In vitro and in vivo activity of a hypotoxic copper(I) complex against dermotropic Leishmania species

ABSTRACT Cutaneous leishmaniasis is a disease caused by protozoa of the genus Leishmania and, currently, the treatment of first choice is meglumine antimoniate. However, due to its limited effectiveness and high toxicity, it is necessary to seek new active principles for leishmaniasis treatment. Metal complexes are gaining importance due to their effectiveness and low toxicity. In this context, the present study aimed to evaluate the in vitro and in vivo antileishmanial activity of the hypotoxic copper(I) complex [HB(pz)3]Cu(PCN). Four dermotropic species of Leishmania were tested with the metal complex and its effectiveness was determined through parasitic viability and infectivity rate, and cytotoxicity was determined using a redox dye (resazurin). For the in vivo tests, hamsters were infected and the lesions treated with a formulated ointment containing the complex, the effectiveness of which was assessed by measuring the diameter of the inoculum/snout location and determining the parasitic load. The results demonstrated moderate toxicity in murine macrophages and human monocytes and better efficacy in Leishmania (V.) braziliensis when compared to the other species tested, with a 50% reduction in the viability of promastigote and amastigote forms (in vitro). General data from daily topical treatment for up to 30 days showed low efficacy for reducing lesions, and no clinical and parasitological cure was observed in the experimental animals. Thus, the [HB(pz)3]Cu(PCN) complex proved to be promising in in vitro studies against L. (V.) braziliensis, and should be further tested in new formulations and new experimental treatment schemes.【摘要】皮肤利什曼病（Cutaneous leishmaniasis）是由利什曼原虫属（Leishmania）原生动物引发的感染性疾病，目前临床一线治疗方案为葡甲胺锑酸盐（meglumine antimoniate）给药。但该药物存在疗效有限、毒性较高的缺陷，因此亟需开发用于利什曼病治疗的新型活性成分。金属配合物（metal complexes）凭借优异的抗寄生虫活性与较低的毒性，逐渐成为抗利什曼病药物研发的热点方向。基于此背景，本研究旨在评估低毒性铜(I)配合物[HB(pz)3]Cu(PCN)的体内外抗利什曼活性。研究选取4种亲皮肤利什曼原虫（Leishmania）物种开展该金属配合物的活性测试，通过检测寄生虫存活率与感染率评估其抗虫效力，并采用氧化还原染料刃天青（resazurin）检测细胞毒性。体内实验阶段，研究人员对仓鼠进行利什曼原虫感染造模，随后使用含有该配合物的配制软膏涂抹病变部位，通过测量接种损伤直径与鼻部病灶直径、检测寄生虫载量，评估治疗效果。实验结果显示，该配合物对小鼠巨噬细胞与人单核细胞具有中等毒性；相较于其余受试物种，其对巴西利什曼原虫巴西亚种（Leishmania (V.) braziliensis）的抗虫效果更佳，可使体外培养的前鞭毛体与无鞭毛体形式的寄生虫存活率降低50%。长达30天的每日局部给药治疗的整体数据表明，该配合物缩小病灶的疗效有限，未在实验动物中实现临床治愈与病原学清除。综上，[HB(pz)3]Cu(PCN)配合物在体外抗巴西利什曼原虫巴西亚种的实验中展现出良好的应用潜力，有待通过新型制剂与优化的实验给药方案开展进一步研究。