STR1 Substrate Development,Complex 3-D Structure Study And Construction Of Novel Alkaloids & N-Containing Heterocyclic Compounds

Plant-derived Pictet-Spengler(P-S)enzyme is one of the core enzymes in alkaloid biosynthesis pathways in plants.The different plant alkaloids according to the P-S enzyme catalytic product can be divided into the benzylisoquinoline alkaloid family,the monoterpene isoquinoline alkaloid family and the monoterpene alkaloid family.The monoterpene indole alkaloids,derived from secologanin through different biosynthesis pathways,have a wide range of biological activities,and some of which have become clinical drugs.Therefore,the study of STR is the basis for obtaining structural diversity,and active monoterpenoid alkaloids.Substrate adaptability and structural biology study of strictosidine synthase(STR1)from Rauvolfia were carried out,and on the basis of the discovery of new substrates,a number of new monoterpenoid alkaloids were obtained by enzymatic and chemical method.In addition,the "one-pot" method was also used to rapidly construct three types of N-containing heterocyclic compound library.To extend the application of STR1 in the synthesis of new alkaloids in vitro,based on the 3-D structural information of STR1 and the study of early substrate adaptability,new candidate substrates were rationally designed and synthesized.After STR1 catalytic activity screening,three new substrates of STR1 were found.It is noteworthy that the new substrate 2-(1H-indol-4-yl)ethanamine(4-IEA)breaks through the basic skeleton of the original substrate(tryptamine).As a novel structure of STR1 substrate,it greatly expands the scope of STR1’s substrate adaptability study.A novel strictosidine analogue 4α-(S)azepino[3,4,5-cd]indole strictosidine,structure-like natural monoterpene alkaloids,obtained from the 4-IEA and secologanin under the catalysis of STR1.The(2-amino-1(1H-indol-3-yl)ethanol(AIE)is the most suitable substrate of STR1 with the exception of tryptamine,and its relative catalytic activity is up to 45%.At the same time,AIE has successfully introduced a group with a large potential for re-modification,laying a material foundation for the construction of a large number of new alkaloid libraries.In this dissertation,the structure-activity relationship between STR1 and its ligands was discussed in detail,and the key structures and conformational factors affecting the catalytic activity of each candidate substrate were elucidated,and the catalytic kinetics and active factors of STR catalytic substrates were studied.Finally,the Kpi buffer catalyzes the stereoselective synthesis of strictosidine analogue from condensation of 4IEA with secologanin.Some of Multiple alkaloids of 4-azepino[3,4,5-cd]indole scaffold,synthesized by enzymatic and chemical method,have been shown to have antimalarial activity through series activity screening.In the third part of the paper,we quickly constructed three types of N-containing heterocyclic compounds through simple and available raw materials.The first one is the SN2 reaction,which is initiated at the electrophilic γ site of Morita-Baylis-Hillman Acetates(MBHAs)to provide a chiral synthesis method of 3,5-disubstituted pyrazoles.The second one,aldol cyclization,plays the key role in the intermolecular reaction of pyrrole-2-carbaldehydes to obtain indolizines.The last one,facilitated by Mummrearrangement,is intramolecular reaction of pyrrole-2-carbonitriles to synthesize pyrrolo[1,2-a]pyrazin-1(2H)-one derivatives.The N-containing heterocyclic compounds have a wide range of biological activities,so the rapid construction of N-containing heterocyclic compounds provide the material basis for the screening of new drugs.