- Compound: O-304
- Developer: Betagenon AB (Uppsala, Sweden)
- Type: Small molecule pan-AMPK activator
- Mechanism: Direct allosteric activation at ADaM site (β subunit)
- AMPK complexes activated: All 12 α/β/γ heterotrimeric combinations
- Clinical stage: Phase 2 completed (T2D); Phase 2 ongoing (HFpEF)
- Format: Oral capsule — no reconstitution required
01 What Is O-304?
O-304 is a small molecule developed by Betagenon AB as a direct, pan-specific activator of AMPK (AMP-activated protein kinase). Unlike indirect AMPK activators — which work by raising AMP:ATP ratios (metformin, phenformin) or via kinase-specific mechanisms (A-769662, which only activates β1-containing complexes) — O-304 activates all 12 known AMPK heterotrimeric complexes through a direct allosteric mechanism.
AMPK is the master cellular energy sensor, activated in conditions of energy deficit and responsible for switching metabolism from anabolic to catabolic modes. Its dysregulation underlies type 2 diabetes, obesity, NAFLD, and heart failure — making a broad, direct AMPK activator a significant research and therapeutic target.
02 AMPK Biology — The Energy Sensor
AMPK is a heterotrimeric serine/threonine kinase composed of:
- α subunit (α1, α2): Catalytic subunit; contains the kinase domain and the AIS (autoinhibitory sequence). Thr172 phosphorylation (by LKB1 or CaMKK2) is required for full activation.
- β subunit (β1, β2): Scaffold subunit; contains the carbohydrate-binding module (CBM) and the ADaM site — the binding site for allosteric small molecule activators including O-304
- γ subunit (γ1, γ2, γ3): Regulatory subunit; contains four CBS domains that bind AMP, ADP, and ATP, providing the energy-sensing function
The 12 possible α/β/γ combinations have distinct tissue distributions, substrate specificities, and sensitivity to activation. β1-containing complexes predominate in liver; β2 in skeletal muscle and heart. Selective β1 activators (like A-769662) are therefore less useful for cardiac research — a gap that O-304's pan-AMPK activity fills.
03 Direct Allosteric Activation Mechanism
O-304 binds the ADaM (allosteric drug and metabolite) site — a hydrophobic pocket at the interface between the kinase domain of the α subunit and the CBM of the β subunit. Binding at this site:
- Directly stabilises the active conformation of the kinase domain
- Protects Thr172 from dephosphorylation by protein phosphatases
- Produces synergistic activation when combined with physiological AMP binding at the γ subunit
- Does not require elevated AMP:ATP ratios — can activate AMPK even under energy-replete conditions
This mechanism is fundamentally different from metformin's Complex I inhibition and avoids the mitochondrial stress inherent in indirect activation. It allows researchers to study AMPK's downstream effects in isolation from mitochondrial perturbation — a significant methodological advantage for deconvolving AMPK-dependent from mitochondrial-dependent cellular responses.
04 Phase 2 Clinical Data
- Significant fasting plasma glucose reduction vs placebo (dose-dependent)
- HbA1c reduction at 12 weeks — statistically significant at highest dose
- No significant hypoglycaemia events (AMPK activation is glucose-dependent via incretin mechanisms)
- Acceptable tolerability profile
- Rationale: AMPK activates cardiac metabolism, reduces myocardial fibrosis, improves mitochondrial function
- Phase 2 initiated — results anticipated 2025–2026
- Rationale supported by preclinical data showing O-304 improved cardiac function in HFpEF mouse models
05 O-304 vs Metformin vs AICAR
| Property | O-304 | Metformin | AICAR |
|---|---|---|---|
| AMPK activation type | Direct, allosteric | Indirect (via Complex I) | Indirect (AICA ribotide → AMP) |
| AMPK complexes activated | All 12 (pan) | All (indirectly) | All (indirectly, via AMP) |
| Mitochondrial inhibition | No | Yes (Complex I) | No |
| Energy depletion required | No | Yes (partial) | Yes (AMP elevation) |
| Oral bioavailability | Yes | Yes | Poor (IV preferred in research) |
| β subunit selectivity | Pan (β1 + β2) | None (indirect) | None (indirect) |
06 Frequently Asked Questions
What is O-304?
O-304 is a small molecule pan-AMPK activator developed by Betagenon AB (Sweden). It activates all 12 known AMPK heterotrimeric complexes (composed of α1/α2 catalytic and β1/β2/γ1/γ2/γ3 regulatory subunits in various combinations) via a direct allosteric mechanism. AMPK (AMP-activated protein kinase) is the cell's master energy sensor — activated by energy deficit (low AMP:ATP ratio). O-304's pan-AMPK activation makes it a broad metabolic research tool for studying AMPK biology across tissue types.
How does O-304 differ from Metformin?
Metformin activates AMPK indirectly by inhibiting mitochondrial Complex I, causing a transient energy deficit (↓ATP, ↑AMP) that triggers AMPK activation. This indirect mechanism requires functional mitochondria and causes some mitochondrial stress. O-304 activates AMPK directly and allosterically — binding to the ADaM (allosteric drug and metabolite) site on the AMPK β subunit. This direct activation occurs independently of mitochondrial inhibition, potentially allowing AMPK activation in tissues where metformin's mitochondrial mechanism is less effective (such as myocardium).
What clinical data exists for O-304?
O-304 completed Phase 2a and Phase 2b trials in type 2 diabetes conducted by Betagenon AB. The Phase 2a trial showed O-304 reduced fasting plasma glucose and HbA1c with a dose-dependent response and acceptable tolerability profile in T2D patients. Phase 2b data demonstrated significant HbA1c reductions. Additionally, a Phase 2 trial in heart failure with preserved ejection fraction (HFpEF) was initiated, given AMPK's cardioprotective roles. Full peer-reviewed publication of Phase 2b results is pending as of 2026.
What does AMPK do in metabolism?
AMPK is a serine/threonine kinase that functions as a cellular energy gauge. When AMP/ADP rises relative to ATP (energy deficit), AMPK is activated and switches the cell from anabolic to catabolic metabolism: it promotes glucose uptake (GLUT4 translocation), fatty acid oxidation (ACC phosphorylation → malonyl-CoA inhibition), mitochondrial biogenesis (PGC-1α activation), and autophagy (ULK1 activation). Simultaneously it inhibits energy-consuming processes: protein synthesis (mTORC1 inhibition), fatty acid synthesis, gluconeogenesis, and cholesterol synthesis.
What research models is O-304 used in?
O-304 is used in research models studying: type 2 diabetes and insulin resistance, NASH/NAFLD (fatty liver disease), heart failure with preserved ejection fraction (HFpEF), skeletal muscle metabolism and exercise physiology, obesity and adipose tissue lipid metabolism, and cellular energy sensing. Its pan-AMPK activity makes it a cleaner tool than indirect activators (metformin, AICAR) for attributing effects specifically to AMPK activation across α1/α2 and β1/β2 subunit combinations.
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