Introduction

SLU-PP-332 is a synthetic small molecule — not a peptide — that acts as a potent agonist of the estrogen-related receptors (ERR), a family of nuclear receptors that govern mitochondrial biogenesis and energy metabolism. It first attracted attention as an “exercise mimetic”: in mice it reproduces several of the metabolic and muscular adaptations normally triggered by endurance training, without the animal having to exercise. Because ERR signaling sits at the center of how cells burn fuel, the compound is studied for metabolic syndrome, obesity, and disorders of mitochondrial function.

What Is SLU-PP-332?

The “SLU” prefix reflects Saint Louis University, where the compound originated; later work has been led by Bahaa Elgenaidi and Thomas Burris and their collaborators, who founded Pelago Pharmaceuticals to develop ERR-targeted drugs. SLU-PP-332 is a pan-ERR agonist: it activates all three receptor subtypes, with half-maximal effective concentrations (EC50) of roughly 98 nM at ERRα, 230 nM at ERRβ, and 430 nM at ERRγ. Unlike estrogens, it engages ERR pathways without estrogenic activity.

As a small molecule its identity is well defined: molecular formula C₁₈H₁₄N₂O₂, molecular weight 290.32 g/mol, CAS 303760-60-3. It is soluble in DMSO and ethanol but not in water, and in the laboratory it is handled as a solid stored cool and protected from light.

How It Works: ERR and Energy Metabolism

The estrogen-related receptors are orphan nuclear receptors that, together with the coactivator PGC-1α, switch on genes controlling mitochondrial function and fuel use. When SLU-PP-332 binds the ligand-binding domain of an ERR, it stabilizes the receptor’s active shape and strengthens its partnership with PGC-1α, turning up that gene program. In cultured muscle cells (C2C12 myocytes) the compound raises expression of the ERR target gene Pdk4 (pyruvate dehydrogenase kinase 4), increases mitochondrial content, and enhances cellular respiration — the biochemical signature of more oxidative, fatigue-resistant muscle.

In living animals this translates into a shift toward oxidative (type IIa) muscle fibers, greater fatty-acid oxidation, and higher energy expenditure. The effect does not come from appetite suppression: treated mice eat the same amount and show no change in their willingness to be active. The compound instead makes muscle behave as though it had been endurance-trained.

The Exercise-Mimetic Research

The landmark study (Billon et al., ACS Chemical Biology, 2023) gave SLU-PP-332 to mice and measured an ERRα-dependent acute aerobic-exercise response. Treated animals ran substantially longer and farther on a treadmill — reported as roughly 70% longer in duration and 45% greater in distance — alongside increased mitochondrial proteins and oxidative fiber markers in muscle. The authors described the compound as effectively instructing skeletal muscle to make the changes endurance training would, which is why it is labeled an exercise mimetic.

Metabolic Syndrome and Obesity

A companion study (Billon et al., Journal of Pharmacology and Experimental Therapeutics, 2023) found that a synthetic ERR agonist of this class alleviates metabolic syndrome in mice. In diet-induced obesity models, dosing reduced fat mass, lowered liver fat, cholesterol, and triglycerides, and improved glucose handling — with reports of on the order of 12% body-weight reduction over about four weeks in obese animals, again without reducing food intake. These results position ERR agonism as a candidate strategy against obesity and its metabolic complications.

Broader ERR Research

ERR activation is being explored beyond muscle and fat. Work in aging kidney tissue (Wang et al., American Journal of Pathology, 2023) showed that ERR agonism reverses mitochondrial dysfunction and inflammation, hinting that the same metabolic reprogramming could be relevant to age-related decline in other organs. The field remains preclinical: SLU-PP-332 is not an approved medicine, and human data are not yet available.

Research Status and Handling

All findings to date come from cell-culture and animal studies. SLU-PP-332 is supplied for in-vitro and analytical research only and is not intended for human or veterinary use. In the laboratory it is typically dissolved in DMSO to make a stock solution, aliquoted, and stored frozen to avoid repeated freeze-thaw cycles.

References

[1] Billon C, Sitaula S, Banerjee S, Welch R, Elgendy B, Hegazy L, et al. Synthetic ERRα/β/γ Agonist Induces an ERRα-Dependent Acute Aerobic Exercise Response and Enhances Exercise Capacity. ACS Chem Biol. 2023;18(4):756-771. doi:10.1021/acschembio.2c00720.
[2] Billon C, Schoepke E, Avdagic A, Chatterjee A, Butler AA, Elgendy B, et al. A Synthetic ERR Agonist Alleviates Metabolic Syndrome. J Pharmacol Exp Ther. 2023;388(2):232-240. doi:10.1124/jpet.123.001733.
[3] Wang XX, Myakala K, Libby AE, Krawczyk E, Panov J, Jones BA, et al. Estrogen-Related Receptor Agonism Reverses Mitochondrial Dysfunction and Inflammation in the Aging Kidney. Am J Pathol. 2023;193(12):1969-1987. doi:10.1016/j.ajpath.2023.07.008.