Alkaloids Of Six Aconitum Plants From Yunnan Province

Aconitum (Ranunculaceae) is a large genus comprising 350 species and distributed in the temperate regions of the Northern Hemisphere. Of the 350 species, about 170 are endemic to China. About 76 Aconitum species in China are used as folk medicines, which are mainly employed for treatment of rheumatoid arthritis and various types of pains. Diterpenoid alkaloids are considered to be the main bioactive and toxic constituents and the significant chemotaxonomic marks of plants from the Aconitum genus. The important pharmacological activities and structural complexity of the diterpenoid alkaloids have long stimulated scientists’ strong interest.In the chapters 1-6 of this thesis, the study on the chemical constituents and their structures of six Aconitum species (A. vilmorinianum Kom., A. duclouxii Levl., A. nagarum Stapf, A. handelianum Comber, A. stapfianum Hand.-Mazz. and A. taronense Fletcher et Lauener) distributed in Yunnan Province was carried out. By variety of chromatographies over various materials, one hundred and thirty-one compounds, including one hundred and seven diterpenoid alkaloids were isolated from these six Aconitum species. Their structures were elucidated on the basis of extensive spectroscopic methods and single crystal X-ray diffraction analysis. These isolated diterpenoid alkaloids covered C18-lappaconine type, C19-aconitine type, C19-lycoctonine type, C19-7,17-seco type, C20-denudatine type and C20-napelline type.This investigation afford nineteen new alkaloids, including two unprecedented diterpenoid alkaloid skeletons. Vilmorine A isolated from A. vilmorinianum possesses a unprecedented rearranged six-membered B ring formed by the C(8)-C(9) linkage. Nagarines A and B found in A. nagarum possess an unprecedented open D ring formed by the C(8)-C(15) breakage. These alkaloids represent the new subtypes of the C19-diterpenoid alkaloids. The possible biogenetic pathway for some novel diterpenoid alkaloids were proposed as well. The other new compounds were assigned to be one benzamide derivative, one C18-lappaconines, one C2o-denudatines, two Ci9-rearraged-type and eleven C19-aconitine type diterpenoid alkaloids. In addition, the chemotaxonomical significance of the isolated diterpenoid alkaloids has also been discussed.In chapter 7, the anti-tumor and antioxidant activities of some isolated alkaloids were evaluated.In chapter 8, bioactive components isolated from Aconitum species from 2009 to 2016 were reviewed. The chemical types, biosynthetic pathways and biological activities were included.This study may play an important role in developing and popularizing the distinctive medicinal plants from the Aconitum genus in Yunnan Province and provide scientific evidences for the chemotaxonomy of the Aconitum plants.