摘要
从昆仑雪菊中分离纯化具有抗氧化活性的单体化合物。以抗氧化活性为指标,采用活性追踪的方法,筛选最佳的昆仑雪菊黄酮类化合物提取溶剂并对粗提物进行分离纯化得到单体化合物,并采用铁离子还原/抗氧化力测定法(FRAP法)、1,1-二苯基-2-硝基苯肼自由基清除法(DPPH法)和2,2-联氮基-双-(3-乙基苯并噻唑啉-6-磺酸)二氨盐自由基清除法(ABTS法)对化合物进行活性评价。结果表明:最佳的提取溶剂为甲醇,利用常压硅胶柱层析和Sephedex LH-20柱层析从粗提物中分离得到2个单体化合物;采用核磁共振(NMR)和电喷雾质谱(ESIMS)鉴定其化学结构:化合物1为2',3,4,4'-四羟基查尔酮,化合物2为4,2',4'-三羟基查尔酮。抗氧化活性测试结果表明,化合物1和化合物2的FRAP值均小于阳性对照α-生育酚,对DPPH自由基清除率的半数抑制浓度(IC50)分别为(45.32±0.26)μmol·L-1和(64.78±0.79)μmol·L-1,均低于阳性对照α-生育酚,对ABTS自由基清除率的IC50分别为(27.49±0.86)μmol·L-1和(32.13±2.79)μmol·L-1,均低于阳性对照α-生育酚。结论:从昆仑雪菊中分离得到的2个黄酮类化合物均具有很强的抗氧化活性。
Coreopsis tinctoria has been widely used as a folk medicine for several disorders in China.It contains quite variable phytochemicals which are particularly rich in flavonoids.Several investigations on their antioxidative effect have been reported.By means of separation and purification,our aim is to obtain monomeric compounds with antioxidant activities from C.tinctoria.Screening for the optimum extract solvent of flavonoids compounds and obtaining the crude extracts from C.tinctoria by bioassay-guided method using antioxidant activities as indicator,the pure compounds were obtained from the crude extract. Their antioxidant activities were evaluated by DPPH,FRAP and ABTS methods,respectively.C.tinctoria was extracted with different organic solvents.The extract was concentrated to obtain crude extract.Using AlCl3 colorimetry,the content of flavonoids in crude extracts was evaluated.Compared with the antioxidant activity and the quality of crude extracts from different solvents,the optimum extract solvent of flavonoids compounds was screened.The compounds were isolated from the crude extract using open column silica gel chromatography and Sephedex LH-20.Their chemical structures were identified by nuclear magnetic resonance（NMR） and electro-spray ionization mass spectrometry（ESIMS）.The FRAP of compounds was evaluated at 100,200,300,400,500 μmol·L-1.The scavenging of DPPH and ABTS free radicals was evaluated at 20,40,60,80,100 μmol·L-1.The results showed that differences in the effects of crude extract and flavonoids content from different solvents were significantly in C.tinctoria（P0.05）.The crude extract contents,much higher than other organic solvents,were（420±1.63） and（500±2.94） mg·g-1in methanol and water,respectively.The content of flavonoids from the methanol extract was（32.29±0.08） mg·g-1which was far higher than other solvent extraction.The crude extract content from water was high,but the flavonoid content was only（0.86±0.04） mg·g-1which was far less than methanol extracts.Differences in the scavenging of DPPH free radicals from different solvents were significantly（P0.05）.Among them,the DPPH radical scavenging activity of methanol extract was stronger than α-tocopherol and several other crude extract. In conclusion,the optimum solvent for flavonoids extract wasmethanol.Two pure compounds were isolated from the methanol crude extract using open column silica gel chromatography and Sephedex LH-20.Their chemical structures were identified as 2＇,3,4,4＇-tetrahydroxy chalcone and 4,2＇,4＇-trihydroxy chalcone by nuclear magnetic resonance（NMR） and electro-spray ionization mass spectrometry（ESIMS）.The antioxidant test results showed that the FRAP of compounds 1 and 2 was less than the positive control α-tocopherol and the DPPH free radicals clear rate of compounds1 and 2 is lower than the positive control with IC50values（45.32±0.26） μmol·L-1and（64.78±0.79） μmol·L-1,respectively,while the ABTS free radical clear rate was lower than the positive control with IC50 values of（27.49±0.86） μmol·L-1and（32.13±2.79） μmol·L-1,respectively.This current study obtained two flavonoids from the C.tinctoria.The antioxidant activities results indicate that 2＇,3,4,4＇-tetrahydroxy chalcone and 4,2＇,4＇-trihydroxy chalcone have powerful antioxidant activities.
出处
《南京农业大学学报》
CAS
CSCD
北大核心
2014年第4期149-154,共6页
Journal of Nanjing Agricultural University
基金
国家自然科学基金项目(31260377)
乌鲁木齐市科学技术计划项目(Y121120008)
关键词
昆仑雪菊
黄酮类化合物
结构鉴定
抗氧化活性
Coreopsis tinctoria
flavonoids compounds
structure identification
antioxidant activities
