The Chemical Modification And Controlled Release Design Of Temozolomide

Glioblastoma multiforme is the most common and aggressive primary intracranial tumor in adults.Temozolomide?TMZ?is a currently widely used first-line treatment agent for glioblastoma treatment.It is an oral prodrug alkylating agent,which can spontaneously degrade and generate diazomethane spontaneously under physiological environment,and perform nucleophilic attack on DNA to exert cell killing effect.In this dissertation,we focus on the stabilization of the hydrolysis intermediate of temozolomide,the alkylated prodrug 5-?3-methyltriazen-1-yl?imidazole-4-carboxamide?MTIC?,and try to make MTIC get rid of the defects of p H instability and non-specific degradation brought about by the prodrug mechanism of temozolomide,and develop a more stable,effective and controllable prodrug strategy.Reduced glutathione is a recognized ideal and ubiquitous internal stimulus,which can rapidly destabilize intracellular nanoparticles,especially in endocytosis/lysosomes,cytosol,and nucleus,and promote the release of intracellular drugs.We designed and constructed a disulfide-stabilized MTIC polymer prodrug micelle nanosystem to achieve the MTIC stabilization and release strategy from the perspective of chemical synthesis.Compared with the small molecule temozolomide,the covalently linked MTIC prodrug nanoparticles exhibited excellent cytotoxicity.On the other hand,from the point of view of covalently linked combination medication,we designed and synthesized TMZ-Dox,an acylhydrazone bond conjugate of temozolomide and doxorubicin,which aims to improve drug effect.Firstly,we caged the active MTIC drug molecule through the"trigger"molecular disulfide bond to synthesize the MTIC prodrug monomer MTICSSM,and subsequently,the amphiphilic block copolymer prodrug was synthesized by RAFT polymerization and prepared prodrug nanoparticles MTICNPs with a hydrodynamic diameter of about135 nm,while having near neutral zeta potential and lower critical micelle concentration?30?g/m L?.Subsequently,we confirmed the storage stability of the nanoparticles and the p H stability of the MTIC drug structure therein,which made the nanoparticles stable for a long time during the circulation in vivo.The use of GSH as the trigger release source of MTIC prodrugs makes the release of the drugs specific,and tests have confirmed that the response of the prodrug nanoparticles has a significant GSH concentration dependence.At the same time,UPLC quickly detected the MTIC molecules released from the nanoparticles in the response process.Through quantitative detection of its by-product AIC,it was found that the drug release amount can reach as high as 90%in the simulated tumor cell environment.Compared with TMZ,MTICNPs have better killing effects on U87MG cells and T98G cells,with IC₅₀ values as low as0.318 mg/m L and 0.111 mg/m L,respectively,after 24-h treatment.Secondly,we have covalently linked temozolomide and doxorubicin through the acylhydrazone bond to synthesize the drug conjugate TMZ-Dox.The nuclear magnetic resonance spectroscopy,high-resolution mass spectrometry and ultraviolet absorption spectrum tests confirmed the correctness of the TMZ-Dox structure.Finally,the anti-tumor effect of TMZ-Dox was evaluated on TMZ-sensitive U87MG cells and TMZ-resistant T98G cells.