Biohackr: Track your protocol. Model the curve.

Educational reference only. Informational material drawn from peer-reviewed literature. Not medical advice and not a recommendation to use, dose, or modify any therapy. Decisions about hormone therapy should be made with a qualified healthcare provider.

Overview

Humanin (HN) is a 24-amino acid peptide that holds the distinction of being the first-discovered mitochondrial-derived peptide (MDP), preceding MOTS-c ([[mots-c]]) by approximately 14 years and establishing the entire MDP research field. The compound was discovered in 2001 by Yuichi Hashimoto in Tokyo using a cDNA library from the unaffected occipital lobe of a deceased Alzheimer's patient, searching for the endogenous factor that protected those neurons. Three different research groups discovered Humanin nearly simultaneously, encoding a 75-base-pair open reading frame within the mitochondrial 16S rRNA region.

The discovery context shapes everything about Humanin. The compound was identified specifically as a 'rescue factor'. Hashimoto's foundational 2001 PNAS paper was titled A rescue factor abolishing neuronal cell death by a wide spectrum of familial Alzheimer's disease genes and Aβ. This means Humanin was conceived from the start as a neuroprotective, anti-apoptotic peptide, in contrast to MOTS-c's metabolic focus. The primary mechanism is direct Bax inhibition (Guo et al. 2003, Nature): Humanin binds the pro-apoptotic Bax protein at the mitochondrial outer membrane and prevents its translocation/activation, blocking cytochrome c release and the downstream caspase cascade. This single mechanism explains Humanin's broad protective effects across diverse cell types and apoptotic stimuli.

Together with MOTS-c, Humanin established the MDP class with complementary functions that are now mapped to distinct mitochondrial rRNA regions:

Humanin (16S rRNA region): Anti-apoptotic, neuroprotective, cytoprotective (protects cells from death)
MOTS-c (12S rRNA region): Metabolic regulator, exercise mimetic (improves cellular function)
SHLPs 1–6 (also 16S rRNA region): Various; some Humanin-like protective effects

This division of labor, protection (16S rRNA peptides) vs metabolic optimization (12S rRNA MOTS-c), is one of the more striking discoveries in mitochondrial biology and a major paradigm shift from the older view of mitochondria as passive energy factories.

Practically, the synthetic analog matters as much as the wild-type. The S14G-Humanin (HNG) analog (single Serine→Glycine substitution at position 14, identified by Yamagishi et al. 2003 through systematic essential-amino-acid analysis) is 1000-fold more potent than wild-type and is used in most modern research. The two forms are therefore not interchangeable, and because both are described as 'humanin', the name alone does not say which peptide a given product contains.

Despite the substantial scientific foundation (~25 years of research, 2001 papers in PNAS and Journal of Neuroscience, the 2003 Nature mechanism paper, and decades of subsequent characterization), Humanin shares MOTS-c's commercial development trajectory: no commercial pharmaceutical development to approval has occurred anywhere. CohBar Inc. (founded by Pinchas Cohen at USC Leonard Davis School of Gerontology) pursued MDP-based therapeutics but has had financial difficulties; Humanin specifically was not advanced to late-stage trials. This commercial gap reflects pharmaceutical economic challenges for endogenous-sequence peptides (limited patent protection, delivery challenges, slow human translation) rather than scientific failure.

Forms

Available forms & half-lives

Form	Approximate half-life
Subcutaneous wild-type Humanin	Short (<1 hour)
Subcutaneous S14G-Humanin (HNG)	Longer than wild-type
Intravenous Humanin/HNG	Short
Intranasal Humanin	Variable
Oral Humanin	Not feasible

What it does

Main effects

Anti-apoptotic / cytoprotective via direct Bax inhibition · Primary mechanism (Guo et al. 2003, Nature); Humanin binds pro-apoptotic Bax at mitochondrial outer membrane and prevents activation/translocation; blocks cytochrome c release and caspase cascade; broad protection across cell types and apoptotic stimuli
Neuroprotection against Alzheimer's disease-relevant insults · The original 2001 discovery indication; protects against Aβ1-43 toxicity and familial AD mutations in APP, PSEN1, PSEN2 (Hashimoto et al. 2001, PNAS + Journal of Neuroscience)
GP130/IL6ST receptor signaling · Modern receptor view (Kim et al. 2016, Oncotarget); activates PI3K→AKT, MEK→ERK1/2, JAK→STAT3 pathways; age-dependent signaling differences in hippocampus
IGFBP-3 binding modulates cell survival · Second mechanism (Ikonen et al. 2003, PNAS); modulates pro-apoptotic functions of IGFBP-3 independent of IGF binding
Stroke / cerebral ischemia protection · PI3K/Akt-mediated neuroprotection in ischemia-reperfusion models (Xu et al. 2006, 2008)
Insulin sensitivity enhancement · Peripheral insulin action regulator (Muzumdar et al. 2009, PLoS One)
Atherosclerosis prevention · Preserves endothelial function and prevents plaque progression in ApoE-deficient mice (Oh et al. 2011, Atherosclerosis)
Chemotherapy protection · Selective protection of normal cells in some contexts (PMC 3982780)
Founding member of the MDP class · Preceded MOTS-c by 14 years; established the entire MDP framework; together they demonstrate that mtDNA encodes bioactive signaling peptides beyond the canonical 13 ETC proteins
Plasma Humanin decreases substantially with aging · Supports the MDP loss as aging mechanism hypothesis; provides rationale for supplementation
S14G-Humanin (HNG) is 1000-fold more potent than wild-type · Single Ser→Gly substitution at position 14; the form used in most modern research

What to watch for

Common side effects

Generally well-tolerated in animal studies and limited human exposure; no major systemic toxicity documented in preclinical work
Theoretical cancer concern from anti-apoptotic mechanism · Cancer cells often resist apoptosis for survival; anti-apoptotic factors could theoretically protect tumor cells from chemotherapy or natural apoptotic clearance; some research suggests selective protection of normal cells in chemo-protection contexts, but long-term effects in cancer history unclear; avoid in active malignancy or recent cancer history
Clinical evidence gap is the central limitation · Despite ~25 years since discovery, no Phase 2-3 controlled human trials; all human evidence is observational (plasma levels, age-related decline correlations, disease-state associations); no regulatory approval anywhere
CohBar Inc. commercial development stagnated · Same pattern as MOTS-c; CohBar financial difficulties; pharmaceutical economic challenges for endogenous-sequence peptides with limited patent protection
Wild-type and HNG are not interchangeable · Wild-type has limited potency and most research uses S14G-HN (HNG); the two differ by roughly 1000-fold, and both are described as humanin, so the potency of unlabelled material is unknown
Mild injection-site reactions · Standard for SC peptide administration
Research chemical quality concerns · No pharmaceutical-grade source exists; identity, concentration, sterility unverified; cysteine residue at position 8 can complicate synthesis quality
No long-term human safety data · Animal long-term studies generally favorable but human chronic-use data nonexistent
Not WADA-prohibited as of current information (verify before use in tested sport)
Endogenous-peptide framing is somewhat reassuring but not sufficient · Identical to natural human peptide (wild-type), no immunogenicity concerns, no 'foreign protein' concerns, but supraphysiological levels effects are not characterized

Key facts

Key facts worth knowing

Humanin is a 24-amino acid peptide encoded by a 75-base-pair open reading frame in the 16S rRNA region of the mitochondrial genome. Sequence: MAPRGFSCLLLLTSEIDLPVKRRA. Molecular weight 2687.18 Da. Like MOTS-c, this mitochondrial DNA origin is fundamental to understanding the compound and the broader MDP class.
Discovered 2001 by Yuichi Hashimoto (Tokyo) using a cDNA library from the unaffected occipital lobe of an Alzheimer's patient, searching for the factor that protected those neurons. The unaffected brain region yielded the rescue factor. Foundational paper titled A rescue factor abolishing neuronal cell death by a wide spectrum of familial Alzheimer's disease genes and Aβ. Three different research groups identified Humanin nearly simultaneously through different approaches. 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. PNAS 2001;98(11):6336-6341.
Humanin is the founding member of the MDP class, preceding MOTS-c by 14 years. The MDP class established that mitochondrial DNA encodes bioactive peptides beyond the 13 canonical ETC proteins, recasting mitochondria as active endocrine organs rather than passive energy factories. Together with MOTS-c (12S rRNA, metabolic) and SHLPs 1-6 (also 16S rRNA, various), Humanin demonstrates a sophisticated mitochondrial-to-distal-tissue signaling system.
Primary mechanism: direct Bax inhibition (Guo et al. 2003, Nature). Humanin binds the pro-apoptotic Bax protein, preventing its activation and mitochondrial outer membrane translocation, blocking cytochrome c release and the downstream caspase cascade. This single mechanism explains Humanin's broad anti-apoptotic effects across cell types and apoptotic stimuli. Guo B, Zhai D, Cabezas E, et al. Humanin peptide suppresses apoptosis by interfering with Bax activation. Nature 2003;423:456-461.
S14G-Humanin (HNG) is 1000-fold more potent than wild-type. Single Serine→Glycine substitution at position 14 identified by Yamagishi et al. 2003 through systematic essential-amino-acid analysis. HNG is used in most modern Humanin research. Practical implication: the two forms are not interchangeable, and a potency or effect figure reported for HNG does not describe wild-type Humanin. Yamagishi Y, Hashimoto Y, Niikura T, Nishimoto I. Identification of essential amino acids in Humanin, a neuroprotective factor against Alzheimer's disease-relevant insults. Peptides 2003;24:585-595.
Multi-pathway mechanism extends well beyond Bax inhibition. Secondary mechanisms include: IGFBP-3 binding modulating IGF-1 signaling and cell survival (Ikonen et al. 2003, PNAS; Cohen co-author); GP130/IL6ST receptor complex activation triggering PI3K→AKT, MEK→ERK1/2, and JAK→STAT3 pathways (Kim et al. 2016, Oncotarget; modern receptor view); FPRL-1/FPRL-2 activation by the N-formyl form (Harada et al. 2004). The combination of mechanisms explains the wide therapeutic application. 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. PNAS 2003;100(22):13042-13047.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.
Plasma Humanin decreases substantially with aging. Cross-sectional studies document inverse correlation with age. Plasma levels decline ~50% from age 20 to 70 in some reports. This supports the broader MDP-loss-as-aging-mechanism hypothesis and provides theoretical rationale for supplementation in aging, though it does NOT establish that exogenous supplementation reverses aging.
Pinchas Cohen and the broader MDP framework. Cohen at USC Leonard Davis School of Gerontology connected Humanin to broader mitochondrial biology (co-authoring the 2003 IGFBP-3 paper), and subsequently discovered MOTS-c (2015, 12S rRNA) and the SHLPs (1-6, also 16S rRNA region near Humanin). Cohen's work transformed Humanin from 'interesting Alzheimer's-related peptide' to 'founding member of a new signaling class.' Founded CohBar Inc. for commercial MDP development.
The theoretical cancer concern is the central unresolved safety question. Cancer cells often resist apoptosis for survival; anti-apoptotic factors could theoretically protect tumor cells. Some research has shown selective protection of normal cells in chemotherapy contexts (reassuring), but long-term effects in cancer history remain unclear. Conservative approach: avoid in active malignancy or recent cancer history. Maintain age-appropriate cancer screening with heightened vigilance for users with personal/family cancer history.
Commercial development gap matches MOTS-c pattern. Despite 25 years of research and substantial preclinical evidence, no Humanin compound has reached commercial pharmaceutical approval. CohBar Inc. pursued MDP-based therapeutics but has had financial difficulties; Humanin specifically not advanced to late-stage trials. The gap reflects pharmaceutical economic challenges for endogenous-sequence peptides (limited patent protection, delivery challenges, slow human translation) rather than scientific failure.

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