Side-by-side comparison of mechanisms, dosing, interactions, and stacking potential.
| Humanin | P21 (Cerebrolysin Analog) | |
|---|---|---|
| Category | Peptides | Peptides |
| Standard Dose | Research indicates dosing remains experimental. Animal studies use 1-10 mcg/day equivalents. Human protocols are not established. | Research indicates 750 mcg-1 mg daily via intranasal administration or subcutaneous injection. |
| Timing | No established timing protocol. Morning dosing suggested for neuroprotective applications. | Morning dosing preferred for cognitive effects. |
| Cycle Duration | Experimental — no established cycle lengths. | 4-8 week cycles with 4-week rest periods. |
| Evidence Level | animal_plus_anecdotal | animal_plus_anecdotal |
Humanin is a 24-amino acid mitochondrial-derived peptide encoded by the 16S rRNA gene of mitochondrial DNA. It binds IGFBP-3 with high affinity (via Phe-6), interfering with IGFBP-3 binding to importin-beta and suppressing IGFBP-3-mediated apoptosis. It also inhibits the pro-apoptotic protein Bax (Bcl-2 family), preventing mitochondrial outer membrane permeabilization and intrinsic apoptosis. Humanin and IGFBP-3 synergistically protect neurons from amyloid-beta-induced apoptosis, and it activates the STAT3 and ERK1/2 pathways for cytoprotection.
Research indicates dosing remains experimental. Animal studies use 1-10 mcg/day equivalents. Human protocols are not established.
No established timing protocol. Morning dosing suggested for neuroprotective applications.
Experimental — no established cycle lengths.
P21 is a tetrapeptide (DGGL — Asp-Gly-Gly-Leu) derived from the most active region of ciliary neurotrophic factor (CNTF, residues 148-151), identified through reverse engineering of Cerebrolysin. An adamantylated glycine enhances BBB permeability and metabolic stability. P21 works through LIF/STAT3 pathway inhibition, BDNF/TrkB/CREB signaling enhancement, and restoration of synaptic proteins (synaptophysin, synapsin I) and glutamate receptors. It promotes neurogenesis and maturation of newborn neurons in the dentate gyrus.
Research indicates 750 mcg-1 mg daily via intranasal administration or subcutaneous injection.
Morning dosing preferred for cognitive effects.
4-8 week cycles with 4-week rest periods.
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