AHK-Cu
Summary
AHK-Cu is the copper complex of the tripeptide alanine-histidine-lysine, a synthetic analog of the natural copper peptide GHK-Cu with alanine replacing glycine as the first residue. In the principal human tissue study, picomolar-to-nanomolar AHK-Cu stimulated elongation of isolated human hair follicles and proliferation of cultured dermal papilla cells while shifting them away from apoptosis. All direct evidence is in vitro or ex vivo; no human trial of AHK-Cu exists.
Also known as: Copper Tripeptide-3, Ala-His-Lys Copper, L-Alanyl-L-Histidyl-L-Lysine Copper
Key Findings at a Glance
- • AHK-Cu at 10^-12 to 10^-9 molar stimulated elongation of human hair follicles ex vivo and proliferation of cultured dermal papilla cells (Pyo 2007), the only direct human tissue study.
- • Nanomolar AHK-Cu shifted dermal papilla cells away from apoptosis, raising the Bcl-2/Bax ratio and lowering cleaved caspase-3 and PARP.
- • AHK-Cu is a single-residue analog of GHK-Cu (alanine for glycine); nearly all broader claims are extrapolated from GHK-Cu research, not measured for AHK-Cu.
- • No human clinical trial of AHK-Cu has been published; delivery studies show intact skin is a major barrier to copper tripeptides, addressable with microneedling.
AHK-Cu Overview & Molecular Profile
AHK-Cu, known in cosmetics as copper tripeptide-3, is the Cu2+ complex of L-alanyl-L-histidyl-L-lysine. It is a synthetic analog of GHK-Cu (copper tripeptide-1), the naturally occurring plasma copper peptide, differing only at the N-terminal residue, where alanine replaces glycine. Interest in AHK-Cu centers on hair biology: a 2007 study from Seoul National University reported that AHK-Cu at 10^-12 to 10^-9 molar stimulated elongation of human hair follicles in organ culture and proliferation of cultured dermal papilla cells, with reduced apoptotic markers. Prior work on the tripeptide-copper complex, summarized in the same paper, reports increased VEGF and decreased TGF-beta1 secretion by dermal fibroblasts, both relevant to follicle cycling. Skin delivery of copper tripeptides is supported by in vitro penetration studies and microneedle-enhanced delivery of GHK-Cu through human skin. AHK-Cu appears in cosmetic serums, but no controlled human study of it has been published, and much of its presumed biology is extrapolated from GHK-Cu rather than measured directly.
Mechanism of Action: Cellular Health & Telomere Research
Copper is an essential cofactor for lysyl oxidase (collagen and elastin crosslinking), superoxide dismutase, and other enzymes, and small histidine-containing peptides serve as delivery vehicles that carry Cu2+ into cells; the histidine residue coordinates the metal. In cultured human dermal papilla cells, nanomolar AHK-Cu promoted proliferation and shifted cells away from apoptosis, elevating the Bcl-2/Bax ratio and reducing the cleaved forms of caspase-3 and PARP. Reported class effects of the tripeptide-copper complex on dermal fibroblasts - increased VEGF production and decreased TGF-beta1 secretion - point toward improved perifollicular vascularization and counteraction of a cytokine implicated in follicle miniaturization. The broader gene-modulating activity documented for GHK-Cu (thousands of genes involved in tissue remodeling and antioxidant defense) is extrapolated to AHK-Cu by structural analogy and has not been measured for AHK-Cu itself.
Research-Observed Effects
Hair Follicle Elongation (Ex Vivo)
Preliminary ResearchThe single direct study (Pyo et al., 2007, Archives of Pharmacal Research) reported that AHK-Cu at 10^-12 to 10^-9 molar stimulated elongation of human hair follicles maintained in organ culture. The effect occurred at remarkably low concentrations, suggesting a signaling rather than nutritional mechanism. This is one study from one laboratory, with no in vivo or human replication.
Dermal Papilla Cell Proliferation and Survival
Preliminary ResearchIn the same 2007 study, nanomolar AHK-Cu increased proliferation of cultured human dermal papilla cells, the mesenchymal cells that govern follicle cycling. Flow cytometry showed a trend toward fewer apoptotic cells, and molecular readouts showed an elevated Bcl-2/Bax ratio with reduced cleaved caspase-3 and cleaved PARP at 10^-9 molar, a coherent anti-apoptotic signature. Evidence remains limited to this single in vitro dataset.
VEGF and TGF-beta1 Modulation
Preliminary ResearchBackground work on the tripeptide-copper complex, summarized in the Pyo 2007 paper, reports that it elevates vascular endothelial growth factor production while decreasing transforming growth factor-beta1 secretion in dermal fibroblasts. Both effects are relevant to hair biology: VEGF supports perifollicular blood supply, and TGF-beta1 is implicated in androgen-driven follicle miniaturization. These findings are indirect for AHK-Cu itself and derive from earlier work on the copper tripeptide class.
Skin Remodeling Support
Preliminary ResearchAHK-Cu is used in cosmetic formulations for skin texture and firmness, a rationale extrapolated from GHK-Cu, for which a 2018 review documents stimulation of collagen, elastin, and glycosaminoglycan synthesis, support of dermal fibroblast function, and modulation of thousands of genes tied to tissue repair and antioxidant defense. Equivalent direct datasets do not exist for AHK-Cu, so class-level expectations should be attributed to the parent peptide, not assumed proven for the analog.
Topical Delivery Feasibility
Preliminary ResearchCopper tripeptides are hydrophilic and penetrate intact skin poorly, but delivery studies support feasibility: copper peptide complexes permeated stratum corneum models in Franz diffusion cell experiments, and polymeric microneedle pretreatment enabled substantial delivery of GHK-Cu through excised human skin without obvious irritation. These studies used GHK-Cu or model copper complexes, not AHK-Cu specifically, but the shared physicochemical class makes the delivery findings relevant.
Safety & Tolerability
AHK-Cu has no published human safety trials: the only direct evidence is in vitro and ex vivo work on human hair follicles and dermal papilla cells. Class-level reassurance comes from long cosmetic use of copper tripeptides and from GHK-Cu studies, not from AHK-Cu itself, and cumulative copper exposure from chronic topical use has not been characterized.
Human data: No published human clinical trials for AHK-Cu. Human exposure occurs through cosmetic products containing copper tripeptide-3, for which no peer-reviewed safety evaluation exists.
Regulatory status: Marketed as a cosmetic ingredient (copper tripeptide-3); not an approved drug for any indication.
- PubMed 17703734
The only direct AHK-Cu study is in vitro and ex vivo (hair follicle organ culture and dermal papilla cell culture) and reports no toxicity endpoints relevant to human exposure; anti-apoptotic effects were seen at nanomolar concentration.
In-vitro - PubMed 25690343
In microneedle-enhanced delivery of the related GHK-Cu through excised human skin, no obvious skin irritation was observed in cellular and porcine models, but the study was a delivery feasibility experiment, not a safety trial, and systemic copper exposure was not assessed.
In-vitro - PubMed 29986520
The GHK-Cu class modulates thousands of genes involved in tissue remodeling and inflammation, implying potent biological activity whose long-term consequences at cosmetic exposure levels are unstudied for AHK-Cu.
Theoretical
Research Protocol Doses Reported in Published Literature
Research Disclaimer: Doses reported below are from published preclinical research protocols. AHK-Cu is not approved by the US FDA for human use; regulatory status can differ in other countries, so see the regulatory status note in the safety section of this page. This information is provided for research reference only and does not constitute a dosing recommendation.
No human dosing has been established in published research. The single direct human tissue study used 10^-12 to 10^-9 molar concentrations in hair follicle organ culture and dermal papilla cell culture. Commercial cosmetic serums commonly incorporate copper tripeptides at fractions of a percent, but no concentration has been validated for AHK-Cu in a controlled human study.
All doses above are reported from published research protocols using laboratory subjects. Refer to the cited studies in the Research Studies section above for original source data.
Research Studies & References
The effect of tripeptide-copper complex on human hair growth in vitro
Pyo HK, Yoo HG, Won CH, et al.
Archives of Pharmacal Research (2007)
The defining study of AHK-Cu evaluated its effects on human hair growth ex vivo and on cultured human dermal papilla cells. AHK-Cu (L-alanyl-L-histidyl-L-lysine-Cu2+) at 10^-12 to 10^-9 molar stimulated elongation of human hair follicles in organ culture and increased proliferation of dermal papilla cells. Mechanistically, 10^-9 molar AHK-Cu elevated the Bcl-2/Bax ratio and reduced cleaved caspase-3 and cleaved PARP, indicating suppression of apoptosis, though the reduction in apoptotic cell counts did not reach statistical significance. The paper also summarizes prior findings that the tripeptide-copper complex elevates VEGF and decreases TGF-beta1 secretion by dermal fibroblasts. The authors proposed that AHK-Cu promotes hair growth by stimulating dermal papilla cell proliferation and precluding their apoptosis.
Regenerative and Protective Actions of the GHK-Cu Peptide in the Light of the New Gene Data
Pickart L, Margolina A
International Journal of Molecular Sciences (2018)
This comprehensive review of GHK-Cu, the parent compound of AHK-Cu, synthesizes gene-expression data showing that the copper tripeptide modulates thousands of human genes involved in tissue repair, antioxidant defense, and inflammatory regulation. Documented actions include stimulation of blood vessel and nerve outgrowth, increased collagen, elastin, and glycosaminoglycan synthesis, and support of dermal fibroblast function. Because AHK-Cu differs from GHK-Cu by a single N-terminal residue, this review is the principal source for class-level biology, but its data was generated on GHK-Cu and should not be cited as direct evidence for AHK-Cu.
Microneedle-Mediated Delivery of Copper Peptide Through Skin
Li H, Low YS, Chong HP, et al.
Pharmaceutical Research (2015)
This delivery study addressed the central pharmacokinetic problem of topical copper tripeptides: their hydrophilicity limits skin absorption. Polymeric microneedle pretreatment of excised human skin enabled delivery of GHK-Cu - 134 nanomoles of peptide and 705 nanomoles of copper permeating over 9 hours, versus essentially none through intact skin - with no obvious signs of irritation in cellular and porcine models. Although performed with GHK-Cu, the study quantifies the skin-barrier constraint that applies equally to AHK-Cu and supports microneedle-assisted delivery as a research strategy for the copper tripeptide class.
Biological activities of selected peptides: skin penetration ability of copper complexes with peptides
Mazurowska L, Mojski M
Journal of Cosmetic Science (2008)
This early formulation-relevant study measured penetration of copper complexes with tripeptides (GHK-Cu and GSH-Cu) through membranes modeling the stratum corneum in Franz diffusion cells. The copper complexes permeated the model horny-layer membranes, and the peptide carrier influenced the dynamics of copper ion diffusion. The work established that peptide complexation shapes transdermal copper delivery, a principle underlying all cosmetic copper tripeptides including AHK-Cu.
Frequently Asked Questions
What is the difference between AHK-Cu and GHK-Cu?
Both are copper-carrying tripeptides that differ only in the first amino acid: GHK-Cu is glycine-histidine-lysine copper (copper tripeptide-1), a peptide naturally present in human plasma, while AHK-Cu is alanine-histidine-lysine copper (copper tripeptide-3), a synthetic analog. GHK-Cu has decades of research including gene-expression profiling; AHK-Cu has one direct human tissue study, focused on hair follicles. Claims made for AHK-Cu are largely extrapolated from GHK-Cu biology.
Does AHK-Cu regrow hair?
The direct evidence is one 2007 study: AHK-Cu at picomolar-to-nanomolar concentrations elongated human hair follicles in organ culture and stimulated dermal papilla cell proliferation with anti-apoptotic effects. There are no published human trials, animal hair-growth studies, or controlled cosmetic studies of AHK-Cu. Whether these ex vivo findings translate to regrowth on a human scalp is unknown.
Is AHK-Cu safe on skin?
No AHK-Cu-specific human safety study has been published. Copper tripeptides as a class have been used in cosmetics for years, and a microneedle delivery study of the related GHK-Cu through human skin reported no obvious irritation, but formal sensitization, irritation, and long-term exposure data for AHK-Cu do not exist. Concentrated leave-on products also raise an unstudied question of cumulative copper exposure.
Why does the peptide carry copper?
Copper is a required cofactor for enzymes central to skin biology, including lysyl oxidase, which crosslinks collagen and elastin, and superoxide dismutase, a frontline antioxidant enzyme. Small histidine-containing peptides bind Cu2+ through the histidine residue and act as delivery vehicles that bring copper into cells. The tripeptide-copper complex also shows signaling effects - on VEGF and TGF-beta1 secretion - beyond simple mineral delivery.
How is AHK-Cu studied and formulated in research?
The direct human tissue study used 10^-12 to 10^-9 molar in follicle organ culture and dermal papilla cell culture. Delivery research on the copper tripeptide class shows intact skin is a substantial barrier: Franz cell models show slow permeation, and microneedling or microemulsion systems increase transport severalfold. Cosmetic serums use fractional-percent concentrations, but no published study validates any specific concentration for AHK-Cu.
Related Peptides
View allGHK-Cu
GHK-Cu is a naturally occurring copper complex of the tripeptide glycyl-L-histidyl-L-lysine. It has been extensively studied for wound healing, skin rejuvenation, and tissue remodeling.
PTD-DBM
PTD-DBM is a 25-amino acid fusion peptide designed to reactivate Wnt/beta-catenin signaling in hair follicles by competitively disrupting the CXXC5-Dishevelled interaction.
SNAP-8
SNAP-8 is a synthetic peptide designed to reduce wrinkles by modulating neuromuscular junction activity. It is an extension of the hexapeptide Argireline.
Follow Peptpedia on Google
Add Peptpedia as a Preferred Source and Google can highlight our links with a "preferred" badge in your Top Stories and AI Overviews.