Discovery of a long-chain carbamoyl aminocarnitine derivative, a reversible carnitine palmitoyltransferase inhibitor with antiketotic and antidiabetic activity

The synthesis and pharmacological activity of reversible CPT I inhibitors as potential antiketotic and antidiabetic drugs are reported. Such inhibitors constitute a series of enantiomerically pure aminocarnitine derivatives having the general formula (CH3)(3)N+CH2CH(ZR)CH2COO- (with Z = ureido, carbamate, sulfonamide, and sulfamide moieties; R = C-7-C-14 linear alkyl chains). A primary pharmacological screening based on the evaluation of CPT I activity in intact rat liver (L-CPT 1) mitochondria revealed the best activity for the (R) forms of ureidic derivative 17 (ZR = NHCONHR, R = C-14), sulfonamidic derivative 7 (ZR = NHSO2R, R = C-12), and sulfamidic derivative 9 (ZR = NHSO2NHR, R = C-11). The IC50 values are 1.1, 0.7, and 0.8 muM, respectively. For the carbamic derivative 11 (ZR = NHCOOR, R = C-8), an IC50 of 9.5 muM was observed. In addition, an extraordinarily high selectivity toward the liver isoform with respect to the heart isoform. (muscle-CPT I equivalent to M-CPT I) was found for the ureidic compound 17 (IC50(M-CPT I) vs IC50(L-CPTI) = 39.4), as well as for other ureidic or carbamic compounds. Diabetic db/db mice treated orally with 17 and 7 for 45 days at a dose of 50 mg/kg twice a day showed a good reduction of serum glucose levels with respect to the untreated db/db mice (P < 0.01). In addition, 17 showed antiketotic activity in normal fasted rats. 17 has been selected for development as a potential antiketotic and antidiabetic drug.