tcsc1552 MB05032

MB05032 is a special and efficacious GNG inhibitor targeted the AMP binding site of fructose 1,6-bisphosphatase (FBPase) with an IC50 value of 16 nM.

IC50 Value: 16 nM (Human Liver FBPase) [1]

Target: Fructose 1, 6-bisphosphatase

Oral delivery of MB05032 was achieved by using the bisamidate prodrug MB06322 (CS-917), which is converted to MB05032 in two steps through the action of an esterase and a phosphoramidase.

in vitro: MB05032 inhibits human liver FBPase with a potency (IC50 = 16 ± 1.5 nM) significantly greater than the natural inhibitor, AMP (IC50 = 1 μM), and the most well characterized AMP mimetic, ZMP (IC50 = 12 ± 1.4 μM). MB05032 inhibits rat FBPase 3-fold weaker (IC50 of 61 ± 4 nM) than human FBPase, whereas AMP is 20-fold weaker as an inhibitor [1]. Inhibition of FBPase activity in islet β-cells by its specific inhibitor MB05032 led to significant increase of their glucose utilization and cellular ATP to ADP ratios and consequently enhanced GSIS in vitro [2].

in vivo: Oral administration of MB06322 to young (8-9 weeks old) ZDF rats with mild diabetes (basal insulin levels of 7.7 ± 0.7 ng/ml) and aged (12-13 weeks) ZDF rats with overt diabetes (basal insulin levels of 0.65 ± 0.16 ng/ml) results in dose-dependent glucose lowering. The dose-response is relatively steep, with 6-10 mg/kg and 30-100 mg/kg being the approximate doses associated with minimal and maximal activity, respectively [1]. Pretreatment of mice with the MB05032 prodrug MB06322 could potentiate GSIS in vivo and improve their glucose tolerance [2].

Toxicity: Neither lactate nor triglycerides increased in 8- to 9-week-old ZDF rats with mild diabetes treated with high doses of MB06322. In ZDF rats with more advanced disease, lactate and triglyceride levels were elevated but only modestly (<2-fold). These results suggest that, unlike inhibitors of other GNG enzymes, FBPase inhibitors may lower glucose with an adequate safety margin [1].

Clinical trial: Evaluation of Glucose Lowering Effect, Safety and Tolerability of CS-917. Phase 2b