Study On Chemical Constituents Of Periploca Chrysantha,Cynanchum Bungei,Cyclocarya Paliurus,and Celastrus Monospermus And Evaluation Of Their Biological Activities

This dissertation dedicates to find new physiologically active ingredients from plants by using modern scientific theories and methods.In the opening chapter,a phytochemical investigation of the ethanol extract of the root barks of Periploca chrysantha led to the isolation and identification of 30compounds,including five new pregnane glycosides and four new phenolic glycosides.The proton signals of oligosaccharide chain overlapped severely in the ¹H NMR spectra of the isolated pregnane glycosides.In 1D-TOCSY experiments,selective irradiation of proton signals revealed the subspectra of each saccharide unit,and the kind of each saccharide unit was further identified by combinatorial analyses of ¹H-¹H COSY spectrum and the coupling constants of each sugar proton signals.In the bioactivity assay,the four new spiroorthoester group-containing pregnane glycosides were found to exhibit significantly inhibitory activities against the proliferation of B and T lymphocytes.In chapter 2,17 compounds were identified from the roots of Cynanchum bungei,including three new 8,14-seco-pregnane glycosides,one new eudesmane-type sesquiterpene,and one new humulane-type sesquiterpene.The absolute configuration of the two new sesquiterpenes were determined by spectroscopic analysis,comparison of the experimental CD and calculated ECD spectra,and X-ray single crystal diffraction analysis.In a preliminary bioactivity assay,seven C₂₁-steroidal glycosides were found to show significantly inhibitory activities against the proliferation of B and T lymphocytes.In chapter 3,41 compounds were isolated from the leaves of Cyclocarya paliurus,including 10 new 3,4-seco-dammaranoid saponins.The saccharide chains of compounds 3-1–3-9 were the same 5-O-acetyl-arabinofuranose linked to C-20 position of the aglycones,and it was the first time discovery that sugar units linked to C-20position of triterpenoids in Juglandaceae plants.The structures of new compounds were elucidated by spectroscopic analysis,chemical transformation,and X-ray single crystal diffraction analysis.In a preliminary bioactivity assay,3-14 was found to exhibit weak inhibitory activities against human and murine 11?-HSD1,and 3-16 was found to show weak activation activity of AMPK.The last chapter dealed with the phytochemical investigation of the stems of Celastrus monospermus,leading to the isolation and identification of 12 new conjugates of the C-6 position of 24,29-dinor-friedelane-type triterpen and the C-8position of catechins.It is the first discovery of conjugates of friedelan-type triterpenoids and catechins in nature.The existence of axial chirality in 4-1 was identified by torsional energy scans,and its absolute configuration was determined by spectroscopic analysis,chemical transformation,modified Mosher's method,and application of experimental DFT calculation methods.