Indoleamine-2,3-dioxygenase 1 (IDO1) catalyses the first and rate limiting step of kynurenine pathway accounting for the major contributor of L-Tryptophan degradation. The Kynurenine metabolites are identified as essential cofactors, antagonists, neurotoxins, immunomodulators, antioxidants as well as carcinogens. The catalytic active site of IDO1 enzyme consists of hydrophobic Pocket-A positioned in the distal heme site and remains connected to a second hydrophobic Pocket-B towards the entrance of the active site. IDO1 enzyme also relates directly to the modulation of the innate and adaptive immune system. Various studies proved that the over expression of IDO1 enzyme play a predominant role in the escape of immunity during cancer progression. Recently, there has been considerable interest in evaluating the potential of IDO1 inhibitors to mobilize the body’s immune system against solid tumours. In the last two decades, enormous attempts to advance new IDO1 inhibitors are on-going both in pharmaceutical industries and in academia which resulted in the discovery of a diverse range of selective and potent IDO1 inhibitors. The IDO1 inhibitors have therapeutic utility in various diseases and in the near future, it may have utility in the treatment of COVID-19. Despite various reviews on IDO1 inhibitors in last five years, none of the reviews provide a complete overview of diverse chemical space including naturally occurring and synthetic IDO1 inhibitors with detailed structure activity relationship studies. The present work provides a complete overview on the IDO1 inhibitors known in the literature so far along with the Structure-Activity Relationship (SAR) in each class of compounds.

Indoleamine-2,3-dioxygenase 1 (IDO1) 催化犬尿氨酸途径的第一步和限速步骤，是L的主要贡献者-色氨酸降解。犬尿氨酸代谢物被鉴定为必需的辅助因子、拮抗剂、神经毒素、免疫调节剂、抗氧化剂以及致癌物。IDO1 酶的催化活性位点由位于远端血红素位点的疏水性 Pocket-A 组成，并保持连接到第二个疏水性 Pocket-B，朝向活性位点的入口。IDO1 酶还与先天性和适应性免疫系统的调节直接相关。各种研究证明，IDO1 酶的过度表达在癌症进展过程中的免疫逃逸中起主要作用。最近，人们对评估 IDO1 抑制剂动员人体免疫系统对抗实体瘤的潜力产生了相当大的兴趣。在过去的二十年来，制药行业和学术界都在大力推进新的 IDO1 抑制剂，这导致发现了多种选择性和有效的 IDO1 抑制剂。IDO1 抑制剂对各种疾病具有治疗作用，在不久的将来，它可能对 COVID-19 的治疗有用。尽管在过去五年中对 IDO1 抑制剂进行了各种评论，但没有一篇评论提供了包括天然和合成 IDO1 抑制剂在内的各种化学空间的完整概述以及详细的结构活性关系研究。目前的工作提供了迄今为止文献中已知的 IDO1 抑制剂以及每类化合物的构效关系 (SAR) 的完整概述。