SS-31 (Elamipretide) Research: What the Studies Show

Educational summary of published scientific literature. Zama Biosciences products are sold for laboratory research only and are not for human or veterinary use. Nothing on this page is medical advice or a claim about any product.

SS-31 is one of the few research peptides whose story runs from a chemistry lab all the way to a regulatory approval. This article covers how the peptide was designed, what it is reported to do inside mitochondria, what the cell and animal literature shows, and where the open questions are. For sequence, molecular data and handling, see the SS-31 research guide.

Where SS-31 came from

SS-31 belongs to the Szeto-Schiller (SS) peptides, named after Hazel Szeto and Peter Schiller, who developed them in the late 1990s and early 2000s. The design is simple: four amino acids alternating between aromatic residues (2′,6′-dimethyltyrosine and phenylalanine) and positively charged residues (D-arginine and lysine). That pattern turned out to let the peptide pass through cell membranes and gather at the inner membrane of mitochondria, a property first described by Zhao et al. (2004).

The compound was later developed by Stealth BioTherapeutics under the name elamipretide.

What the mechanistic studies report

• Cardiolipin binding. The best-supported mechanism is that SS-31 binds cardiolipin, a phospholipid found almost only in the inner mitochondrial membrane. Cardiolipin anchors and organizes the proteins of the electron transport chain (Birk et al., 2013).
• Electron transport and cytochrome c. By interacting with cardiolipin, SS-31 is reported to help keep cytochrome c in its electron-carrying role and to support more efficient electron transfer, which reduces the leak of reactive oxygen species (Szeto, 2014).
• Mitochondrial structure. Electron-microscopy studies in animal models describe better-preserved cristae, the folded inner-membrane structures where energy production happens.
• Not a classical antioxidant. Early work framed SS-31 as an antioxidant because the dimethyltyrosine can scavenge radicals. Later work places more weight on its effect on membrane structure than on direct scavenging.

The preclinical literature

Animal studies have examined SS-31 in models of ischemia–reperfusion (kidney and heart), age-related decline in mitochondrial function, and genetic mitochondrial disorders. The recurring finding across these papers is preserved mitochondrial structure and energy output under stress. As with most preclinical work, models, concentrations and endpoints vary between laboratories.

Clinical development and approval

Elamipretide went through several clinical programs in mitochondrial disease. A phase 2/3 trial in Barth syndrome, a rare genetic disorder of cardiolipin metabolism, reported results in 2021 (Thompson et al., 2021). On September 19, 2025, the FDA granted elamipretide accelerated approval as Forzinity for Barth syndrome. Accelerated approval means continued approval depends on confirmatory studies.

That approval covers a specific pharmaceutical product for one condition. Research-grade SS-31 is a laboratory reagent and is not that medicine.

Limits and open questions

• Outside Barth syndrome, clinical results in other mitochondrial conditions have been mixed, and several programs did not meet their main endpoints.
• Concentration–response in models varies widely between studies, which makes cross-study comparison hard.
• Cardiolipin specificity: how selective the binding is in living tissue, compared with other anionic lipids, is still being studied.

The takeaway

SS-31 is a small, designed peptide that concentrates in mitochondria and binds cardiolipin. It has a broad preclinical literature on mitochondrial structure and energy production, and in 2025 it became the first approved therapy for Barth syndrome in its pharmaceutical form. For laboratories it remains a standard tool for studying the inner mitochondrial membrane.

Frequently asked questions

What does SS-31 do in research models?

It concentrates at the inner mitochondrial membrane and binds cardiolipin, which studies link to better-preserved mitochondrial structure and more efficient electron transport.

Is SS-31 the same as elamipretide?

Yes. SS-31 is the research name and elamipretide is the drug name. The approved medicine Forzinity is a regulated pharmaceutical product; research-grade SS-31 is not.

Is SS-31 FDA approved?

Elamipretide received FDA accelerated approval on September 19, 2025, for Barth syndrome only. Research-grade SS-31 is for laboratory use and is not for human or veterinary use.

Related reading

• SS-31 research guide: sequence and technical data
• MOTS-c research: what the studies show
• NAD+ research guide
• Full Research Library

Research-grade SS-31 is available to registered researchers. Sign in or create your researcher account →

References

1. Zhao K, Zhao GM, Wu D, et al. Cell-permeable peptide antioxidants targeted to inner mitochondrial membrane inhibit mitochondrial swelling, oxidative cell death, and reperfusion injury. Journal of Biological Chemistry. 2004;279(33):34682–34690.
2. Birk AV, Liu S, Soong Y, et al. The mitochondrial-targeted compound SS-31 re-energizes ischemic mitochondria by interacting with cardiolipin. Journal of the American Society of Nephrology. 2013;24(8):1250–1261.
3. Szeto HH. First-in-class cardiolipin-protective compound as a therapeutic agent to restore mitochondrial bioenergetics. British Journal of Pharmacology. 2014;171(8):2029–2050.
4. Thompson WR, Hornby B, Manuel R, et al. A phase 2/3 randomized clinical trial followed by an open-label extension to evaluate the effectiveness of elamipretide in Barth syndrome. Genetics in Medicine. 2021;23(3):471–478.

Research Use Only. This article summarizes third-party scientific literature for educational purposes. Zama Biosciences products are not drugs, supplements or medical devices and are not for human or veterinary use. Statements have not been evaluated by the FDA.