MOTS-c

MOTS-c is a 16-amino-acid peptide (sequence MRWQEMGYIFYPRKLR) encoded by an open reading frame within the mitochondrial 12S rRNA gene (MT-RNR1). It was characterized by Lee and colleagues in 2015 as the founding member of a class of mitochondria-encoded signaling molecules, sometimes termed mitokines.

The primary molecular mechanism involves inhibition of the folate cycle and associated de novo purine biosynthesis in skeletal muscle cells. This blockade accumulates AICAR (5-aminoimidazole-4-carboxamide ribonucleotide), a well-characterized activator of AMP-activated protein kinase (AMPK). Downstream AMPK signaling promotes glucose uptake via GLUT4 translocation, enhances fatty acid oxidation, and stimulates mitochondrial biogenesis through PGC-1alpha.

Under metabolic stress — glucose restriction, oxidative challenge, or exercise — MOTS-c undergoes nuclear translocation in an AMPK-dependent manner. In the nucleus it associates with the NRF2 transcription factor to modulate genes bearing antioxidant response elements, enhancing cellular stress resilience and survival. A 2026 study in transgenic mice confirmed that MOTS-c also improves intrinsic mitochondrial bioenergetic efficiency and reduces reactive oxygen species emission via this PGC-1alpha/AMPK axis, without increasing mitochondrial protein content, suggesting functional optimization of existing networks rather than organelle proliferation.

MOTS-c is secreted into the bloodstream and acts in an endocrine-like fashion; circulating concentrations rise measurably with aerobic exercise, supporting its classification as an exercise-induced mitokine.

Evidence for MOTS-c is predominantly preclinical. The foundational study (Lee et al., Cell Metabolism, 2015; PMID 25738459; n = 7-10 per group in mice) showed that intraperitoneal MOTS-c (0.5-5 mg/kg/day) prevented high-fat-diet-induced obesity and insulin resistance and improved glucose tolerance without apparent toxicity.

Reynolds et al. (Nature Communications, 2021; DOI 10.1038/s41467-020-20790-0) demonstrated that MOTS-c is exercise-induced in both rodents and humans. Skeletal muscle MOTS-c expression rose approximately 11.9-fold during exercise and 18.9-fold after a four-hour recovery period in human subjects; circulating plasma levels increased roughly 1.6-fold during exercise. Aged mice treated with exogenous MOTS-c (15 mg/kg/day) for two weeks approximately doubled their running time and preserved muscle homeostasis, supporting an "exercise mimetic" designation.

Human observational data show that plasma MOTS-c declines with age — roughly 21% lower in adults aged 70-81 compared with those aged 18-30 (Mohtashami et al., Int J Mol Sci, 2022; PMID 36233287) — and is measurably lower in patients with inadequately controlled type 2 diabetes (Kong et al., Diabetes Metab J, 2023).

The most rigorous human evidence comes from CohBar's Phase 1a/1b trial (NCT03998514) of CB4211, a synthetic MOTS-c analog. Phase 1b randomized 20 obese adults with NAFLD to 25 mg CB4211 once daily by subcutaneous injection or placebo for four weeks. Topline results announced August 2021 reported no serious adverse events, with statistically significant reductions in ALT (-21% vs. +4% placebo, p less than 0.05), AST (-28% vs. +11% placebo, p less than 0.05), and fasting glucose (-6% vs. placebo, p less than 0.05). Liver fat reduction was similar across arms, and a trend toward weight loss did not reach significance. These were exploratory endpoints in a Phase 1 safety study; they indicate a metabolic signal but do not constitute proof of efficacy.

A Phase 2a RCT (NCT07505745) examining subcutaneous MOTS-c in adults with prediabetes and overweight or obesity was registered and initiated; no published results are available as of mid-2026.

Typical dosage: 5-10 mg (weekly).

No approved human dosage exists for MOTS-c or any native MOTS-c preparation. Preclinical mouse studies employed intraperitoneal doses of 0.5-5 mg/kg/day (Lee et al. 2015) and up to 15 mg/kg/day over two weeks in the exercise-aging model (Reynolds et al. 2021).

The only formal human dosing tested under controlled conditions comes from the CohBar Phase 1b trial (NCT03998514): 25 mg of the MOTS-c analog CB4211 administered once daily by subcutaneous injection for four weeks in obese adults with NAFLD. Phase 1a escalated through single and multiple ascending doses in 65 healthy adults; specific dose levels per cohort have not been published in peer-reviewed literature.

Community and compounding-pharmacy protocols — which are entirely empirical, carry no regulatory validation, and are based on self-experimentation reports — typically describe subcutaneous doses of 5-10 mg administered once or twice weekly, with cycle lengths of 8-12 weeks. Some sources cite lower daily dosing in the range of 1-2 mg/day by daily subcutaneous injection. There is no published dose-response relationship in humans for native MOTS-c.

MOTS-c was added to the World Anti-Doping Agency Prohibited List in January 2024 under Section S4.4 (Metabolic Modulators / AMPK activators) and is prohibited at all times for athletes subject to anti-doping regulation. No Therapeutic Use Exemption is available.

This information is provided for educational and reference purposes only and does not constitute medical advice. MOTS-c has no approved therapeutic indication; administration outside a properly supervised clinical trial carries unknown risks.

No compound-specific stability data has been identified for this peptide. The general lyophilized-peptide handling framework applies — see Storage & handling for temperature, reconstitution diluent, and beyond-use dating principles.

No peer-reviewed clinical trials have examined MOTS-c in combination with other compounds in humans. The following pairings are discussed in the peptide self-experimentation community and must be treated as anecdotal, without controlled evidence.

• SS-31 (elamipretide), a tetrapeptide that stabilizes cardiolipin in the inner mitochondrial membrane and reduces mitochondrial ROS, is frequently paired with MOTS-c on the rationale that the two address complementary mitochondrial targets: SS-31 at membrane architecture and bioenergetic efficiency, MOTS-c at metabolic signaling and nuclear gene regulation. No controlled human data support this combination.

• NAD+ precursors (nicotinamide riboside, NMN) are combined with MOTS-c on the hypothesis that raising intracellular NAD+ levels augments the AMPK and SIRT1 pathways also engaged by MOTS-c. The mechanistic rationale is plausible but has not been tested in any clinical trial.

• BPC-157 is occasionally listed alongside MOTS-c in community longevity stacks; no published mechanism connects their physiological actions, and this pairing is entirely anecdotal.

MOTS-c is not currently FDA-approved for any indication. Effective April 22, 2026, the FDA removed MOTS-c from Category 2 of its Section 503A bulk drug substances list after the original nominators withdrew their nominations. This removal lifts the prior “significant safety risk” designation but does not place MOTS-c on the 503A Bulks List. Compounding pharmacies may prepare it with a valid physician prescription and pharmaceutical-grade API from an FDA-registered manufacturer. The FDA’s Pharmacy Compounding Advisory Committee (PCAC) is scheduled to review this substance at its July 23–24, 2026 public meeting. Removed from FDA Category 2 effective April 22, 2026. Selected for PCAC review Day 1 — July 23, 2026. PCAC agenda: BPC-157, KPV, TB-500, MOTS-c. NOT currently on 503A Bulks List — requires physician Rx. Source: FDA Advisory Committee Calendar / Lengea Law, May 2026.

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Reported side effects: Well-tolerated. Minimal reported side effects

In the CohBar Phase 1a/1b trial (NCT03998514), the MOTS-c analog CB4211 was administered to 65 healthy adults (Phase 1a, up to one week of dosing) and 20 obese subjects with NAFLD (Phase 1b, 25 mg/day SC for four weeks). No serious adverse events were reported in either phase. The most common adverse effect was mild-to-moderate injection site reactions — described as transient, painless subcutaneous nodules — occurring in more than 10% of CB4211-treated subjects; these prompted a temporary protocol amendment before Phase 1a resumed. Liver enzymes (ALT, AST), renal function markers (creatinine), and lipid panels remained within normal ranges across both phases.

Anecdotally, individuals self-administering unregulated MOTS-c purchased from research chemical vendors have reported: injection site irritation or erythema, mild headache, transient fatigue, palpitations, and insomnia. None of these reports are systematically documented.

Critical safety limitations are substantial. No published human trial has exceeded four weeks in duration, leaving long-term effects entirely unknown, including potential mitochondrial feedback suppression, endocrine crosstalk with sex hormones or thyroid axis, and oncological risks — since mitochondrial signaling intersects with apoptosis and cell proliferation pathways. No safety data exist for pregnant or breastfeeding individuals, children, adolescents, or those with active malignancies. Co-administration with glucose-lowering medications (insulin, sulfonylureas, GLP-1 agonists) carries a theoretical hypoglycemia risk given MOTS-c's documented glucose-lowering activity in preclinical models.

MOTS-c is not approved by any regulatory authority and has been banned by WADA since January 2024.