ABSTRACT
In an effort to discover novel, noncarbohydrate inhibitors of influenza virus neuraminidase we hypothesized that compounds which contain positively charged amino groups in an appropriate position to interact with the Asp 152 or Tyr 406 side chains might be bound tightly by the enzyme. Testing of 300 α- and β-amino acids led to the discovery of two novel neuraminidase inhibitors, a phenylglycine and a pyrrolidine, which exhibited
K
i
values in the 50 μM range versus influenza virus A/N2/Tokyo/3/67 neuraminidase but which exhibited weaker activity against influenza virus B/Memphis/3/89 neuraminidase. Limited optimization of the pyrrolidine series resulted in a compound which was about 24-fold more potent than 2-deoxy-2,3-dehydro-
N
-acetylneuraminic acid in an anti-influenza cell culture assay using A/N2/Victoria/3/75 virus. X-ray structural studies of A/N9 neuraminidase-inhibitor complexes revealed that both classes of inhibitors induced the Glu 278 side chain to undergo a small conformational change, but these compounds did not show time-dependent inhibition. Crystallography also established that the α-amino group of the phenylglycine formed hydrogen bonds to the Asp 152 carboxylate as expected. Likewise, the β-amino group of the pyrrolidine forms an interaction with the Tyr 406 hydroxyl group and represents the first compound known to make an interaction with this absolutely conserved residue. Phenylglycine and pyrrolidine analogs in which the α- or β-amino groups were replaced with hydroxyl groups were 365- and 2,600-fold weaker inhibitors, respectively. These results underscore the importance of the amino group interactions with the Asp 152 and Tyr 406 side chains and have implications for anti-influenza drug design.
摘要
为了发现新型的、非碳水化合物的流感病毒神经氨酸酶抑制剂,我们假设在适当的位置含有带正电荷的氨基,能与 Asp 152 或 Tyr 406 侧链相互作用的化合物可能会与该酶紧密结合。对 300 种 α- 和 β- 氨基酸进行测试后,我们发现了两种新型神经氨酸酶抑制剂,一种是苯甘氨酸,另一种是吡咯烷,它们的 K
K
i
值在 50 μM 范围内,但对 B 型流感病毒/孟菲斯/3/89 神经氨酸酶的活性较弱。对吡咯烷系列进行有限的优化后,一种化合物的药效比 2-脱氧-2,3-脱氢-N
N
在使用 A/N2/Victoria/3/75 病毒进行的抗流感细胞培养试验中,该化合物的效力是 2-脱氧-2,3-脱氢-N-乙酰神经氨酸的 24 倍。对 A/N9 神经氨酸酶抑制剂复合物的 X 射线结构研究表明,这两类抑制剂都能诱导 Glu 278 侧链发生微小的构象变化,但这些化合物并没有表现出时间依赖性抑制作用。晶体学研究还证实,苯甘氨酸的 α-氨基与 Asp 152 羧酸根形成氢键是意料之中的。同样,吡咯烷的 β-氨基也与 Tyr 406 的羟基相互作用,这是已知的第一个与这个绝对保守的残基相互作用的化合物。用羟基取代α-或β-氨基的苯甘氨酸和吡咯烷类似物的抑制作用分别弱365倍和2600倍。这些结果凸显了氨基与 Asp 152 和 Tyr 406 侧链相互作用的重要性,对设计抗流感药物具有重要意义。