【摘要】 对李子果肉的总酚含量与可溶性缩合单宁含量进行了测定,并利用基质辅助激光解吸附离子化飞行时间质谱(MALDI-TOF MS)联合核磁共振(NMR)技术详细研究了李子果肉单宁的类型、聚合度及平均分子质量。同时用二苯基苦基肼自由基(DPPH·)法研究了李子果肉单宁的抗氧化活性。结果表明:李子果肉中总酚质量分数为8.29%±1.30%,可溶性缩合单宁质量分数为1.43%±0.93%;构成该单宁的黄烷-3-醇结构单元主要是表儿茶酚,在化学结构上属于原花青定类型,且大部分聚合物的结构单元之间存在A型和B型2种连接方式,平均聚合度为5.3,平均分子质量为1583.7u;李子果肉单宁具有较高的自由基清除能力,其半数有效浓度(EC)为57.98mg/L。更多还原

【Abstract】 Contents of total phenolics and extractable condensed tannins in Prunus salicina Lindl.fruits were determined.Type of condensed tannins,degree of polymerization and distribution of polymer were characterized by matrix-assisted laser desorption-ionization time-of-flight mass spectrometry(MALDI-TOF MS) and nuclear magnetic resonance(NMR) spectroscopy.The effects of tannins from P.salicina fruits on scavenging free radicals were determined by using 1,1-diphenyl-2-picryhydrazyl(DPPH·) free radical test.The results were showed as follows: total phenolics and extractable condensed tannins were 8.29 %±1.30 % and 1.43 %±0.93 %,respectively;Epicatechin was the basic units occurring in condensed tannins,A-type and B-type lin-kages were most common among the structural units of polymers.The average degree of polymerization was 5.3,and mean molecular weight was 1 583.7 u.EC50 value was 57.98 mg/L by DPPH· scavenging test.更多还原