Analysis and Identification of In Vitro Metabolites of Exercise Mimetic SLU‐PP‐332 ERRα/β/γ Agonist for Doping‐Control Purposes

Exercise mimetics mimic physical activity and prevent development and progression of chronic metabolic diseases, including obesity and Type 2 diabetes. The World Anti-Doping Agency (WADA) prohibits the use of exercise mimetics and metabolic modulators in sports. SLU-PP-332 is a small, synthetic ERRα/β/γ agonist recently developed using a rational drug design approach. SLU-PP-332 has been shown to increase oxidative muscle fibers, fatty acid oxidation, and enhance exercise endurance. In mouse models of metabolic syndrome, it increased energy expenditure and insulin sensitivity and conferred cardiac protection against pressure overload-induced heart failure by transcriptionally activating a wide spectrum of metabolic genes involved in fatty acid metabolism and mitochondrial function. The identification of metabolites of this emerging therapeutic molecule is a critical step towards detecting its misuse. The aim of the study was identification of Phase I and II metabolites generated in vitro using pooled human liver S9 fractions. Metabolites were analyzed using liquid chromatography-high-resolution mass spectrometry (LC-MS/HRMS). Five monohydroxylated (M1-M5), three dihydroxylated (M6-M8), and four reduced dihydroxylated metabolites (M9-M12) were identified. Metabolites M13 and M19 showed direct glucuronidation and sulfation of the parent compound, respectively. Metabolites M14-M18 and M20-M22 showed glucuronidation and sulfation with hydroxylation of the naphthalene or phenolic rings, respectively. M1, M7, M9, M10, M13, M14, M19, and M20 were the most abundant of the 22 metabolites and potentially useful for doping-control purposes. Further studies are necessary to fully elucidate the structures of the metabolites.