Two Compounds, Structure-function Relationship Of Biological Sources

In this thesis, the structure function relationships of 2 kinds of molecules from different biological resources were studied.The crystal structure and antitumor activity relationship of Rabdosia diter-penes and/or diterpenoids was described in the part â…  , while the interaction between 5S RNA and TF â…¢ A from Xenopus was described in the part â…¡ .In the part â… , a series of compounds of Rabdosin diterpenes and/or diterpenoids were analysed by X — ray crystallography. On the basis of these structures and other reported crystal structures of Robdosia, joined with the reported antitumor activity data, the structure activity relationship was proposed.There is plenty of diterpene and/or diterpenoid isolated from different species of Rabdosia. The research results for such kind of compounds indicated that many of such kind of compounds showed antitumor activities. Such a result led to great interest of scientist.With 10 crystal structures analysed in this thesis and other 24 crystal structures analysed by other authors , the diterpene and/or diterpenoid compounds from Rabdosia were accurately classified, while many others were predicted into these classes. With the structural classes and activities data, the structure activity relationship of such kind of compounds was analysed and proposed, namely①α—methylene—cyclotentanone, 14β—OH, and the oxygen atom near to the 15—one act together as the activity center;â‘¡The different orientation of C₁₇ will effect on the activity;â‘¢On the basis of the activity center, different skeletons of the molecules will have no effect on the activity;â‘£The ring A of the skeletons will have no contribution to the activity.The proposal on activity center was similar to the previous study, while the proposal on effect of the different orientation of C₁₇ and the space position of the oxygen atom was the first exposure . The proposal concerning no effect of the skeleton to activity was revealed first as well.All the 10 crystal structures were reported at the first time.According to the proposal, we predicted that the 4—epi—henryin A acetate and Longikaurin B in the 10 compounds will probably possess antitumor actisity being as the Trichorabdal B, Xindongnin A, and phyllostachysin A. Other 4 compounds will have no activity or very weak activity bing as sculponeatin B.