Structure-activity relationship profiling of N-substituted 8-trifluoromethyl-9H-purin-6-amines as mitochondrial protonophores

Mitochondrial dysfunction is a common cellular defect linked to the pathogenesis of diabetes, obesity, and metabolic dysfunction-associated fatty liver disease. Accordingly, there is increasing interest in treating these diseases with mitochondria-targeted agents, such as mitochondrial protonophores. Herein, we report a library of N-substituted 8-trifluoromethyl-9H-purin-6-amine derivatives derived from the potent protonophore BAM15. Our structure-activity relationship (SAR) study revealed that this scaffold has a wide range of tolerated substitutions that elicit sub-micromolar potency and improved in vivo pharmacokinetic properties relative to BAM15. We found that lead compound SHK1112218 was demonstrated to be a bona fide mitochondrial protonophore through a mitochondrial stress test. Upon further investigation, it displayed an EC₅₀ of 0.48 μM in rat L6 myoblasts and demonstrated a half-life of 13 h in mice. Taken together, these findings encourage the further exploration of the promising N-substituted 8-trifluoromethyl-9H-purin-6-amine scaffold in vivo models and as structural inspiration for the future development of mitochondrial protonophores.