The Synthesis Of Dihydropyridine Carrier-mutual Brain-targeting Prodrug And Study On Targeted Performance

The chemical structure of dihydropyridine carrier-mutual brain-targeting prodrug(DHPP) is similar to nicotinamide adenine dinucleotide(NADH) , and can be fast identified and deoxidized to according pyridine quaternary ammonium salt by NADH-NAD+ coenzyme . Since redox system, which is catalyzed by coenzyme, distributes inconsistently in the body, in which brain tissue less than the peripheral circulatory system, the formation of brain tissue is slower than plasma. Pyridine quaternary ammonium salt(PQAS) can be eliminated readily from peripheral circulatory system because of its good hydrophily performance . The 1,4-dihydropyridine form allows BBB penetration, and generates PQAS salt which is'locked'in the brain , then release parent drug and non-neurotoxicity carrier slowly. The non-neurotoxicity carrier can be eliminated from brain readily. This relative stable brain-targeting drug delivery system can concentrate in the brain and release parent drug slowly. The main research of this thesis is as follows:1. The synthesis of DHPPTacrine (THA), the first line drug for Alzheimer's disease (AD) in clinical treatment, was selected as parent drug. Firstly freed the drug's amino through alkali treatment, then linked with halogenate acetyl chloride and nicotinic acid or its derivate. The resultants reacted with alkylation reagent to PQAS. Finally PQAS was deoxidized in water/DCM heterogeneous system. The structure of DHPP was determined by NMR and MS.2. The synthesis of nicotinamide formoononetin and 3,5-pyridine dicarboxylate formoononetinFormononetin, which can be used for treating AD as an important complementary drug, was selected as parent drug. To prepare nicotinamide formoononetin by DCC/DMAP coupling reagents in anhydrous pyridine, and prepare 3,5-pyridine dicarboxylate formoononetin through 3,5-pyridine dicarboxylic chlorine. The structure of targeted molecular were determined by NMR and MS.3. Study on the methodology of determining the concentration of drugTen rats (male:female=1:1) were sacrificed and obtained blood from abdominal aorta . Brain, heart, liver, lung and kidney were removed, weighed and frozen in -20℃. Each organ was diluted 2:1 with normal saline and homogenized . 1.6μg/mL,16μg/mL,32μg/mL,48μg/mL,64μg/mL,72μg/mL,96μg/mL THA standard solution (contained internal standard caffeine)were prepared to samples, then detected by HPLC. Chromatographic condition: C18 column(250mm×4.6mm); 0.1M Phosphate buffered saline(PBS)(pH=6.1): Acetonitrile (62:38); flow: 1.0mL/min; temperature: 37℃; sample size; 20μL; sample time: 11min. Working curves were as follows. Brain:Y=179354X+383439,r2=0.997; Plasma:Y=202854X+275920,r2=0.9975; Liver:Y=192344X+403239,r2=0.9946; Heart:Y=184554X+372999,r2=0.9980; Lung:Y=189354X+372320 r2=0.9946; Kidney: Y=229364X+415239 r2=0.9945 Respective precent recovery and precision were met the requirement .4. Study on the distribution of drug in tissue homogenates and plasmaTen rats (male:female=1:1) were administrated 10mg/kg THA and 15.5mg/kg DHPP-1 respectively . Rat were sacrificed at different time intervals following administration : 5min,10min,40min,1h,2h,4h,6h,8h,12h,24h .Brain, blood, heart, liver , lung and kidney were removed, weighed and frozen in -20℃. Each organ was diluted 2:1 with normal saline and homogenized. 500μL plasma and homogenates (contained internal standard caffeine) were extracted with methanol. and detected by HPLC. The result shows that concentration of QAS in brain is higher than other organs and plasma, and DHPP-1 releases parent drug slowly. It indicates that this dihydropyridine carrier-mutual prodrug be provided with a good brain-targeting and slow released ability, also can eliminate from the peripheral system easily.