CP-91149

CP-91149 displays 200-fold higher inhibitory activity against human liver glycogen phosphorylase a (HLGPa) than caffeine (IC50 = 26 μM). This compound (10-100 μM) inhibits -stimulated glycogenolysis in isolated rat hepatocytes in a dose-dependent manner, and in primary human hepatocytes with IC50 of ~2.1 μM. [1] It also potently inhibits the activities of human muscle phosphorylase a and b with IC50 of 0.2 μM and ~0.3 μM, respectively. Treatment with this chemical at 2.5 μM induces inactivation of phosphorylase and sequential activation of glycogen synthase in hepatocytes, and increases glycogen synthesis by 7-fold at 5 mM glucose and by 2-fold at 20 mM glucose. It can partially counteract the effects of phosphorylase overexpression. [2] This compound also potently inhibits brain GP with IC50 of 0.5 μM in A549 cells. Treatment at 10-30 μM causes significant glycogen accumulation in A549 and HSF55 cells. It treatment increases G1-phase cells with a significant reduction of the S-phase population in HSF55 cells, correlated with increased expression of p21 and p27. [3] This chemical also promotes the dephosphorylation and activation of GS (glycogen synthase) in non-engineered or GP-overexpressing cultured human muscle cells, but exclusively in glucose-deprived cells. [4]

Oral administration of CP-91149 to diabetic ob/ob mice at 25-50 mg/kg causes rapid (3 hours) glucose lowering by 100-120 mg/dl without producing hypoglycemia, resulting from inhibition of glycogenolysis in vivo. This compound treatment does not lower glucose levels in normoglycemic, nondiabetic mice. [1] In the non-fasted Goto-Kakizaki (GK) rats, administration of this chemical in combination with CS-917 suppresses hepatic glycogen reduction by CS-917 and decreases plasma glucose more than single administration of CS-917. [5]

• Ensayo enzimático de Phosphorylase

  La actividad de la glucógeno fosforilasa a hepática humana (HLGPa, 85 ng) se mide en la dirección de la síntesis de glucógeno por la liberación de fosfato del glucosa-1-fosfato a 22°C en 100 μL de tampón que contiene 50 mM Hepes (pH 7,2), 100 mM KCl, 2,5 mM EGTA, 2,5 mM MgCl₂, 0,5 mM glucosa-1-fosfato y 1 mg/mL de glucógeno. El fosfato se mide a 620 nm, 20 minutos después de la adición de 150 μL de HCl 1 M que contiene 10 mg/mL de molibdato de amonio y 0,38 mg/mL de verde de malaquita. Se añaden concentraciones crecientes de este compuesto al ensayo en 5 μL de DMSO al 14%.

• Líneas celulares

  HSF55 and T98G

• Concentraciones

  Dissolved in DMSO, final concentrations ~50 μM

• Tiempo de incubación

  72 hours

• Método

  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 488nm for excitation and at 650nm for emission. The cell cycle profile is analyzed using Modifit's Sync Wizard.

• Modelos animales

  Obese, diabetic male C57BL/6J-Lep^(ob/ob) mice and their lean, nondiabetic C57BL/6J-/+ littermates

• Dosificaciones

  ~50 mg/kg

• Administración

  Orally