AbstractNew amiridine‐thiouracil conjugates with different substituents in the pyrimidine fragment (R = CH3, CF2Н, CF3, (CF2)2H) and different spacer lengths (n = 1–3) were synthesized. The conjugates rather weakly inhibit acetylcholinesterase (AChE) and exhibit high inhibitory activity (IC50 up to 0.752 ± 0.021 µM) and selectivity to butyrylcholinesterase (BChE), which increases with spacer elongation; the lead compounds are 11c, 12c, and 13c. The conjugates are mixed‐type reversible inhibitors of both cholinesterases and practically do not inhibit the structurally related off‐target enzyme carboxylesterase. The results of molecular docking to AChE and BChE are consistent with the experiment on enzyme inhibition and explain the structure–activity relationships, including the rather low anti‐AChE activity and the high anti‐BChE activity of long‐chain conjugates. The lead compounds displace propidium from the AChE peripheral anion site (PAS) at the level of the reference compound donepezil, which agrees with the mixed‐type mechanism of AChE inhibition and the main mode of binding of conjugates in the active site of AChE due to the interaction of the pyrimidine moiety with the PAS. This indicates the ability of the studied conjugates to block AChE‐induced aggregation of β‐amyloid, thereby exerting a disease‐modifying effect. According to computer calculations, all synthesized conjugates have an ADME profile acceptable for drugs.
摘要 合成了嘧啶片段中具有不同取代基(R = CH3、CF2Н、CF3、(CF2)2H)和不同间隔长度(n = 1-3)的新型脒基硫脲嘧啶共轭物。这些共轭物对乙酰胆碱酯酶(AChE)的抑制作用较弱,而对丁酰胆碱酯酶(BChE)则表现出较高的抑制活性(IC50 达 0.752 ± 0.021 µM)和选择性,其选择性随间隔长度的增加而增加;先导化合物为 11c、12c 和 13c。这些共轭物是两种胆碱酯酶的混合型可逆抑制剂,对结构相关的非靶标酶羧酸酯酶几乎没有抑制作用。与 AChE 和 BChE 的分子对接结果与酶抑制实验结果一致,并解释了结构-活性关系,包括长链共轭物较低的抗 AChE 活性和较高的抗 BChE 活性。先导化合物从 AChE 外周阴离子位点(PAS)置换出丙啶的程度与参考化合物多奈哌齐相同,这与 AChE 抑制的混合型机制以及共轭物在 AChE 活性位点的主要结合方式一致,即嘧啶分子与 PAS 相互作用。这表明所研究的共轭物能够阻断 AChE 诱导的 β 淀粉样蛋白的聚集,从而发挥疾病调节作用。根据计算机计算,所有合成的共轭物都具有药物可接受的 ADME 特性。