A Trace ‘Tides Primer: Understanding elamipretide and the Szeto Schiller peptide family

By: Laura Mildon

SS-31 is a synthetic peptide containing four amino acid residues. It is also known as elamipretide, MTP-131, and Bendavia in the research literature. Its scientific interest centers on interactions with the inner mitochondrial membrane, where cells carry out much of their energy production.

Its regulatory history requires precision. In September 2025, FDA granted accelerated approval to the prescription medicine Forzinity, containing elamipretide, for a specific Barth syndrome indication. That approval does not extend to research materials labeled SS-31 or establish general wellness, longevity, or performance benefits. This article examines the molecule and its published research without providing directions for use.

Chemical identity

The D designation on arginine specifies its stereochemistry, or spatial arrangement. Dmt is a modified tyrosine residue. These details and the terminal amide are part of the molecule’s identity; a four-letter sequence alone would omit them.

The formula above describes the parent peptide. A hydrochloride or other salt includes counterions and has a different formula and formula weight. The FDA-approved medicine contains elamipretide hydrochloride; an ingredient name alone does not make a research preparation equivalent to that medicine.

PubChem chemical identity and authentic two dimensional structure

Molecular structure

The linked PubChem record provides a structure based on defined chemical connectivity and stereochemistry. A molecular formula counts atoms but cannot uniquely determine their arrangement. An accurate illustration must preserve the D-arginine residue, the methyl groups on tyrosine, and the terminal amide.

History and scientific rationale

SS refers to Szeto–Schiller, the peptide family associated with Hazel H. Szeto and Peter W. Schiller. These peptides were designed synthetically rather than isolated as naturally occurring human peptides. A foundational 2004 paper by Zhao and colleagues described the family’s mitochondrial targeting and antioxidant behavior. That publication is a documented early milestone, rather than proof of an exact first-synthesis date.

A later mechanistic study by Birk and colleagues in 2013 linked SS-31 to cardiolipin, a phospholipid enriched in the inner mitochondrial membrane. The research moved beyond describing an antioxidant effect to examining interactions with a specific membrane component.

Why cardiolipin matters

Mitochondria produce ATP, a molecule that cells use to transfer energy. Their inner membrane forms folds called cristae and contains proteins involved in electron transport. Cardiolipin helps organize this membrane and its protein machinery.

Laboratory studies examined how SS-31 interacts with cardiolipin and influences the behavior of cytochrome c, a protein involved in electron transfer. Under some experimental conditions, cytochrome c can also participate in reactions that damage membrane lipids. These experiments help explain the research rationale; they do not establish a universal effect in every tissue or disease.

Selected published research

Early mitochondrial studies in 2004

Zhao and colleagues studied synthetic peptide antioxidants in cultured neuronal cells, isolated mitochondria, and an isolated-heart model. They reported reduced oxidative injury and changes in mitochondrial swelling and cytochrome c release. This was foundational preclinical work on the SS peptide family, not a clinical demonstration of broad benefits from SS-31.

Zhao and colleagues in Journal of Biological Chemistry 2004

Cardiolipin interactions in 2013

Birk and colleagues investigated SS-31 using biochemical experiments and a rat model of interrupted kidney blood supply followed by restoration of flow. Their findings connected cardiolipin binding with mitochondrial membrane structure and energy recovery in that experimental setting. The model does not establish a clinical kidney indication.

Birk and colleagues in Journal of the American Society of Nephrology 2013

The Barth syndrome trial published in 2021

Thompson and colleagues reported a randomized, blinded crossover trial involving 12 participants. The controlled phase did not meet its primary walking-distance and fatigue endpoints. Improvements reported during the subsequent open-label extension deserve separate interpretation because that phase lacked a concurrent blinded placebo comparison. The study included a manufacturer-employed author.

Thompson and colleagues in Genetics in Medicine 2021

Later clinical findings and their limits

Primary mitochondrial myopathy in 2023

The MMPOWER-3 phase 3 trial randomized 218 participants with primary mitochondrial myopathy. It did not meet its primary endpoints for walking distance or fatigue at 24 weeks. This negative result is important: a plausible mitochondrial mechanism does not guarantee improvement across mitochondrial disorders.

MMPOWER 3 randomized trial in Neurology 2023

Longer follow up in Barth syndrome in 2024

The TAZPOWER extension publication reported longer-term observations in a small cohort: 10 participants entered the extension and eight reached week 168. The authors reported improvements in functional measures. The absence of a concurrent placebo group and the small number of participants limit causal interpretation and generalization.

TAZPOWER open label extension in Genetics in Medicine 2024

FDA status and the research material distinction

On September 19, 2025, FDA granted accelerated approval to Forzinity to improve muscle strength in adults and pediatric patients with Barth syndrome weighing at least 30 kg. Barth syndrome is a rare genetic disorder involving abnormal cardiolipin metabolism. This is a specific prescription-drug indication, not an over-the-counter supplement authorization.

FDA based accelerated approval on improved knee extensor strength, a measure considered reasonably likely to predict patient benefit. The agency required a randomized, blinded, placebo-controlled post-approval trial to confirm that this change translates into patient benefit. Accelerated approval is an FDA approval pathway with a requirement to verify benefit; it should not be described as proof of every proposed use.

FDA announcement of accelerated approval in September 2025

A research product labeled SS-31 is not Forzinity. Shared chemical terminology does not establish equivalent manufacturing controls, formulation, purity, sterility, or regulatory authorization. FDA approval of the named medicine cannot be transferred to a separate research product.

FDA prescribing information for Forzinity including chemistry and clinical studies

What the evidence supports

SS-31 is a defined synthetic tetrapeptide with substantial mechanistic research and disease-specific clinical development. The evidence includes early laboratory findings, clinical trials with unmet primary endpoints, and an accelerated approval for one medicine and indication. Claims about reversing aging, improving everyday energy, or enhancing athletic performance do not follow from that record.

This article concerns scientific and regulatory context. The closing disclaimer refers to the research product discussed here and does not negate the separate FDA approval of Forzinity.

Sources and regulatory context checked October 15, 2026.

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DISCLAIMER: These statements are for research purposes only and have not been evaluated by the FDA. This product is not intended to diagnose, treat, cure, or prevent any disease.