SS-31

SS-31 (also called elamipretide, Bendavia, MTP-131) is a mitochondrial-targeted tetrapeptide developed by Hazel Szeto and Peter Schiller. It selectively binds cardiolipin on the inner mitochondrial membrane to stabilize cristae structure and preserve electron-transport-chain coupling under stress.

SS-31 partitions into the inner mitochondrial membrane and binds cardiolipin — the unique phospholipid that anchors respiratory-chain supercomplexes. By stabilizing cardiolipin-protein interactions, SS-31 preserves OXPHOS efficiency, reduces electron leak (ROS generation), and protects against ischemia-reperfusion injury.

No. Stealth BioTherapeutics has submitted regulatory packages for elamipretide in Barth syndrome and dry age-related macular degeneration; full FDA approval has not been granted as of 2026-05. Research-grade SS-31 is supplied for laboratory use only.

Both are mitochondrial-relevant peptides but with different mechanisms. SS-31 is a synthetic 4-aa peptide that binds cardiolipin to preserve membrane structure. MOTS-c is an endogenous 16-aa peptide encoded by mitochondrial DNA that activates AMPK and modulates nuclear gene expression. They target different aspects of mitochondrial biology.

Not currently listed on the WADA Prohibited List as of 2026.

Approximately 3 hours plasma in humans, sufficient for once-daily subcutaneous dosing in the Stealth clinical program.

Primary mitochondrial myopathy, Barth syndrome, dry age-related macular degeneration (geographic atrophy), heart failure with preserved ejection fraction, and ischemia-reperfusion injury in cardiac and renal contexts.

Clinical trials report mostly mild injection-site reactions and occasional headache. The peptide has been well-tolerated across multiple Phase 2/3 trials.