ATX-304

ATX-304 is a synthetic small molecule, not a peptide, that activates AMP-activated protein kinase (AMPK), the cell's main energy-sensing enzyme. Most of the literature calls it O304; a 2025 paper refers to "ATX-304 (formerly O304)" [1]. Researchers study it because AMPK controls glucose uptake, fat burning and fat synthesis, and ATX-304/O304 has been tested in a phase IIa trial in people with type 2 diabetes [3]; a 2026 review describes it as clinical-stage [6]. This monograph covers its identity, mechanism and published evidence, with human, animal and cell data kept separate.

Chemical identity and structure

• Names: ATX-304; formerly O304 [1].
• CAS number: 1261289-04-6. The 2025 JCI Insight study names the supplier as Betagenon AB, Umeå, Sweden [1].
• Molecule type: small molecule. The ChEMBL record (CHEMBL3652451) gives the formula as C24H27FN8O2 and the molecular weight as 478.53 [2].
• Class: described as a pan-AMPK activator [3][7].

Mechanism of action

AMPK is switched on by energy shortage, such as exercise or caloric restriction [3]. Two linked actions are described for ATX-304/O304:

1. AMPK activation. One paper reports that O304 activates AMPK by inhibiting protein phosphatase 2C, which keeps AMPK switched on [4]. A 2026 review instead groups O304 with activators that bind AMPK directly at the ADaM site [6]. The exact binding mode is not settled. In the cisplatin kidney-injury study, ATX-304 increased phosphorylation of acetyl-CoA carboxylase, which the authors took as evidence of AMPK activation [7].
2. Mitochondrial uncoupling. Two groups report that O304 acts as a mitochondrial uncoupler [4][5]. In vascular smooth muscle and HepG2 cells it raised oxygen use with ATP synthase blocked and lowered mitochondrial membrane potential [4]. Norlin et al. argue this creates the energy demand behind increased muscle glucose uptake and use [5].

Protection against cisplatin was lost in AMPK-null mouse embryonic fibroblasts, which the authors read as AMPK dependence [7].

What the research shows

Human evidence

• One phase IIa proof-of-concept trial has been published. It enrolled people with type 2 diabetes who were already taking metformin. The authors report that O304 lowered fasting plasma glucose and HOMA-IR, improved peripheral microvascular perfusion and reduced blood pressure [3]. The abstract does not give the number of participants, the trial length or detailed safety results.
• A later mouse paper describes O304 as "well tolerated in humans" [8]; this is the authors' statement, not a published safety dataset.
• No published human trial was found for MASLD, kidney disease, pain, aging or any other indication.

Animal evidence

• Glucose metabolism and β-cells: In diet-induced obese mice, O304 increased muscle glucose uptake and reduced β-cell stress [3]. In mice it increased insulin-independent glucose uptake and use in skeletal muscle and heart while preventing glycogen build-up, and in db/db mice it preserved insulin secretion, β-cell mass and pancreatic insulin content [5]. In high-fat-diet mice it largely prevented diet-related gene-expression and chromatin changes in islets, including the rise in the β-cell stress marker Aldh1a3 [9].
• Heart and aging: In mice, O304 activated cardiac AMPK, increased cardiac glucose uptake and improved left-ventricular stroke volume without increasing heart weight in mice or rats [3]. In diabetic mice it reverted diabetic cardiomyopathy [5]. In aged mice it improved insulin resistance, cardiac function and exercise capacity [8]. In naturally aging mice it reduced markers of kidney senescence and fibrosis [10].
• Liver (MASLD): In a mouse model of progressive fatty liver disease, ATX-304 reduced body fat mass and blood cholesterol and reduced steatosis and fibrosis overall. The effects varied markedly between liver lobes ("pronounced local heterogeneities") [1]. These changes came with a shift toward fatty-acid oxidation and away from lipid synthesis [1]. The authors say the cause of the heterogeneity is unclear and that larger samples are needed [1].
• Kidney injury: In cisplatin-induced kidney injury, ATX-304-treated mice had lower serum creatinine, lower NGAL and less tissue damage than controls [7].
• Vascular: In a mouse abdominal aortic aneurysm model, O304 reduced aneurysm formation and blood pressure and kept vascular smooth muscle cells in their contractile state [11].
• Pain: In three mouse studies by one group (post-operative incision, lumbar disc puncture), O304 reduced mechanical hypersensitivity [12][13][14]. Two of these studies also reported normalized AMPK-pathway markers in dorsal root ganglia [12][14]. In the disc-puncture study, burrowing behavior did not improve [14].
• Tool-compound use: In a rat doxorubicin heart-damage study, O304 was used to test AMPK involvement and partly reversed the protection from ginkgolide B [15].

Cell and organism evidence

• In primary kidney tubular cells, ATX-304 protected against cisplatin injury, changed 66 of 126 metabolites measured and increased basal oxygen consumption without changing maximal respiration [7].
• In vascular smooth muscle cells and HepG2 cells, O304 behaved like an uncoupler. It extended C. elegans lifespan via the AMPK–mTOR axis and autophagy, and relaxed isolated rat mesenteric arteries independently of the endothelium [4].
• In mouse hippocampal neurons with NTRK1 knockdown, pre-treatment with O304 and rapamycin reversed the suppression of mitophagy and the neuronal damage; the abstract does not separate the effect of O304 alone [16].

Evidence quality

• Human data are thin: one phase IIa trial in type 2 diabetes, with size and safety not reported in the abstract [3]. No human data support liver, kidney, pain or longevity claims.
• Few research groups: much of the metabolic work comes from one research line [3][5][8][9]; other groups have reported uncoupling, vascular, kidney and pain findings [4][7][10][11][12].
• Animal results may not apply to humans: the MASLD and kidney results come from model-specific mouse studies, and the liver effects were uneven [1][7].
• The mechanism is not fully settled. Sources disagree on how ATX-304 activates AMPK (phosphatase inhibition or allosteric binding) [4][6], and mitochondrial uncoupling is reported as a second action alongside AMPK activation [4][5].
• Context matters. At least one study found that O304 counteracted a protective effect [15].

Research context

No direct AMPK activator has reached the market [1]; a 2026 review discusses the translational challenges facing the class [6]. ATX-304 is studied in metabolic, cardiovascular/aging and kidney-injury models and used as a tool to test AMPK involvement [15][16]. Its "exercise mimetic" label reflects mouse findings only [8].

Storage and handling

Supplied as a dry solid; store sealed, dry, cold and protected from light as the supplier's specification sheet directs. No published stability studies were found. VialTalk does not provide preparation guidance.

Quality and COA considerations

• The COA should name the compound as ATX-304/O304 and give CAS 1261289-04-6 [1].
• Identity should be confirmed by mass spectrometry matching a molecular weight of about 478.5 (C24H27FN8O2) [2], ideally with NMR. Peptide-style tests do not apply because ATX-304 is not a peptide.
• Purity should be shown by HPLC with the chromatogram attached, along with residual-solvent and water-content data where available.
• Check that the lot number on the COA matches the vial label, and look for an independent third-party test.

Key references

1. Holm et al., JCI Insight 2025 — https://pubmed.ncbi.nlm.nih.gov/40197369/
2. ChEMBL CHEMBL3652451 — https://www.ebi.ac.uk/chembl/explore/compound/CHEMBL3652451
3. Steneberg et al., JCI Insight 2018 — https://pubmed.ncbi.nlm.nih.gov/29925691/
4. Li et al., Chem Biol Interact 2025 — https://pubmed.ncbi.nlm.nih.gov/41130350/
5. Norlin et al., Commun Biol 2023 — https://pubmed.ncbi.nlm.nih.gov/37626210/
6. Amatya et al., Int J Mol Sci 2026 — https://doi.org/10.3390/ijms27188358
7. Katerelos et al., Biomed Pharmacother 2024 — https://pubmed.ncbi.nlm.nih.gov/38749175/
8. Ericsson et al., Commun Biol 2021 — https://pubmed.ncbi.nlm.nih.gov/34795407/
9. López-Pérez et al., Sci Rep 2021 — https://pubmed.ncbi.nlm.nih.gov/34949756/
10. Zhu et al., Front Pharmacol 2022 — https://pubmed.ncbi.nlm.nih.gov/35308246/
11. Sun et al., Front Pharmacol 2024 — https://pubmed.ncbi.nlm.nih.gov/39679375/
12. Das et al., Reg Anesth Pain Med 2019 — https://pubmed.ncbi.nlm.nih.gov/31229963/
13. Das et al., Reg Anesth Pain Med 2019 — https://pubmed.ncbi.nlm.nih.gov/31541009/
14. Das et al., Anesth Analg 2022 — https://pubmed.ncbi.nlm.nih.gov/36201356/
15. Rong et al., Arch Biochem Biophys 2026 — https://pubmed.ncbi.nlm.nih.gov/42624274/
16. Yang et al., Cell Death Discov 2023 — https://pubmed.ncbi.nlm.nih.gov/37907480/

Research-use note: ATX-304 is an investigational compound that is not approved for any human use. This monograph summarizes published research for educational purposes. It does not give usage or treatment guidance.