Ss 31: Chemical Properties
17 PubMed CitationsExpert ReviewedGMP CertifiedLast Reviewed: April 2026
Chemical Properties
| Molecular Formula | C₃₂H₄₉N₉O₅ (free base) |
| Molecular Weight | 639.8 g/mol (free base); 749.2 g/mol (HCl salt) |
| CAS Number | 736992-21-5 (free base); 72244098-12-0 (HCl salt) |
| PubChem CID | 11764719 |
| Sequence (3-Letter) | D-Arg-Dmt-Lys-Phe-NH₂ (Dmt = 2',6'-dimethyltyrosine) |
| InChI Key | SFVLTCAESLKEHH-WKAQUBQDSA-N |
| Structure | Linear tetrapeptide; D-amino acid (D-Arg), non-natural amino acid (Dmt), C-terminal amide |
| Net Charge | 3+ at physiological pH |
| Alternating Motif | Aromatic-cationic (Dmt/Phe = aromatic; D-Arg/Lys = cationic) |
| Synonyms | Elamipretide, Forzinity™, MTP-131, Bendavia, RX-31 |
| Bioavailability (SC) | ~92–100% in humans |
| Half-Life | ~3–4 hours (SC, humans); ~1–2 hours (rodents) |
Identifiers
| Purity Standard | ≥98% by RP-HPLC |
| Identity Confirmation | MS molecular mass ~639.8 Da; LC-MS/MS for plasma quantification (LLOQ 0.1 ng/mL) |
| Counter-Ion | Acetate or HCl (HCl = commercial Forzinity; acetate = clinical development) |
| Detection Methods | RP-HPLC, LC-MS/MS, ELISA |
| Metabolism | C-terminal proteolysis → M1 (tripeptide) + M2 (dipeptide); NOT CYP450 substrate |
| Excretion | ~100% urinary (parent + metabolites) |
References
- 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.
- 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.
- FDA Press Announcement. FDA approves first treatment for rare genetic heart muscle disease. September 19, 2025.
- Campbell MD, Duan J, Bhatt SK, et al. Improving mitochondrial function with SS-31 reverses age-related redox stress and improves exercise tolerance in aged mice. Free Radical Biology and Medicine. 2019;134:268-281.
- Sabbah HN. Elamipretide (SS-31) improves mitochondrial function and prevents cellular apoptosis in heart failure and its comorbidities. Expert Opinion on Investigational Drugs. 2021;30(12):1227-1244.
- Sabbah HN, Gupta RC, Kohli S, et al. Chronic therapy with elamipretide (MTP-131), a novel mitochondria-targeting peptide, improves left ventricular and mitochondrial function in dogs with advanced heart failure. Circulation: Heart Failure. 2016;9(2):e002206.
- Sabbah HN, Klewer SE, O'Brien T, et al. Elamipretide and NF-κB/NLRP3 inflammasome inhibition. Biomedicine & Pharmacotherapy. 2025;183:118056.
- Zhao W, Xu Z, Cao J, et al. Elamipretide (SS-31) improves mitochondrial dysfunction, synaptic integrity, and cognition in an Alzheimer's disease model. Scientific Reports. 2019;9(1):13137.
- 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, a genetic disorder of mitochondrial cardiolipin metabolism. Genetics in Medicine. 2024;101138.
- Karaa A, Haas R, Goldstein A, et al. Randomized dose-escalation trial of elamipretide in adults with primary mitochondrial myopathy. Neurology. 2018;90(14):e1212-e1221.
- Birk AV, Chao WM, Bracken C, et al. Targeting mitochondrial cardiolipin and the cytochrome c/cardiolipin complex to promote electron transport and optimize mitochondrial ATP synthesis. British Journal of Pharmacology. 2014;171(8):2017-2028.
- Cousins D, Brar P, McFarlane T, et al. Phase 2 study of elamipretide (SS-31) in age-related macular degeneration (ReCLAIM-2). Ophthalmology Retina. 2023.
- Saad A, Herrmann SMS, Eirin A, et al. Phase 2a clinical trial of mitochondrial protection (elamipretide) during stent revascularization in patients with atherosclerotic renal artery stenosis. Circulation: Cardiovascular Interventions. 2017;10(9):e005130.
- 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;6(5):1067-1076.
- Chiao YA, Rabinovitch PS, Bhatt SK, et al. Late-life restoration of mitochondrial function reverses cardiac dysfunction in old mice. eLife. 2020;9:e55513.
- Lincoff AM, Bhatt DL, Fischell T, et al. Elamipretide and post–cardiac arrest outcomes (EMBRACE STEMI). American Heart Journal. 2014;168(2):222-228.
- FDA Integrated Review NDA 215244 — Forzinity (elamipretide) Approval Package. 2025.
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