Research Unit in Bioinformatics (RUBi), Department of Biochemistry and Microbiology, Rhodes University, P.O. Box 94, Grahamstown 6140, South Africa.
College of Veterinary Medicine, Animal Resources and Biosecurity (COVAB), Makerere University, P.O. Box 7062, Kampala 00256, Uganda.
Molecules. 2019 Jan 1;24(1):142. doi: 10.3390/molecules24010142.
Pteridine reductase 1 (PTR1) is a trypanosomatid multifunctional enzyme that provides a mechanism for escape of dihydrofolate reductase (DHFR) inhibition. This is because PTR1 can reduce pterins and folates. Trypanosomes require folates and pterins for survival and are unable to synthesize them de novo. Currently there are no anti-folate based Human African Trypanosomiasis (HAT) chemotherapeutics in use. Thus, successful dual inhibition of dihydrofolate reductase (DHFR) and pteridine reductase 1 (PTR1) has implications in the exploitation of anti-folates. We carried out molecular docking of a ligand library of 5742 compounds against PTR1 and identified 18 compounds showing promising binding modes. The protein-ligand complexes were subjected to molecular dynamics to characterize their molecular interactions and energetics, followed by in vitro testing. In this study, we identified five compounds which showed low micromolar Trypanosome growth inhibition in in vitro experiments that might be acting by inhibition of PTR1. Compounds RUBi004, RUBi007, RUBi014, and RUBi018 displayed moderate to strong antagonism (mutual reduction in potency) when used in combination with the known DHFR inhibitor, WR99210. This gave an indication that the compounds might inhibit both PTR1 and DHFR. RUBi016 showed an additive effect in the isobologram assay. Overall, our results provide a basis for scaffold optimization for further studies in the development of HAT anti-folates.
蝶呤还原酶 1(PTR1)是一种原生动物多功能酶,为二氢叶酸还原酶(DHFR)抑制的逃逸提供了一种机制。这是因为 PTR1 可以还原蝶呤和叶酸。锥虫需要叶酸和蝶呤才能生存,并且不能从头合成它们。目前,尚无基于抗叶酸的人类非洲锥虫病(HAT)化学疗法在使用。因此,成功地双重抑制二氢叶酸还原酶(DHFR)和蝶呤还原酶 1(PTR1)在抗叶酸的利用中具有重要意义。我们对 PTR1 进行了 5742 种化合物的配体库的分子对接,并鉴定了 18 种具有有前途的结合模式的化合物。将蛋白质-配体复合物进行分子动力学模拟以表征其分子相互作用和能量学,然后进行体外测试。在这项研究中,我们鉴定了五种在体外实验中表现出低微摩尔锥虫生长抑制作用的化合物,这些化合物可能通过抑制 PTR1 起作用。化合物 RUBi004、RUBi007、RUBi014 和 RUBi018 在与已知的 DHFR 抑制剂 WR99210 联合使用时显示出中度至强拮抗作用(相互降低效力)。这表明这些化合物可能同时抑制 PTR1 和 DHFR。RUBi016 在等对图测定中表现出相加作用。总的来说,我们的结果为进一步研究 HAT 抗叶酸的发展提供了支架优化的基础。