Background: The intentional dissemination of the “anthrax letter” led the researchers to increase their efforts towards the development of medical countermeasures against anthrax bioterrorism. A virulent strain of Bacillus anthracis secretes deadly three protein exotoxin (protective antigen, lethal factor and edema factor) that is the causative agent of anthrax and considered as serious biological weapons.

Objective: Due to limited existing therapeutics options, there is still an insecure situation to combat anthrax. This prompted us to design a multifunctional inhibitor instead of a traditional one that competes simultaneously with the Protective Antigen (PA), Lethal Factor (LF) and Edema Factor (EF) for their binding sites.

Methods: We integrated a pharmacophore modeling approach with the virtual screening and molecular docking analysis in the context of unique structural characteristics of deadly anthrax toxins.

Results: Initially, we screened 56,000 natural compounds against designed pharmacophore consensus that returned 351 hits. Out of these initial screening hits, only 100 compounds passed out through Lipinski filter that comprised of 12 chemically relevant clusters. By exclusion of duplicate and based on their fit score in each cluster, 15 unique compounds were selected for detailed study. Putative multifunctional compounds subjected to deep structural analysis in the milieu of anthrax toxins binding pockets to gauge critical structural crunch.

Conclusion: Our integrative approach provides a novel therapeutic window to develop a small molecular inhibitor that simultaneously targets three components of anthrax deadly toxin at the molecular level to elicit the desired biological process.

背景：“炭疽信”的有意传播促使研究人员加大力度，开发针对炭疽生物恐怖主义的医学对策。炭疽芽孢杆菌的强毒株分泌致命的三种蛋白质外毒素（保护性抗原，致死因子和浮肿因子），是炭疽的病原体，被认为是严重的生物武器。

目的：由于现有治疗方法的局限性，对抗炭疽的情况仍然不安全。这促使我们设计了一种多功能抑制剂，而不是传统的抑制剂，它与保护性抗原（PA），致死因子（LF）和水肿因子（EF）同时竞争其结合位点。

方法：在致命炭疽毒素的独特结构特征的背景下，我们将药效团建模方法与虚拟筛选和分子对接分析相结合。

结果：最初，我们根据设计的药效基团共识筛选出了56,000种天然化合物，得出351个结果。在这些最初的筛选结果中，只有100种化合物通过Lipinski过滤器排出，该过滤器由12个化学相关的簇组成。通过排除重复项并根据它们在每个簇中的拟合度得分，选择15种独特的化合物进行详细研究。推测的多功能化合物在炭疽毒素结合口袋的环境中进行了深入的结构分析，以衡量关键的结构紧缩。

结论：我们的综合方法为开发一种小分子抑制剂提供了一种新颖的治疗方法，该抑制剂可在分子水平上同时靶向炭疽致命毒素的三个成分，从而引发所需的生物学过程。