Anilides of (R)-trifluoro-2-hydroxy-2-methylpropionic acid as inhibitors of pyruvate dehydrogenase kinase

The optimization of a series of anilide derivatives of (R)-3,3,3-trifluoro-2-hydroxy-2-methylpropionic acid as inhibitors of pyruvate dehydrogenase kinase (PDHK) is described that started from N-phenyl-3,3,3-trifluoro-2-hydroxy-2-methylpropanamid 1 (IC50 = 35 +/- 1.4 mu M). It was found that small electron-withdrawing groups on the ortho position of the anilide, i.e., chloro, acetyl, or bromo, increased potency 20-40-fold. The oral bioavailability of the compounds in this series is optimal (as measured by AUC) when the anilide is substituted at the 4-position with an electron-withdrawing group (i.e., carboxyl, carboxyamide, and sulfoxyamide). N-(2-Chloro-4-isobutylsulfamoylphenyl)-(R)-3,3,3-trifluoro-2-hydroxy-2-methylpropionamide (10a) inhibits PDHK in the primary enzymatic assay with an IC50 Of 13 +/- 1.5 nM, enhances the oxidation of [C-14]lactate into (CO2)-C-14 in human fibroblasts, lowers blood lactate levels significantly 2.5 and 5 h after oral doses as low as 30 mu mol/kg, and increases the ex vivo activity of PDH in muscle, kidney, liver, and heart tissues. However, in contrast to sodium dichloroacetate (DCA), these PDHK inhibitors did not lower blood glucose levels. Nevertheless, they are effective at increasing the utilization and disposal of lactate and could be of utility to ameliorate conditions of inappropriate blood lactate elevation.