毛桐中生物碱提取物对造血前列腺素 D2 合酶（H-PGDS）的抑制作用。
Inhibition of hematopoietic prostaglandin D2 synthase (H-PGDS) by an alkaloid extract from Combretum molle.
机构信息
Department of Biochemistry, University of Zimbabwe, Mt, Pleasant, Harare, Zimbabwe.
出版信息
BMC Complement Altern Med. 2014 Jul 5;14:221. doi: 10.1186/1472-6882-14-221.
BACKGROUND
Hematopoietic prostaglandin D2 synthase (H-PGDS, GST Sigma) is a member of the glutathione S-transferase super family of enzymes that catalyses the conjugation of electrophilic substances with reduced glutathione. The enzyme catalyses the conversion of PGH2 to PGD2 which mediates inflammatory responses. The inhibition of H-PGDS is of importance in alleviating damage to tissues due to unwarranted synthesis of PGD2. Combretum molle has been used in African ethno medicinal practices and has been shown to reduce fever and pain. The effect of C. molle alkaloid extract on H-PGDS was thus, investigated.
METHODS
H-PGDS was expressed in Escherichia coli XL1-Blue cells and purified using nickel immobilized metal affinity chromatography. The effect of C. molle alkaloid extract on H-PGDS activity was determined with 1-chloro-2, 4-dinitrobenzene (CDNB) as substrate. The effect of C. molle alkaloid extract with time on H-PGDS was determined. The mechanism of inhibition was then investigated using CDNB and glutathione (GSH) as substrates.
RESULTS
A specific activity of 24 μmol/mg/min was obtained after H-PGDS had been purified. The alkaloid extract exhibited a 70% inhibition on H-PGDS with an IC50 of 13.7 μg/ml. C. molle alkaloid extract showed an uncompetitive inhibition of H-PGDS with Ki = 41 μg/ml towards GSH, and non-competitive inhibition towards CDNB with Ki = 7.7 μg/ml and Ki' = 9.2 μg/ml.
CONCLUSION
The data shows that C. molle alkaloid extract is a potent inhibitor of H-PGDS. This study thus supports the traditional use of the plant for inflammation.
背景
造血前列腺素 D2 合酶（H-PGDS，GST Sigma）是谷胱甘肽 S-转移酶超家族的一种酶，可催化亲电物质与还原型谷胱甘肽的结合。该酶催化 PGH2 向 PGD2 的转化，介导炎症反应。抑制 H-PGDS 对于减轻由于不必要的 PGD2 合成而导致的组织损伤非常重要。Combretum molle 已在非洲传统医学实践中使用，并已被证明可降低发热和疼痛。因此，研究了 C. molle 生物碱提取物对 H-PGDS 的影响。
方法
在大肠杆菌 XL1-Blue 细胞中表达 H-PGDS，并使用镍固定金属亲和层析法进行纯化。用 1-氯-2,4-二硝基苯（CDNB）作为底物测定 C. molle 生物碱提取物对 H-PGDS 活性的影响。然后，用 CDNB 和谷胱甘肽（GSH）作为底物研究 C. molle 生物碱提取物随时间对 H-PGDS 的影响。
结果
H-PGDS 纯化后获得 24μmol/mg/min 的比活。生物碱提取物对 H-PGDS 的抑制率为 70%，IC50 为 13.7μg/ml。C. molle 生物碱提取物对 H-PGDS 表现出非竞争性抑制，Ki 值为 41μg/ml 对 GSH，对 CDNB 表现出竞争性抑制，Ki 值为 7.7μg/ml，Ki'值为 9.2μg/ml。
结论
数据表明，C. molle 生物碱提取物是 H-PGDS 的有效抑制剂。因此，该研究支持该植物用于炎症的传统用途。
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