Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
Department of Chemistry, Durham University, Science Laboratories, South Road, Durham, United Kingdom.
PLoS Negl Trop Dis. 2021 Nov 15;15(11):e0009951. doi: 10.1371/journal.pntd.0009951. eCollection 2021 Nov.
With current drug treatments failing due to toxicity, low efficacy and resistance; leishmaniasis is a major global health challenge that desperately needs new validated drug targets. Inspired by activity of the natural chalcone 2',6'-dihydroxy-4'-methoxychalcone (DMC), the nitro-analogue, 3-nitro-2',4',6'- trimethoxychalcone (NAT22, 1c) was identified as potent broad spectrum antileishmanial drug lead. Structural modification provided an alkyne containing chemical probe that labelled a protein within the parasite that was confirmed as cytosolic tryparedoxin peroxidase (cTXNPx). Crucially, labelling is observed in both promastigote and intramacrophage amastigote life forms, with no evidence of host macrophage toxicity. Incubation of the chalcone in the parasite leads to ROS accumulation and parasite death. Deletion of cTXNPx, by CRISPR-Cas9, dramatically impacts upon the parasite phenotype and reduces the antileishmanial activity of the chalcone analogue. Molecular docking studies with a homology model of in-silico cTXNPx suggest that the chalcone is able to bind in the putative active site hindering access to the crucial cysteine residue. Collectively, this work identifies cTXNPx as an important target for antileishmanial chalcones.
由于毒性、低疗效和耐药性，目前的药物治疗都失败了；利什曼病是一个主要的全球健康挑战，迫切需要新的经过验证的药物靶点。受天然查耳酮 2'，6'-二羟基-4'-甲氧基查耳酮（DMC）活性的启发，硝基类似物 3-硝基-2'，4'，6'-三甲氧基查耳酮（NAT22，1c）被鉴定为有效的广谱抗利什曼病药物先导物。结构修饰提供了一种含有炔基的化学探针，可标记寄生虫内的一种蛋白质，该蛋白质被确认为细胞质硫氧还蛋白过氧化物酶（cTXNPx）。至关重要的是，在前鞭毛体和巨噬细胞内无鞭毛体生活形式中都观察到标记，没有宿主巨噬细胞毒性的证据。在寄生虫中孵育查耳酮会导致 ROS 积累和寄生虫死亡。通过 CRISPR-Cas9 敲除 cTXNPx ，会对寄生虫表型产生重大影响，并降低查耳酮类似物的抗利什曼活性。用 cTXNPx 的同源模型进行分子对接研究表明，查耳酮能够结合在假定的活性位点，阻碍关键半胱氨酸残基的进入。总的来说，这项工作确定 cTXNPx 是抗利什曼病查耳酮的一个重要靶点。
