What it is
MOTS-c is a 16-amino-acid peptide whose name stands for Mitochondrial Open reading frame of the Twelve-S rRNA type-c. It was first described in 2015 by Lee and colleagues at the University of Southern California, UCLA and the National Institute on Aging, who reported that the peptide is encoded by a short open reading frame sitting inside the mitochondrial 12S rRNA gene, part of mitochondrial DNA rather than the nuclear genome (Lee et al., Cell Metabolism, 2015). That placement mirrors an earlier discovery, humanin, a peptide encoded within the neighboring mitochondrial 16S rRNA gene; MOTS-c was found by extending the same search logic to the 12S rRNA region. Reviews since have grouped MOTS-c with humanin and a family of related peptides called SHLP1 through SHLP6 under the umbrella term “mitochondrial-derived peptides.”
A wild-type sequence for the peptide, Met-Arg-Trp-Gln-Glu-Met-Gly-Tyr-Ile-Phe-Tyr-Pro-Arg-Lys-Leu-Arg, has been reported in later work describing an engineered analogue built from that same backbone (Zhang et al., Redox Biology, 2026). That paper was not the original discovery report, so the sequence given here should be understood as carried forward from a secondary source rather than read directly off the 2015 paper’s own figures.
No approved MOTS-c drug exists anywhere, for any indication, in any species. There is no FDA label, no EMA label and no other regulatory monograph. As of this compilation, MOTS-c had entered registered human clinical development for the first time, more than a decade after its discovery, through a single Phase 2a trial that had not yet reported results.
How it works, and where the animal-to-human line falls
The 2015 discovery paper proposed a specific biochemical mechanism: MOTS-c was reported to inhibit the folate cycle and the purine synthesis pathway tethered to it, an effect that led to accumulation of an AMP-like intermediate called AICAR and, downstream of that, activation of AMPK, a central cellular energy sensor (Lee et al., 2015). A same-issue commentary described this plainly as MOTS-c promoting “biosynthesis of an endogenous AMP analog, AICAR,” with AICAR itself already known as a compound that activates AMPK when given directly (Zarse and Ristow, Cell Metabolism, 2015). This mechanism was demonstrated in HEK293 and HeLa human cell lines and in mouse tissue, not in isolated human tissue or in any human trial, and the 2015 paper identified skeletal muscle as the peptide’s primary apparent target organ based on that same preclinical work.
The downstream effects reported for this mechanism are, without exception in the literature reviewed for this entry, animal findings. In mice, MOTS-c treatment was reported to prevent age-related and high-fat-diet-induced insulin resistance, and to prevent diet-induced obesity, relative to untreated control mice (Lee et al., 2015). Later mouse and cell-culture work built out a broader circuit around that finding: a reciprocal relationship between MOTS-c and PGC-1alpha, in which pharmacologic AMPK inhibition or PGC-1alpha knockdown lowered MOTS-c expression in mouse muscle tissue and C2C12 muscle cell culture, while treadmill training raised MOTS-c, PGC-1alpha, GLUT4 and phosphorylated AMPK together in high-fat-diet mice (Yang et al., Biochimica et Biophysica Acta, 2021). A separate group reported that MOTS-c and adiponectin regulate one another through an adiponectin-APPL1-SIRT1-PGC-1alpha chain, again in mice and C2C12 cells, with adiponectin-knockout mice and high-fat-diet mice both showing reduced plasma and muscle MOTS-c (Guo et al., Diabetologia, 2020). A third group reported that MOTS-c prevented palmitic-acid-induced atrophy in cultured mouse myotubes and lowered plasma myostatin in diet-induced-obese mice, acting through a signaling chain from CK2 through PTEN, mTORC2, AKT and FOXO1 (Kumagai et al., American Journal of Physiology, 2021).
A separate strand of mouse and cell-culture work has examined MOTS-c as a stress-response signal rather than a metabolic one. In rat lung ischemia-reperfusion injury and cultured endothelial cells, oxidative stress was reported to trigger a chain of events ending in MOTS-c moving into the cell nucleus, where it bound antioxidant-response-element promoters and reduced oxidative lung damage in the treated rats (Li et al., Redox Biology, 2025). A follow-up paper engineered a modified version of the peptide specifically because native MOTS-c was described, in the researchers’ own words, as having “poor membrane permeability due to its high polarity” — a stated pharmacokinetic limitation for the parent molecule, tested only in mouse lung cells and mice with radiation-induced lung injury, not in humans (Zhang et al., 2026).
A dedicated review of this literature summarized the human-mechanism picture bluntly: no confirmatory human cell or tissue study of any of these pathways — folate-cycle inhibition, the PGC-1alpha loop, the adiponectin axis, the anti-atrophy signaling, or the nuclear stress-response pathway — was located in the sources reviewed for this entry. Every mechanistic claim traces to mouse tissue or to cell lines such as HEK293, HeLa and C2C12, not to human subjects.
Research evidence
One registered human trial, and it has not reported
A search of ClinicalTrials.gov located exactly one interventional trial in which MOTS-c itself is administered to human participants: NCT07505745, registered under the name “MOTS-MET,” a Phase 2a, randomized, double-blind, placebo-controlled study sponsored by Hudson Biotech. The trial was designed to enroll 120 adults aged 18 to 65 with prediabetes and overweight or obesity, randomized 1:1 to MOTS-c or placebo by subcutaneous injection over a 12-week treatment period, with a further 4-week safety follow-up. Its stated co-primary endpoints are the change from baseline in insulin sensitivity, measured by the Matsuda Index derived from an oral glucose tolerance test, and the incidence of treatment-emergent adverse events through 16 weeks. Secondary endpoints include changes in HbA1c and fasting and post-load glucose, plus testing for anti-drug antibodies. The trial’s status, as retrieved for this entry, was recruiting, at a single site in Shenzhen, China, with a stated study start date of February 2026 and a stated study completion date of May 2028. No results had been posted.
This means there is, at the time of this writing, no completed human interventional study of MOTS-c of any kind, for any purpose. Every claim of a demonstrated effect in a human being — metabolic, exercise-related, anti-aging or otherwise — rests on something other than a finished dosing trial, because no finished dosing trial exists yet.
What exists instead: associations with circulating levels, not treatment outcomes
In the absence of an interventional trial, the human evidence base for MOTS-c consists of studies measuring the peptide’s naturally occurring, or “circulating,” levels in blood or muscle and looking for associations with disease states. These are correlational studies; none of them administered MOTS-c to anyone. A systematic review and meta-analysis pooling six case-control studies and one cross-sectional study, 602 participants in total, found that plasma MOTS-c was lower overall in a combined obesity-and-diabetes group compared with controls, but a subgroup analysis reversed that direction by condition: MOTS-c was significantly higher than controls in people with obesity, and significantly lower than controls in people with type 2 diabetes (Zhou et al., Diabetology and Metabolic Syndrome, 2024). The review’s own authors described monitoring MOTS-c as having “prospects” as a future screening tool, framing it as a hypothesis for further study rather than an established diagnostic or therapeutic fact. That split finding is worth sitting with, because it runs against any simple story in which low MOTS-c is bad and restoring it is the fix; in this pooled dataset, two different metabolic diseases moved circulating MOTS-c in opposite directions.
Other correlational findings, all observational and all in specific patient populations, include: lower serum and muscle MOTS-c in women with polycystic ovary syndrome compared with matched controls, with an inverse correlation to testosterone (Kutuk et al., Scientific Reports, 2026); higher serum MOTS-c in diabetic heart-failure patients taking an SGLT2 inhibitor compared with those not taking one, reported by the study authors as hypothesis-generating rather than as evidence that MOTS-c itself was administered or caused the difference (Asil et al., European Journal of Pharmacology, 2024); and a rise in serum MOTS-c within 24 hours of cardiopulmonary bypass surgery that outperformed traditional markers at predicting subsequent lung injury in one surgical cohort, a prognostic biomarker association, not a treatment finding (Li et al., 2025).
The “exercise mimetic” framing often attached to MOTS-c has been tested directly in humans, and the result is weaker than the mouse literature suggests. In a randomized trial of exercise modality (not of MOTS-c dosing) with thirty healthy adults split across endurance exercise, resistance exercise and a control arm, circulating humanin rose significantly after endurance exercise, while MOTS-c showed only “a trend to increase” that did not reach statistical significance; at rest, plasma MOTS-c was not correlated with fitness markers such as VO2 or muscle mitochondrial DNA copy number (von Walden et al., Journal of Applied Physiology, 2021). A dedicated review of this area concluded that evidence for exercise producing chronic changes in MOTS-c is “conflicting,” explicitly separating the largely consistent mouse findings — improved exercise capacity, weight loss and insulin sensitivity in young and aged mice given MOTS-c — from unresolved human data, and describing MOTS-c as a candidate “exercise-sensitive myokine,” a hypothesis rather than an established human fact (Woodhead and Merry, Biochimica et Biophysica Acta, 2021). A more recent study comparing adults with cerebral palsy to typically developing controls found no meaningful difference in resting MOTS-c between groups and no significant between-group change after a bout of exercise (Horwath et al., Experimental Physiology, 2026).
One further caveat applies to nearly all of the circulating-level studies above. A mass-spectrometry method built specifically to detect MOTS-c in doping-control samples found that endogenous MOTS-c levels measured by a commonly used immunoassay could not be confirmed by the more specific liquid-chromatography method, documenting an assay-discordance problem between ELISA-based measurement and mass spectrometry (Knoop, Thomas and Thevis, Rapid Communications in Mass Spectrometry, 2019). Most of the human correlational studies cited above, including the polycystic-ovary-syndrome and heart-failure findings, relied on immunoassay methods of the kind this paper found could not be confirmed against a more specific technique. That does not necessarily invalidate comparisons made within a single study using one consistent assay, but it is a reason to treat any absolute circulating-MOTS-c number, cited anywhere, with some caution.
Safety
Human safety data for MOTS-c are not thin; they are essentially absent, because no human interventional trial has completed. The one registered trial, NCT07505745, was designed to generate the first such data, listing the incidence of treatment-emergent adverse events through 16 weeks as a co-primary endpoint alongside vital signs, ECG, standard laboratory panels and testing for anti-drug antibodies as secondary safety measures. None of that data existed at the time of this compilation, because the trial had not reported.
No dedicated animal toxicology study, such as a repeat-dose or GLP toxicology study, was located for MOTS-c. The mouse studies described in the mechanism and evidence sections above reported metabolic and cell-signaling effects, not formal toxicology endpoints such as organ histopathology or hematology panels. No human pharmacokinetic study exists for MOTS-c; the only pharmacokinetic-adjacent fact identified is that native MOTS-c has been described in the literature as having poor membrane permeability due to its polarity, a cell-uptake observation rather than a measured half-life or clearance value in any species. No serum half-life figure, in animals or humans, was identified in the sources reviewed. Anti-drug antibody testing was written into NCT07505745’s endpoints, which suggests the trial’s sponsor anticipated immunogenicity as an open question, consistent with immunogenicity being a documented issue for other injectable peptides; no MOTS-c-specific immunogenicity data exists yet either way.
Regulatory status
MOTS-c has no approved indication anywhere and no regulatory label of any kind. It has, however, drawn specific regulatory and anti-doping attention distinct from most unapproved research peptides. In the FDA’s review of substances nominated for its Category 2 “Bulk Drug Substances for Use in Compounding That May Present Significant Safety Risks” list, MOTS-c was among a group of peptides listed as withdrawn from consideration by whoever had nominated it for that review — a specific administrative status meaning the nomination was withdrawn, not that the substance was found safe or unsafe. A Federal Register notice for the FDA’s Pharmacy Compounding Advisory Committee meeting held in July 2026 listed “MOTs-C (free base and acetate each)” among substances scheduled for committee discussion, alongside several other unapproved research peptides, indicating MOTS-c was under active regulatory consideration for compounding status at that time.
On the anti-doping side, two dedicated papers have treated MOTS-c as a substance of interest well before any human trial existed. A 2016 survey of emerging performance-enhancement threats listed MOTS-c, by way of its folate-cycle and AMPK-activating mechanism, among compounds “necessitating preventive and proactive anti-doping measures,” in the same category as direct AMPK activators and PPAR-delta agonists (Thevis and Schanzer, Rapid Communications in Mass Spectrometry, 2016). A 2019 paper built and validated, to World Anti-Doping Agency standards, a mass-spectrometry assay specifically to detect synthetic MOTS-c in doping-control plasma samples, concluding that it appeared advisable to monitor potential use of synthetic MOTS-c in sport (Knoop, Thomas and Thevis, 2019). The precise section of the current World Anti-Doping Agency Prohibited List under which MOTS-c is formally categorized was not independently confirmed for this entry.
The mouse-to-human gap
The honest summary of MOTS-c, more than a decade after its discovery, is a large and mechanistically detailed mouse and cell-culture literature sitting on one side of a line, and almost nothing on the other. The mouse findings are not modest: reversal of diet-induced obesity, restoration of insulin sensitivity, improved exercise capacity, prevention of muscle atrophy and reduced organ damage in injury models have all been reported in mice or in cultured cells. None of that has been tested against a placebo in a completed human trial. The single registered human study opened enrollment in February 2026 and, as of this compilation, had reported no results. Everything else on the human side is an association between naturally occurring MOTS-c levels and a disease state — obesity, type 2 diabetes, polycystic ovary syndrome, heart failure — measured with an assay method that a validation study found does not agree with a more specific mass-spectrometry technique. No human dose has ever been established as safe or effective for any purpose, because no completed human dosing study exists to establish one.
That gap is worth stating without softening, because MOTS-c is already being discussed, and sold, in a research-peptide and longevity market years ahead of any human outcome data telling anyone whether the mouse effects translate at all. For most peptides in this kind of survey, the tension is between a narrow approved use and a much broader circulating one. For MOTS-c, the tension is more basic than that: it is the difference between a striking animal literature and a human record that, to date, amounts to one recruiting trial and a handful of correlational studies that were never designed to test whether giving a person MOTS-c does anything at all.