AHK-Cu – Peptide Lexicon

AHK-Cu

Alanine-histidine-lysine copper complex

PreclinicalSkin· Copper Peptide

AHK-Cu is the copper(II) complex of the tripeptide L-alanyl-L-histidyl-L-lysine (AHK), mostly marketed by peptide suppliers as Copper Tripeptide-3; no CosIng entry of that name exists, and the registered INCI name Tripeptide-3 designates a different peptide (composed of glycine, serine and valine). It belongs to the same substance class as the far more extensively studied GHK-Cu, but is documented much more thinly in the scientific literature: the primary literature indexed on PubMed essentially amounts to a single ex vivo and cell culture study on human hair follicles (Pyo et al., 2007). In research, AHK-Cu therefore appears almost exclusively in the context of hair follicle and scalp research and in cosmetic formulations.

Published on Aug 12, 2026

Mechanism of action

No established mechanism of action exists for AHK-Cu. The central primary study (Pyo et al., 2007) reported that AHK-Cu at concentrations of 1 pM to 1 nM (10^-12 to 10^-9 M) stimulated the elongation of human hair follicles ex vivo and the proliferation of cultured dermal papilla cells. At 1 nM (10^-9 M), the Bcl-2/Bax ratio was elevated and the cleaved forms of caspase-3 and PARP were reduced, although the observed decrease in apoptotic papilla cells was not statistically significant. On this basis the authors discuss a combination of stimulated proliferation and reduced apoptosis of dermal papilla cells; no receptor or molecular target has been identified. Older statements about fibroblast effects (increased VEGF, decreased TGF-beta1) refer, in that publication's introduction, to the tripeptide-copper complex of the GHK-Cu literature rather than to AHK-Cu, and are not supported by independently published primary studies on AHK-Cu indexed on PubMed. Chemically, short histidine-containing peptides bind copper(II) ions, with coordination geometry and redox behaviour depending strongly on the sequence: for GHK-Cu and the albumin N-terminus peptide DAHK-Cu, crystal and solution structures including redox properties have been characterized (Hureau et al., 2011), whereas comparable structural data for the AHK-Cu complex are not available. Likewise, the mechanism discussed for GHK-Cu, copper delivery into cells with broad modulation of gene expression (Pickart & Margolina, 2018), has not been investigated for AHK-Cu and cannot be extrapolated to this substance.

State of evidence

The evidence on AHK-Cu is exclusively preclinical and unusually narrow even within that category. At the time of source verification (August 2026), a PubMed search for the substance essentially returns a single primary study: the ex vivo and cell culture work by Pyo et al. (2007) on human hair follicles and dermal papilla cells, in which part of the reported effects, the reduction of apoptotic cells, was not statistically significant. Beyond that, PubMed returns no further indexed primary contribution on AHK-Cu; whatever else circulates about the substance comes from manufacturer and supplier material and is not peer-reviewed literature. Controlled human trials are entirely lacking, as are published pharmacokinetic data including any systemic half-life, and no clinical development programme exists. AHK-Cu holds no marketing authorization as a medicine in any jurisdiction. The contrast with the related GHK-Cu is stark: GHK-Cu has a considerably more extensive, although likewise predominantly preclinical, literature, whereas the data base for AHK-Cu rests practically on a single research group and a single publication, with no independent replication. No conclusions about efficacy or safety in humans can be drawn from this evidence.

Storage and handling

Lyophilized peptides are generally stored cool, dry and protected from light; for long-term storage, temperatures around -20 °C are commonly cited in the literature. After reconstitution, peptide solutions are typically kept refrigerated at 2-8 °C in laboratory practice and used within a few days. These are generic peptide-handling notes; no product-specific stability data for AHK-Cu, for example on the behaviour of the copper complex in solution, have been published.

Questions about the research

What is AHK-Cu studied for in research?: AHK-Cu appears in the scientific literature almost exclusively in the context of hair follicle research: the central study examined the elongation of human hair follicles ex vivo and the proliferation of cultured dermal papilla cells (Pyo et al., 2007). In addition, the substance appears under the supplier name Copper Tripeptide-3 in scalp and skin care formulations; no CosIng entry of that name exists, and no independent controlled studies of such formulations have been published. No conclusions about effects in humans can be drawn from this evidence.
How does AHK-Cu differ from GHK-Cu?: Both are copper(II) complexes of tripeptides but differ in sequence: GHK-Cu is based on glycyl-L-histidyl-L-lysine, AHK-Cu on L-alanyl-L-histidyl-L-lysine. GHK was described in human serum in 1973 (Pickart & Thaler, 1973); no comparable endogenous role has been documented for AHK. The most important difference is the state of the evidence: GHK-Cu has an extensive, predominantly preclinical literature including characterized copper coordination chemistry, whereas AHK-Cu essentially rests on a single primary study without independent replication. Neither complex is approved as a medicine, and no reliable human data on efficacy or safety exist for either.

Sources

Pyo et al., Arch Pharm Res 2007DOI: 10.1007/BF02978833PMID: 17703734
Hureau et al., Chemistry 2011 (Cu-GHK/Cu-DAHK, nicht AHK-Cu)DOI: 10.1002/chem.201100751PMID: 21780203
Pickart & Margolina, Int J Mol Sci 2018 (Review zu GHK-Cu)DOI: 10.3390/ijms19071987PMID: 29986520
Pickart & Thaler, Nat New Biol 1973 (GHK, Kontext)PMID: 4349963

AHK-Cu

Alanine-histidine-lysine copper complex

PreclinicalSkin· Copper Peptide

Published on Aug 12, 2026

Mechanism of action

State of evidence

Storage and handling

Questions about the research

What is AHK-Cu studied for in research?

AHK-Cu appears in the scientific literature almost exclusively in the context of hair follicle research: the central study examined the elongation of human hair follicles ex vivo and the proliferation of cultured dermal papilla cells (Pyo et al., 2007). In addition, the substance appears under the supplier name Copper Tripeptide-3 in scalp and skin care formulations; no CosIng entry of that name exists, and no independent controlled studies of such formulations have been published. No conclusions about effects in humans can be drawn from this evidence.

How does AHK-Cu differ from GHK-Cu?

Both are copper(II) complexes of tripeptides but differ in sequence: GHK-Cu is based on glycyl-L-histidyl-L-lysine, AHK-Cu on L-alanyl-L-histidyl-L-lysine. GHK was described in human serum in 1973 (Pickart & Thaler, 1973); no comparable endogenous role has been documented for AHK. The most important difference is the state of the evidence: GHK-Cu has an extensive, predominantly preclinical literature including characterized copper coordination chemistry, whereas AHK-Cu essentially rests on a single primary study without independent replication. Neither complex is approved as a medicine, and no reliable human data on efficacy or safety exist for either.