The aim of this study was to gain insight into the feasibility of enhancing the delivery of L-Dopa and dopamine to the brain by linking these neurotransmitters and L-Dopa ethyl ester to 2-phenyl-3-carboxymethyl-imidazopyridine compounds giving rise to the so-called Dopimid compounds. A number of Dopimid compounds were synthesized and both stability and binding studies to dopaminergic and benzodiazepine receptors were performed. To evaluate whether Dopimid compounds are P-gp substrates, [3H]ritonavir uptake experiments and bi-directional transport studies on confluent MDCKII-MDR1 monolayers were carried out. The brain penetration properties of Dopimid compounds were estimated by the Clark’s computational model and evaluated by investigation of their transport across BBMECs monolayers. The dopamine levels following the intraperitoneal administration of the selected Dopimid compounds were measured in vivo by using brain microdialysis in rat. Tested compounds were adequately stable in solution buffered at pH 7.4 but undergo faster cleavage in dilute rat serum at 37°C. Receptor binding studies showed that Dopimid compounds are essentially devoid of affinity for dopaminergic and benzodiazepine receptors. [3H]ritonavir uptake experiments indicated that selected Dopimid compounds, like L-Dopa and dopamine hydrochloride, are not substrates of P-gp and it was also confirmed by bi-directional transport experiments across MDCKII-MDR1 monolayers. By Clark’s model a significant brain penetration was deduced for L-Dopa ethyl ester and dopamine derivatives. Transport studies involving BBMECs monolayers indicated that some of these compounds should be able to cross the BBB. Interestingly, the rank order of apparent permeability (P app) values observed in these assays parallels that calculated by the computational approach. Brain microdialysis experiments in rat showed that intraperitoneal acute administration of some Dopimid compounds induced a dose-dependent increase in cortical dopamine output. Based on these results, it may be concluded that some Dopimid compounds can be proposed as novel L-Dopa and dopamine prodrugs.
本研究的目的是探讨通过将这些神经递质和L-Dopa
乙酯与2-苯基-3-羧甲基-
咪唑并
吡啶化合物连接,从而增强L-Dopa和
多巴胺向大脑输送的可行性,形成所谓的Dopimid化合物。合成了一些Dopimid化合物,并进行了稳定性和对
多巴胺能以及苯二氮卓类受体的结合研究。为了评估Dopimid化合物是否为P-gp底物,进行了[3H]
利托那韦摄取实验和在趋同MDCKII-MDR1单层上的双向转运研究。通过Clark的计算模型估算了Dopimid化合物的脑穿透特性,并通过调查其在BBM
ECs单层上的转运进行了评估。在大鼠体内使用脑微透析测量了选定Dopimid化合物腹腔给药后的
多巴胺水平。测试的化合物在pH 7.4的缓冲溶液中稳定性良好,但在37°C的稀释大鼠血清中分解速度较快。受体结合研究表明,Dopimid化合物基本上对
多巴胺能和苯二氮卓类受体没有亲和力。[3H]
利托那韦摄取实验表明,选定的Dopimid化合物,如L-Dopa和
氯化
多巴胺,并非P-gp底物,这也通过在MDCKII-MDR1单层上的双向转运实验得到了确认。根据Clark的模型,推断出L-Dopa
乙酯和
多巴胺衍
生物具有显著的脑穿透性。涉及BBM
ECs单层的转运研究表明,这些化合物中的一些应该能够穿过血脑屏障。有趣的是,在这些实验中观察到的表观渗透性(P app)值的排序与计算方法得出的结果相似。在大鼠的脑微透析实验中,腹腔急性给药某些Dopimid化合物会引起皮层
多巴胺输出的剂量依赖性增加。基于这些结果,可以得出结论,某些Dopimid化合物可以被提议作为新型的L-Dopa和
多巴胺前药。