The powerhouse problem: mitochondria make most of a cell’s energy, and their decline is one of the recognized hallmarks of ageing. Three compounds dominate mitochondrial research in Canada right now: MOTS-C, SS-31 and NAD+. They are often bought together, but they work at completely different points in the system. Think of a power plant: one is a signal the plant sends to headquarters, one reinforces the plant’s walls, and one is the fuel carrier. This guide explains each.
Why mitochondria matter in ageing research
In 2013, a landmark review in Cell (López-Otín et al.) listed mitochondrial dysfunction as one of the hallmarks of ageing. As cells age, mitochondria tend to produce energy less efficiently, leak more reactive oxygen species and communicate less effectively with the rest of the cell. Each compound in this guide targets a different part of that picture.
The three compounds at a glance
| MOTS-C | SS-31 | NAD+ | |
|---|---|---|---|
| What it is | 16-aa peptide encoded in mitochondrial DNA | Synthetic tetrapeptide | Dinucleotide coenzyme |
| Where it acts | Signals to the nucleus and muscle (AMPK) | Inner mitochondrial membrane (cardiolipin) | Electron transport, sirtuins, PARPs |
| Power-plant analogy | The message | The walls | The fuel carrier |
| Key paper | Lee et al., Cell Metab 2015 | Szeto, Br J Pharmacol 2014 | Verdin, Science 2015 |
| Human data | Early, observational | Trials in rare mitochondrial diseases | Precursor trials (NMN, NR) |
MOTS-C: the message from the mitochondria
Almost every protein in a cell is encoded in the nucleus. MOTS-C is a rare exception: its 16-amino-acid sequence is hidden inside the mitochondrial 12S rRNA gene. Discovered at the University of Southern California, it is studied as a way mitochondria report on the cell’s metabolic state.
Lee and colleagues (2015, Cell Metabolism) reported that MOTS-C acted on skeletal muscle through the folate cycle and AMPK, improving insulin sensitivity and preventing diet-induced obesity in mice. Reynolds and colleagues (2021, Nature Communications) reported improved physical performance in mice of several ages, and rising MOTS-C levels in human muscle after exercise.
SS-31: the membrane guardian
SS-31 belongs to the Szeto-Schiller peptides, small cell-permeable tetrapeptides (D-Arg-Dmt-Lys-Phe-NH2) that concentrate in mitochondria. Its target is cardiolipin, a lipid found almost exclusively in the inner mitochondrial membrane, where it holds the protein complexes of the electron transport chain in place.
When cardiolipin is oxidized, those complexes work less efficiently and leak more reactive oxygen species. Szeto’s 2014 review in the British Journal of Pharmacology describes how SS-31 binding is associated with preserved membrane structure, better electron transport efficiency and reduced oxidative stress in preclinical models. Under the name elamipretide, it moved into human trials for rare mitochondrial diseases, including primary mitochondrial myopathy and Barth syndrome.
NAD+: the fuel carrier
NAD+ is not a peptide but a coenzyme. It carries electrons from food breakdown into the mitochondrial respiratory chain, and it is consumed by sirtuins and the PARP enzymes that repair DNA. NAD+ levels fall with age in many tissues, driven by rising consumption (especially by the enzyme CD38) and reduced recycling.
Verdin’s 2015 review in Science and Rajman, Chwalek and Sinclair’s 2018 review in Cell Metabolism summarize why restoring NAD+ became one of the most studied strategies in ageing biology. Our NAD+ research guide covers NAD+ vs NMN vs NR in detail.
Why labs study them together
Because each works at a different level, they answer different questions in the same model:
- Is the energy supply limited? NAD+ availability.
- Is the machinery damaged? Cardiolipin and membrane integrity with SS-31.
- Is the communication broken? Mitochondria-to-nucleus signalling with MOTS-C.
Longevity-focused designs sometimes add Epithalon, studied in telomerase models, to look at a separate hallmark of ageing.
Keep perspective: mitochondrial research is moving fast, but almost all of the data on these compounds is preclinical or from small or disease-specific trials. They are research tools, not proven anti-ageing treatments.
Frequently asked questions
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What is the difference between MOTS-C and SS-31?
MOTS-C is a signalling peptide encoded in mitochondrial DNA that acts through AMPK. SS-31 is a synthetic tetrapeptide that binds cardiolipin to protect the inner mitochondrial membrane.
Is NAD+ a peptide?
No. NAD+ is a dinucleotide coenzyme. It is studied alongside mitochondrial peptides because it fuels the same energy system.
What is SS-31 also called?
Elamipretide, its clinical name. It has also been known as Bendavia and MTP-131.
Where is MOTS-C encoded?
In the mitochondrial 12S rRNA gene, which makes it one of the few known mitochondrial-derived peptides.
Related reading
- What is MOTS-c?
- SS-31 (elamipretide): FDA approval
- MOTS-c side effects
- Epitalon side effects: why none reported is not safe
- NAD+ injection side effects
- NAD+ research guide
- Research peptides in Canada: full category map
- How to store peptides
Selected research references
- Lee C, Zeng J, Drew BG, et al. The mitochondrial-derived peptide MOTS-c promotes metabolic homeostasis and reduces obesity and insulin resistance. Cell Metab. 2015;21(3):443–454. PubMed
- Reynolds JC, et al. MOTS-c is an exercise-induced mitochondrial-encoded regulator of age-dependent physical decline and muscle homeostasis. Nat Commun. 2021;12:470. PMC
- Szeto HH. First-in-class cardiolipin-protective compound as a therapeutic agent to restore mitochondrial bioenergetics. Br J Pharmacol. 2014;171(8):2029–2050. PubMed
- Verdin E. NAD+ in aging, metabolism, and neurodegeneration. Science. 2015;350(6265):1208–1213. PubMed
- López-Otín C, Blasco MA, Partridge L, Serrano M, Kroemer G. The hallmarks of aging. Cell. 2013;153(6):1194–1217. PubMed
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