Matsuda H, Morikawa T, Toguchida I, Park J Y, Harima S, Yoshikawa M
Kyoto Pharmaceutical University, Japan.
Bioorg Med Chem. 2001 Jan;9(1):41-50. doi: 10.1016/s0968-0896(00)00215-7.
The methanolic extracts from five kinds of rhubarb were found to show scavenging activity for DPPH radical and .O2-. Two new anthraquinone glucosides were isolated from the rhizome of Rheum undulatum L. together with two anthraquinone glucosides, a naphthalene glucoside, and 10 stilbenes. In the screening test for radical scavenging activity of rhubarb constituents, stilbenes and a naphthalene glucoside showed activity, but anthraquinones and sennosides did not. In addition, most stilbenes inhibited lipid peroxidation of erythrocyte membrane by tert-butyl hydroperoxide. Detailed examination of the scavenging effect on various related compounds suggested the following structural requirements; 1) phenolic hydroxyl groups are essential to show the activity; 2) galloyl moiety enhances the activity; 3) glucoside moiety reduces the activity; 4) dihydrostilbene derivatives maintain the scavenging activity for the DPPH radical, but they show weak activity for .O2-. In addition, several stilbenes with both the 3-hydroxyl and 4'-methoxyl groups inhibited xanthine oxidase.
研究发现，五种大黄的甲醇提取物对DPPH自由基和超氧阴离子均具有清除活性。从波叶大黄根茎中分离出两种新的蒽醌糖苷，以及两种蒽醌糖苷、一种萘糖苷和10种芪类化合物。在大黄成分的自由基清除活性筛选试验中，芪类化合物和一种萘糖苷具有活性，而蒽醌类化合物和番泻苷则没有活性。此外，大多数芪类化合物可抑制叔丁基过氧化氢引起的红细胞膜脂质过氧化。对各种相关化合物清除作用的详细研究表明，具有以下结构要求：1）酚羟基对显示活性至关重要；2）没食子酰基部分可增强活性；3）糖苷部分会降低活性；4）二氢芪衍生物对DPPH自由基保持清除活性，但对超氧阴离子显示较弱活性。此外，几种同时具有3-羟基和4'-甲氧基的芪类化合物可抑制黄嘌呤氧化酶。
