Studies On The Chemical Constituents And Bioactivities Of Two Dysoxylum And Two Croton Species

The genus Dysoxylum (Meliaceae), trees or shrubs, comprising about200species, is mainly distributed in India and Southeast Asia. About14species being native to China mainly grows in the southern Provinces of China, there are10species in the southern and southwest of Yunnan province. Many plants in this genus are used as a folk medicine by indigenous Fijians, New Zealand and Papua New Guinea to treat many diseases, such as fever, spasms and limb numbness. Dysoxylum hongkongense are used as a medicine for treating malaria in China. The woods of this genus are faintly fragrant and suitable for furniture. The timber obtained from these plants is of enormous economic importance. Dysoxylum lenticellatum C. Y. Wu and Dysoxylum cupuliforme H. L. Li (Meliaceae) are tall tree distributed mainly in Yunnan Province. However, there has been little report about the chemical constituents and no report about the bioactivity of Dysoxylum.lenticellatum.The Croton L. is a genus of the family Euphorbiaceae and many for trees or shrubs, rare herbs. About800species are mainly distributed in tropic or subtropics. In China there are21species mainly grows in southwest and southeast Provinces of China. Most of these plants are toxic, and have been used in the treatment the stomach swelling in Chinese folklore medicine. Plants of the the genus Croton L. are rich sources of structurally diverse and biologically significant diterpenes, which has antitumor, anti-HIV, antibiotic, antioxidant, anti-inflammatory analgesic, and hypoglycemic activities. The chemical constituents and bioactivity has little been reported of Croton laevigatus and Croton damayeshu.The chemical constituents and their bioactivities of Dysoxylum lenticellatum, Dysoxylum cupuliforme, Croton laevigatus and Croton damayeshu were studied in this thesis. The chemical constituents of104compounds were isolated by means of silica gel and Sephadex LH-20gel columm chromatography, MCI gel columm chromatography, preparative thin layer chromatography and recrystallization etc. The structures of these compounds, which belonged to tirucallane-type triterpenoids, oleanane-type triterpenoids, labdane-type diterpenoids, sesquiterpenes, lignans, flavonoids and sterols etc, were elucidated on the basis of modern spectroscopic methods, including IR, UV, CD, EI-MS, HRESIMS, ID NMR (1H NMR,13C NMR, DEPT and NOE),2D NMR (1H-1H COSY, HSQC, HMBC, NOESY and ROESY), and single-crystal X-ray crystallography, the CD exciton chirality method, and comparison with authentic samples or the data from literature, and there were26new compounds.Thirty-seven compounds were isolated and elucidated from Dysoxylum lenticellatum. They were identified as tirucallane-type triterpenoids, oleanane-type triterpenoids, and sterols etc, ten of which were new compounds. And thirty-five compounds were isolated and elucidated from Croton laevigatus. They were identified as labdane-type diterpenoids, sesquiterpenes, and lignans and flavonoids etc, among them, sixteen were new diterpenoids. Fourteen compounds were isolated from Dysoxylum cupuliforme. They were identified as oleanane-type triterpenoids, sterols and flavonoids etc. Eighteen compounds were isolated from Croton damayeshu. They were identified as lignans, coumarin and flavonoids. Moreover, some compounds were evaluated for cytotoxic activity against HL-60(human promyelocytic leukemia) and SMMC-7721(human hepatoma) tumor cells and vasodilative effects on intact rat aortic rings precontracted with phenylephrine (10-6M). Compounds1.4,1.5,1.11,1.15and1.18showed very weak cytotoxicity; compound1.12showed significant vasodilative effects on intact rat aortic rings with a diastolic degree of87.4%at10μg/mL.In the end of the thesis, one review was made on the systemic summarization for the chemnical constituents and bioactivitives of the genus Dysoxylum.The results would be a supplement for the research on bioaetivity of chemical constituents as well as strueture-activity relationship in traditional Chinese medieine, helpful referenee for pharmacology, chemotaxonomy and sereening new medicines, and may benefit utilizing and developing the natural resourees of our country.