Puerol A (1) from Amorpha fruticosa showed highly potent inhibition against both monophenolase (IC50 = 2.2 μM) and diphenolase (IC50 = 3.8 μM) of tyrosinase. We tried to obtain a full story of enzyme inhibitory behavior for inhibitor 1 because the butenolide skeleton has never been reported as a tyrosinase inhibitor. Puerol A was proved as a reversible, competitive, simple slow-binding inhibitor, according to the respective parameters; k3 = 0.0279 μM−1 min−1 and k4 = 0.003 min−1. A longer lag-phase and a reduced static-state activity of the enzyme explained that puerol A had a tight formation of the complex with Emet. Dose-dependent inhibition was also confirmed by high-performance liquid chromatography (HPLC) analysis using N-acetyl-l-tyrosine as a substrate, which was completely inhibited at 20 μM. A high binding affinity of 1 to tyrosinase was confirmed by fluorescence quenching analysis. Moreover, puerol A decreased melanin content in the B16 melanoma cell dose-dependently with an IC50 of 11.4 μM.

中文翻译：

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来自紫花的具有 But-2-Enolide 结构的 Puerol A 的酪氨酸酶抑制和动力学细节

来自 Amorpha fruticosa 的 Puerol A (1) 对酪氨酸酶的单酚酶 (IC50 = 2.2 μM) 和双酚酶 (IC50 = 3.8 μM) 显示出高度有效的抑制作用。我们试图获得抑制剂 1 的酶抑制行为的完整故事，因为丁烯内酯骨架从未被报道为酪氨酸酶抑制剂。根据各自的参数，Puerol A 被证明是一种可逆的、竞争性的、简单的慢结合抑制剂；k3 = 0.0279 μM-1 min-1 和 k4 = 0.003 min-1。较长的滞后期和酶的静态活性降低解释了puerol A与Emet紧密形成的复合物。使用 N-乙酰基-l-酪氨酸作为底物的高效液相色谱 (HPLC) 分析也证实了剂量依赖性抑制，在 20 μM 时完全抑制。通过荧光猝灭分析证实了 1 对酪氨酸酶的高结合亲和力。此外，puerol A 剂量依赖性地降低 B16 黑色素瘤细胞中的黑色素含量，IC50 为 11.4 μM。