Regulated as cosmetic ingredients

AHK-Cu

Last reviewed 2026-08-05

Reviewed by HelixEvoLabs Research Team

Technical and cosmetic-regulatory reference for AHK-Cu, a copper tripeptide for which registry identification and characterisation data are largely absent from primary sources.

Identity and nomenclature

INN: Not verified
INCI name: Not verified
Synonyms: L-alanyl-L-histidyl-L-lysine copper(II), Cu(II)AHK
Development codes: Not verified

Mechanism

AHK-Cu is described in the published literature as the copper(II) complex of the tripeptide L-alanyl-L-histidyl-L-lysine. No coordination-chemistry study of the copper complex has been published, so its stoichiometry, donor set and geometry are not established by measurement.

The tripeptide differs from glycyl-L-histidyl-L-lysine only by substitution of alanine for glycine at the N-terminal residue, which retains the N-terminal copper-binding motif. A comparable coordination mode would therefore be chemically reasonable.

That reasoning is inference, not evidence. A literature search returned no potentiometric, EPR, circular dichroism, calorimetric or crystallographic study of the copper-AHK system, so there are no measured stability constants, no measured speciation and no confirmed geometry for this compound. Any such value quoted elsewhere has been transferred from GHK-Cu.

Analytical data sheet

AHK-Cu

Identity

Molecular formula: Not verified
Molecular weight: Not verified
CAS number: Not verified
UNII: Not verified
Chemical name: Not verified
Appearance: Not verified

Primary structure

AHK

3 residues

Modifications

The free tripeptide is registered: alanylhistidyllysine, CAS 126828-32-8, UNII 1AVY5QO8WR, molecular formula C15H26N6O4, molecular weight 354.41. It has three defined stereocentres, one more than the glycine-containing analogue, because alanine is chiral.
No UNII exists for the copper complex. Five independent queries of the FDA substance registry returned no record, and the registry entry for the free peptide contains no relationship to any copper substance, in contrast to the corresponding glycyl analogue which carries explicit links to the cupric cation.
No CAS Registry Number for the copper complex could be verified. Two numbers circulate; both are well formed by check digit, but neither is attributable from an acceptable source, and one of them designates a monohydrochloride rather than the neutral complex. Neither is recorded here.
The INCI name Copper Tripeptide-3, which circulates widely for this compound, is wrong. The EU cosmetic inventory defines Tripeptide-3 as a synthetic peptide containing glycine, serine and valine residues. This compound is alanine-histidine-lysine. The three residues do not overlap at all, so Copper Tripeptide-3 designates a different substance and should not be accepted on an incoming specification as meaning AHK-Cu. This is a refutation rather than a failure to verify.
A second candidate designation exists and cannot be confirmed either. The EU inventory carries COPPER TRIPEPTIDE-34 and COPPER TRIPEPTIDE-34 HCL, both defined only as the complex formed by copper with Tripeptide-34, both listing skin conditioning as their sole function, and both carrying no registry number, no EC number and no safety opinion. The inventory holds no standalone entry for Tripeptide-34, so the definition is circular within the database and the residue composition cannot be established from it. Whether either entry denotes this compound remains open.

Solubility

No solubility data established from a primary source.

Storage

No storage conditions established from a primary source.

Stability

No stability data established from a primary source.

Analytical methods

No validated method or acceptance criterion is published for this compound in a primary source. Where an approved product exists, limits are commonly withheld from the public assessment record as commercially confidential.

Impurities and degradation products

No impurity profile established from a primary source.

Handling

No official safety source, REACH registration or harmonised classification was located for this substance. Occupational controls are set by the receiving facility under its own assessment, and cannot be inferred from data published for a related peptide.

Ingredient safety assessment

No expert-panel or committee opinion covering this compound was located.

Reported research findings

ex vivo
The study reported elongation of human hair follicles ex vivo and proliferation of dermal papilla cells in vitro. It reported that the observed reduction in the number of apoptotic dermal papilla cells was not statistically significant, alongside an elevated Bcl-2 to Bax ratio and reduced levels of the cleaved forms of caspase-3 and PARP.
Ex vivo human hair follicle organ culture with companion in vitro cultured human dermal papilla cells, at concentrations from 10 to the minus twelve to 10 to the minus nine molar, with annexin V and propidium iodide labelling, flow cytometry and Western blot
Limitations: This is the only primary study of this compound located in any acceptable source. There were no human subjects, only donor tissue. The apoptosis result, which is the finding most often repeated downstream, did not reach statistical significance in the paper itself; the supporting evidence was protein-level Western blot change. The authors framed their conclusion explicitly as a proposal rather than a demonstration.
review
The review classifies the evidence for this compound as experimental evidence in an ex vivo human hair follicle model, distinguishing it from compounds it classifies as having clinical evidence, and states that its signalling mechanism is less well characterised than that of the glycyl analogue.
Narrative review of short peptides investigated in relation to hair loss
Limitations: A secondary source. It is included to characterise the state of the evidence base rather than to report a finding about the compound.

Regulatory status by jurisdiction

United States
Cosmetic Ingredient Review / FDA
No established classification
No established classification. The Cosmetic Ingredient Review assessment covering related copper tripeptides states that its data and conclusions are not applicable to other peptide sequences, and a full-text search of that assessment returns no occurrence of this compound or its circulating INCI designation.
Safety Assessment of Tripeptide-1, Hexapeptide-12, their Metal Salts and Fatty Acyl Derivatives, and Palmitoyl Tetrapeptide-7 as Used in CosmeticsVerified 2026-07-30
European Union
European Commission
Cosmetic ingredient
No cosmetic ingredient database record could be found for this compound under any name searched. It appears in none of the annexes to Regulation (EC) No 1223/2009, and no Scientific Committee on Consumer Safety opinion covers it or copper peptides as a class. Its position therefore rests entirely on the general safety obligation rather than on any listing.
Consolidated Regulation (EC) No 1223/2009, annexes searched for this ingredientVerified 2026-07-31
United Kingdom
Office for Product Safety and Standards
Cosmetic ingredient
Lawful as a cosmetic ingredient in Great Britain on the same basis as any unlisted functional ingredient. It appears in none of the annexes to assimilated Regulation (EC) No 1223/2009, and the word tripeptide does not occur anywhere in the Great Britain annexes.
Regulation (EC) No 1223/2009, as assimilated law applying in Great BritainVerified 2026-07-31

Regulatory classification by jurisdiction, with source document and verification date
Jurisdiction	Classification	Summary	Source	Verified
United StatesCosmetic Ingredient Review / FDA	No established classification	No established classification. The Cosmetic Ingredient Review assessment covering related copper tripeptides states that its data and conclusions are not applicable to other peptide sequences, and a full-text search of that assessment returns no occurrence of this compound or its circulating INCI designation. The Cosmetic Ingredient Review conclusion reached for Copper Tripeptide-1 does not extend to this compound	Safety Assessment of Tripeptide-1, Hexapeptide-12, their Metal Salts and Fatty Acyl Derivatives, and Palmitoyl Tetrapeptide-7 as Used in Cosmetics	2026-07-30
European UnionEuropean Commission	Cosmetic ingredient	No cosmetic ingredient database record could be found for this compound under any name searched. It appears in none of the annexes to Regulation (EC) No 1223/2009, and no Scientific Committee on Consumer Safety opinion covers it or copper peptides as a class. Its position therefore rests entirely on the general safety obligation rather than on any listing. Absence from the annexes is not an approval. Compliance rests on the Article 3 general safety obligation, an Article 10 safety report prepared by a qualified assessor, a responsible person established in the territory, notification to the competent authority, and Article 19 labelling using the common ingredient nomenclature Copper is not prohibited as a class. Annex II lists individually named copper substances only, several restricted to hair dye products, and non-nano metallic copper is a permitted Annex IV colorant, reference 132, colour index 77400, without conditions Nanoparticulate and colloidal metallic copper are prohibited in the European Union under Annex II reference 1726, added by Commission Regulation (EU) 2024/858. This bites only on nano or colloidal copper raw material, not on this complex No confirmable common ingredient name exists for this compound, which is a labelling exposure under Article 19 rather than a prohibition	Consolidated Regulation (EC) No 1223/2009, annexes searched for this ingredient	2026-07-31
United KingdomOffice for Product Safety and Standards	Cosmetic ingredient	Lawful as a cosmetic ingredient in Great Britain on the same basis as any unlisted functional ingredient. It appears in none of the annexes to assimilated Regulation (EC) No 1223/2009, and the word tripeptide does not occur anywhere in the Great Britain annexes. Absence from the annexes is not an approval. Compliance rests on the Article 3 general safety obligation, an Article 10 safety report prepared by a qualified assessor, a responsible person established in the territory, notification to the competent authority, and Article 19 labelling using the common ingredient nomenclature Copper is not prohibited as a class. Annex II lists individually named copper substances only, several restricted to hair dye products, and non-nano metallic copper is a permitted Annex IV colorant, reference 132, colour index 77400, without conditions Great Britain has NOT adopted the European Union prohibition on nano and colloidal copper, and Annex II reference numbers have diverged between the two jurisdictions, so entries must not be cross-cited by number Northern Ireland follows the live European Union Regulation rather than the Great Britain consolidation, including the nano copper prohibition, and requires a responsible person established in Northern Ireland or the European Union The Cosmetic Ingredient Review conclusion reached for Copper Tripeptide-1 does not extend to this compound, and no Great Britain or European Union safety opinion covers it	Regulation (EC) No 1223/2009, as assimilated law applying in Great Britain	2026-07-31

Supply classification and permitted use

AHK-Cu is used as a cosmetic ingredient. It has no settled regulatory classification, no confirmed INCI designation and no expert-panel safety assessment covering it. Material is supplied to businesses as a cosmetic raw material for formulation and manufacturing purposes. No medicinal claims are made for it.

The safety assessment conclusions reached for Copper Tripeptide-1 do not extend to this compound, and the assessing body has said so explicitly.
Because no registry identifier for the copper complex could be verified, incoming material should be identified against a supplier specification and confirmed analytically rather than by registry number.
Responsibility for the safety assessment of a finished cosmetic product rests with the responsible person placing that product on the market.

How supply classifications work · Documented safety signals

References

[1]LegislationConsolidated Regulation (EC) No 1223/2009 on cosmetic products, consolidated text of 1 May 2026 — EUR-Lex, 2026 · accessed 2026-07-31
[2]LegislationRegulation (EC) No 1223/2009 on cosmetic products, as assimilated law applying in Great Britain — UK Statute Law Database, 2026 · accessed 2026-07-31
[3]LegislationThe Cosmetic Products Enforcement Regulations 2013 (S.I. 2013/1478) — UK Statute Law Database, 2013 · accessed 2026-07-31
[4]RegulatorRegulation 1223/2009 and the Cosmetic Products Enforcement Regulations 2013: Great Britain — Office for Product Safety and Standards, 2026 · accessed 2026-07-31
[5]NomenclatureCosIng ingredient record, TRIPEPTIDE-3 — European Commission, 2026 · accessed 2026-07-31
[6]NomenclatureCosIng ingredient records, COPPER TRIPEPTIDE-34 and COPPER TRIPEPTIDE-34 HCL — European Commission, 2026 · accessed 2026-08-05
[7]NomenclatureALANYLHISTIDYLLYSINE — Global Substance Registration System record, UNII 1AVY5QO8WR — US Food and Drug Administration, 2026 · accessed 2026-07-30
[8]Safety assessmentSafety Assessment of Tripeptide-1, Hexapeptide-12, their Metal Salts and Fatty Acyl Derivatives, and Palmitoyl Tetrapeptide-7 as Used in Cosmetics — Final Report — Cosmetic Ingredient Review, 2014 · accessed 2026-07-30
[9]Peer-reviewedPyo HK, Yoo HG, Won CH, Lee SH, Kang YJ, Eun HC, Cho KH, Kim KH. The effect of tripeptide-copper complex on human hair growth in vitro — Springer, Archives of Pharmacal Research, 2007 · doi:10.1007/BF02978833 · PMID 17703734 · accessed 2026-07-30
[10]Peer-reviewedFan C, Chen Y, Huang Q, et al.. Overview of Short Peptides for Hair Loss — MDPI, Biomedicines, 2026 · doi:10.3390/biomedicines14040864 · accessed 2026-07-30

Scope of this reference

This knowledge base is scientific and regulatory reference material for businesses. It is not medical advice, not a recommendation, and not product promotion. Regulatory classification differs by jurisdiction, by form and by route of administration, and a statement recorded for one territory does not describe the position in another.

HelixEVO does not supply medicinal products for human administration. Material is supplied to businesses for research and manufacturing purposes only. Where a compound holds no marketing authorisation, human administration outside an authorised clinical trial is not a lawful supply route.

Every regulatory and analytical statement carries its source and the date it was last verified. Where a value could not be established from a primary source it is recorded as unverified rather than estimated.