Secondary Metabolites Of Three Plants And Their Biological Functions

This thesis consists of five chapters.The first chapter summarized the recent research progress of plant secondary metabolites.The following three chapters expounded the chemical constituents and their bioactivities from three plants respectively,including Euphorbia fischeriana Steud,Dracocephalum taliense and Ambrosia trifida L.The last chapter was the summarization of this paper and perspectives of the research.By chromatography technique and spectroscopic methods,such as NMR,MS,UV and IR,32 compounds were isolated and identified from different organs of above-mentioned three plants,including 5 new compounds.The structure of compounds included terpenoids and steroids.The biological activities including antifeedant activity against Helicoverpa armigera,cytotoxic activity and anti-inflammatory activity were evaluated.Plant latex,a sticky endo genous fluid,is flowed inside laticifers and secreted immediately after plant tissue being injured.E.fischeriana,belonging to the genus Euphorbia,is a perennial herbaceous plant with white latex.The latex of E.fischeriana showed strong antifeedant activity against H.armigera,with EC50 of 0.015 ?L/cm2.The latex methanol extract showed obvious growth inhibitory activity against the larvae of H.armigera.The phytotoxic effect of the latex extracts of E.fischeriana exhibited significant growth inhibition against the root of Arabidopsis thaliana(IC50 = 116.24 ± 9.17 ?g/m L).Microscopic observation showed that the latex extracts can cause root-tip cells to wrong arrangement and epidermal cells to serious damage.In order to find the major active lactic metabolites,eight aliphatic tigliane diterpenoids were successfully isolated and identified from the latex methanol extract of E.fischeriana,including three new compounds(LY-2,3 and 5).Two major compounds(LY-1 and 4)exhibited remarkable antifeedant activity against H.armigera,with EC50 values at 2.59 and 15.32 ?g/cm2,respectively.The quantification analysis of the exact contents LY-1 and LY-4 in the latex,root,stem,and leaves of E.fischeriana that found both two compounds mainly accumulated in the latex,with the contents of 655.19 ± 9.86 and 4319.07 ± 143.26 ?g/g,respectively.LY-1 and LY-4 could be released into rhizosphere soil,with the contents of 3.67 ± 0.19 and 12.33 ± 0.93 ?g/g,respectively.Collectively,the latex of E.fischeriana and their diterpenoids could contribute to plant defensing phytophagous insects and other plants.Dracocephalum taliense is a medical plant belonging to Labiatae.Seventeen compounds were identified from the root of D.taliense,including 2 new compounds(DY-1 and 6).And DY-6 showed obvious cytotoxic activity to NCI-H1975 and Hep G2,with the IC50 of 7.17 ± 0.26 and 6.58 ± 0.14 ?M respectively.The paper enriched the diversity of constituents from the root of D.taliense,which provided scientific basis for finding medical constituents of this plant root.Ambrosia trifida brings great damage to the plant diversity of northeast of China.Seven compounds were isolated from the root of A.trifida.They were identified as steroids and phenols.Studying the constituents of A.trifida could provide theory to study the invasive mechanisms.