牛蒡根中黄酮苷类化学成分及其抗氧化活性构效关系的研究

目的研究牛蒡Arctium lappa根中的黄酮苷类化学成分及其抗氧化活性,分析构效关系。方法采用重结晶、硅胶柱色谱、RP18柱色谱、Sephadex LH-20柱色谱和PHPLC等多种分离手段,对黄酮苷类化合物进行分离纯化,通过现代波谱学方法(NMR、ESI-MS)鉴定其结构,并采用DPPH法、ABTS法和FRAP法对分离得到的化合物进行抗氧化活性测试。结果从牛蒡根55%乙醇提取物中分离得到8个黄酮苷类化合物,分别鉴定为柚皮素-7-芸香糖苷(1)、橙皮苷(2)、淫羊藿苷(3)、芒柄花苷(4)、异芒柄花苷(5)、新甘草苷(6)、新异甘草苷(7)、甘草苷(8);经3种不同方法测试,分析了这一类化合物的抗氧化活性构效关系。结论化合物3为首次从该植物中分离得到,其他化合物均为首次从该属植物中分离得到;化合物1和8显示出较强抗氧化活性;黄酮的B环上的3′-OH和4′-OCH3结构具有较高电子离域并且能形成氢键,很大程度提高了其结构的稳定性,增强了其抗氧化活性。

Flavonoid glycoside compounds from roots of Arctium lappa and structure-activity relationship of anti-oxidantion

Objective To investigate the flavonoid glycoside compounds from the roots of Arctium lappa and their structure-activity relationship(SAR) of anti-oxidantion.Methods The compounds were isolated by column chromatography over silica gel, RP-C₁₈, Sephadex LH-20, and PHPLC.Their structures were elucidated by spectroscopic analysis and their anti-oxidant activities were evaluated by DPPH, ABTS, and FRAP assays.Results Eight flavonoid glycoside compounds were isolated from 55% ethanol extract in the roots of A.lappa, which were identified as nairutin(1), hesperidin(2), icariin(3), ononin(4), isoononin(5), neoliquiritin(6), neoisoliquiritin(7), and liquiritin(8).The anti-oxidant activities of these compounds were tested by three different methods(DPPH, ABTS, and FPAR), and their SAR were further analyzed.Conclusion Compound 3 is isolated from the roots of A.lappa for the first time, all others were from the plants of Arctium L.for the first time;Compounds 1 and 8 have shown the strongest anti-oxidant activity;The-OH on C-3' and-OCH₃ on C-4' in the B ring in regard to the anti-oxidant activity of these compounds by participating in electron delocalization and hydrogen bonding.