Side-by-side · Research reference
HumaninvsP21
Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.
AAnimal-StrongHUMAN-REVIEWED14/52 cited
BAnimal-MechanisticHUMAN-REVIEWED8/36 cited
Humanin
Mitochondrial-Derived Peptide · Cytoprotective
SQ · Experimental
P21
CNTF-Derived Neuropeptide · Animal Model Evidence
Animal onlyEvidence level
SQ · Site unspecified · Frequency unknown
01Mechanism of Action
Parameter
Humanin
P21
Primary target
Intracellular: Bax, Bim, tBid (pro-apoptotic Bcl-2 family). Extracellular: FPRL1/2 G-protein-coupled receptorsZhu 2022Lue 2021
CNTF receptor alpha (CNTFRα) / LIF receptor (LIFR) / gp130 complex on neural stem cells
Pathway
Humanin binds Bax/Bim → inhibits mitochondrial outer membrane permeabilization (MOMP) → blocks cytochrome c release → prevents caspase activation → cell survival
CNTF mimetic → CNTFRα/LIFR/gp130 heterotrimer → JAK/STAT3 signaling → neurogenesis, stem cell proliferation, neuroprotection
Downstream effect
Suppression of apoptosis, mitochondrial stabilization, reduced oxidative stress, preservation of germ cells and neurons under stressZhu 2022Lue 2021Velentza 2024
Increased neural stem cell self-renewal, globose basal cell activation (Mash1+ cells), olfactory sensory neuron regeneration, hippocampal neurogenesis, neuroprotection in developmental disorders
Feedback intact?
Not applicable — peptide acts as anti-apoptotic signal, not hormonal axis
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Origin
Encoded by short open reading frame in mitochondrial 16S rRNA gene (MTRNR2). 24-28 amino acids. 13 homologous variants (MTRNR2L1-L13) identified.Zhu 2022Shahzaib 2026
Small-molecule peptide mimetic derived from full-length ciliary neurotrophic factor (CNTF), designed to retain receptor activation with improved pharmacokineticsMottolese 2024
Antibody development
Not reported in animal models
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02Dosage Protocols
Parameter
Humanin
P21
Standard experimental dose (HNG)
4 mg/kg IP (rat)
Most common dose in rodent models.
—
Ex vivo bone culture
1 µg/mL
Protective against venetoclax-induced bone growth retardation.
—
Frequency
Daily (IP)
—
Duration
8–12 weeks in animal studies
Not specified
Evidence basis
Animal models (rat, mouse)Huang 2025El 2022Velentza 2024
Animal models only
CDKL5 KO mice, methimazole-induced olfactory injury, CNTF-/- knockout models.Mottolese 2024Cox 2026Jia 2020
Human data
None — no clinical trials reported
—
Analog (HNG)
Gly[14]-humanin — more potent variant
Substitution at position 14 enhances cytoprotective activity.
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Human dosing
—
No established protocol
No clinical trial data available.
Animal models (mice)
—
Dose and route not specified in abstractsMottolese 2024Jia 2020
In vitro and in vivo studies demonstrate efficacy; precise dosing protocols not disclosed.
Route
—
Presumed subcutaneous or intraperitoneal (animal studies)
03Metabolic / Fat Loss Evidence
Parameter
Humanin
P21
Direct fat loss evidence
None
—
Mechanism overlap
Mitochondrial health may indirectly influence metabolic efficiency, but no quantified effect
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04Side Effects & Safety
Parameter
Humanin
P21
Animal model safety
Well-tolerated in rat and mouse studies at 4 mg/kg for 8–12 weeks
—
Human safety data
None — no clinical trials
None available
No clinical trials in humans.
Theoretical fibrillation risk
Induces amyloid-like fibrillation of Bax/BID. Long-term sequelae unknown.
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Injection site reaction
Not reported in animal studies (IP route)
—
Reproductive safety
Protective in POI model (cyclophosphamide-induced), no adverse effects on fertility notedHuang 2025
—
Animal tolerability
—
Well-tolerated in mouse models; no toxicity reported in available abstracts
Theoretical risks
—
Uncontrolled stem cell proliferation, immune response to peptide, unknown long-term CNS effects
Absolute Contraindications
Humanin
- ·Unknown — no human data
P21
- ·Use in humans not validated
Relative Contraindications
Humanin
- ·Active malignancy (theoretical risk of anti-apoptotic effect on tumour cells)
P21
- ·Active malignancy (theoretical — neurotrophic signaling may affect tumour growth)
- ·Pregnancy or lactation (no safety data)
05Administration Protocol
Parameter
Humanin
P21
1. Route (experimental)
Intraperitoneal (IP) in animal models. Subcutaneous route untested. No human protocols exist.
Not established. No FDA approval, no clinical trial data.
2. Reconstitution
Synthetic peptide reconstituted in sterile saline or PBS. No commercial formulation available.
In vivo studies used systemic administration (route not specified in abstracts) in mouse models of neurodegeneration, olfactory injury, and CDKL5 deficiency disorder. In vitro studies used primary cell cultures.
3. Timing
Daily administration in animal studies. Optimal timing not characterized.
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4. Storage
Lyophilised powder: -20 °C. Reconstituted: 4 °C, use within 7 days. Avoid freeze-thaw cycles.
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5. Human use
No FDA approval, no IND, no clinical trials. Experimental research tool only.
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06Stack Synergy
Humanin
+ MOTS-c
Multi-pathwayBoth are mitochondrial-derived peptides. MOTS-c enhances metabolic efficiency and insulin sensitivity via AMPK activation, while humanin prevents mitochondrial apoptosis. Combined, they address mitochondrial function (MOTS-c) and survival signaling (humanin), supporting cellular resilience under metabolic and oxidative stress.
- Humanin
- 4 mg/kg IP · daily (animal model)
- MOTS-c
- 5 mg/kg IP · daily (animal model)
- Frequency
- Once daily
- Primary benefit
- Mitochondrial health, metabolic efficiency, anti-apoptotic signaling
P21
— no documented stacks