Focused library synthesis and medicinal chemistry on an oxadiazole-isopropylamide core proteasome inhibitor provided the lead compound that strongly inhibits CT-L activity. Structure activity relationship studies indicate the amide moiety and two phenyl rings are sensitive toward synthetic modifications. Only para-substitution in the A-ring was important to maintain potent CT-L inhibitory activity. Hydrophobic residues in the A-ring's para-position and meta-pyridyl group at the B-ring significantly improved inhibition. The meta-pyridyl moiety improved cell permeability. The length of the aliphatic chain at the para position of the A-ring is critical with propyl yielding the most potent inhibitor, whereas shorter (i.e. ethyl, methyl or hydrogen) or longer (i.e. butyl, propyl and hexyl) chains demonstrating progressively less potency. Introduction of a stereogenic center next to the ether moiety (i.e. substitution of one of the hydrogens by methyl) demonstrated chiral discrimination in proteasome CT-L activity inhibition (the S-enantiomer was 35-40 fold more potent than the R-enantiomer).
通过对一种噁二唑-
异丙基酰胺核心
蛋白酶体
抑制剂进行重点文库合成和药物
化学研究,获得了能强烈抑制 CT-L 活性的先导化合物。结构活性关系研究表明,
酰胺分子和两个
苯基环对合成修饰很敏感。只有 A 环中的对位取代对保持 CT-L 的强效抑制活性非常重要。A 环的对位疏
水残基和 B 环的元
吡啶基能显著改善抑制作用。偏
吡啶基提高了细胞渗透性。A 环对位
脂肪族链的长度至关重要,丙基产生的抑制作用最强,而较短的链(即乙基、
甲基或
氢基)或较长的链(即丁基、丙基和己基)的抑制作用则逐渐减弱。在醚分子旁边引入一个立体中心(即用
甲基取代其中一个
氢)可在
蛋白酶体 CT-L 活性抑制方面显示出手性差异(S-对映体的效力比 R-对映体高 35-40 倍)。