素没食子酸酯的儿茶素。 SDS-聚丙烯酰胺电泳显示，在与茶叶提取物或儿茶素一起孵育的样品中，主要的高分子量蛋白质聚集体消失。从儿茶素的化学结构来看，儿茶素在非酶糖基化的早期阶段可以作为抗氧化剂或自由基清除剂。