The Studies On The Structural Modification Of Pretubulysin And Antitumor Activity In Vitro

Natural products are regarded as an important source of excavation lead compounds in the development of new drugs due to their wide source,novel structure and low toxicity.Both tubulysin and pretubulysin mentioned in this paper are a kind of natural products extracted from myxobacteria with antitumor activity.Tubulysin compounds have complicated synthetic routes due to the large number of chiral centers,and other defects such as low yield,and high molecular weight.Pretubulysin,as its precursor compound,has a simplified structure and comparable activity.Therefore,according to principles of modern drug design,an amide bond is used instead of a carbon-carbon single bond in the Tuv part,a hydrogen bond acceptor and donor being introduced,and a series of compounds based on pretubulysin structure are designed and synthesized to overcome the deficiencies.The preliminary evaluation of its anti-tumor activity in vitro is carried out,and the computer-assisted drug design software SYBYL is used to evaluate the molecular docking score.At the same time,based on the preliminary work of the research group,the structure-activity relationship is further explored and summarized.In this project,pretubulysin is used as a lead compound,and a total of 16 compounds of four classes are synthesized and modified,all of which are new compounds.The synthesis route is that bromination is carried out by using ethyl pyruvate as a raw material,and reacting with thiourea to form a ring getting ethyl 2-amimothiazole-4-carboxylate.The amino is protected by Boc protecting group,and then hydrolysis obtaining a free carboxylic acid.Further condensing with phenethylamine,methylamine,L-phenylalanine ethyl ester or benzyl-amine to obtain a dipeptide compound,followed by removal of the Boc protecting group under the action of trifluoroacetic acid,and condensation with N-Fmoc-N-methyl-L-Val to obtain a structure similar to the tripeptide compound.Then the Fmoc protecting group is removed by piperidine to obtain a naked secondary amine,which can be finally reacted with an carboxylic acid or directly with an phenyl isocyanate containing a different substituent to obtain a final target compounds.And the structure ofthe target compounds is determined by nuclear magnetic resonance spectroscopy,carbon spectroscopy,or mass spectrometry.The antitumor activity of the compounds on KB,MCF-7 cancer cells in vitro is investigated by MTT assay,and some of the compounds show a certain degree of growth inhibition on cancer cells.Molecular docking is performed on the target compounds using computer-aided drug design software SYBYL.According to the results of the anti-tumor activity of the compound in vitro,the results of the structure-activity relationship can be summarized as follows: when the nitrogen-terminal Mep moiety is substituted with aromatic ring containing a substituent,the electron-donating group is beneficial to activity;the unsubstituted heteroatom-containing aromatic ring has a slightly lower activity;the activity of linking methylamine of the Tup moiety is slightly lower than that of a larger volume group such as phenethylamine or phenylalanine ethyl ester.