Laboratorio de Química Orgánica y Farmacéutica, Departamento de Ciencias Farmacéuticas, Universidad de Salamanca, Campus Miguel de Unamuno, E-37007 Salamanca, Spain; Instituto de Investigación Biomédica de Salamanca (IBSAL), Facultad de Farmacia, Universidad de Salamanca, Campus Miguel de Unamuno, E-37007 Salamanca, Spain; Centro de Investigación de Enfermedades Tropicales de la Universidad de Salamanca (CIETUS), Facultad de Farmacia, Universidad de Salamanca, Campus Miguel de Unamuno, E-37007 Salamanca, Spain.
Laboratory of Cell Death and Cancer Therapy, Department of Molecular Biomedicine, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), E-28040 Madrid, Spain.
Bioorg Chem. 2020 May;98:103755. doi: 10.1016/j.bioorg.2020.103755. Epub 2020 Mar 13.
Colchicine site antimitotic agents typically suffer from low aqueous solubilities and are formulated as phosphate prodrugs of phenolic groups. These hydroxyl groups are the aim of metabolic transformations leading to resistance. There is an urgent need for more intrinsically soluble analogues lacking these hydroxyl groups. The 3,4,5-trimethoxyphenyl ring of combretastatin A-4 is a liability in terms of solubility but it is considered essential for high cytotoxic and tubulin polymerization inhibitory (TPI) activity. We have synthesized 36 new analogues of combretastatin A-4 replacing the trimethoxyphenyl moiety with more polar pyridine based moieties, measured their aqueous solubility, and studied their anti-proliferative effects against 3 human cancer cell lines. We show here that pyridine rings can be successful replacements for the trimethoxyphenyl ring, resulting in potent and more soluble analogues. The more straightforward replacement, a 2,6-dimethoxypyridine ring led to inactive analogues, but a 2-methoxy-6-methylsulfanylpyridine moiety led to active analogues when combined with different B rings. This replacement led to potent cytotoxic activity against sensitive human cancer cell lines due to tubulin inhibition, as shown by cell cycle analysis, confocal microscopy, and tubulin polymerization inhibitory activity studies. Cell cycle analysis also showed apoptotic responses following treatment. Docking studies suggested binding at the colchicine site of tubulin and provided a good agreement with the observed SAR. A 2-methoxy-6-methylsulfanylpyridine moiety is a good trimethoxyphenyl ring replacement for the development of new colchicine site ligands.
秋水仙碱位点抗有丝分裂剂通常水溶性低，并被制成酚羟基的磷酸盐前药。这些羟基是导致耐药性的代谢转化的目标。因此，迫切需要缺乏这些羟基的更内在溶解的类似物。对于来源于 Combretastatin A-4 的 3,4,5-三甲氧基苯基环，其在溶解度方面是不利的，但被认为对于高细胞毒性和微管蛋白聚合抑制（TPI）活性是必需的。我们已经合成了 36 种 Combretastatin A-4 的新类似物，用更极性的吡啶基取代了三甲氧基苯基部分，测量了它们的水溶解度，并研究了它们对 3 个人类癌细胞系的抗增殖作用。我们在这里表明，吡啶环可以成功替代三甲氧基苯基环，从而得到有效且更易溶解的类似物。更直接的替代物，2,6-二甲氧基吡啶环导致无活性类似物，但当与不同的 B 环结合时，2-甲氧基-6-甲硫基吡啶部分导致活性类似物。这种替代导致对敏感的人类癌细胞系产生强烈的细胞毒性活性，这是由于微管蛋白抑制，如细胞周期分析、共聚焦显微镜和微管蛋白聚合抑制活性研究所示。细胞周期分析还显示了处理后的凋亡反应。对接研究表明结合在微管蛋白的秋水仙碱位点，并与观察到的 SAR 提供了很好的一致性。2-甲氧基-6-甲硫基吡啶部分是开发新的秋水仙碱位点配体的良好的三甲氧基苯基环替代物。
