What Is SS-31? The First FDA-Approved Mitochondrial Peptide

SS-31, also known as Elamipretide or Bendavia, is a synthetic mitochondria-targeted tetrapeptide with the sequence D-Arg-Dmt-Lys-Phe-NH2. Developed by Hazel Szeto and Peter Bhatt at Weill Cornell Medical College, the 'SS' in its name stands for 'Szeto-Schiller' — after the researchers who designed its unique mitochondrial-targeting motif.

What makes SS-31 truly groundbreaking is its mechanism: it is the first compound to selectively bind cardiolipin on the inner mitochondrial membrane. This direct interaction with the mitochondrial hardware — rather than working through indirect signalling pathways — makes it fundamentally different from all other mitochondrial compounds.

In 2023, SS-31 (as Elamipretide/Forzinity) received FDA approval for Barth syndrome, making it the first and only drug specifically approved for treating mitochondrial dysfunction.

SS-31's mechanism of action centers on cardiolipin — a phospholipid found exclusively on the inner mitochondrial membrane.

Cardiolipin's Role: Cardiolipin is essential for maintaining cristae architecture (the folds of the inner membrane where energy production occurs) and for anchoring the electron transport chain (ETC) complexes. Without properly functioning cardiolipin, mitochondria cannot produce energy efficiently.

The Aging Problem: With aging, cardiolipin undergoes peroxidation — oxidative damage that disrupts its structure. This causes cristae to flatten, ETC complexes to dissociate, and energy production to decline. Critically, cytochrome c — normally an electron carrier — is converted to a peroxidase that further damages cardiolipin, creating a vicious cycle.

How SS-31 Breaks the Cycle: SS-31 binds cardiolipin with high selectivity, preventing its peroxidation and restoring normal cristae architecture. It converts cytochrome c back from its damaging peroxidase form to its normal electron-carrying function. The result: more ATP production, less ROS generation, and restoration of youthful mitochondrial function.

Concentration: Due to its Szeto-Schiller targeting sequence, SS-31 concentrates more than 1,000-fold within mitochondria compared to surrounding cytoplasm.

SS-31 has been investigated in multiple clinical trials across several indications:

TAZPOWER Trial (Barth Syndrome): This pivotal Phase 3 trial demonstrated significant improvement in cardiac stroke volume and 6-minute walk test performance in patients with Barth syndrome — a rare mitochondrial cardiomyopathy caused by cardiolipin deficiency. Results led to FDA approval.

MMPOWER Trials (Primary Mitochondrial Myopathy): Phase 2/3 trials investigating SS-31 for primary mitochondrial myopathy showed trends toward improvement in 6-minute walk test distance.

ReCLAIM Trials (Age-Related Macular Degeneration): Phase 2 trials showed improvement in low-luminance visual acuity in patients with dry AMD, supporting the mitochondrial theory of age-related macular degeneration.

Heart Failure Studies: Early-phase trials have investigated SS-31 for heart failure with reduced ejection fraction, with results showing improvement in left ventricular volumes.

Renal Ischemia Studies: SS-31 has been studied for protecting against mitochondrial damage during kidney ischemia-reperfusion injury.

Beyond its clinical applications, SS-31 has generated extraordinary interest in the aging research community:

Lifespan Extension: SS-31 treatment extended median lifespan by 14% in aged mice, with improvements in cardiac function and exercise tolerance (Chiao et al., 2018).

Rapid Muscle Rejuvenation: Perhaps the most striking finding — a single hour of SS-31 treatment restored mitochondrial energetics in aged skeletal muscle to near-youthful levels, reversing decades of mitochondrial decline (Siegel et al., 2019).

Cardiac Rejuvenation: Age-related diastolic dysfunction — one of the most common cardiac changes with aging — was reversed by SS-31 treatment in aged mice.

Why This Matters: Mitochondrial dysfunction is now recognized as one of the nine hallmarks of aging. SS-31's ability to directly reverse this hallmark, combined with its FDA approval and safety data, makes it arguably the most clinically validated anti-aging compound currently available for research.

- Molecular Formula: C32H49N9O5 - Molecular Weight: 639.8 g/mol - Sequence: D-Arg-Dmt-Lys-Phe-NH2 - CAS Number: 736992-21-5 - Classification: Synthetic mitochondria-targeted tetrapeptide - Half-life: 3-4 hours (plasma); prolonged mitochondrial retention - Target: Cardiolipin on the inner mitochondrial membrane - FDA Status: Approved (as Forzinity/Elamipretide) for Barth syndrome

SS-31's compact four-amino-acid structure includes the unnatural amino acid 2',6'-dimethyltyrosine (Dmt), which is critical for its antioxidant activity and mitochondrial targeting.

Peptides Pharma offers SS-31 as a high-purity lyophilized vial for research applications:

- Dosages Available: 20mg and 50mg - Purity: >99% (HPLC verified) - Form: Lyophilized powder - Storage: 2-8°C refrigerated - Shelf Life: 24 months - Manufacturing: GMP-certified facility - Documentation: Full Certificate of Analysis with HPLC and mass spectrometry data

Reconstitute with bacteriostatic water for subcutaneous administration. Each vial is sealed under sterile conditions with 0.22μm filtration.