Side-by-side · Research reference

ACE-031vsMOTS-c

Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.

APhase 2HUMAN-REVIEWED10/44 cited

BAnimal-StrongHUMAN-REVIEWED16/68 cited

ACE-031

ActRIIB-Fc Fusion · Phase 2 Halted

Phase 2Highest trial stage

2011Development halted

~58.4 kDaMolecular weightReichel 2025

SQ · Weekly dosing investigated

MOTS-c

Mitokine · Mitochondria-Encoded

5–10 mgWeekly doseLee 2015

AnimalEvidence levelLee 2015 Reynolds 2021

Min–hrsHalf-life

SQ · Variable · 2–3×/week

01Mechanism of Action

Parameter

ACE-031

MOTS-c

Primary target

Myostatin, GDF11, activin A — TGF-β superfamily ligands

Mitochondrial 12S rRNA sORF → folate-AICAR-AMPK axisLee 2015

Pathway

Soluble decoy receptor binds circulating myostatin/TGF-β ligands → prevents ActRIIB activation → SMAD2/3 pathway inhibition

Folate cycle inhibition → ↑AICAR → AMPK phosphorylation → PGC-1α upregulationLee 2015 Kim 2018

Downstream effect

Disinhibition of myogenic signaling, increased skeletal muscle mass and strength

Enhanced fatty acid oxidation, GLUT4-mediated glucose uptake, mitochondrial bioenergetics, anti-inflammationLee 2015

Feedback intact?

—

Stress-responsive, AMPK-dependent nuclear translocationKim 2018

Origin

Recombinant fusion protein: human ActRIIB extracellular domain + IgG1-Fc fragmentReichel 2025

Endogenous 16-AA mitokine; mtDNA-encoded; declines with age; upregulated by exerciseReynolds 2021

Antibody development

—

02Dosage Protocols

Parameter

ACE-031

MOTS-c

Clinical dosing

Weekly or biweekly SQ injections (exact doses undisclosed pre-halt)

Phase 2 DMD trial protocol not fully published.

—

Black market products

Variable purity; 12/14 tested products contained target protein plus contaminantsReichel 2025

SDS-PAGE revealed multiple protein bands; quality control absent.Reichel 2025

—

Evidence basis

Phase 2 trial discontinued — incomplete dataset

Animal + anecdotalLee 2015 Reynolds 2021 A first-in-human phase 1 study 2021

Phase 1a/1b CB4211 analog trial completed 2021; no native MOTS-c RCT published.

Half-life

Days to weeks (Fc-fusion typical kinetics)

IgG1-Fc domain confers extended circulation time.

Minutes to hours (estimated)

Systemically unstable; native MOTS-c PK in humans not fully characterised.

Duration investigated

12–24 weeks (trial cut short)

—

Standard dose

—

5–10 mg / weekLee 2015

Experimental, extrapolated from animal data. No human RCT-derived dose.

Frequency

—

2–3× per week

Short half-life may necessitate more frequent dosing for saturation.

Lower / starter dose

—

2.5–5 mg / week

Recommended due to limited human data.

Duration

—

4–12 weeks (experimental)

Optimal cycle length unknown.

Reconstitution

—

Bacteriostatic water, 1–2 mL

10 mg/mL at 1 mL.

Timing

—

Pre-workout or fasted state preferred

Activity-context amplifies AMPK response.

03Metabolic / Fat Loss Evidence

Parameter

ACE-031

MOTS-c

Primary fat target

—

Diet-induced / metabolic obesity; systemic fat utilization

Quantified reduction

—

Significant HFD fat gain ↓Lee 2015

Murine models, dose-dependent (5 & 15 mg/kg).

IGF-1 impact

—

No direct IGF-1 pathway; AMPK-mediated

Effect on lean mass

—

High dose significantly ↑ lean mass in mice

Insulin sensitivity

—

Reversed HFD insulin resistance in 7 days (mice)Lee 2015

Triglycerides

—

AMPK-driven FA oxidation suggests TG benefit (not directly measured)

Glucose metabolism

—

Improved glucose tolerance; GLUT4 upregulationLee 2015

Effect reversibility

—

Unknown — no long-term follow-up data

Context dependency

—

No effect in normal-chow mice; requires metabolic stressReynolds 2021

Key publication

—

Lee Cell Metab 2015 · Reynolds Nat Commun 2021 · Kim Cell Metab 2018Lee 2015 Reynolds 2021 Kim 2018

04Side Effects & Safety

Parameter

ACE-031

MOTS-c

Epistaxis (nosebleeds)

Significant incidence in Phase 2 DMD trial — primary safety signal

—

Telangiectasia

Dilated capillaries / spider veins observed

—

Vascular abnormalities

Mechanism: ActRIIB/ALK1 pathway disruption affects vascular homeostasis

—

Injection site reactions

Local erythema, induration (biologics class effect)

—

Antibody development

Potential for anti-drug antibodies (Fc-fusion proteins); incidence not reported

—

Black market contaminants

12/14 tested products contained multiple unidentified proteins alongside ACE-031Reichel 2025

—

Injection site reaction

—

Mild irritation (reported)

Fluid retention / Edema

—

Not reported

Glucose intolerance

—

Improves glucose toleranceLee 2015

Cardiovascular

—

Heart palpitations (anecdotal); cardiac hypertrophy reversed in diabetic rats

Cancer risk

—

Contradictory data — some models suggest pro-proliferative effects

CNS / Neurological

—

Insomnia, headache (anecdotal reports)

GI symptoms

—

Nausea, stomach discomfort (reported)

Antibody formation

—

No data (no long-term human trials)

Pregnancy / OB

—

Avoid — insufficient safety data

Evidence quality

—

Phase 1 analog (CB4211); preclinical; anecdotal humanA first-in-human phase 1 study 2021

Absolute Contraindications

ACE-031

·History of vascular disorders (epistaxis, telangiectasia, HHT)
·Pregnancy (TGF-β pathway critical for fetal development)
·Active malignancy (myostatin inhibition may affect tumour growth)
·Use of non-pharmaceutical grade ACE-031 (contamination risk)Reichel 2025

MOTS-c

·Pregnancy / breastfeeding (insufficient data)

Relative Contraindications

ACE-031

·Coagulation disorders or anticoagulant use (epistaxis risk)
·Hereditary hemorrhagic telangiectasia (HHT) family history
·Cardiovascular disease (vascular remodeling effects unknown)

MOTS-c

·Active cancer or cancer predisposition
·AMPK pathway deficiency (efficacy nullified)
·Use with cancer-promoting medications (theoretical)

05Administration Protocol

Parameter

ACE-031

MOTS-c

1. Pharmaceutical status

ACE-031 is not FDA-approved or commercially available. Phase 2 development was discontinued in 2011 due to safety concerns. Any ACE-031 on the black market is unregulated research chemical.

Add 1–2 mL bacteriostatic water. At 10 mg/vial, 1 mL gives 10 mg/mL concentration. Roll gently to dissolve.

2. Black market quality

12 of 14 tested black market ACE-031 products contained the target protein but also carried multiple unidentified protein contaminants detectable by SDS-PAGE. Two products contained no ACVR2B-immunoreactive material.Reichel 2025

Subcutaneous — abdomen, thigh, or deltoid. Rotate sites to avoid lipohypertrophy. Pinch fat layer.

3. Detection in sport

ACE-031 is prohibited under WADA S4.3 (Myostatin Inhibitors). Gel electrophoresis and Western blotting using ACVR2B-specific antibodies can detect the ~58.4 kDa protein in biological samples.Reichel 2025

Pre-workout or fasted state preferred — metabolic context amplifies AMPK response. 2–3× per week.

4. Clinical trial route

Phase 2 protocol used subcutaneous injections at weekly or biweekly intervals. Exact dosing protocols remain unpublished.

Lyophilised: room temp, protected from light. Reconstituted: refrigerate, use within 21–30 days. Short systemic stability.

5. Needle

—

27–31G insulin syringe. Short needle (4–6 mm) for SQ delivery. Clean technique mandatory.

06Stack Synergy

ACE-031

— no documented stacks

MOTS-c

+ Ipamorelin

Moderate

View Ipamorelin →

MOTS-c activates AMPK/PGC-1α for mitochondrial efficiency and fatty acid oxidation; ipamorelin stimulates GH for anabolic recovery and sleep depth. Pathways are complementary — MOTS-c handles metabolic flexibility and glucose handling while ipamorelin drives recovery and body recomposition through GH. Theoretical synergy is high; clinical data is lacking.

MOTS-c: 5 mg SQ · pre-workout (2–3×/wk)
Ipamorelin: 200–300 mcg SQ · pre-sleep (daily)
Primary benefit: Metabolic flexibility + GH recovery + ROS reduction