SLU-PP-332

RATIONALE: Estrogen-related receptor (ERR) agonists such as the drug candidates SLU-PP-332 and SLU-PP-915 are currently being investigated as exercise mimetics, given their ability to trigger human physiological processes similar to those initiated by actual physical activity. This capability prompted the consideration of these compounds as drugs potentially relevant for sports drug testing programs. METHODS: The two pan-ERR agonists SLU-PP-332 and SLU-PP-915 were characterized using liquid chromatography-high resolution (tandem) mass spectrometry (LC-HRMS/MS). Furthermore, the in vitro metabolic transformation products of both compounds prepared by means of human liver S9 fraction (S9 fraction) and human liver microsomes (HLMs) were analyzed. In addition, selected metabolites of SLU-PP-915 were synthesized and their structures were analyzed by nuclear magnetic resonance (NMR) spectroscopy. RESULTS: A total of nine metabolites were identified for SLU-PP-332, consisting of six Phase-I metabolites and three Phase-II conjugates. Conversely, the analysis of SLU-PP-915 yielded only Phase-I transformation products, with a total of seven metabolites identified. In both cases, an in-depth structural elucidation was conducted to obtain a comprehensive overview of the detected metabolites. Furthermore, three metabolites of SLU-PP-915 were confirmed through chemical synthesis and NMR. CONCLUSION: The results obtained in this study gave an in-depth view into the analysis and in vitro metabolism of the newly developed pan-ERR agonists SLU-PP-332 and SLU-PP-915. This may help to uncover the illicit use of these novel compounds as potential performance-enhancing substances.

UNLABELLED: Physical inactivity contributes to the development of chronic diseases. Activation of orphan nuclear receptors estrogen-related receptors (ERRα/β/γ) has emerged as a molecular strategy to mimic exercise-induced benefits. AIM: To systematically review the current evidence on the physiological, molecular, and clinical effects of synthetic pan-ERR agonists, especially SLU-PP-332 and SLU-PP-915, in preclinical models and their potential as exercise mimetics. METHODS: A systematic review of scientific literature from 2020 to 2024 was conducted, including experimental studies in animals and cell models. Molecular mechanisms, effects on energy metabolism, muscle function, renal aging, and metabolic syndrome were analyzed. RESULTS: Pan-ERR agonists induce a gene expression program like acute aerobic exercise, dependent on ERRα, including activation of Ddit4 and Slc25a25. They enhance fatty acid oxidation, increase type IIa muscle fibers (oxidative-glycolytic, with mixed substrate utilization including fatty acids and glucose), and improve endurance. SLU-PP-332 and SLU-PP-915 reduce adiposity, improve glycemic control, and increase basal energy expenditure in obesity models, without evident toxicity. Additionally, they restore mitochondrial function and reduce inflammation in aging kidneys. CONCLUSIONS: Pharmacological activation of ERRα/β/γ is a promising strategy as an exercise mimetic, with potential therapeutic applications in metabolic diseases, aging, and muscle-related conditions. Clinical trials are needed to confirm their efficacy and safety in humans.

Estrogen receptor-related receptors (ERRα, ERRβ, and ERRγ) are orphan nuclear receptors that regulate genes involved in mitochondrial biogenesis, oxidative phosphorylation, fatty acid oxidation, and the Krebs cycle. ERRs are essential for skeletal muscle adaptation to aerobic exercise and represent promising targets for exercise mimetic therapeutics. We previously developed an ERR pan-agonist, SLU-PP-332 (332), which improves aerobic performance in mice but lacks oral bioavailability. Here, we characterize SLU-PP-915 (915), a chemically distinct ERR pan-agonist that is orally bioavailable and exhibits potent in vivo exercise mimetic activity. Compound 915 enhances aerobic exercise performance (distance and duration) to a similar extent as 332 when administered intraperitoneally and maintains comparable efficacy when administered orally, adjusted for systemic exposure. Both compounds robustly induce the expression of DNA damage-inducible transcript 4 (Ddit4), a gene induced by acute aerobic exercise, with levels matching or exceeding levels induced by treadmill running, depending on the muscle examined. Notably, 915 synergizes with exercise training to further enhance Ddit4 and mitochondrial gene expression. These findings position orally active ERR agonists such as 915 as promising agents for the treatment of metabolic disorders (eg, obesity, type 2 diabetes, and metabolic disease-associated steatohepatitis), cardiovascular disease (heart failure), and muscle-related pathologies, including sarcopenia and muscular dystrophies. SLU-PP-915 offers a valuable chemical tool for exploring the chronic therapeutic potential of ERR activation. SIGNIFICANCE STATEMENT: The nuclear receptor estrogen receptor-related receptor plays an important role in driving the physiological adaptations to exercise. The article describes the ability of a pan-estrogen receptor-related receptor agonist SLU-PP-915, which also displays oral bioavailability, to enhance exercise capacity.

Estrogen-related receptors (ERRs) are master regulators of mitochondrial metabolism and exercise-responsive transcription, yet only a limited number of synthetic agonists with suitable potency and drug-like properties have been reported. SLU-PP-332 is a well-established exercise mimetic and widely used chemical probe for ERR activation; however, the structural features governing its potency, efficacy, selectivity, and drug-like properties have not been systematically elucidated. Here, we report the first comprehensive structure-activity relationship (SAR) analysis of the SLU-PP-332 scaffold, integrating chemical synthesis, cell-based functional assays, downstream gene-expression profiling, and computational modeling. Through iterative modification of core pharmacophoric elements, we identify key structural determinants that control ERRα and ERRγ agonism, transcriptional efficacy, ligand efficiency, and physicochemical properties. While SLU-PP-332 remains a strong benchmark for ERR activation, several analogues achieve comparable or context-dependent transcriptional responses while exhibiting improved ligand efficiency, solubility, or metabolic stability. Computational docking and molecular dynamics simulations reveal how subtle structural modifications influence ERR engagement and signaling outcomes. Together, this work defines design principles for tuning ERR agonism and provides a foundational SAR roadmap for the rational development of next-generation ERR agonists and exercise-mimetic therapeutics.

BACKGROUND: Cardiac metabolic dysfunction is a hallmark of heart failure (HF). Estrogen-related receptors ERRα and ERRγ are essential regulators of cardiac metabolism. Therefore, activation of ERR could be a potential therapeutic intervention for HF. However, in vivo studies demonstrating the potential usefulness of ERR agonist for HF treatment are lacking, because compounds with pharmacokinetics appropriate for in vivo use have not been available. METHODS: Using a structure-based design approach, we designed and synthesized 2 structurally distinct pan-ERR agonists, SLU-PP-332 and SLU-PP-915. We investigated the effect of ERR agonist on cardiac function in a pressure overload-induced HF model in vivo. We conducted comprehensive functional, multi-omics (RNA sequencing and metabolomics studies), and genetic dependency studies both in vivo and in vitro to dissect the molecular mechanism, ERR isoform dependency, and target specificity. RESULTS: Both SLU-PP-332 and SLU-PP-915 significantly improved ejection fraction, ameliorated fibrosis, and increased survival associated with pressure overload-induced HF without affecting cardiac hypertrophy. A broad spectrum of metabolic genes was transcriptionally activated by ERR agonists, particularly genes involved in fatty acid metabolism and mitochondrial function. Metabolomics analysis showed substantial normalization of metabolic profiles in fatty acid/lipid and tricarboxylic acid/oxidative phosphorylation metabolites in the mouse heart with 6-week pressure overload. ERR agonists increase mitochondria oxidative capacity and fatty acid use in vitro and in vivo. Using both in vitro and in vivo genetic dependency experiments, we show that ERRγ is the main mediator of ERR agonism-induced transcriptional regulation and cardioprotection and definitively demonstrated target specificity. ERR agonism also led to downregulation of cell cycle and development pathways, which was partially mediated by E2F1 in cardiomyocytes. CONCLUSIONS: ERR agonists maintain oxidative metabolism, which confers cardiac protection against pressure overload-induced HF in vivo. Our results provide direct pharmacologic evidence supporting the further development of ERR agonists as novel HF therapeutics.

Physical exercise induces physiologic adaptations and is effective at reducing the risk of premature death from all causes. Pharmacological exercise mimetics may be effective in the treatment of a range of diseases including obesity and metabolic syndrome. Previously, we described the development of SLU-PP-332, an agonist for the estrogen-related receptor (ERR)α, β, and γ nuclear receptors that activates an acute aerobic exercise program. Here we examine the effects of this exercise mimetic in mouse models of obesity and metabolic syndrome. Diet-induced obese or ob/ob mice were administered SLU-PP-332, and the effects on a range of metabolic parameters were assessed. SLU-PP-332 administration mimics exercise-induced benefits on whole-body metabolism in mice including increased energy expenditure and fatty acid oxidation. These effects were accompanied by decreased fat mass accumulation. Additionally, the ERR agonist effectively reduced obesity and improved insulin sensitivity in models of metabolic syndrome. Pharmacological activation of ERR may be an effective method to treat metabolic syndrome and obesity. SIGNIFICANCE STATEMENT: An estrogen receptor-related orphan receptor agonist, SLU-PP-332, with exercise mimetic activity, holds promise as a therapeutic to treat metabolic diseases by decreasing fat mass in mouse models of obesity.