Mitochondria-targeted tetrapeptide researched for restoring cellular energy production, reducing oxidative stress, and treating mitochondrial dysfunction.
Last Updated: May 2026
SS-31 (also Elamipretide, MTP-131, Bendavia) is a synthetic mitochondria-targeted tetrapeptide that selectively binds cardiolipin in the inner mitochondrial membrane, restoring cellular energy production and reducing oxidative stress. It is the most clinically-advanced compound in the mitochondria-targeted peptide class, with Phase 3 trials completed for Barth syndrome and ongoing development for other mitochondrial disease indications. SS-31 is not currently FDA-approved but has been advancing through formal clinical development pathways by Stealth BioTherapeutics.
SS-31 (Elamipretide) is a synthetic tetrapeptide (D-Arg-2'6'-dimethylTyr-Lys-Phe-NH₂) designed to cross cell and mitochondrial membranes and selectively bind cardiolipin in the inner mitochondrial membrane, where it stabilizes electron transport chain function and reduces reactive oxygen species production. Cardiolipin is the signature mitochondrial phospholipid required for cristae structure and Complex I-V function; SS-31 binding protects cardiolipin from peroxidation. Evidence level: Human RCT (Phase 3 for Barth syndrome); preclinical extensive across mitochondrial disease models.
In Phase 3 trials for Barth syndrome (a rare X-linked cardiolipin remodeling disorder), SS-31 has shown improvements in muscle function and quality of life markers, supporting Stealth BioTherapeutics' NDA submission for that indication. Phase 2 trials have explored SS-31 in age-related macular degeneration, primary mitochondrial myopathy, and heart failure with mixed but generally favorable results. The Barth syndrome indication represents the most advanced regulatory pathway. Evidence level: Phase 3 (Barth syndrome, regulatory submission pending); Phase 2 (multiple other indications).
SS-31 has the most advanced clinical development of any mitochondria-targeted peptide, distinguished by the specific cardiolipin-binding mechanism that differentiates it from broader antioxidants and from non-mitochondrial-targeted compounds.
| Compound | Mitochondrial mechanism | Clinical stage | Specific advantage |
|---|---|---|---|
| SS-31 (Elamipretide) | Cardiolipin binding, ETC stabilization | Phase 3 (Barth syndrome) | Selective mitochondrial targeting |
| MOTS-c | Mitochondrial-derived peptide | Preclinical | Mitochondrial-genome encoded |
| NAD+ | Sirtuin/energy coenzyme | Preclinical + observational | NAD+ pathway support |
SS-31's safety profile in Phase 2 and Phase 3 trials has been favorable — common side effects include mild injection-site reactions and occasional gastrointestinal events. Discontinuation rates due to adverse events have been low across trials. The targeted mitochondrial mechanism appears to avoid the broad off-target effects associated with non-selective antioxidants. Evidence level: Phase 2/3 human safety; cumulative trial data substantial.
SS-31 (Elamipretide) is not currently FDA-approved but is in formal clinical development by Stealth BioTherapeutics with a Phase 3 program in Barth syndrome and an NDA submission process advancing. EMA pathways are parallel. Among the compounds on Peptigrity, SS-31 has one of the clearest pharma-sponsored development paths and the most realistic near-term approval prospect for a non-FDA-approved compound. Current status in FDA peptide regulation 2025–2026 timeline.
Because the Stealth BioTherapeutics-sponsored clinical material is not the research-grade SS-31 sold by third-party laboratories — those are different supply chains. Research-grade SS-31 is subject to wider purity variance, occasional underdosing, and inconsistent endotoxin control. Independent HPLC purity testing and mass spectrometry identity confirmation are the meaningful purity signals for research-grade material. Guidance in how-to-test-peptides hub.
Peptigrity purchases SS-31 vials anonymously at standard customer pricing, sends them to ISO-accredited third-party labs for HPLC and mass spectrometry analysis, and publishes the unedited certificate of analysis. The lab test table above this section shows the cross-shop dataset. Methodology in how we calculate trust scores.
SS-31 binds cardiolipin in the inner mitochondrial membrane, stabilizing electron transport chain function and reducing oxidative stress, with Phase 3 clinical evidence in Barth syndrome and Phase 2 evidence across multiple mitochondrial disease indications.
Not yet. SS-31 (Elamipretide) is in formal clinical development by Stealth BioTherapeutics with an NDA submission process advancing for Barth syndrome. It is among the most advanced non-FDA-approved compounds on Peptigrity in terms of regulatory pathway.
SS-31 is legal to purchase as a research chemical for laboratory use in most jurisdictions, but it is not approved for human consumption. Country breakdown in peptide legal status guide.
SS-31 targets the mitochondrial membrane specifically (cardiolipin binding, ETC stabilization); NAD+ supports cellular energy more broadly (sirtuin activation, redox reactions). They engage different aspects of mitochondrial function and are not mechanistically interchangeable.
Independent third-party HPLC certificate of analysis from a lab the vendor does not own or pay, with mass spectrometry identity confirmation. COA interpretation in red flags in peptide certificates of analysis.
No. SS-31 is not approved for human consumption and Peptigrity is an independent review platform, not a medical authority. Clinical trial dosing has varied by indication. Anyone considering use should consult a licensed physician.
This section is for educational and informational purposes only and does not constitute medical advice. SS-31 (Elamipretide) is not currently FDA-approved but is in formal clinical development by Stealth BioTherapeutics. Always consult a qualified healthcare provider before using any peptide or research compound. Peptigrity is an independent review platform and does not sell, endorse, or recommend specific products or vendors.
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