31种黄酮、酚酸类化合物和10种中药清除DPPH能力考察

DPPH radical scavenging activities of 31 flavonoids and phenolic acids and 10 extracts of Chinese materia medica

目的:考察中药中黄酮、酚酸类成分清除DPPH自由基活性及构效关系,中药乙醇提取物清除DPPH自由基的活性及其与黄酮、酚酸类成分总量之间的关系。方法:以中药中常见的31种黄酮、酚酸类化合物和10种中药为研究对象,以DPPH法对上述41个样品的抗氧化活性进行评价,以高效液相色谱-库仑阵列检测技术检测黄酮及酚酸类化合物的氧化电位,以Folin-C iocalteu法测定中药中黄酮和酚酸类成分的总量。结果:31种化合物清除DPPH自由基的能力有很大差别,其中以(-)-EGCg清除DPPH自由基的能力最强,其IC50值为6.7μmol.L-1;氧化电位值50 mV;提取物中,茶叶提取物中总黄酮和酚酸类成分的含量最高,为82.9%(以芦丁计),清除DPPH自由基能力最强,IC50值为0.012 g.L-1;红花醇提物总黄酮和酚酸类成分的含量最低,为7.01%(以芦丁计),其清除DPPH自由基能力最弱,其IC50值为1.3 g.L-1。结论:黄酮、酚酸类成分清除DPPH自由基的能力与化合物中酚羟基的取代个数和位置有关;中药清除DPPH自由基能力(Y)与总黄酮和酚酸类成分含量(X)之间存在相关性,Y=7.779X-0.48,r=0.929 5,即总黄酮和酚酸类成分含量高,清除DPPH自由基能力强。

Objective： To investigate DPPH radical scavenging activities of 31 flavonoids and phenolic acids and 10 extracts of Chinese materia medica. Method： The antioxidant activities of the above samples were evaluated by a DPPH method, the half-wave oxidation potentials （ E1/2 ） of the 31 compounds were determined by an HPLC-ConlArray method, at the same time, phenolic contents of the the total compounds in the 10 extracts of Chinese materia medica were analyzed by Folin-Ciocalteu method. Result： The 31 compounds showed a 50% inhibition of DPPH radical in the concentration range of 6.7-3 500umol·L^-1 , in which （ - ）-EGCg demonstrated the strongest activity with the ICso value of 6. 7umol·L^-1. The E1/2 of 31 compounds spanned a wide potential range of more than 0. 6 V. Myricetin had the lowest E1/2 value （20 mV） whereas apigenin and.vitexin-2＇-O-rhamnoside had the highest E1/2 value （620 mV）. Among the 10 herb extracts,having 82% phenolic acid, tea extract showed the strongest DPPH radical scavenging activity with the ICs0 value of 0. 011 7 umol·L^-1 whereas safflower demonstrated the weakest DPPH radical scavenging activity with the IC50 value of 1. 250umol·L^-1 , in which only 7% phenolic acids was tested. Conclusion： The DPPH radical scavenging activities of the 31 compounds were founded to be related to their chemical structures, such as the number and position of hydroxyl groups. And a qualitative relationship was found between DPPH radical scavenging activities and E1/2 values of the 31 compounds, the lower the E1/2 values, the higher the DPPH radical scavenging activities. A quantitative relationship was obtained to describe the DPPH radical scavenging activity of the herb extracts： Y= 7. 779X^-0.48 ,r =0. 929 5, where Y stands for the concentration for 50% inhibition of DPPH radical, and X stands for the concentration of total phenohc compannds, namely the extracts with higher content of flavonoids and phenolic acid exhibited the stronger DPPH radical scavenging activity.