Abstract：
Bacterial resistance is spreading in an alarming manner, outpacing the rate of development of new antibacterial agents and surging the need for effective alternatives. Prenylated flavonoids are a promising class of natural antibiotics with reported activity against a wide range of resistant pathogens. Here, a large library of natural flavonoids (1718 structures) was virtually screened for potential candidates inhibiting the B-subunit of gyrase (Gyr-B). Twenty-eight candidates, predominated by prenylated flavonoids, appeared as promising hits. Six of them were selected for further in vitro antibacterial and Gyr-B enzyme inhibitory activities. Auriculasin is presented as the most potent antibacterial candidate, with a MIC ranging from 2 to 4 µg/ml against two clinically isolated multidrug-resistant Escherichia coli strains. Mechanistic antibacterial analysis revealed auriculasin inhibitory activity towards the Gyr-B enzyme on the micromolar scale (IC50 = 0.38 ± 0.15 µM). Gyr-B interaction was further detailed by conducting an isothermal titration calorimetric experiment, which revealed a competitive inhibition with a high affinity for the Gyr-B active site, achieved mostly through enthalpic interactions (ΔGbinding = -10.69 kcal/mol). Molecular modeling and physics-based simulations demonstrated the molecule\'s manner of fitting inside the Gyr-B active site, indicating a very potential nucleus for the future generation of more potent derivatives. To conclude, prenylated flavonoids are interesting antibacterial candidates with anti-Gyr-B mechanism of action that can be obtained from a plant-derived flavonoid.
摘要：
细菌耐药性正在以惊人的方式蔓延，超过了新抗菌剂的开发速度，并且对有效替代品的需求激增。戊烯化类黄酮是一类有前途的天然抗生素，据报道具有针对多种抗性病原体的活性。这里,我们对一个大型天然类黄酮库(1718个结构)进行了虚拟筛选,筛选出抑制促旋酶B亚基(Gyr-B)的潜在候选物.28名候选人,以异戊二烯化类黄酮为主，看起来很有希望。选择其中的六个用于进一步的体外抗菌和Gyr-B酶抑制活性。Auriculasin被认为是最有效的抗菌候选药物，对两种临床分离的多重耐药大肠杆菌菌株的MIC范围为2至4µg/ml。机理抗菌分析显示，在微摩尔尺度（IC50=0.38±0.15µM）上，木耳蛋白对Gyr-B酶的抑制活性。通过进行等温滴定量热实验，进一步详述了Gyr-B相互作用，这揭示了对Gyr-B活性位点具有高亲和力的竞争性抑制作用，主要通过焓相互作用实现(ΔG结合=-10.69千卡/摩尔)。分子建模和基于物理学的模拟证明了分子在Gyr-B活性位点内的拟合方式，表明了未来一代更有效的衍生物的非常潜在的核心。最后，戊烯化类黄酮是具有抗Gyr-B作用机制的令人感兴趣的抗菌候选物,其可以从植物来源的类黄酮获得。
