7种茶氨酸类似物的合成及清除自由基活性

Synthesis and Activity of Scavenging Free Radicals of 7 Analogs of Theanine

摘要:

茶氨酸清除自由基活性影响其多种药理作用，研究5位不同取代的茶氨酸类似物清除自由基作用，以期发现具有优异清除活性的先导化合物。本文以L-谷氨酸为起始原料，经邻苯二甲酸酐保护、酰化开环、肼解脱保护等反应合成了7种茶氨酸类似物,结构均经IR、1H NMR 和13C NMR等手段确认，并测定了其清除DPPH自由基和羟自由基活性。结果表明：2-氨基-5-氧代-5-((4-羟基苯基)氨基)戊酸清除自由基活性最强，0.002 mol?L-1 时清除DPPH自由基率为90%，0.004 mol?L-1 时清除羟自由基率达95%；2-氨基-5-氧代-5-((4-氨基苯基)氨基)戊酸次之。由此可见，茶氨酸5位连有对位无取代或被供电子基团取代的苯基时，可提高其清除DPPH自由基和羟自由基活性，且基团供电子性越大，清除活性越强。

Abstract:

Multiple pharmacological activities were influenced of its activity of scavenging free radicals. The activity that different substituted theanine analogs at 5 position scavenge free radicals was studied in order to find the lead compound whose ability of scavenging free radicals was excellent. 7 kinds of analogs of theanine were synthesized via protection of phthalic anhydride, acylation and opening ring, deprotection of hydrazine hydrate from L-glutamic acid in the paper. The structures of the synthesized compounds was confirmed by IR,1H NMR and 13C NMR, and their activity of scavenging DPPH free radical and hydroxyl free radical were determined as well. The results indicated that the activity of scavenging free radical of 2-amino-5-((4-hydroxyphenyl)amino)-5-oxopentanoic acid was the best of the seven chemicals, whose rate of scavenging DPPH free radical was 90% at 0.002 mol?L-1 and rate of scavenging hydroxyl free radical was 95% at 0.004 mol?L-1. Followed was 2-amino-5-((4-aminophenyl)amino)-5-oxopentanoic acid. These showed that it could enhance the theanine ability of scavenging DPPH free radical and hydroxyl free radical that its 5 position was substituted by phenyl linking with nothing or electron donating group at 4 position. And the electron donating ability of group was stronger, the activity of scavenging free radicals was better.