Linagliptin (BI 1356) is a potent, orally bioavailable dihydropurinedione-based inhibitor of dipeptidyl peptidase 4 (DPP-4), with hypoglycemic activity.

DPP4:1 nM

Linagliptin 在体外对 DPP-4 有强效抑制作用，对 hERG 通道和 M1 受体的亲和力较低（IC50 295 nM）。[1] Linagliptin 是一种 Ki 值为 1 nM 的竞争性抑制剂，对 DPP-4 的选择性比 DPP-8、DPP-9、氨基肽酶 N 和 P、聚乙二醇肽酶、胰蛋白酶、凝血酶和凝血酶高 10 000 倍，在体外比成纤维细胞活化蛋白高 90 倍。[2]

在雄性 Wistar 大鼠、比格犬和恒河猴体内，Linagliptin 显示出高效、持久和强效的 DPP-4 抑制活性，口服 1 mg/kg后，三种动物的抑制率均超过 70%。在口服葡萄糖耐量试验前 45 分钟给 db/db 小鼠口服Linagliptin ，可降低血浆葡萄糖偏移量，降低幅度从 0.1 mg/kg（抑制 15%）到 1 mg/kg（抑制 66%），呈剂量依赖性。[1] 通过抑制 DPP-4 活性，Linagliptin 可减少促炎标志物环氧化酶-2 和巨噬细胞炎症蛋白-2 的表达，并促进肥胖/肥胖小鼠愈合伤口中肌成纤维细胞的形成。[3]

EDTA plasma (20 μL) is diluted with 30 μL of DPP-4 assay buffer (100 mM Tris and 100 mM NaCl, adjusted to pH 7.8 with HCl) and mixed with 50 μL of H-Ala-Pro-7-amido-4-trifluoromethylcoumarin. The 200 mM stock solution in dimethylformamide is diluted 1:1000 with water to yield a final concentration of 100 μM. The plate is incubated at room temperature for 10 min, and fluorescence in the wells is determined by using a Victor 1420 Multilabel Counter at an excitation wavelength of 405 nm and an emission wavelength of 535 nm. For the detection of DPP-4 activity in wound lysates, 100 μg of protein from the respective wound lysates are used instead of 20 μL of plasma. Active GLP-1 is also detected from 100 μg of respective wound tissue samples and analyzed by using the Mouse/Rat Total Active GLP-1 Assay Kit.

A total of 4.0×107 keratinocytes per well are seeded into 24-well plates. After reaching 50% confluence, cells are starved for 24 h with DMEM. Proliferation of cells is assessed by using 1 μCi/mL of [3H]methyl-thymidine in DMEM in the presence of 10% fetal bovine serum and increasing concentrations of linagliptin (3, 30, 300, or 600 nM) for 24 h. Cells are then washed twice with phosphate-buffered saline and incubated in 5% trichloroacetic acid at 4°C for 30 min, and the DNA is solubilized in 0.5mol/LNaOH for 30 min at 37°C. Finally, [3H]thymidine incorporation is determined.