Study On Chemical Constituents And Antioxidant Activities Of Smallanthus Sonchifolius Leaves

Objective: Rapidly screening of antioxidant activities components of Smallanthus sonchifolius leaves by the quantitative pattern-activity relationship approach.Methods: 1.The crude extract was extracted from the leaves of Smallanthus sonchifolius by 70% ethanol and separated into petroleum ether extract,ethyl acetate extract,n-butanol extract and aqueous extract by the method of solvent extraction.The ethyl acetate extract with high activity was chosen as the research object,and separated into 17 fractions using normal phase silica chromatographic column.HPLC-DAD method was established for analysis of ethyl acetate extract and 17 fractions to gain chromatograms and spectrogram,and the antioxidant effect of ethyl acetate extract and 17 fractions was tested by scavenging DPPH free radicals activity.2.Combined spectral data graph with antioxidant activity of the ethyl acetate extract and 17 fractions,using quantitative pattern-activity relationship approach,including model population analysis,good/bad analysis method and weight analysis method for rapid screening of antioxidant activity components in the ethyl acetate extract.The ethyl acetate extract was separated by column chromatography to prepare of active components and groups,the reliability of the screening model was finally tested by the DPPH free radical scavenging test.Results: 1.The results of DPPH radical scavenging activity of ethyl acetate extract and the 17 fractions showed that the free radical scavenging activity of NO.5-8 fractions was the highest,which was significantly higher than positive control BHT(P < 0.05).2.The analysis results of the quantitative pattern relationship approach indicated that the retention time of active component groups ranged 2-12,53-64 min and the retention time of active component was 3,3.6,5.7,7.6,11.7,18.6,20.9 min etc.,respectively.The compounds were prepared by normal and reversed phase column chromatography and analysis by NMR,the results showed that the monomer compounds were Uvedalin(1),Ethyl caffeate(2),Methyl caffeate(3),Enhydrin(4),Homoeriodictyol(5),Quercetin 3,7-dimethyl ether(6),Uvedafolin(7)and Chlorogenic acid(8),respectively.Among then,Ethyl caffeate(2),Methyl caffeate(3),Homoeriodictyol(5),Quercetin 3,7-dimethyl ether(6),and Chlorogenic acid(8)are high active component predicted by the quantitative pattern-activity relationship approach.DPPH free radical scavenging activity test results show that the prediction of the active compounds was higher than that of the positive control BHT and negative control(1),(4),(7),even higher than the highest activity of sample No.5,the screening methods was proved to be reliable and effective.The activity of active ingredients group(the RT was 2-12 min)was higher than that of the active component monomer compounds,indicating the existence of synergistic reaction of each component group.Conclusion: The Smallanthus sonchifolius leaf was rich in antioxidant active compnents.The results of the quantitative pattern relationship approach were showed that the method were reliable and could be hopeful used for screening of bioactive components of other Chinese herbal.