Diacylglycerol acyltransferase-1 (DGAT-1) is the enzyme that catalyzes the final and committed step of triglyceride formation, namely, the acylation of diacylglycerol with acyl coenzyme A. DGAT-1 deficient mice demonstrate resistance to weight gain on high fat diet, improved insulin sensitivity, and reduced liver triglyceride content. Inhibition of DGAT-1 thus represents a potential novel approach for the treatment of obesity, dyslipidemia, and metabolic syndrome. In this communication, we report the identification of the lead structure 6 and our lead optimization efforts culminating in the discovery of potent, selective, and orally efficacious carboxylic acid derivatives of 2-phenyl-5-trifluoromethyloxazole-4-carboxamides. In particular, compound 29 (DGAT-1 enzyme assay, IC(50) = 57 nM; CHO-K1 cell triglyceride formation assay, EC(50) = 0.5 μM) demonstrated dose dependent inhibition of weight gain in diet induced obese (DIO) rats (0.3, 1, and 3 mg/kg, p.o., qd) during a 21-day efficacy study. Furthermore, compound 29 demonstrated improved glucose tolerance determined by an oral glucose tolerance test (OGTT).
CGS 35601 is a potent triple inhibitor of endothelin-converting enzyme-1, neutral endopeptidase 24.11, and angiotensin-converting enzyme. It inhibited the activities of these three enzymes with IC50 values of 55, 2 and 22 nM, respectively. In conscious rats, CGS 35601 suppressed the big endothelin-1-induced pressor response by 82% and 72% at 30 and 120 minutes, respectively, following injection at a dose of 10 mg/kg, intravenously. At the same dose, CGS 35601 increased plasma atrial natriuretic peptide (ANP) immunoreactivity by 170% for up to 4 hours in conscious rats infused with ANP, and it inhibited the angiotensin I-induced pressor response by 74-94% within the first 2 hours after dosing. Similar in vivo activities were also observed with its orally active prodrug, CGS 37808. This compound blocked the big endothelin-1- induced pressor response by 71% and 67% at 30 and 120 minutes, respectively, after an oral dose of 10 mgEq/kg in conscious rats. It also increased plasma ANP immunoreactivity by 103% for up to 4 hours and inhibited the angiotensin I-induced pressor response by an average of 49% within the first 4 hours after the same dosing regimen. By suppressing the biosyntheses of endothelin-1 and angiotensin II, two potent vasoconstrictors, while simultaneously potentiating the circulating levels of ANP, a vasorelaxant and diuretic, CGS 35601 and CGS 37808 may represent novel agents for the treatment of cardiovascular and renal diseases.
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