Chintakrindi Anand S, Martis Elvis A F, Gohil Devanshi J, Kothari Sweta T, Chowdhary Abhay S, Coutinho Evans C, Kanyalkar Meena A
Department of Pharmaceutical Chemistry, Prin. K. M. Kundnani College of Pharmacy, Plot 23, Jote Joy Building, Rambhau Salgaonkar Marg, Cuffe Parade, Mumbai 400005, India.
Curr Comput Aided Drug Des. 2016;12(4):272-281. doi: 10.2174/1573409912666160713111242.
With cases of emergence of drug resistance to the current competitive inhibitors of neuraminidase (NA) such as oseltamivir and zanamavir, there is a present need for an alternative approach in the treatment of avian influenza. With this in view, some flavones and chalcones were designed based on quercetin, the most active naturally occurring noncompetitive inhibitor.
We attempt to understand the binding of quercetin to H5N1-NA, and synthetic analogs of quercetin namely flavones and its precursors the chalcones using computational tools.
Molecular docking was done using Libdock. Molecular dynamics (MD) simulations were performed using Amber14. We synthesized the two compounds; their structures were confirmed by infrared spectroscopy, 1H-NMR, and mass spectrometry. These molecules were then tested for H5N1-NA inhibition and kinetics of inhibition.
Molecular docking studies yielded two compounds i.e., 4'-methoxyflavone and 2'-hydroxy-4-methoxychalcone, as promising leads which identified them as binders of the 150-cavity of NA. Furthermore, MD simulation studies revealed that quercetin and the two compounds bind and hold the 150 loop in its open conformation, which ultimately perturbs the binding of sialic acid in the catalytic site. Estimation of the free energy of binding by MM-PBSA portrays quercetin as more potent than chalcone and flavone. These molecules were then determined as non-competitive inhibitors from the Lineweaver-Burk plots rendered from the enzyme kinetic studies.
We conclude that non-competitive type of inhibition, as shown in this study, can serve as an effective method to block NA and evade the currently seen drug resistance.
鉴于目前对神经氨酸酶（NA）的竞争性抑制剂（如奥司他韦和扎那米韦）出现耐药性的病例，目前需要一种治疗禽流感的替代方法。有鉴于此，基于最具活性的天然非竞争性抑制剂槲皮素，设计了一些黄酮类化合物和查耳酮。
我们试图使用计算工具了解槲皮素与H5N1-NA的结合情况，以及槲皮素的合成类似物黄酮类化合物及其前体查耳酮。
使用Libdock进行分子对接。使用Amber14进行分子动力学（MD）模拟。我们合成了这两种化合物；通过红外光谱、1H-NMR和质谱确认了它们的结构。然后测试这些分子对H5N1-NA的抑制作用和抑制动力学。
分子对接研究产生了两种化合物，即4'-甲氧基黄酮和2'-羟基-4-甲氧基查耳酮，作为有前景的先导化合物，确定它们为NA的150腔结合剂。此外，MD模拟研究表明，槲皮素和这两种化合物结合并使150环保持开放构象，最终扰乱催化位点中唾液酸的结合。通过MM-PBSA估算结合自由能，结果表明槲皮素比查耳酮和黄酮更有效。然后根据酶动力学研究绘制的Lineweaver-Burk图确定这些分子为非竞争性抑制剂。
我们得出结论，如本研究所示，非竞争性抑制类型可作为阻断NA和规避目前所见耐药性的有效方法。
