CP-91149 is a selective glycogen phosphorylase (GP) inhibitor with IC50 of 0.13 μM in the presence of glucose, 5- to 10-fold less potent in the absence of glucose.

GP:0.13 μM

CP-91149 显示出比咖啡因（IC50 = 26 μM）高出200倍的对人肝糖原磷酸化酶a (HLGPa) 的抑制活性。CP-91149 (10-100 μM) 以剂量依赖的方式抑制分离大鼠肝细胞中由胰高血糖素刺激的糖原分解，且在原代人肝细胞中的IC50约为2.1 μM。[1] CP-91149 也强烈抑制人类肌肉磷酸化酶a和b的活性，其IC50分别为0.2 μM和约0.3 μM。2.5 μM的CP-91149处理能够导致磷酸化酶失活，并顺序激活肝细胞中的糖原合成酶，以及在5 mM和20 mM葡萄糖的条件下分别使糖原合成增加7倍和2倍。CP-91149 能够部分对抗磷酸化酶过表达的效果。[2] CP-91149 同样能强烈抑制A549细胞中的脑GP，其IC50为0.5 μM。10-30 μM的CP-91149处理在A549和HSF55细胞中导致显著的糖原积累。CP-91149处理增加了HSF55细胞中G1期细胞比例，并显著减少S期细胞群，这与p21和p27的表达增加有关。[3] CP-91149 还促进了非基因改造或糖原磷酸化酶过表达的人类肌肉细胞中糖原合成酶的去磷酸化与激活，但这一作用仅在葡萄糖匮乏的细胞中观察到。[4]

口服CP-91149给糖尿病ob/ob小鼠（剂量为25-50 mg/kg）能在3小时内快速降低血糖100-120 mg/dl，且不会引起低血糖，其降糖作用来源于体内糖原分解的抑制。CP-91149治疗对于正常血糖水平的非糖尿病小鼠不会降低血糖水平。[1] 在非禁食状态的Goto-Kakizaki（GK）大鼠中，CP-91149与CS-917联合使用能够抑制CS-917导致的肝糖原减少，并且比单独使用CS-917更能显著降低血浆葡萄糖水平。[5]

Phosphorylase enzyme assay: Human liver glycogen phosphorylase a (HLGPa, 85 ng) activity is measured in the direction of glycogen synthesis by the release of phosphate from glucose-1-phosphate at 22°C in 100 μL of buffer containing 50 mM Hepes (pH 7.2), 100 mM KCl, 2.5 mM EGTA, 2.5 mM MgCl2, 0.5 mM glucose-1-phosphate, and 1 mg/mL glycogen. Phosphate is measured at 620 nm, 20 minutes after the addition of 150 μL of 1 M HCl containing 10 mg/mL ammonium molybdate and 0.38 mg/mL malachite green. Increasing concentrations of CP-91149 are added to the assay in 5 μL of 14% DMSO.

Cells are exposed to various concentrations of CP-91149 for 72hours. Viability is determined with manual cell counts following staining with trypan blue exclusion assay. Cells are fixed with 70% ethanol. DNA is stained with propidium iodide and the intensity of fluorescence is measured using a Becton-Dickinson flow cytometer at 488 nM for excitation and at 650 nM for emission. The cell cycle profile is analyzed using Modifit's Sync Wizard.(Only for Reference)