Discovery of potent and specific fructose-1,6-bisphosphatase inhibitors and a series of orally-bioavailable phosphoramidase-sensitive prodrugs for the treatment of type 2 diabetes.
Excessive glucose production by the liver coupled with decreased glucose uptake and metabolism by muscle, fat, and liver results in chronically elevated blood glucose levels in patients with type 2 diabetes. Efforts to treat diabetes by reducing glucose production have largely focused on the gluconeogenesis pathway and rate-limiting enzymes within this pathway such as fructose-1,6-bisphosphatase (FBPase). The first potent FBPase inhibitors were identified using a structure-guided drug design strategy (Erion, M. D.; et al. J. Am. Chem. Soc. 2007, 129, 15480-15490) but proved difficult to deliver orally. Herein, we report the synthesis and characterization of a series of orally bioavailable FBPase inhibitors identified following the combined discoveries of a low molecular weight inhibitor series with increased potency and a phosphonate prodrug class suitable for their oral delivery. The lead inhibitor, 10A, was designed with the aid of X-ray crystallography and molecular modeling to bind to the allosteric AMP binding site of FBPase. High potency (IC50 = 16 nM) and FBPase specificity were achieved by linking a 2-aminothiazole with a phosphonic acid. Free-energy perturbation calculations provided insight into the factors that contributed to the high binding affinity. 10A and standard phosphonate prodrugs of 10A exhibited poor oral bioavailability (0.2-11%). Improved oral bioavailability (22-47%) was achieved using phosphonate diamides that convert to the corresponding phosphonic acid by sequential action of an esterase and a phosphoramidase. Oral administration of the lead prodrug, MB06322 (30, CS-917), to Zucker Diabetic Fatty rats led to dose-dependent inhibition of gluconeogenesis and endogenous glucose production and consequently to significant blood glucose reduction.
Dang
Qun
Q
Department of Medicinal Chemistry, Metabasis Therapeutics, Inc., La Jolla, California 92037, USA.
Kasibhatla
Srinivas Rao
SR
Reddy
K Raja
KR
Jiang
Tao
T
Reddy
M Rami
MR
Potter
Scott C
SC
Fujitaki
James M
JM
van Poelje
Paul D
PD
Huang
Jingwei
J
Lipscomb
William N
WN
Erion
Mark D
MD
D000284:Administration, Oral; D000818:Animals; D001665:Binding Sites; D018360:Crystallography, X-Ray; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy* / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000138:chemical synthesis* / Q000737:chemistry / Q000627:therapeutic use*; D006597:Fructose-Bisphosphatase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D005947:Glucose / Q000096:biosynthesis; D022781:Hepatocytes / Q000378:metabolism; D006867:Hydrolases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008297:Male; D008958:Models, Molecular; D015394:Molecular Structure; D011355:Prodrugs / Q000008:administration & dosage / Q000138:chemical synthesis* / Q000737:chemistry / Q000627:therapeutic use*; D051381:Rats; D012680:Sensitivity and Specificity; D013237:Stereoisomerism; D013329:Structure-Activity Relationship
D004791:Enzyme Inhibitors; D011355:Prodrugs; D006867:Hydrolases; D006597:Fructose-Bisphosphatase; C049021:phosphoamidase; D005947:Glucose