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紫荆、湖北紫荆中单宁化学结构及其抗氧化活性研究

Chemical Structure of Tannins in Cercis chinensis and Cercis glabra and Their Antioxidant Activity

  • 摘要: 对紫荆叶片、湖北紫荆叶片及荚果中可溶缩合单宁(ECT)含量进行了测定,并利用核磁共振(NMR)联合反相高效液相色谱-质谱(RP-HPLC-MS)技术对其化学结构进行了分析,同时采用DPPH法及铁离子还原/抗氧化能力(FRAP)法研究了其抗氧化能力。研究结果表明:紫荆叶片、湖北紫荆叶片及荚果中单宁的质量分数分别为151.56、 96.75和198.12 mg/g;构成3种缩合单宁的黄烷-3-醇的结构单元主要为原花青素及原翠雀素,且其结构单元C3位上具有棓酰化结构;3种缩合单宁均表现出一定的抗氧化活性,清除DPPH自由基(DPPH·)的半数抑制质量浓度(IC50)值为67.02~97.70 mg/L,均优于阳性对照BHA;当质量浓度为125 mg/L时,3种缩合单宁的总抗氧化能力FRAP值为3.51~5.56 mmol/g,低于阳性对照BHA的6.51 mmol/g。紫荆叶片单宁表现出优异的抗氧化活性,其清除DPPH·的IC50值为67.02 mg/L,优于阳性对照Vc(76.65 mg/L);其总抗氧化能力FRAP值达到5.56 mmol/L。

     

    Abstract: The contents of extractable condensed tannins(ECT) in Cercis chinensis, Cercis gigantea leaves and pods were determined. The chemical structure were analyzed by nuclear magnetic resonance(NMR) combined with reversed-phase high performance liquid chromatography-mass spectrometry(RP-HPLC-MS), and the antioxidant activities were determined by DPPH scavenging assay and ferric reducing/antioxidant power(FRAP) assay. The results showed that the mass fractions of tannins in C. chinensis, C. glabra leaves and pods were 151.56, 96.75 and 198.12 mg/g, respectively. The structural units of flavan-3-ols which constituted three condensed tannins, were mainly procyanidin and prodelphidin, and there were galloacylated structures at the C3 position in their structural unit. All three condensed tannins had certain antioxidant activity. The median inhibitory concentration(IC50) values of the three condensed tannins for scavenging DPPH free radicals(DPPH) were 67.02-97.70 mg/L, which were all higher than that of positive control BHA. The FRAP values of three condensed tannins was 3.5156 mmol/g at the mass fraction of 125 mg/L, which were lower than the positive control BHA(6.51 mmol/g). Among them, the tannins of C. chinensis leaves showed excellent antioxidant activity, and its IC50 values of clearance rate of DPPH was 67.02 mg/L, which was better than the positive control Vc(76.65 mg/L). Meanwhile, its FRAP value was 5.56 mmol/L.

     

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