Key Laboratory of Ethnomedicine in Ministry of Education, School of Pharmacy, Minzu University of China, Haidian District, Beijing 100081, China.
Beijing Key Lab of Traditional Chinese Medicine Collateral Disease Theory Research, School of Traditional Chinese Medicine, Capital Medical University, Fengtai District, Beijing 100069, China.
Bioorg Chem. 2024 May;146:107320. doi: 10.1016/j.bioorg.2024.107320. Epub 2024 Mar 29.
Spleen tyrosine kinase (Syk) plays a crucial role as a target for allergy treatment due to its involvement in immunoreceptor signaling. The purpose of this study was to identify natural inhibitors of Syk and assess their effects on the IgE-mediated allergic response in mast cells and ICR mice. A list of eight compounds was selected based on pharmacophore and molecular docking, showing potential inhibitory effects through virtual screening. Among these compounds, sophoraflavanone G (SFG) was found to inhibit Syk activity in an enzymatic assay, with an IC value of 2.2 μM. To investigate the conformational dynamics of the SYK-SFG system, we performed molecular dynamics simulations. The stability of the binding between SFG and Syk was evaluated using root mean square deviation (RMSD) and root mean square fluctuation (RMSF). In RBL-2H3 cells, SFG demonstrated a dose-dependent suppression of IgE/BSA-induced mast cell degranulation, with no significant cytotoxicity observed at concentrations below 10.0 μM within 24 h. Furthermore, SFG reduced the production of TNF-α and IL-4 in RBL-2H3 cells. Mechanistic investigations revealed that SFG inhibited downstream signaling proteins, including phospholipase Cγ1 (PLCγ1), as well as mitogen-activated protein kinases (AKT, Erk1/2, p38, and JNK), in mast cells in a dose-dependent manner. Passive cutaneous anaphylaxis (PCA) experiments demonstrated that SFG could reduce ear swelling, mast cell degranulation, and the expression of COX-2 and IL-4. Overall, our findings identify naturally occurring SFG as a direct inhibitor of Syk that effectively suppresses mast cell degranulation both in vitro and in vivo.
脾酪氨酸激酶（Syk）作为免疫受体信号转导的靶点，在过敏治疗中起着至关重要的作用。本研究旨在鉴定 Syk 的天然抑制剂，并评估它们对肥大细胞和 ICR 小鼠 IgE 介导的过敏反应的影响。根据药效团和分子对接，选择了一个包含 8 个化合物的列表，通过虚拟筛选显示出潜在的抑制作用。在这些化合物中，槐属黄酮 G（SFG）在酶促测定中被发现抑制 Syk 活性，IC 值为 2.2μM。为了研究 SYK-SFG 系统的构象动力学，我们进行了分子动力学模拟。使用均方根偏差（RMSD）和均方根波动（RMSF）评估 SFG 和 Syk 之间结合的稳定性。在 RBL-2H3 细胞中，SFG 表现出剂量依赖性抑制 IgE/BSA 诱导的肥大细胞脱颗粒作用，在 24 小时内浓度低于 10.0μM 时没有观察到明显的细胞毒性。此外，SFG 降低了 RBL-2H3 细胞中 TNF-α和 IL-4 的产生。机制研究表明，SFG 以剂量依赖的方式抑制下游信号蛋白，包括磷脂酶 Cγ1（PLCγ1）以及丝裂原活化蛋白激酶（AKT、Erk1/2、p38 和 JNK）。被动皮肤过敏反应（PCA）实验表明，SFG 可以减少耳肿胀、肥大细胞脱颗粒以及 COX-2 和 IL-4 的表达。总的来说，我们的研究结果表明，天然存在的 SFG 是 Syk 的直接抑制剂，可有效抑制体外和体内肥大细胞脱颗粒。
