SS-31: The Complete Guide
A four-amino-acid peptide that concentrates over a thousand-fold in the inner mitochondrial membrane, stabilising the lipid that organises the cell's energy production machinery. Also known as Elamipretide, with one of the most substantial clinical evidence bases of any mitochondrial-targeted compound.
What is SS-31?
Here is the simplest way to understand SS-31: every cell in your body contains tiny structures called mitochondria — the cellular power plants that produce nearly all the energy your cells use to function. The mitochondria themselves contain an inner membrane where the actual energy production happens, and that inner membrane has a specific lipid called cardiolipin that organises everything correctly. Picture cardiolipin as the wiring inside the power plant — keeping the protein machinery aligned so the plant runs efficiently. SS-31 is a peptide designed to enter mitochondria, bind to cardiolipin, and keep that wiring in good order.
SS-31 was developed by Dr. Hazel Szeto and colleagues, and is one of only a handful of peptides ever designed to specifically target the inside of mitochondria. The name SS-31 reflects the original research lab (Szeto-Schiller). The compound is also known as Elamipretide in clinical contexts, and as Bendavia or MTP-131 in earlier development codes. Research suggests SS-31 concentrates over a thousand-fold in the inner mitochondrial membrane within minutes of administration — a level of selectivity rare in peptide research.
What sets SS-31 apart in the longevity research family is its mechanism. Most antioxidants — vitamin C, vitamin E, glutathione — work outside the mitochondria, trying to neutralise damaging free radicals after they have been produced. Research suggests SS-31 works upstream of that. By stabilising cardiolipin and the energy-production machinery itself, research suggests it reduces the production of damaging molecules at the source rather than mopping them up after the fact. SS-31 has also reached human clinical trials under the Elamipretide name — examined in research on heart failure, mitochondrial myopathy, and age-related macular degeneration. That clinical research base is one of the more substantial datasets of any mitochondrial-targeted compound.
Research Applications
Research on SS-31 spans mitochondrial energy production, cardiolipin biology, age-related cellular decline, and a substantial human clinical research programme conducted under the Elamipretide name. Here is where the published research has focused:
Mitochondria are the energy-producing structures inside every cell in the body. Research suggests SS-31 is one of only a few peptides that penetrates directly into mitochondria, stabilising cardiolipin — the lipid that organises the inner-membrane machinery responsible for ATP (cellular energy) production.
The heart contains more mitochondria per cell than almost any other tissue — it needs constant energy to beat. SS-31 (as Elamipretide) has been studied in clinical trials for heart failure (PROGRESS-HF), examining whether mitochondrial stabilisation supports cardiac performance in research subjects with reduced heart function.
Mitochondrial function naturally declines with age — research suggests this is part of why energy levels drop, recovery slows, and organ function decreases as people age. Research suggests SS-31 may slow or partially reverse some of those changes at the cellular level by maintaining mitochondrial efficiency.
When mitochondria malfunction, they leak electrons that combine with oxygen to form damaging molecules called reactive oxygen species (ROS) — cellular rust. Research suggests SS-31 reduces ROS production at the source by keeping the electron transport chain organised, rather than trying to neutralise ROS after the fact like conventional antioxidants do.
SS-31 (as Elamipretide) has reached multiple human clinical trials — including EMBRACE (mitochondrial myopathy), PROGRESS-HF (heart failure), and ReCLAIM (age-related macular degeneration). This produces a clinical evidence base most research peptides will never reach.
Beyond the heart, research suggests SS-31 supports kidney function, retinal cell health, and skeletal muscle performance — all tissues with high mitochondrial density that depend heavily on efficient cellular energy production. The 2013 Birk study in renal ischaemia is one of the foundational papers in this area.
How SS-31 Works
The big-picture answer first: SS-31 enters cells, makes its way into the mitochondria, binds to a specific lipid called cardiolipin in the inner membrane, and keeps the energy-production machinery organised. By keeping that machinery tidy, research suggests it produces more energy and leaks fewer damaging byproducts.
Cell-penetrating design: SS-31's amino acid sequence (D-Arg-Dmt-Lys-Phe) gives it a specific combination of positive charge and aromatic character that allows it to cross cell membranes without needing a transporter to escort it through. Research suggests SS-31 concentrates over a thousand-fold in the inner mitochondrial membrane within minutes of administration. This is unusually fast and selective for a peptide.
Cardiolipin in plain language: imagine the inner mitochondrial membrane as the floor of a power plant, with all the energy-production machinery (the electron transport chain) bolted to the floor in a precise arrangement. Cardiolipin is the special flooring material that holds everything in place. When cardiolipin is healthy, the machinery stays organised and produces ATP efficiently. When cardiolipin is damaged — by oxidation or by aging — the flooring warps, the machinery shifts out of alignment, and energy production drops while damaging byproducts increase. Research suggests SS-31 binds cardiolipin and keeps it stable, which keeps the machinery aligned.
Reduced electron leakage: a well-organised electron transport chain produces ATP efficiently with very little leakage. When the chain is disorganised, electrons leak before they reach the end of the chain — and those leaked electrons combine with oxygen to form superoxide, one of the most damaging free radicals in cellular biology. Research suggests by stabilising cardiolipin, SS-31 reduces electron leakage at the source. This is fundamentally different from how conventional antioxidants work. Vitamin E, vitamin C, and glutathione all neutralise free radicals after they have been produced. Research suggests SS-31 prevents excess production in the first place.
Why mitochondrial targeting matters: mitochondria are notoriously hard to reach pharmacologically. Most compounds that try to support mitochondrial function struggle to get inside in meaningful concentrations. Research suggests SS-31's engineered design solves this — it accumulates inside mitochondria at concentrations far higher than in surrounding tissue. This is part of why SS-31 has been able to advance through human clinical research where many other mitochondrial compounds have stalled.
Storage Guidelines
Store at 2–8°C in a cool, dry place. Protect from light and moisture. Refrigerate once in solution form.
Frequently Asked Questions
Technical Specifications
Compiled by the Southern Pacific Labs research team. Last updated August 2026.
Published References
- Szeto HH. “First-in-class cardiolipin-protective compound as a therapeutic agent to restore mitochondrial bioenergetics.” British journal of pharmacology, 2014. PubMedA foundational review by Hazel Szeto — the researcher who developed SS-31 and led most of the early work characterising the compound. The starting point for understanding how SS-31 works and why cardiolipin protection matters in mitochondrial research.
- Siegel MP, Kruse SE, Percival JM, et al. “Mitochondrial-targeted peptide rapidly improves mitochondrial energetics and skeletal muscle performance in aged mice.” Aging cell, 2013. PubMedA pivotal aging study showing SS-31 improved mitochondrial function and muscle performance in aged research animals — one of the studies that connected SS-31 to longevity research alongside its therapeutic applications in heart and kidney research.
- 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 : JASN, 2013. PubMedThe mechanistic paper demonstrating SS-31's direct interaction with cardiolipin and its effects on mitochondrial energy production after ischaemic injury. Important reading for understanding the molecular mechanism behind the compound's broader effects.
- Dai DF, Hsieh EJ, Chen T, et al. “Global proteomics and pathway analysis of pressure-overload-induced heart failure and its attenuation by mitochondrial-targeted peptides.” Circulation. Heart failure, 2013. PubMedA comprehensive study of how SS-31 affects the broader protein landscape in heart failure research models — useful for understanding why one cardiolipin-binding peptide can have such wide-ranging effects on cardiac function.
Browse all SS-31 research on PubMed →
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