MOTS-c vs SS-31
Both are studied as mitochondrial-support peptides, and both are increasingly researched together as a “mechanism-paired” stack — but they work through entirely different pathways, and are at very different points in their clinical development.
At a Glance
| MOTS-c | SS-31 | |
|---|---|---|
| Category | Longevity & Cellular Health | Longevity & Cellular Health |
| Molecular class | 16-amino-acid peptide encoded within mitochondrial DNA | Synthetic tetrapeptide (4 amino acids) |
| Origin | Discovered 2015, USC (Lee et al.) | Developed early 2000s, Szeto & Schiller |
| Primary mechanism | Activates AMPK / PGC-1α signaling | Binds cardiolipin at the inner mitochondrial membrane |
| Primary research focus | Metabolic regulation, insulin sensitivity, exercise physiology | Mitochondrial membrane protection, oxidative stress |
| Clinical trial stage | Early — Phase 2a trial ongoing, no results posted yet | Advanced — FDA accelerated approval granted for one specific indication |
| Regulatory status | Not approved; under FDA review for the 503A Bulks List | Approved (as FORZINITY/elamipretide) for Barth syndrome only |
How They Differ
MOTS-c activates AMPK (AMP-activated protein kinase) and the PGC-1α pathway — the same signaling route that aerobic exercise triggers in muscle tissue. That's the basis for its research role in metabolic regulation, glucose uptake, and insulin sensitivity, and why it's studied as a mitochondrial-nuclear communication signal rather than a purely structural compound. See its full discovery history.
SS-31 works completely differently: it's a synthetic, cell-penetrating tetrapeptide that concentrates directly at the inner mitochondrial membrane and binds cardiolipin, a phospholipid essential to how the electron transport chain organizes itself. By protecting cardiolipin from oxidative damage, SS-31 is studied for its ability to preserve mitochondrial structure and function under stress, rather than for signaling effects. See its full discovery history.
Clinical Trial Data
MOTS-c: An earlier Phase 1a/1b trial tested CB4211, a novel analog of MOTS-c developed by CohBar (a related but distinct molecule, not MOTS-c itself) — it met its primary endpoint, well-tolerated with no serious adverse events, but was not advanced further due to the sponsoring company's financial and operational difficulties, not a failure of efficacy. Separately, a Phase 2a trial of MOTS-c itself is currently underway ("MOTS-MET," NCT07505745), a randomized, double-blind, placebo-controlled study in 120 adults with prediabetes and overweight or obesity, measuring insulin sensitivity via oral glucose tolerance test; results have not yet been posted.
SS-31: The TAZPOWER trial studied SS-31 (as elamipretide) in 12 genetically-confirmed Barth syndrome patients, across a 28-week randomized, double-blind, placebo-controlled phase followed by a 168-week open-label extension. The blinded 28-week phase did not reach statistical significance against placebo on its primary endpoints (6-Minute Walk Test and fatigue score); the positive results came from the open-label extension, where knee extensor muscle strength improved more than 45% and 6-Minute Walk Test distance improved by 96.1 meters at week 168 versus the extension's own baseline (p=.003), also outperforming an untreated natural-history control group. The FDA's accelerated approval of FORZINITY (elamipretide) in September 2025 was based on this muscle-strength and open-label data, specifically for Barth syndrome — the first FDA-approved mitochondria-targeted therapeutic. Separately, the MMPOWER trial program tested SS-31 in primary mitochondrial myopathy and produced mixed, inconclusive results, underlining that its approval is specific to Barth syndrome rather than mitochondrial dysfunction broadly.
MOTS-c vs SS-31 questions
Has either MOTS-c or SS-31 been approved by the FDA?
SS-31, under the brand name elamipretide (marketed as FORZINITY), received FDA accelerated approval specifically for Barth syndrome, a rare genetic mitochondrial disorder, based on the TAZPOWER trial. That approval covers one specific rare-disease indication — it is not a general approval for anti-aging, longevity, or wellness use. MOTS-c has not been approved for any use; a Phase 2a trial in prediabetes and obesity is currently underway, and an FDA advisory committee has recommended it for inclusion on the 503A Bulks List, though a final decision is still pending.
Does this comparison mean MOTS-c and SS-31 are approved for a particular use?
No. This page compares MOTS-c and SS-31 for educational and research context only. Both are sold strictly for laboratory research use and are not evaluated or approved for human or animal use, with the narrow exception noted above of SS-31's specific Barth syndrome drug approval under a different formulation and brand name.
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