Three Longevity Peptides Under Study: MOTS-c, Epithalon and SS-31

Longevity science has moved from “live longer” to a sharper question: which specific processes break down as cells age, and can they be supported? Three peptides keep coming up in that conversation. Two of them act on mitochondria, the structures that produce most of a cell’s energy. The third is linked to telomeres, the protective caps on chromosomes. Their evidence bases are very different in size and quality, so it is worth considering them one at a time. Longevity Partner Content.

MOTS-C: a signal written in the mitochondria

Most proteins are encoded in the DNA of the cell nucleus. MOTS-c is unusual: it is a 16-amino-acid peptide encoded inside mitochondrial DNA, in the gene for a mitochondrial ribosomal RNA. Its discovery, published in Cell Metabolism in 2015, helped establish that mitochondria don’t just make energy; they also send signals to the rest of the body.

In that first study, MOTS-c activated AMPK, a central energy sensor that also responds to exercise, and protected mice from diet-induced obesity and insulin resistance. A 2021 follow-up in Nature Communications found that MOTS-C levels rise with exercise in humans, and that treating older mice improved their physical capacity. Circulating levels appear to decline with age.

Evidence level: strong mechanistic and animal data from multiple groups; human interventional trials are still early. Research-grade MOTS-c peptide is now a common tool in metabolic and exercise-biology labs.

Epithalon: the telomere hypothesis

Epithalon (also spelled Epitalon) is a four-amino-acid peptide, alanine-glutamate-aspartate-glycine, developed by Vladimir Khavinson’s group in St. Petersburg as a synthetic version of epithalamin, an extract of the pineal gland. Its claim to fame is a 2003 report that it switched on telomerase, the enzyme that rebuilds telomeres, in cultured human cells and lengthened their telomeres.

The same group has published animal studies reporting effects on lifespan, circadian rhythm and melatonin production in older animals.

Evidence level: intriguing but narrow. Most of the published work comes from one research group, and independent replication is limited. Research-grade epithalon lets other labs test these findings, which is exactly what the field needs.

SS-31: a mitochondria-targeted peptide that made it to approval

SS-31, also known as elamipretide, is a small four-amino-acid peptide designed to reach the inner membrane of mitochondria. There it binds cardiolipin, a lipid that holds the energy-producing machinery together.

When cardiolipin is damaged, mitochondria leak electrons and produce less energy; SS-31 is designed to stabilise it. SS-31 has the most clinical history of the three. In September 2025, the FDA granted accelerated approval to elamipretide, under the brand name Forzinity, for Barth syndrome, a rare inherited mitochondrial disease. It is the first mitochondria-targeted therapy to receive FDA approval. In aging research, a 2019 study found that SS-31 reversed age-related redox stress and improved exercise tolerance in old mice.

Evidence level: the strongest of the three, with human trial data in mitochondrial disease. Its role in normal aging remains a research question. Laboratories studying mitochondrial aging use research-grade SS-31 peptide.

How the three compare 

The honest bottom line

All three peptides point to real hallmarks of aging: declining mitochondrial function and shortened telomeres.
Only one has crossed into approved medicine, and that was for a rare disease rather than aging itself. The lifestyle factors with the best human evidence for healthy aging (regular exercise, strength training, sleep, and a mostly whole-food diet) also happen to work on the same pathways. Peptides are where the science is heading; the habits are where the proof already is.

References

Lee C, et al. The mitochondrial-derived peptide MOTS-c promotes metabolic homeostasis and reduces obesity and insulin resistance. Cell Metabolism. 2015;21(3):443-454.

Reynolds JC, et al. MOTS-c is an exercise-induced mitochondrial-encoded regulator of age-dependent physical decline and muscle homeostasis. Nature Communications. 2021;12(1):470.

Khavinson VK, Bondarev IE, Butyugov AA. Epithalon peptide induces telomerase activity and telomere elongation in human somatic cells. Bulletin of Experimental Biology and Medicine. 2003;135(6):590-592.

Campbell MD, 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.

US FDA. FDA grants accelerated approval to first treatment for Barth syndrome. September 2025.

This article is for educational purposes only. Research peptides referenced are supplied for laboratory research and are not for human use.