7-But-2-ynyl-9-(6-methoxy-pyridin-3-yl)-6-piperazin-1-yl-7,9-dihydro-purin-8-one is a novel competitive and selective inhibitor of dipeptidyl peptidase IV with an antihyperglycemic activity

7-But-2-ynyl-9-(6-methoxy-pyridin-3-yl)-6-piperazin-1-yl-7,9-dihydro-purin-8-one (ER-319711) is a novel dipeptidyl peptidase (DPP)-IV inhibitor discovered in our laboratories. In this study, we have characterized this DPP-IV inhibitor in vitro and in vivo as an antidiabetic agent. The trifluoroacetate salt form of ER-319711, ER-319711-15, inhibited human DPP-IV with an IC(50) value of 0.089 microM, whereas its IC(50) values toward human DPP8 and DPP9 were >100 microM. Inhibition kinetic pattern analysis indicated that ER-319711-15 inhibited DPP-IV in a competitive manner. ER-319711-15 (1 mg/kg) reduced glucose excursion in an oral glucose tolerance test (OGTT) using Zucker fa/fa rats, with significant increases in plasma insulin and active glucagon-like peptide-1 levels. In an OGTT using mice fed a high-fat diet in which ER-319711-15 (0.1-10 mg/kg) was orally administered at 0 h, and glucose was loaded at 0 and 5 h, this compound improved glucose tolerance dose dependently at both 0- and 5-h glucose loading. Next, we compared efficacy of ER-319711-15, E3024, a competitive DPP-IV inhibitor having an imidazopyridazinone structure, or vildagliptin, a slow-binding and long-acting DPP-IV inhibitor, at the same dose, 10 mg/kg, in the same procedures. At the first glucose challenge, all compounds lowered area under the curve (AUC) values of delta blood glucose between 0 and 2 h significantly to the same degree. At the second glucose load, the AUC values between 5 and 7 h were significantly decreased by ER-319711-15 and vildagliptin, but not by E3024. Therefore, ER-319711 might be a potent, competitive, and selective DPP-IV inhibitor with an antihyperglycemic activity.