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Humanin

Humanin is a mitochondria-derived micro-peptide composed of 24 amino acids, encoded within a short open reading frame (sORF) of the mitochondrial 16S ribosomal RNA gene (MT-RNR2). Unlike most peptides studied in cellular biology, Humanin is not nuclear-encoded, placing it in a distinct and emerging class of signaling molecules known as mitochondria-derived peptides (MDPs). Humanin was first discovered in 2001 by Hashimoto and colleagues during functional expression screening of a cDNA library constructed from postmortem brain tissue of an Alzheimer’s disease patient. Specifically, it was identified in the relatively preserved occipital lobe—a brain region that remains intact even in advanced Alzheimer’s—suggesting that Humanin may function as a survival factor that helps protect neurons from disease-related damage. Since its initial discovery, Humanin has been extensively studied in cellular stress response, apoptosis regulation, mitochondrial signaling, and aging biology research. Its unique mitochondrial origin and broad intracellular interactions have made it a focal point in investigations exploring how mitochondria communicate with the rest of the cell under stress conditions. Humanin is now recognized as the first identified mitochondrial-derived peptide with systemic biological activity. The peptide may exist in two different forms depending on where it is synthesized within the cell. If translated inside the mitochondria, the peptide contains 21 amino acids; if translated in the cytoplasm (cytosol), the result is a 24-amino acid peptide. Both forms have been shown to possess biological activity in preclinical models. Humanin levels have been observed to decline with age in several experimental models. Notably, offspring of centenarians have been found to have significantly higher circulating Humanin levels, and Humanin levels remain stable in long-lived species such as naked mole-rats, further supporting its potential role in longevity and cellular resilience.

Molecular Formula: C₁₁₉H₂₀₄N₃₄O₃₂S₂

Molecular Weight: 2687.3 g/mol

Sequence: Met-Ala-Pro-Arg-Gly-Phe-Ser-Cys-Leu-Leu-Leu-Leu-Thr-Ser-Glu-Ile-Asp-Leu-Pro-

Val-Lys-Arg-Arg-Ala

CAS Number: 330936-69-1

PubChem SID: 16131438

Synonyms: Formyl Humanin, HNGF6A Protein, HN Peptide

How It Works

Mitochondrial Signaling and Cellular Stress Response

Humanin is widely investigated for its role in mitochondrial stress signaling. In preclinical models, Humanin expression increases in response to cellular stressors such as oxidative damage, metabolic dysfunction, and inflammatory stimuli. Research indicates that Humanin participates in mitochondrial–nuclear cross-talk, influencing cellular survival pathways that determine whether a cell adapts to stress or undergoes programmed cell death (apoptosis). Despite lacking a classical signal peptide, Humanin has been detected in both intracellular and extracellular compartments in experimental models. Studies suggest that Humanin may utilize non-canonical secretion pathways, with specific hydrophobic motifs contributing to its cellular trafficking. Humanin abundance in experimental systems is influenced by transcriptional regulation of its mitochondrial template and by post-translational degradation mechanisms, including proteasome-mediated turnover.

Regulation of Apoptosis Pathways

One of the most extensively characterized properties of Humanin is its interaction with the intrinsic (mitochondrial) apoptosis pathway. In vitro and animal studies demonstrate that Humanin can bind to and modulate members of the Bcl-2 protein family, including Bax, Bid, and tBid. Bax is a pro-apoptotic protein that promotes cell death by disrupting the mitochondrial outer membrane. By binding to the inactive form of Bax, Humanin inhibits changes in the Bax protein and thereby helps prevent cellular apoptosis. Through these interactions, Humanin has been shown to influence:

mitochondria, a critical step in the apoptotic cascade Humanin also binds with other intracellular molecules such as actinin-4 and phosphoprotein 8, both of which are involved in cellular apoptosis. Binding with these proteins is thought to contribute to Humanin’s broader cytoprotective potential.

Receptor-Mediated Signaling Mechanisms

Beyond its intracellular activity, Humanin engages cell-surface receptor complexes, including the formyl peptide receptor-like 1 (FPRL1), formyl peptide receptor-like 2 (FPRL2), and the CNTFR/WSX-1/gp130 heterotrimeric receptor complex. Activation of these receptors initiates downstream signaling cascades involving:

By binding to FPRL1 and FPRL2 receptors, Humanin may also prevent amyloid-beta from interacting with these receptors, which could mitigate certain forms of neurological degradation observed in Alzheimer’s disease models.

Oxidative Stress and Redox Biology

Humanin is examined in the context of oxidative stress regulation. Experimental models show that Humanin signaling is associated with changes in reactive oxygen species (ROS) handling and antioxidant pathway activation. Mitochondria are particularly susceptible to ROS, and the presence of such ROS may reduce mitochondrial functioning. Studies suggest that Humanin may inhibit these reactive oxygen species to some degree, thereby mitigating mitochondrial degeneration. Studies in neuronal, vascular, retinal, and hepatic cell systems suggest that Humanin may influence:

Neuroendocrine and Metabolic Signaling

Preclinical studies explore Humanin’s interaction with neuroendocrine and metabolic signaling pathways, including cross-talk with insulin-like growth factor (IGF) signaling and AMP- activated protein kinase (AMPK). These investigations aim to map how mitochondrial peptides influence cellular energy sensing, metabolic stress adaptation, and neuroendocrine communication.

Benefits

Neuroprotection

Humanin was originally discovered as a neuroprotective factor. Preclinical studies demonstrate that Humanin and its analogs protect against neuronal cell death induced by Alzheimer’s disease- related insults, including amyloid-beta peptides and familial Alzheimer’s disease genes (APP, presenilin-1, presenilin-2). The peptide suppresses neuronal apoptosis through both intracellular and extracellular mechanisms and has shown protective effects in pharmacological models of memory impairment. Circulating central nervous system levels of Humanin are reduced in Alzheimer’s disease patients relative to age-matched controls.

Cytoprotection Across Multiple Tissue Types

Beyond neurons, research suggests Humanin exerts protective effects on cells in heart tissue, muscle cells, retinal pigment epithelial cells, vascular endothelial cells, and chondrocytes. This broad cytoprotective profile positions Humanin as a versatile cellular defense peptide rather than a tissue-specific agent.

Cardiovascular Protection

Studies in aging mouse models demonstrate that exogenous Humanin analog (HNG) treatment attenuated myocardial fibrosis and apoptosis. HNG inhibited interstitial fibrosis, reduced fibroblast proliferation in the aging myocardium, and significantly increased the ratio of cardiomyocytes to fibroblasts in aging hearts. The cardioprotective effect appears to be mediated through upregulation of the Akt/glycogen synthase kinase-3β pathway.

Anti-Aging and Longevity

Humanin levels decline with age across multiple experimental models. Humanin overexpression extends lifespan in C. elegans models, and HNG treatment improves metabolic healthspan in middle-aged mice. Offspring of centenarians have significantly higher circulating Humanin levels compared to age-matched controls, suggesting a relationship between Humanin and successful aging.

Metabolic Support

Research indicates that Humanin interacts with insulin signaling pathways and AMPK-mediated energy sensing. Studies suggest potential benefits in models of insulin resistance and metabolic dysfunction, making it a subject of interest in diabetes and metabolic syndrome research.

Retinal Protection

Humanin and related mitochondria-derived peptides have been studied for protective effects against age-related macular degeneration in retinal pigment epithelial cell models. The peptide helps protect these cells from oxidative damage, a key driver of retinal degeneration.

Stroke and Ischemia

The potent Humanin analog HNG has demonstrated neuroprotective effects in focal cerebral ischemia/reperfusion injury models in mice, reducing infarct volume and neurological deficits when administered both before and after ischemic events. This suggests a potential therapeutic role in ischemia-related neural damage.

What the Science Shows

Humanin has substantial preclinical research support, though human clinical trials remain limited. The following represents key findings from the published literature.

Discovery and Initial Characterization (Hashimoto et al., 2001) Humanin cDNA was discovered through functional expression screening of a brain cDNA library from an Alzheimer’s disease patient. The initial studies showed that Humanin could protect cells from apoptosis induced by amyloid-beta (Aβ)1–43 and further demonstrated protection against other mutated genes that cause familial Alzheimer’s disease, including APP, presenilin-1, and presenilin-2. Importantly, Humanin did not protect against Huntington’s disease or amyotrophic lateral sclerosis models, suggesting specificity for Alzheimer’s-related pathology.

Bax Interaction and Anti-Apoptotic Activity (Guo et al., 2003) Published in Nature, this study demonstrated that Humanin peptide suppresses apoptosis by interfering with Bax activation. The research showed that Humanin directly binds Bax protein, preventing its translocation to mitochondrial membranes—a critical step in the intrinsic apoptosis pathway. This provided a clear molecular mechanism for Humanin’s cytoprotective effects.

HNG Analog: 1,000-Fold Potency Increase

Substitution of glycine for serine at position 14 in the Humanin sequence (creating the HNG analog) increases cytoprotective activity by approximately 1,000-fold while also improving temperature resistance. HNG has become the standard analog used in most preclinical studies due to its enhanced potency and stability.

Cognitive Protection (Yen et al., 2018) This study demonstrated that Humanin prevents age-related cognitive decline in mice and is associated with improved cognitive age in humans. The findings provided translational evidence linking Humanin levels to cognitive preservation during aging.

Cardiac Fibrosis Attenuation in Aging Mice

Exogenous HNG treatment in aging mice attenuated myocardial fibrosis and apoptosis. Interstitial collagen deposition, which increased significantly in aged mice compared to young mice, was significantly reduced after HNG treatment. The protective effect was mediated through the Akt/glycogen synthase kinase-3β pathway.

Stroke Neuroprotection

In a mouse model of focal cerebral ischemia/reperfusion injury, HNG pretreatment (0.1 μg intracerebroventricularly or 1 μg intraperitoneally) significantly reduced infarct volume and improved neurological outcomes. Post-treatment at 0, 2, 4, and 6 hours after ischemia also showed protective effects. The neuroprotection was mediated at least in part by inhibiting ERK activation.

Metabolic Signaling (Muzumdar et al., 2009) Published in Science, this study examined Humanin’s interaction with metabolic signaling pathways, establishing connections between the mitochondrial peptide and insulin sensitivity, AMPK activation, and systemic metabolic regulation.

Neuroprotective Action Review (2023) A comprehensive review of Humanin and Humanin analogs confirmed their neuroprotective action across various cellular and animal models of neurodegenerative diseases, with particular emphasis on Alzheimer’s disease. The review documented multiple intracellular and extracellular anti-cell death mechanisms and highlighted the development of increasingly potent synthetic analogs for research applications.

Dosing Protocol

Humanin dosing protocols are not well-established due to the limited number of human clinical trials. The following information is derived from preclinical research, community experience, and anecdotal reports. No FDA-approved dosing protocol exists for Humanin.

Injectable Protocol (Community Consensus) Humanin is typically administered via subcutaneous injection: Protocol Dose Frequency Duration Conservative 100 to 300 mcg Daily 2 to 4 weeks Standard 1 to 2 mg 2 to 3x weekly 2 to 4 weeks Higher Dose 5 to 10 mg/week Divided into 2 to 3 2 to 4 weeks on, 2 to 4 injections weeks off Some biohackers have reported using 1 mg twice daily for 15 consecutive days based on bodyweight considerations and the peptide’s short half-life (approximately 30 minutes to 2 hours). Others report 25 to 50 mcg daily of the more potent HNG analog, which is approximately 1,000-fold more active than native Humanin.

Weight-Based Protocol

A weight-based approach of 0.04 mg/kg as a single subcutaneous injection has been referenced in clinical discussions. For an 80 kg individual, this would equal approximately 3.2 mg. This dosage should not be exceeded without medical supervision.

Cycle Recommendations

Most protocols recommend cyclical use:

Draw Volumes by Vial Size

10 mg Vial (2 mL reconstitution = 5 mg/mL = 5,000 mcg/mL) Dose Volume Units on Syringe 250 mcg 0.05 mL 5 units 500 mcg 0.10 mL 10 units 1 mg 0.20 mL 20 units 2 mg 0.40 mL 40 units

10 mg Vial (1 mL reconstitution = 10 mg/mL = 10,000 mcg/mL) Dose Volume Units on Syringe 250 mcg 0.025 mL 2.5 units 500 mcg 0.05 mL 5 units 1 mg 0.10 mL 10 units 2 mg 0.20 mL 20 units

Reconstitution Instructions

1. Remove the plastic cap from the vial and wipe the rubber stopper with an alcohol swab. 2. Draw 1 to 2 mL of bacteriostatic water into a sterile syringe. 3. Insert the needle through the rubber stopper at an angle. 4. Direct the stream of water down the inside wall of the vial, not directly onto the powder. 5. Allow the water to gently dissolve the peptide without shaking or swirling aggressively. 6. If any powder remains undissolved after 2 to 3 minutes, gently roll the vial between your palms. 7. The solution should be clear and colorless when fully reconstituted. 8. Label the vial with the date and concentration.

Side Effects and Cautions

Common Side Effects

Humanin is generally considered well-tolerated in research settings. Since it is naturally produced by the body’s own mitochondria, it does not disrupt the endocrine system or suppress natural hormone production. The most commonly reported side effects include:

Most side effects are rare and transient.

Theoretical Concerns

with both cell survival and, in certain contexts, tumor promotion. The short half-life of Humanin may mitigate this concern, but long-term safety data is lacking.

amplify the effects of other compounds affecting energy metabolism, such as AMPK activators or MOTS-c.

Most protocols recommend cyclical use with periodic breaks.

Contraindications and Precautions

Who Should Avoid Humanin

signaling that could theoretically promote tumor cell survival)

Use with Care

signaling pathways; monitor blood glucose)

Comparison to Similar Compounds

Compound Type Primary Use Route Stability Synergy Humanin Mitochondrial- Cytoprotection, Subcutaneous Low (short — derived neuroprotection half-life) peptide MOTS-c Mitochondrial- Metabolic Subcutaneous Moderate Synergistic derived regulation, peptide AMPK activation BPC-157 Gastric peptide Tissue repair, Subcutaneous/Oral Good Synergistic gut healing Epithalon Tetrapeptide Telomerase Subcutaneous Good Compatible activation, anti- aging SS-31 Synthetic Mitochondrial Subcutaneous/IV Good Synergistic (Elamipretide) peptide bioenergetics

Humanin and MOTS-c are both mitochondria-derived peptides with complementary longevity and metabolic benefits. While MOTS-c primarily activates AMPK and targets metabolic regulation, Humanin focuses on cytoprotection, neuroprotection, and anti-apoptotic signaling. Stacking the two provides broad mitochondrial support through different mechanisms. SS-31 (Elamipretide) directly targets mitochondrial proteins involved in bioenergetics, while Humanin primarily acts via cell-surface receptors to promote cell survival.

Success Tips

Consider Stacking for Comprehensive Mitochondrial Support

Humanin’s effects are amplified when combined with complementary compounds:

insulin sensitivity. Ideal for metabolic support and fat loss.

and soft tissues while Humanin defends mitochondria and reduces inflammation.

comprehensive anti-aging support.

Optimize Timing

dosing is important for sustained effects.

Support Endogenous Production

While direct supplementation provides exogenous Humanin, supporting the body’s natural mitochondrial health can complement peptide use:

endogenous Humanin expression.

deprivation impairs mitochondrial function.

mitochondrial health and may complement Humanin’s effects.

may enhance Humanin’s metabolic benefits.

Cycle Appropriately

Humanin is best used in cycles of 2 to 4 weeks on, followed by 2 to 4 weeks off. This approach allows assessment of response and reduces theoretical concerns about chronic STAT3 activation.

Foundation First

Peptides support cellular function. They do not replace the fundamentals: adequate sleep, stress management, whole food nutrition, and regular exercise. An optimized foundation allows peptides to work more effectively.

Storage and Handling

Before Reconstitution

After Reconstitution

For best results, rehydrate just before use. Humanin’s short half-life and susceptibility to degradation make proper storage critical for maintaining peptide integrity.

Legal Status

United States: Not FDA-approved for clinical use. Available through research chemical suppliers for research purposes only. No human clinical trials have established therapeutic dosing. Clinical Development: Humanin and its analogs continue to be studied in preclinical models. Multiple Humanin analogs (HNG, Colivelin, and others) have been developed with enhanced potency and stability for research applications. International: Available for research purposes in most countries. Not approved for clinical use in any jurisdiction.

Frequently Asked Questions

What makes Humanin different from other peptides? Humanin is unique because it is encoded by mitochondrial DNA rather than nuclear DNA, making it one of the first identified mitochondria-derived peptides with systemic biological activity. Unlike most therapeutic peptides that are designed synthetically, Humanin is a naturally occurring peptide produced by the body’s own mitochondria. Its decline with age and its

association with centenarian populations make it particularly interesting for longevity research. Is Humanin the same as MOTS-c? No. Both are mitochondria-derived peptides, but they have different sequences, different receptor targets, and different primary mechanisms. MOTS-c primarily activates AMPK and targets metabolic regulation and exercise mimetics, while Humanin focuses on cytoprotection, neuroprotection, and anti-apoptotic signaling through Bcl-2 family interactions and the STAT3/PI3K/Akt pathways. They are complementary and often stacked together. What is HNG and how does it differ from native Humanin? HNG is a synthetic analog of Humanin in which glycine is substituted for serine at position 14 in the amino acid sequence. This single amino acid change increases the cytoprotective activity approximately 1,000-fold and improves temperature stability. HNG is the most commonly used analog in preclinical research. Can Humanin help with Alzheimer’s disease? Humanin was originally discovered as a neuroprotective factor against Alzheimer’s-related insults, and extensive preclinical research supports its protective effects against amyloid-beta toxicity and familial Alzheimer’s disease genes. However, it has not yet been tested as a therapeutic agent in human Alzheimer’s patients. All available evidence remains preclinical. Why does Humanin have such a short half-life? Humanin is a small peptide (24 amino acids) that is subject to standard peptide degradation pathways, including proteasome-mediated turnover and enzymatic breakdown. Its half-life is estimated at approximately 30 minutes to 2 hours depending on the route of administration and the specific analog used. This short half-life is one reason why more stable analogs like HNG have been developed for research applications. Can I use Humanin long term? Most protocols recommend cyclical use (2 to 4 weeks on, 2 to 4 weeks off) rather than indefinite daily supplementation. Long-term safety data does not exist. Concerns about chronic STAT3 activation and unknown effects of prolonged supplementation warrant a cautious, cycled approach. Does Humanin interact with other peptides? Humanin is commonly stacked with MOTS-c (for complementary mitochondrial support), BPC- 157 (for tissue healing), and CJC-1295/Ipamorelin (for growth hormone and anti-aging support). Because Humanin enhances mitochondrial signaling, it may amplify the effects of other compounds affecting energy metabolism. Consult a healthcare professional before combining peptides.

References

1. Hashimoto Y, Niikura T, Tajima H, et al. A rescue factor abolishing neuronal cell death by a wide spectrum of familial Alzheimer’s disease genes and Aβ. Proceedings of the National Academy of Sciences. 2001;98(11):6336–6341. 2. Hashimoto Y, Ito Y, Niikura T, et al. Mechanisms of neuroprotection by a novel rescue factor humanin from Swedish mutant amyloid precursor protein. Biochemical and Biophysical Research Communications. 2001;283(2):460–468. 3. Guo B, Zhai D, Cabezas E, et al. Humanin peptide suppresses apoptosis by interfering with Bax activation. Nature. 2003;423(6938):456–461. 4. Muzumdar RH, Huffman DM, Atzmon G, et al. Humanin: a novel central regulator of peripheral insulin action. PLoS ONE. 2009;4(7):e6334. 5. Yen K, Wan J, Mehta HH, et al. Humanin prevents age-related cognitive decline in mice and is associated with improved cognitive age in humans. Scientific Reports. 2018;8:14212. 6. Ikonen M, Liu B, Hashimoto Y, et al. Interaction between the Alzheimer’s survival peptide humanin and insulin-like growth factor-binding protein 3 regulates cell survival and apoptosis. Proceedings of the National Academy of Sciences. 2003;100(22):13042–13047. 7. Tajima H, Niikura T, Hashimoto Y, et al. Evidence for in vivo production of Humanin peptide, a neuroprotective factor against Alzheimer’s disease-related insults. Neuroscience Letters. 2002;324(3):227–231. 8. Ma ZW, Liu DX. Humanin decreases mitochondrial membrane permeability by inhibiting the membrane association and oligomerization of Bax and Bid proteins. Acta Pharmacologica Sinica. 2018;39(6):1012–1021. 9. Kim SJ, Guerrero N, Wassef G, et al. The mitochondrial-derived peptide humanin activates the ERK1/2, AKT, and STAT3 signaling pathways and has age-dependent signaling differences in the hippocampus. Oncotarget. 2016;7(30):46899–46912. 10. Niikura T. Humanin and Alzheimer’s disease: The beginning of a new field. Biochimica et Biophysica Acta General Subjects. 2022;1866(1):130024. 11. Zhao ST, Zhao L, Li JH. Neuroprotective peptide humanin inhibits inflammatory response in astrocytes induced by lipopolysaccharide. Neurochemical Research. 2013;38(3):581–588. 12. Evangelatos GP, Zikos C, Livaniou E, Evangelatos GP. Neuroprotective action of humanin and humanin analogues: research findings and perspectives. Biology. 2023;12(12):1534.

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