Cellular Senescence Research
FDA Approved
SS-31
Also known as: Elamipretide, MTP-131, Bendavia, SS-31 peptide
Mitochondria-targeted tetrapeptide that binds cardiolipin on the inner mitochondrial membrane. Studied in mitochondrial research.
Research overview
SS-31 (elamipretide; earlier codes MTP-131 and Bendavia) is a synthetic four-amino-acid peptide, D-Arg-Dmt-Lys-Phe-NH2, where Dmt is a modified tyrosine. It is one of the Szeto-Schiller peptides from Szeto's laboratory at Weill Cornell Medical College, and Stealth BioTherapeutics developed it as a medicine. It has been studied widely in cells and animals. A phase 3 placebo-controlled trial in 218 adults with primary mitochondrial myopathy did not meet its primary goals for walking distance or fatigue (Karaa et al., Neurology 2023). In Barth syndrome, a rare inherited disorder of the mitochondrial lipid cardiolipin, a 12-person placebo-controlled crossover trial also missed its primary goals; walking distance was better than at the start during an open-label follow-up with no placebo group (Thompson et al., Genet Med 2021).
In September 2025 the US FDA granted elamipretide (as Forzinity) accelerated approval for Barth syndrome, based on knee muscle strength, and requires a further placebo-controlled trial to confirm the result. It is not authorised in the EU. The material supplied here is not the licensed medicine. Supplied for laboratory research use only.
Mechanism of action
SS-31 carries two positive charges and two ring-shaped (aromatic) groups, which let it enter cells and gather at the inner mitochondrial membrane, where it binds cardiolipin, a negatively charged lipid. In cell, isolated-mitochondria and animal studies this binding was linked to more stable membrane folds (cristae), less production of reactive oxygen species and changes in the membrane's surface charge (Mitchell et al., 2020). How these effects relate to clinical outcomes in people is still being studied.