Abstract：
We present new small-molecular probes targeting the human PD-L1 protein. The molecules were designed by incorporating a newly discovered N-methylmorpholine substituent into a known biphenyl-based structure. Four prototype derivatives of 4-methyl-3,4-dihydro-2H-benzo[b][1,4]oxazine-7-carbonitrile (STD4), comprising a morpholine substituent fused with a biphenyl core at different orientations were first verified for their potential binding to PD-L1 using the molecular docking method. A more favorable 7-phenyl derivative of STD4 was then equipped with an amide bond, pyridine, and either a tris(hydroxymethyl)aminomethane or serinol tail leading to two final molecules. Among them, compound 1c showed activity in three bioassays, i.e., the homogenous time-resolved fluorescence (HTRF) assay, immune checkpoint blockade (ICB) assay, and T-cell activation (TCA) assay. Our work shows that morpholine can substitute for dioxane and becomes a promising component in PD-L1-targeting molecules. This finding unlocks new avenues for optimizing PD-L1-targeting compounds, presenting exciting prospects for future developments in this field.
摘要：
我们提出了靶向人类PD-L1蛋白的新的小分子探针。通过将新发现的N-甲基吗啉取代基引入已知的基于联苯的结构中来设计分子。4-甲基-3,4-二氢-2H-苯并[b][1,4]恶嗪-7-甲腈（STD4）的四种原型衍生物，首先使用分子对接方法验证包含与不同取向的联苯核心融合的吗啉取代基的它们与PD-L1的潜在结合。然后，将更有利的STD4的7-苯基衍生物配备酰胺键，吡啶,和三（羟甲基）氨基甲烷或丝氨醇尾导致两个最终分子。其中,化合物1c在三个生物测定中显示出活性，即，均相时间分辨荧光(HTRF)分析，免疫检查点阻断（ICB）测定，和T细胞活化(TCA)测定。我们的工作表明，吗啉可以替代二恶烷，并成为PD-L1靶向分子中有前途的成分。这一发现为优化PD-L1靶向化合物开辟了新的途径，为这一领域的未来发展提供了令人兴奋的前景。
