Activation of the aminopeptidase (AP) activity of leukotriene A hydrolase (LTAH) presents a potential therapeutic strategy for resolving chronic inflammation. Previously, ARM1 and derivatives were found to activate the AP activity using the alanine--nitroanilide (Ala-NA) as a reporter group in an enzyme kinetics assay. As an extension of this previous work, novel ARM1 derivatives were synthesized using a palladium-catalyzed Ullmann coupling reaction and screened using the same assay. Analogue , an aminopyrazole (AMP) analogue of ARM1, was found to be a potent AP activator with an AC of 0.12 μM. An X-ray crystal structure of LTAH in complex with AMP was refined at 2.7 Å. Despite its AP activity with Ala-NA substrate, AMP did not affect hydrolysis of the previously proposed natural ligand of LTAH, Pro-Gly-Pro (PGP). This result highlights a discrepancy between the hydrolysis of more conveniently monitored chromogenic synthetic peptides typically employed in assays and endogenous peptides. The epoxide hydrolase (EH) activity of AMP was measured in vivo and the compound significantly reduced leukotriene B (LTB) levels in a murine bacterial pneumonia model. However, AMP did not enhance survival in the murine pneumonia model over a 14-day period. A liver microsome stability assay showed metabolic stability of AMP. The results suggested that accelerated Ala-NA cleavage is not sufficient for predicting therapeutic potential, even when the full mechanism of activation is known.

中文翻译：

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白三烯A4水解酶氨肽酶活性二芳基醚调节剂的合成与评价


激活白三烯 A 水解酶 (LTAH) 的氨肽酶 (AP) 活性为解决慢性炎症提供了一种潜在的治疗策略。此前，在酶动力学测定中，ARM1 及其衍生物被发现使用丙氨酸-硝基苯胺 (Ala-NA) 作为报告基团来激活 AP 活性。作为先前工作的延伸，使用钯催化的乌尔曼偶联反应合成了新型 ARM1 衍生物，并使用相同的测定法进行筛选。 Analogue 是 ARM1 的氨基吡唑 (AMP) 类似物，被发现是一种有效的 AP 激活剂，AC 为 0.12 μM。 LTAH 与 AMP 复合物的 X 射线晶体结构精炼为 2.7 Å。尽管 AMP 具有 Ala-NA 底物的 AP 活性，但它并不影响先前提出的 LTAH 天然配体 Pro-Gly-Pro (PGP) 的水解。该结果凸显了通常用于测定的更方便监测的显色合成肽的水解与内源肽之间的差异。在体内测量了 AMP 的环氧化物水解酶 (EH) 活性，该化合物显着降低了小鼠细菌性肺炎模型中的白三烯 B (LTB) 水平。然而，AMP 并没有提高小鼠肺炎模型 14 天的存活率。肝微粒体稳定性测定显示 AMP 的代谢稳定性。结果表明，即使完整的激活机制已知，加速的 Ala-NA 裂解也不足以预测治疗潜力。