Study On The Chemical Constituents And Bioactivities Of Three Medicinal Plants

The dissertation is comprised of five chapters. The first chapter reviews the advances in the monoterpenoid indole alkaloids and bioactivities of the genus of Vinca Linn. The second to fourth chapters discuss the phtochemistical and bioactive studies on Vinca major, Laggera pterodonta, and Flueggea virosa. The last chapter, conclusion of this dissertation is made.The genus Vinca (Apocynaceae) is well-documented to be a storehouse of C19-C20indole alkaloids of diverse structural patterns, many of which are of considerable therapeutic value. Many of them, such as reserpine, vincristine, and yohimbine, are well known for their pharmacological significance. This review covered literature from1953to2013, in which144natural occurring constituents were presented and75references were cited.A chemical investigation on Vinca major led to the isolation of44compounds, including12new ones. Of them, compounds land2possessed unusual carbon skeletons. Vincamajorine A (1), a monoterpenoid indole alkaloid with C2O skeletal carbon arranged compactly in seven rings, and vincamajorine B (2), an alkaloid with an unprecedented6/5/7/5/6pentacyclic ring system, this alkaloid might be a skeleton rearranged derivative form10-deoxysarpagine. New compounds were tested for cytotoxicity against SW480, SMMC-7721, HL-60, SCF-7and A-549cell lines using the MTT method. However, all were found to be inactive with IC50values of>40μM.Laggera pterodonta, widely distributed in the southwest of China, especially in Yunnan province, has been used as folk medicine since ancient times. Pharmacological investigations have indicated that the extract of L. pterodonta has antileukaemia, antibacterial, anti-inflammatory, and antimalarial activities. Previous research has also revealed that flavonols, which account for the anti-inflammatory activity, and eudesmane sesquiterpenes represent the main secondary metabolites of this plant. Phytochemical studies on Laggera pterodonta led to the isolation of25compounds, including16sesquiterpenes and9flavonols, compounds1-3are new sesquiterpenes. All sesquiterpenes were tested for anti-inflammatory and cytotoxic activity, but none of them showed any activity.The roots of Flueggea Virosa Roxb. ex Willd (Euphorbiaceae), a traditional Chinese medicine, have been used for the treatment of rheumatism, pruritus, cephalic eczema, leucorrhoea, and injuries. The investigation of the leaves and stems of Flueggea Virosa led to the isolation of11known alkaloids, All the alkaloids belong to the group of securinine-type alkaloids, that have unique tricyclic skeleton with an α,β-unsaturated-y-lactone ring.Conclusion of this dissertation was made. A total of80compounds, including15new ones, were isolated from these species. Their structures were established on the basis of extensive spectroscopic methods and calculational chemistry analysis. Of these compounds, monoterpenoid indole alkaloids are an important part, including two novel carbon skeletons, such as vincamajorines A and B, and series of new and bioactive compounds. As a whole, the discovery of these compounds enriched the family of natural products, and the structural elucidation of these compounds enhanced our understanding towards the relationship amomg the monoterpenoid indole alkaloids types.Compounds isolated from the above mentioned three plants are listed below, and the chemical structures are also show in the following figures.