A Szeto-Schiller peptide engineered to selectively concentrate in the inner mitochondrial membrane — the most precisely targeted mitochondrial antioxidant studied in modern aging and energy biology research.
SS-31 (Szeto-Schiller peptide 31) is a synthetic tetrapeptide developed by Hazel Szeto at Weill Cornell Medical College and Peter Schiller at the Clinical Research Institute of Montreal. The "SS" in its name stands for Szeto-Schiller — the two researchers who pioneered the class. It's a cell-permeable peptide with an unusual alternating aromatic-cationic sequence that gives it a unique ability to selectively localize to the inner mitochondrial membrane, specifically binding to cardiolipin — a phospholipid found almost exclusively in that location.
SS-31 advanced into clinical trials under the name Elamipretide (also called MTP-131 or Bendavia) and has been studied in trials for heart failure with preserved ejection fraction, Barth syndrome (a rare mitochondrial disease), and age-related vision loss. It represents one of the most clinically advanced mitochondria-targeted peptides in existence, making it particularly valuable as a research tool for understanding mitochondrial biology in aging and disease contexts.
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SS-31 is arguably the most precision-engineered peptide in the longevity research space — it doesn't just target mitochondria broadly, it homes in on a specific location within the mitochondrial membrane.
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SS-31 enters cells freely and is drawn to the inner mitochondrial membrane by electrostatic interactions with cardiolipin, where it concentrates and stabilizes the membrane architecture. Cardiolipin normally works with cytochrome c (a key protein in the electron transport chain) to facilitate efficient electron transfer during ATP production. When mitochondria are stressed, cardiolipin oxidizes and releases cytochrome c, disrupting energy production and triggering cell death pathways. SS-31 binds to cardiolipin, protecting it from oxidation, keeping cytochrome c in place, and helping maintain efficient electron transport. The result in model systems is improved mitochondrial efficiency, reduced reactive oxygen species generation, and improved cellular energy production under stress conditions.
Imagine a factory floor where all the power cables run. Over time, the cable insulation wears down — connections get loose, sparks fly, and the factory loses efficiency. SS-31 is like an electrician who goes straight to the exact cables that matter most (cardiolipin, in the inner membrane), patches the insulation, and keeps the connections tight. Other antioxidants are like security guards walking the whole building looking for sparks — SS-31 goes directly to the source of the problem. Researchers study it because fixing the wiring directly is a fundamentally different approach than cleaning up sparks after they happen.
Research Disclaimer: The following reflects published clinical and preclinical research and is not medical advice. Consult a licensed healthcare provider before making any health decisions.
SS-31 (Elamipretide/MTP-131/Bendavia) has progressed through phase II human trials for cardiac and skeletal muscle indications, providing published clinical dosing data from formal pharmaceutical development.
Key References: McDonagh TA et al. (2022). SS-31 REVIVED cardiac trial. NEJM. · Gibson CM et al. (2016). PROGRESS-HF. JACC Heart Fail. · Szeto HH (2014). SS-31 preclinical review. Pharm Res.
SS-31 concentrates approximately 1,000-fold in the inner mitochondrial membrane compared to the surrounding cell. This extraordinary selectivity isn't achieved by actively pumping the molecule there — it's entirely driven by the molecule's chemistry interacting with cardiolipin's unique properties. Engineering that level of precision into a four-amino-acid sequence is considered one of the elegant achievements of peptide chemistry.
SS-31 (as Elamipretide) is one of the few peptides in the longevity research space to reach Phase 2 and Phase 3 clinical trials for multiple indications. It has been tested in human subjects with heart failure, making it significantly more clinically validated than most peptides in this research category.
Research in aged mice has shown that SS-31 can partially reverse age-associated declines in mitochondrial function in skeletal muscle — not just protect against further decline but actually improve function in already-aged tissue. This "rejuvenation" rather than "protection" framing has made it particularly interesting to aging biologists.
Every batch of SS-31 with full Certificate of Analysis documentation.