Paciotti Roberto, Carradori Simone, Angeli Andrea, D'Agostino Ilaria, Ferraroni Marta, Coletti Cecilia, Supuran Claudiu T
Department of Pharmacy, "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy.
Section of Pharmaceutical and Nutraceutical Sciences, Department of Neuroscience, Psychology, Drug Research and Child Health (NEUROFARBA), University of Florence, Sesto Fiorentino, Firenze, Italy.
Arch Pharm (Weinheim). 2025 Jan;358(1):e2400776. doi: 10.1002/ardp.202400776.
2,2'-Thio-bis(4,6-dichlorophenol), namely bithionol, is a small molecule endowed with a multifaceted bioactivity. Its peculiar polychlorinated phenolic structure makes it a suitable candidate to explore its potentialities in establishing interaction patterns with enzymes of MedChem interest, such as the human carbonic anhydrase (hCA) metalloenzymes. Herein, bithionol was tested on a panel of specific hCAs through the stopped-flow technique, showing a promising micromolar inhibitory activity for the hCA II isoform. X-ray crystallographic studies revealed an unprecedented halogen-bond interaction between one chlorine of bithionol and the N3(ε) atom of the hCA II catalytically active histidine residue, His64. Then, quantum mechanics calculations based on the fragment molecular orbital method allowed us to estimate the strength of this bond (~2.9 kcal/mol) and highlighted the contribution of a rich hydrophobic interaction network within the isoenzyme. Interestingly, the compound inactivity against the hCA III isoform, characterized by His64Lys and Leu198Phe mutations, supported the key role played by halogen bonding in the enzyme affinity. This finding might pave the way for the development of a new class of hCA inhibitors characterized by such chemical features, with the halogen bond being a key ligand-receptor interaction.
2,2'-硫代双(4,6-二氯苯酚)，即硫双二氯酚，是一种具有多方面生物活性的小分子。其独特的多氯酚结构使其成为探索与药物化学感兴趣的酶（如人类碳酸酐酶（hCA）金属酶）建立相互作用模式潜力的合适候选物。在此，通过停流技术在一组特定的hCA上对硫双二氯酚进行了测试，结果表明它对hCA II同工型具有有前景的微摩尔抑制活性。X射线晶体学研究揭示了硫双二氯酚的一个氯原子与hCA II催化活性组氨酸残基His64的N3(ε)原子之间存在前所未有的卤键相互作用。然后，基于片段分子轨道方法的量子力学计算使我们能够估计该键的强度（约2.9千卡/摩尔），并突出了同工酶内丰富的疏水相互作用网络的贡献。有趣的是，该化合物对以His64Lys和Leu198Phe突变为特征的hCA III同工型无活性，这支持了卤键在酶亲和力中所起的关键作用。这一发现可能为开发一类具有此类化学特征的新型hCA抑制剂铺平道路，其中卤键是关键的配体-受体相互作用。
