藏药“曲玛孜”作用于黄嘌呤氧化酶和尿酸转运体抗痛风药效物质及构效关系研究

Gout is a serious metabolic disease to human health, and the current existing drugs with side effects are far from satisfaction. The treatment of ethnopharmacology is promising, however, the active ingredients, mechanism and structure-activity relationships of Tibetan medicine “Qumazi” remains to be further studied. Our previous research revealed that the 70% ethanol extract of Rheum pumilum and Polygonum sibiricum could reduce the level of serum uric acid and XOD in hyperuricemia mice. Specially, the 70% ethanol extract of P. sibiricum can also regulate the kidney uric acid transporter (GLUT9, OAT1 and URAT1) in mice. In addition, 20 compounds, of 8 active constituents, were isolated and identified from those two plants, and sesquiterpenoids were obtained from P. sibiricum for the first time. Therefore, guided by hyperuricemia mice model and LC-MS analysis, the investigations of R. palmatum and P. sibiricum were performed to elucidate the active compounds and mechanism of the regulation of xanthine oxidase, renal uric acid transporter, and the structure-activity relationships in vivo, cell and molecular level. This research may provide chemical and preliminary pharmacological basis for the active ingredients and variety systematization of “Qumazi”.

痛风是严重威胁人类健康的代谢性疾病，现有药物不能满足临床需求，从民族药中寻找抗痛风药物前景广阔。特色藏药“曲玛孜”具有抗痛风作用，然而，其抗痛风药效物质基础、构效关系及作用机制尚待进一步阐述。本课题前期发现小大黄和西伯利亚蓼(曲玛孜两种法定基原植物)70%乙醇提取物具有抑制黄嘌呤氧化酶活性，同时西伯利亚蓼乙醇提取物也具有调控小鼠肾脏尿酸转运体（GLUT9、OAT1、URAT1)作用；基于上述活性基础我们从两种植物共分离鉴定20个单体化合物，发现8个活性成分，且从西伯利亚蓼中首次得到倍半萜类成分。基于此，本项目采用天然药物化学、现代药理学和分子生物学等方法，以小鼠高尿酸血症模型为指导，开展小大黄和西伯利亚蓼活性成分分离、结构修饰、黄嘌呤氧化酶和尿酸转运体调控研究，在体内、细胞、分子多种水平阐明“曲玛孜”抗痛风药效物质基础，为揭示“曲玛孜”抗痛风活性成分和进一步的品种整理提供化学和药理学基础。

本项目采用多种色谱方法对藏药曲玛孜基原植物西伯利亚蓼和小大黄进行化学成分分离鉴定，得到黄酮、倍半萜、蒽醌、二苯乙烯类为主的46个化合物。采用ELISA法研究单体化合物对体外黄嘌呤氧化酶(XOD)抑制活性，结果发现8个活性较好的化合物，其中大黄酸和异牡荆苷活性最好，其IC50值分别为8.40±0.23和15.49±0.88μM。建立用人肺癌细胞(A549细胞)和HK-2细胞筛选模型，测定各单体化合物对A549细胞XOD活性及尿酸转运体的表达，结果发现6个化合物（大黄酸、大黄素甲醚、芦丁、异牡荆苷、白藜芦醇、4-(α-L-rhamnopyranosyloxy)benzaldehyde）既可以抑制黄嘌呤氧化酶也可以调控尿酸转运体活性；采用小鼠高尿酸血症模型对单体化合物进行活性筛选，结果表明大黄酸、大黄素甲醚、芦丁、异牡荆苷、白藜芦醇具有降尿酸的作用，其作用机制为抑制XOD活性和调控尿酸转运体的表达两种途径。