Unsymmetric hydroxylamine and hydrazine BAM15 derivatives as potent mitochondrial uncouplers

Chemical mitochondrial uncouplers are protonophoric, lipophilic small molecules that transport protons from the mitochondrial intermembrane space into the matrix independent of ATP synthase, thus uncoupling nutrient oxidation from ATP production. Our previous work identified BAM15 (IC50 0.27 mu M) as a potent and efficacious mitochondrial uncoupler with potential for obesity treatment. In this paper, we investigate in vitro and in vivo properties of hydroxylamine and hydrazine BAM15 derivatives and reveal the high uncoupling nature of these compounds. Our structure-activity relationship studies revealed that the hydroxylamine BAM15 analogs are more potent than hydrazine ones. For example, the most potent of the hydrazine series was 5a with an EC50 value of 4.6 mu M and 103 % activity of BAM15 while compound 4e was the best among the hydroxylamine series with EC50 value of 340 nM and 118 % BAM15 mitochondrial uncoupling activity in rat L6 myoblasts. Pharmacokinetic profiling of 5a and 4e revealed low exposure (2-220 nM) and short half-life (15-27 min) in mice.