Nucleoside ribohydrolases as targets for Trichomonas vaginalis therapeutic agents. This project will evaluate two essential nucleoside ribohydrolase enzymes as targets for novel antitrichomonal drugs.

项目摘要 滴虫病是最普遍的非病毒性性传播疾病。尽管临床 感染的表现通常是温和的，免疫系统可能伴随受损。 滴虫感染的个体对更严重的疾病有更高的易感性， 宫颈癌、HIV-1和盆腔炎。最近，滴虫感染也 与前列腺癌和良性前列腺增生有关。病原体是 寄生原生动物阴道毛滴虫。对现有5-硝基咪唑类药物的耐药性 近年来，抗滴虫药物显著增加，表明需要新的治疗方法 with novel新mechanisms机制of action行动. T.阴道毛 代表了用于开发新型抗滴虫剂的优良靶标。这条路的第一步 是核苷水解释放出核碱基。必需的酶 腺苷/鸟苷优先核苷核糖水解酶（AGNH）和尿苷核苷核糖水解酶 (UNH)已被表征并发现具有不同的底物特异性。两者的抑制剂 使用基于NMR的活性测定来鉴定酶以筛选NIH临床保藏中心。缺乏 两组抑制剂之间的任何显著结构关系进一步表明， 核糖水解酶是不同的、可药用的靶点。然而，从细胞中鉴定出的抑制剂 由NIH临床收集所采样的有限化学空间具有低配体效率， 因此，开发目标验证所需的化学工具的起点很差。该项目将 通过使用基于片段的方法来定义最关键的 酶/抑制剂相互作用。片段多样性文库包含更广泛的化学性质， 空间比包含在NIH临床收藏，并将提供最佳的起点， 开发目标验证化学工具。该建议的具体目标是：1）识别配体- AGNH和UNH的有效片段抑制剂; 2）确定AGNH和UNH的化学工具 IC 50值< 1 μ M;和3）通过证明相关性来验证AGNH和UNH作为靶标 酶抑制和抗滴虫活性之间的联系拟议的研究将利用现有的 核磁共振方法，计算和药物化学，和T。迷走神经生长抑制测定。的 该项目的总体长期目标是验证AGNH和UNH作为新的 抗滴虫剂，并鉴定这些酶的抑制剂，其对5- 硝基咪唑敏感株和5-硝基咪唑抗性株。流浪汉

PROJECT SUMMARY Trichomoniasis is the most prevalent non-viral sexually transmitted disease. Although clinical manifestations of infection are typically mild, the immune system can be concomitantly compromised. Individuals with trichomonal infections have a higher susceptibility to more serious conditions such as cervical cancer, HIV-1, and pelvic inflammatory disease. More recently, trichomonal infection has also been associated with prostate cancer and benign prostatic hyperplasia. The causative agent is the parasitic protozoan Trichomonas vaginalis. Resistance to the existing 5-nitroimidazole class of antitrichomonal drugs has increased markedly in recent years indicating the need for new therapies with novel mechanisms of action. Nucleoside salvage pathway enzymes required by T. vaginalis represent excellent targets for developing novel antitrichomonal agents. The first step in this pathway is the hydrolysis of nucleosides to release the nucleobases. The essential enzymes adenosine/guanosine preferring nucleoside ribohydrolase (AGNH) and uridine nucleoside ribohydrolase (UNH) have been characterized and found to have distinct substrate specificities. Inhibitors of both enzymes were identified using NMR-based activity assays to screen the NIH Clinical Collection. Lack of any significant structural relationship between the two sets of inhibitors further indicates that the two ribohydrolase enzymes are distinct, druggable targets. However, the inhibitors identified from the limited chemistry space sampled by the NIH Clinical Collection have low ligand efficiencies and are thus poor starting points for developing the chemical tools needed for target validation. This project will circumvent this limitation by using a fragment-based approach to define the most critical enzyme/inhibitor interactions. A fragment diversity library encompasses a much broader chemistry space than is contained within the NIH Clinical Collection and will provide the optimal starting points for developing target validation chemical tools. The specific aims of this proposal are: 1) To identify ligand- efficient fragment inhibitors of AGNH and UNH; 2) To identify chemical tools for both AGNH and UNH with IC50 values < 1 M; and 3) To validate AGNH and UNH as targets by demonstrating a correlation between enzyme inhibition and antitrichomonal activity. The proposed studies will utilize established NMR methods, computational and medicinal chemistry, and T. vaginalis growth inhibition assays. The overall long-term goals of this project are to validate AGNH and UNH as molecular targets for novel antitrichomonal agents, and to identify inhibitors of these enzymes that possess efficacy against both 5- nitroimidazole-sensitive and 5-nitroimidazole-resistant strains of T. vaginalis.