Category: Longevity Research | Reading time: 5 min | For research use only
SS-31 (also known as Elamipretide, MTP-131, or Bendavia) is a synthetic tetrapeptide belonging to the Szeto-Schiller (SS) peptide family, developed by Hazel Szeto and Peter Schiller at Weill Cornell Medical College in the early 2000s. It is specifically engineered to target and concentrate within the inner mitochondrial membrane — a property that makes it a unique research tool for investigating mitochondrial function, cardiolipin biology, and oxidative stress in cellular aging models.
SS-31 has one of the most extensive mitochondria-targeted peptide research records available, with publications spanning cardiac, renal, neurological, and skeletal muscle research domains, and a substantial clinical trial program that distinguishes it from most research peptides.
This article summarizes published research on SS-31 for scientific and educational purposes. All compounds discussed are strictly for laboratory and research use only.
Molecular Profile
- Common names: SS-31, Elamipretide, MTP-131, Bendavia
- Sequence: D-Arg-Dmt-Lys-Phe-NH₂ (where Dmt = 2',6'-dimethyltyrosine)
- Molecular weight: 639.8 g/mol
- Charge: +3 (highly cationic at physiological pH)
- Key structural feature: Alternating aromatic and cationic residues enabling membrane penetration
- Form: Lyophilized powder (research grade)
- Stability: Store at −20°C; protect from light
- Solubility: Highly water-soluble due to cationic charge
The alternating aromatic-cationic motif is not accidental — it is the engineered basis for SS-31's selective accumulation in the inner mitochondrial membrane (IMM). The cationic residues interact with the negative mitochondrial membrane potential (−180 mV), while the aromatic residues interact with the lipid environment of the IMM. This dual interaction concentrates SS-31 at the IMM at concentrations estimated to be 5,000-fold higher than cytoplasmic levels.
The Cardiolipin Connection
SS-31's primary characterized molecular target is cardiolipin — a unique phospholipid found almost exclusively in the inner mitochondrial membrane, where it comprises approximately 20% of total lipid content.
Cardiolipin serves multiple critical functions in mitochondrial biology:
- Structural scaffold for electron transport chain (ETC) complexes I, III, IV, and V
- Required for assembly and stability of respiratory supercomplexes
- Regulates cytochrome c binding and release (relevant to apoptosis signaling)
- Maintains cristae morphology — the folded inner membrane structure that maximizes surface area for ATP synthesis
What happens to cardiolipin with age and stress: Cardiolipin is particularly vulnerable to oxidative damage because it is located adjacent to the primary site of reactive oxygen species (ROS) generation — the electron transport chain. Oxidized cardiolipin loses its ability to maintain ETC complex organization, resulting in electron leak, reduced ATP production efficiency, and increased ROS generation — a self-reinforcing cycle of mitochondrial dysfunction.
SS-31's mechanism: Research has documented SS-31's interaction with cardiolipin, with studies reporting that SS-31 binds to and stabilizes cardiolipin, preventing its oxidation and preserving its structural functions. This cardiolipin-protective mechanism is the proposed basis for SS-31's documented effects on electron transport chain efficiency, ATP production, and mitochondrial morphology in experimental models.
Mechanisms Studied in Preclinical Research
Electron transport chain efficiency Studies using isolated mitochondria and intact cell models have examined SS-31's effect on oxygen consumption rates, ATP production, and electron transport chain complex activity. Published data reports improved coupling efficiency (ATP produced per oxygen consumed) in SS-31-treated mitochondria from aged tissues, with researchers attributing this to cardiolipin stabilization and improved ETC complex organization.
Reactive oxygen species reduction Multiple studies have documented reduced mitochondrial ROS production in SS-31-treated cell and tissue models. Research in aged animal models has reported reductions in mitochondrial superoxide levels and hydrogen peroxide production, correlating with preserved cardiolipin oxidation status.
Mitochondrial morphology Mitochondria undergo fission (fragmentation) under stress conditions and in aged cells, producing smaller, dysfunctional organelles. Research has examined SS-31's effect on mitochondrial morphology using fluorescence microscopy and electron microscopy, reporting preservation of elongated, networked mitochondrial morphology in treated cells compared to fragmented patterns in stressed controls.
Cristae structure preservation Electron microscopy studies have examined SS-31's effect on mitochondrial cristae — the internal membrane folds where ATP synthesis occurs. Research in aged and ischemic tissue models has documented preserved cristae density and morphology in SS-31-treated samples, a structural finding consistent with the cardiolipin-stabilization mechanism.
Cytochrome c retention Cardiolipin normally retains cytochrome c at the inner mitochondrial membrane. When cardiolipin is oxidized, cytochrome c is released — a critical event in apoptosis initiation. Research has examined SS-31's effect on cytochrome c retention under stress conditions, with studies reporting reduced cytochrome c release and attenuated apoptotic signaling in treated models.
Areas of Active Research
Cardiac ischemia-reperfusion models SS-31 has one of the most developed cardiac research profiles among mitochondria-targeted peptides. Studies in rodent cardiac ischemia-reperfusion models have examined infarct size, cardiac function recovery, and cardiomyocyte survival. The compound has progressed to clinical trials for heart failure with preserved ejection fraction (HFpEF) — the BRILLIANCE-HF and PRIZE trials — making it one of very few research peptides with an active cardiac clinical trial program.
Renal research Published studies have examined SS-31 in models of acute kidney injury (AKI), chronic kidney disease, and renal ischemia-reperfusion. Renal tubular cells have high mitochondrial density and are particularly vulnerable to mitochondrial dysfunction. Research has reported preservation of tubular cell ATP levels and reduced tubular injury markers in SS-31-treated models.
Skeletal muscle and aging Age-related muscle loss (sarcopenia) is associated with mitochondrial dysfunction in muscle fibers. Research using aged rodent models has examined SS-31's effects on muscle fiber mitochondrial function, exercise capacity, and muscle mass parameters. The RESTORE trial examined SS-31 in human subjects with mitochondrial myopathy.
Neurodegeneration models Mitochondrial dysfunction is implicated in multiple neurodegenerative conditions. Research has examined SS-31 in models of Alzheimer's disease, Parkinson's disease, and traumatic brain injury, investigating neuroprotection, synaptic mitochondrial function, and neuronal survival parameters.
Diabetic complications High glucose environments produce mitochondrial oxidative stress in vascular endothelial cells, contributing to diabetic vascular complications. Research in diabetic animal models and endothelial cell cultures has examined SS-31's effect on mitochondrial function under hyperglycemic conditions.
Clinical Trial Program
SS-31/Elamipretide is one of the few research peptides with an active clinical development program:
- BRILLIANCE-HF: Phase 2 trial in heart failure with preserved ejection fraction (HFpEF)
- PRIZE: Phase 2 trial in HFpEF examining exercise capacity
- MMPOWER-3: Phase 3 trial in Barth syndrome (a rare mitochondrial cardiomyopathy) — primary endpoint not met, but safety data established
- RESTORE: Open-label study in primary mitochondrial myopathy
The clinical program provides a human pharmacokinetic and safety profile that supports research design and contextualizes preclinical findings.
Key Published Research
- Szeto HH. (2014). First-in-class cardiolipin-protective compound as a therapeutic agent to restore mitochondrial bioenergetics. British Journal of Pharmacology, 171(8), 2029–2050.
- Birk AV, et al. (2013). The mitochondrial-targeted compound SS-31 re-energizes ischemic mitochondria by interacting with cardiolipin. Journal of the American Society of Nephrology, 24(8), 1250–1261.
- Bhatt DL, et al. (2017). Elamipretide (MTP-131), a novel cardiolipin-targeted compound, in STEMI patients.Journal of the American College of Cardiology, 69(11 Suppl), 1–1.
- Cheng G, et al. (2017). Mitochondria-Targeted Drugs for the Treatment of Cardiac Diseases. Acta Pharmacologica Sinica, 38, 1095–1107.
- Sabbah HN. (2016). Targeting the mitochondria in heart failure: a translational perspective. JACC: Basic to Translational Science, 5(1), 88–106.
Research Considerations
SS-31's targeting specificity for the inner mitochondrial membrane is both its research advantage and a consideration for experimental design. Its effects are fundamentally mitochondrial — researchers investigating non-mitochondrial mechanisms should ensure their model and readouts are appropriate for the compound's actual mechanism of action.
The D-amino acid content (D-Arg at position 1) provides proteolytic stability, but researchers should note that D-amino acid-containing peptides have different metabolic profiles than all-L peptides. This should be considered in pharmacokinetic study design.
NordBioLab supplies SS-31 as a research-grade lyophilized tetrapeptide with ≥98% purity (HPLC verified) and full COA documentation per batch.
All products and information provided by NordBioLab are strictly for scientific research and laboratory use only. Not for human or veterinary consumption. This article does not constitute medical advice.