Chemical Constituents Of Two Medicinal Plants And Preparation Of Diverse Indole Alkaloids

The dissertation is comprised of five chapters. Chapter one was studied on the chemical constituents of the twigs of Croton caudatus, together with the cytotoxic activity, anti-bacterial activity, and anti-HIV activity evaluation of some compounds, and found four bioactive compounds. Chapter two was studied on the chemical constituents of the cecidogenous leaves of Alstonia scholaris (genus Apocynaceae), and was evaluated for the new skeleton compound’s bioactivity of regulating hippocampal neural stem cells (NSCs) proliferation in vitro. Chapter three was studied on the roots of Alstonia scholaris, fourtheen compounds were isolated and elucidated. Chapter four was studied on the twigs of Alstonia scholaris, eleven compounds were isolated and elucidated. Chapter five was studied on the preparation of diverse indole alkaloids, and was evaluated for some compounds’ bioactivity of nerve growth factor and Calcium imaging, then found four bioactive compounds.A total 82 compounds, including 24 new ones, were isolated and identified from the above mentioned three species by various chromatographic methods. Their structures were established on the basis of extensive spectroscopic data and X-ray diffraction analysis. Structural type of the isolates involved diterpenes, tetraterpenes, megastigmane glycosides, flavonoids, lignans, indole alkaloids and so on.1、Chemical constituents from C. caudatus and their bioactivitiesCroton caudatus, belongs to Euphorbiaceae genus Croton, was climbing shrubs, which is mainly distributed in the southwest of Yunnan provence, India, Sri Lanka, Indochina, and Malaysia. Phytochemical investigations on the genus Croton have revealed its predominant secondary metabolites as diterpenoids. We were studied on the twigs of Cronton caudatus from xishuangbannan area. This has led to the isolation of 11 compounds, including 4 diterpenoids,1 megastigmane glycoside,3 flavonoids,2 lignans, and 1 tetraterpene. Among them,4 new compouds were identified, including 3 tigliane type diterpenoids and 1 megastigmane glycoside. In addition,3 new tigliane type diterpenoids were evaluated for their cytotoxic activity against five human cell lines; besides,1 new megastigmane glycoside was evaluated for its antibacterial activity and anti-HIV activity.2、Chemical constituents from cecidogenous leaves of A. scholaris and their bioactivityAlstonia scholaris, belongs to Apocynaceae genus Alstonia, is an evergreen tree. Its leaves are called "dengtaiye" in Chinese, and an effective Dai medicine for the treatment of whooping cough, chronic bronchus, et al. Now we can buy over-the-counter products of its leaves particles made by Yunnan Datang Hanfang and Kunming Zhenhua pharmaceutical co. LTD. We were studied on the cecidogenous leaves of Alstonia scholaris, and this has led to the isolation of 21 compounds, including 1 new skeleton indole alkaloid,19 alkaloids and 1 lignan.3、Chemical constituents from roots of A. scholarisDuring our research, we found the HPLC fingerprint analysis of the extracts of leaves and roots of A. scholaris showed some obvious difference. Motivated by the intriguing architectures, and bioactivities of monoterpenoid indole alkaloids in this plant, we were studied on the roots of Alstonia scholaris, and this has led to the isolation of 14 known compounds.4、Chemical constituents from twigs of A. scholarisThe twig of A. scholaris is effective to treat headache, whooping cough, chronic bronchus et al., besides, it can also be useful to stop bleeding, to detumescence, and to preparation of pesticides. Previous investigation on cecidogenous leaves and roots of A. scholaris have revealed diverse skeletons of monoterpenoid indole alkaloids from this plant, this intrigued us to study on the twigs of Alstonia scholaris, and this has led to the isolation of 11 known compounds.5、Preparation of diverse indole alkaloids and their bioactivitiesIn nature, the skeletons of monotepenoids indole alkaloids are diversity and numerous, but mostly can be trade back to tryptamine and secologanin. Generally, tryptamine and secologanin with the molar ratio of 1:1 make the Mannich reaction. But, during our group’s previous investigation on Winchia calophylla, alstrostines A and B can trade back to tryptamine and secologanin with the molar ratio of 1:2. This motivated us to thinking about the diversity of the pathways of biosynthesis. As results, we were studied on the tryptamine and swertimarin one pot systhesis of alkaloids, and this has led to the isolation of 24 compounds, including 19 new ones.