SS-31 (Elamipretide) — the mitochondria-targeted tetrapeptide

SS-31, also known by its development-stage name Elamipretide, is a synthetic tetrapeptide that selectively binds cardiolipin — the phospholipid concentrated on the inner mitochondrial membrane where the electron-transport chain operates. The cardiolipin-binding mechanism distinguishes SS-31 from most antioxidant supplements, which act in cytosol or extracellular fluid rather than at the membrane site where reactive oxygen species are generated. The molecule has been studied in research models of primary mitochondrial dysfunction, age-related retinal-disease research, and cardiolipin-deficiency genetic-disease research.

Structure and chemistry

SS-31 is a tetrapeptide with the sequence D-Arg-2′,6′-dimethyltyrosine-Lys-Phe-NH₂. Two of the four residues are non-standard: the N-terminal arginine is the D-stereoisomer (rather than the natural L-form), and the second residue is 2′,6′-dimethyltyrosine — a tyrosine modified with two methyl groups at the 2′ and 6′ positions of the aromatic ring. The C-terminus is an amide rather than a free carboxyl. These modifications collectively give SS-31 its characteristic properties: cell-membrane permeability without an active transport mechanism, resistance to peptidase cleavage that would otherwise degrade a four-residue peptide within minutes, and a net 3+ charge at physiological pH.

Molecular weight is approximately 640 Da. The compound is synthesised by solid-phase peptide synthesis. The lyophilised form is a white powder; the reconstituted solution is colourless and clear.

The cardiolipin-binding mechanism

Cardiolipin is a distinctive phospholipid found almost exclusively on the inner mitochondrial membrane, where it makes up 15-20% of the lipid content. Its structure — two phosphate groups joined to four fatty-acid chains — gives it a strong negative charge and a conical shape that helps the inner membrane fold into the cristae structures where electron-transport-chain complexes sit. Cardiolipin is also a structural anchor for several electron-transport-chain proteins and is required for the assembly of respiratory supercomplexes.

SS-31's net 3+ charge drives electrostatic attraction to cardiolipin's phosphate groups. Once at the membrane, the peptide's aromatic residues (dimethyltyrosine and phenylalanine) insert into the lipid bilayer, anchoring it at the membrane-water interface. The bound peptide does three things in the published mechanism literature:

• Stabilises cristae structure. SS-31 binding preserves the tight curvature of mitochondrial cristae under conditions (ischaemia, oxidative stress, ageing) that would otherwise cause cristae unfolding and matrix swelling.
• Preserves electron-transport-chain supercomplex assembly. Complexes I, III, and IV organise into respiratory supercomplexes anchored on cardiolipin scaffolds. SS-31 binding stabilises these assemblies under stress, maintaining electron-flow efficiency.
• Reduces reactive-oxygen-species generation. A direct downstream consequence — when electrons flow through an organised supercomplex they leak less to molecular oxygen, reducing superoxide and hydrogen-peroxide production at the source rather than scavenging downstream.

Honest take: most antioxidant research is downstream — quench ROS after they are produced. SS-31 is upstream — reduce ROS production at the membrane source by preserving the structural organisation that makes electron transport efficient. That mechanistic distinction is the reason the molecule continues to attract research interest despite a difficult clinical-trial history.

Clinical-trial program

SS-31, under the development name Elamipretide, has been the subject of an extensive clinical-trial program across three research indications. The honest summary across all three is that the randomised co-primary endpoints have been missed; secondary-endpoint signals have informed the ongoing research framework. The three indications:

• Primary mitochondrial myopathy. Phase-2 and phase-3 randomised trials in patients with genetically-confirmed primary mitochondrial myopathy. Phase-2 results showed improvement on the 6-minute walk test and patient-reported fatigue measures; the phase-3 trial did not meet its primary endpoint, with secondary endpoints suggesting benefit in pre-specified subgroups (Karaa et al., Neurology 2023).
• Geographic-atrophy dry AMD. A phase-2 randomised trial in geographic-atrophy-stage dry AMD did NOT meet its co-primary endpoints (mean change in low-luminance best-corrected visual acuity and mean change in geographic-atrophy area). Secondary signals reported were a 43% reduction in macular ellipsoid-zone attenuation rate and a higher proportion of patients achieving ≥10-letter LL-BCVA gain vs placebo (Ehlers et al., Ophthalmology Science 2024).
• Barth syndrome. A rare-disease genetic indication with cardiolipin-deficiency pathology. The randomised-phase trial in this indication did NOT meet its primary endpoints; the open-label extension reported significant 6-minute-walk-test improvement and BTHS-SA scale improvement at 36 weeks (Reid Thompson et al., Genetics in Medicine 2021).

Regulatory history: FDA submitted via expanded-access protocols and rare-disease pathways. As of mid-2026, SS-31/Elamipretide does not have a routine approved clinical indication in the US or in the UAE. The research-grade material continues to be available through laboratory supply chains for non-clinical investigation.

Current research-use protocols

Published research protocols use SS-31 across three administration routes:

• Subcutaneous research protocols. The most-common route in animal-model studies. Doses range 1-10 mg/kg/day in rodent work, scaling down for larger species. Plasma half-life is ~2 hours; tissue uptake (especially heart, kidney, brain) is much longer.
• Intravenous research protocols. Used in acute ischaemia-reperfusion models where rapid mitochondrial protection is the endpoint. Single bolus or short infusion.
• Topical ophthalmic. Eye-drop formulations in the AMD research program. Concentrations range 1-5% solution, dosed daily.

UAE research-supply landscape

SS-31 is supplied in the UAE as lyophilised research-grade powder. Wellness Labs catalogues SS-31 in 10 mg and 50 mg vials, alongside the Khavinson bioregulator and Longevity-group compounds that share a similar mechanism-of-aging research framing. Quality verification follows the same framework as the rest of the catalogue: third-party RP-HPLC purity ≥98%, mass-spectrometry parent-ion confirmation at ~640 Da, batch-traceable Certificate of Analysis.

Reconstitution math

Common reconstitution choices for the 10 mg and 50 mg vial sizes:

• 10 mg / 2 mL bacteriostatic water = 5 mg/mL = 5000 μg/mL. A 500 μg dose is 0.1 mL = 10 units on a U-100 insulin syringe; a 1 mg dose is 0.2 mL = 20 units.
• 50 mg / 5 mL bacteriostatic water = 10 mg/mL = 10,000 μg/mL. A 1 mg dose is 0.1 mL = 10 units; a 2 mg dose is 0.2 mL = 20 units.
• 50 mg / 2 mL bacteriostatic water = 25 mg/mL. Use only when small-volume draws of high-concentration solution are protocol-required.

The interactive reconstitution calculator handles the dose-volume math for non-standard vial-volume combinations.

Open research questions

• Whether the mitochondrial-protection effect translates from animal models and rare-disease populations to broader age-related disease research (cardiac, neurological).
• The optimal chronic-administration protocol for mitochondrial-dysfunction research — single daily dose vs split dosing, with the >2-hour plasma half-life vs much longer tissue residence as the key variable.
• Whether tissue-specific cardiolipin profiles (different fatty-acid compositions in different tissues) explain the variable trial outcomes across indications.

Further reading

• MOTS-C — the mitochondrial-derived 16-residue peptide. Adjacent mitochondrial-research compound.
• NAD+ research overview. Cellular-energy axis adjacent to the mitochondrial-membrane research SS-31 addresses.
• Glutathione research overview. The other major antioxidant-research molecule in the UAE wellness category.
• Bacteriostatic water — the verification framework. The diluent for SS-31 reconstitution.
• Reconstitution calculator.

Last reviewed 2 June 2026. Editorial inbox: info@uaewellnesslab.com.