Visceral Leishmaniasis (VL) and its aggressive cutaneous exacerbation known as Post Kala-azar Dermal Leishmaniasis (PKDL) cause a huge disease burden in tropics and sub-tropic endemic zones worldwide. Contemporary treatment modalities have been associated with various complications. Encouraged from the recent marked antimalarial effects from plant derived glycosides; here we have chemically synthesized a library of diverse Glycoside derivatives (Gly 1-12) and evaluated their inhibitory efficacy against Ag83 strain of Leishmania donovani. In vitro activity of Glycoside-2 (Gly 2) on Ag83 strain, unravelled its prominent anti-leishmanial property with IC50 value of 1.13 micromolar. In-silico studies also unveiled the efficacy of Gly 2 to bind to the membrane surface of parasite. The toxic effect of Gly 2 causes necrosis like death in promastigotes by abrogating its proliferation leading to imbalanced redox homeostasis by disruption of mitochondrial membrane potential. Additionally, Gly 2 treatment demonstrated increased susceptibility of parasites towards complement mediated lysis and displayed strong lethal effect on amastigote macrophage infection model mimicking pathophysiological condition of body. This lead molecule was quite effective against the clinical PKDL strain BS12 with IC50 value of 1.97 micromolar making it the most suitable drug so far which can target both VL and PKDL simultaneously. Based on the above experimental validations we narrowed our thoughts regarding the potent role of Gly 2 targeting surface protein of L. donovani such as Gp63, a zinc metalloprotease. Further analysis of structure activity relationship (SAR) of these glycoside derivatives, demonstrated exceptional binding affinity of Gly 2 towards Gp63, a zinc metalloprotease of L. donovani; with strong H-bond interactions of Gly 2 with catalytic domain in the alpha-helix B region of Gp63. The strong confined interactions between Gly 2 and the target protein Gp63 in a physiologically relevant cellular environment was further assessed by Cellular Thermal Shift Assay (CETSA) which corroborated with our previous results. Taken together, this study reports the serendipitous discovery of glycoside derivative Gly 2 with enhanced leishmanicidal activity and proves to be novel chemotherapeutic prototype against VL and PKDL.

中文翻译：

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靶向新型糖苷的金属蛋白酶Gp63表现出潜在的抗菌活性

内脏利什曼病（VL）及其侵害性皮肤病情恶化，称为后黑热病后皮肤利什曼病（PKDL），在全球热带和亚热带流行地区造成巨大的疾病负担。当代治疗方式已经与各种并发症相关。受到植物来源糖苷最近的显着抗疟作用的鼓舞；在这里，我们已经化学合成了多种糖苷衍生物（Gly 1-12）的文库，并评估了它们对多形利什曼原虫Ag83菌株的抑制作用。糖苷2（Gly 2）对Ag83菌株的体外活性揭示了其突出的抗Leishmanial性质，IC50值为1.13微摩尔。硅内研究还揭示了Gly 2与寄生虫膜表面结合的功效。Gly 2的毒性作用通过消除其增殖而导致坏死，如前鞭毛体中的死亡，从而通过破坏线粒体膜电位而导致氧化还原稳态失衡。另外，Gly 2处理证明了寄生虫对补体介导的裂解的敏感性增加，并且对模仿身体病理生理状况的鞭毛巨噬细胞感染模型显示出强大的致死作用。该前导分子对临床PKDL菌株BS12非常有效，IC50值为1.97微摩尔，使其成为迄今为止最适合同时靶向VL和PKDL的药物。基于上述实验验证，我们缩小了关于针对多诺氏乳杆菌的Gly 2靶向表面蛋白（例如锌金属蛋白酶Gp63）的有效作用的想法。对这些糖苷衍生物的结构活性关系（SAR）的进一步分析表明，Gly 2对多巴氏乳杆菌（L. donovani）的锌金属蛋白酶Gp63具有非凡的结合亲和力。与Gly 2的强H键相互作用与Gp63的α-螺旋B区域中的催化结构域。通过细胞热位移分析（CETSA）进一步评估了生理相关细胞环境中Gly 2与靶蛋白Gp63之间的强受限相互作用，这与我们之前的结果相符。两者合计，这项研究报告了意外发现的糖苷衍生物Gly 2具有增强的杀菌作用，并被证明是针对VL和PKDL的新型化学疗法原型。多诺氏杆菌的锌金属蛋白酶；与Gly 2的强H键相互作用与Gp63的α-螺旋B区域中的催化结构域。通过细胞热位移分析（CETSA）进一步评估了生理相关细胞环境中Gly 2与靶蛋白Gp63之间的强受限相互作用，这与我们之前的结果相符。两者合计，这项研究报告了意外发现的糖苷衍生物Gly 2具有增强的杀菌作用，并被证明是针对VL和PKDL的新型化学疗法原型。多诺氏杆菌的锌金属蛋白酶；与Gly 2的强H键相互作用与Gp63的α-螺旋B区域中的催化结构域。通过细胞热位移分析（CETSA）进一步评估了生理相关细胞环境中Gly 2与靶蛋白Gp63之间的强受限相互作用，这与我们之前的结果相符。两者合计，这项研究报告了意外发现的糖苷衍生物Gly 2具有增强的杀菌作用，并被证明是针对VL和PKDL的新型化学疗法原型。通过生理学上相关的细胞环境中的Gly 2和目标蛋白Gp63之间的强受限相互作用，通过细胞热位移分析（CETSA）进行了进一步评估，这与我们之前的结果相符。两者合计，这项研究报告了意外发现的糖苷衍生物Gly 2具有增强的杀菌作用，并被证明是针对VL和PKDL的新型化学疗法原型。通过细胞热位移分析（CETSA）进一步评估了生理相关细胞环境中Gly 2与靶蛋白Gp63之间的强受限相互作用，这与我们之前的结果相符。两者合计，这项研究报告了意外发现的糖苷衍生物Gly 2具有增强的杀菌作用，并被证明是针对VL和PKDL的新型化学疗法原型。