Institute for Glycomics , Griffith University, Gold Coast Campus , Queensland 4222 , Australia.
ACS Chem Biol. 2018 Jun 15;13(6):1544-1550. doi: 10.1021/acschembio.8b00150. Epub 2018 May 21.
A novel approach to human parainfluenza virus 3 (hPIV-3) inhibitor design has been evaluated by targeting an unexplored pocket within the active site region of the hemagglutinin-neuraminidase (HN) of the virus that is normally occluded upon ligand engagement. To explore this opportunity, we developed a highly efficient route to introduce nitrogen-based functionalities at the naturally unsubstituted C-3 position on the neuraminidase inhibitor template N-acyl-2,3-dehydro-2-deoxy-neuraminic acid ( N-acyl-Neu2en), via a regioselective 2,3-bromoazidation. Introduction of triazole substituents at C-3 on this template provided compounds with low micromolar inhibition of hPIV-3 HN neuraminidase activity, with the most potent having 48-fold improved potency over the corresponding C-3 unsubstituted analogue. However, the C-3-triazole N-acyl-Neu2en derivatives were significantly less active against the hemagglutinin function of the virus, with high micromolar IC values determined, and showed insignificant in vitro antiviral activity. Given the different pH optima of the HN protein's neuraminidase (acidic pH) and hemagglutinin (neutral pH) functions, the influence of pH on inhibitor binding was examined using X-ray crystallography and STD NMR spectroscopy, providing novel insights into the multifunctionality of hPIV-3 HN. While the 3-phenyltriazole- N-isobutyryl-Neu2en derivative could bind HN at pH 4.6, suitable for neuraminidase inhibition, at neutral pH binding of the inhibitor was substantially reduced. Importantly, this study clearly demonstrates for the first time that potent inhibition of HN neuraminidase activity is not necessarily directly correlated with a strong antiviral activity, and suggests that strong inhibition of the hemagglutinin function of hPIV HN is crucial for potent antiviral activity. This highlights the importance of designing hPIV inhibitors that primarily target the receptor-binding function of hPIV HN.
一种针对人类副流感病毒 3 (hPIV-3) 抑制剂设计的新方法已通过针对病毒血凝素-神经氨酸酶 (HN) 活性部位内一个未探索的口袋进行评估，该口袋在配体结合时通常被封闭。为了探索这一机会，我们通过区域选择性 2,3-溴代叠氮化物开发了一种在神经氨酸酶抑制剂模板 N-酰基-2,3-去氢-2-脱氧神经氨酸 (N-酰基-Neu2en) 的天然未取代 C-3 位引入含氮官能团的高效途径。在该模板的 C-3 位引入三唑取代基可提供对 hPIV-3 HN 神经氨酸酶活性具有低微摩尔抑制作用的化合物，其中最有效的化合物对相应的 C-3 未取代类似物的效力提高了 48 倍。然而，C-3-三唑 N-酰基-Neu2en 衍生物对病毒的血凝素功能的活性显著降低，确定了高微摩尔 IC 值，并且表现出微不足道的体外抗病毒活性。鉴于 HN 蛋白的神经氨酸酶（酸性 pH）和血凝素（中性 pH）功能的不同 pH 最佳值，使用 X 射线晶体学和 STD NMR 光谱学研究了 pH 对抑制剂结合的影响，为 hPIV-3 HN 的多功能性提供了新的见解。虽然 3-苯基三唑- N-异丁酰基-Neu2en 衍生物可以在 pH 4.6 下结合 HN，适合神经氨酸酶抑制，但在中性 pH 下抑制剂的结合大大减少。重要的是，这项研究首次清楚地表明，HN 神经氨酸酶活性的强烈抑制不一定与强大的抗病毒活性直接相关，并表明强烈抑制 hPIV HN 的血凝素功能对于强大的抗病毒活性至关重要。这突出了设计主要针对 hPIV HN 受体结合功能的 hPIV 抑制剂的重要性。
