AHK-Cu

AHK-Cu is the shorthand for L-alanyl-L-histidyl-L-lysine copper(II) complex, a synthetic tripeptide in which the amino acid sequence Ala-His-Lys (alanine, histidine, lysine) is chelated to a copper(II) ion. Its INCI (cosmetic ingredient) name is Copper Tripeptide-3, and its PubMed substance name is (alanyl-histidyl-lysine)copper(II).

AHK-Cu is structurally distinct from GHK-Cu (glycyl-L-histidyl-L-lysine copper complex, INCI: Copper Tripeptide-1), which is a different tripeptide that shares the copper-chelating histidine-lysine motif. The two compounds are often grouped together in cosmetic marketing but have separate amino acid sequences, different primary research focuses, and substantially different published evidence bases. GHK-Cu has several hundred indexed studies; AHK-Cu has one.

AHK-Cu is synthesized chemically (solid-phase peptide synthesis) and is not derived from a natural endogenous source. It appears primarily in leave-on cosmetic and topical research contexts, where it is often combined with other peptides in multi-ingredient formulations.

• Hair follicle elongation ex vivo A single published study using isolated human hair follicle organ cultures found that AHK-Cu at concentrations of 10^-12 to 10^-9 M stimulated measurable elongation of follicles compared to untreated controls.[1]
• Dermal papilla cell proliferation and survival In cell culture experiments using isolated human dermal papilla cells (DPCs), the same study found that AHK-Cu at 10^-9 M reduced markers of apoptosis, elevated the Bcl-2/Bax ratio (an indicator of cell survival signaling), and reduced cleaved caspase-3 and PARP levels, suggesting an anti-apoptotic effect on these follicle-supporting cells.[1]
• Dermal fibroblast biology (background context) The 2007 study cites prior unpublished or separately published work indicating that "the tripeptide-copper complex" stimulates dermal fibroblast proliferation, elevates vascular endothelial growth factor (VEGF) production, and decreases transforming growth factor-beta1 (TGF-beta1) secretion. This background work is cited as known context for AHK-Cu but is not independently indexed on PubMed as of mid-2026.[1]

The indexed evidence base for AHK-Cu is extremely thin. Exhaustive searches of PubMed using the compound's full chemical name, INCI name, abbreviation, and related search terms return one verifiable study: Pyo et al. (2007), conducted at Seoul National University's Department of Dermatology. [1] That study used ex vivo human hair follicle cultures and isolated dermal papilla cell cultures, both of which are in vitro models. No animal models, no human clinical trials, and no independent replications appear in PubMed-indexed literature as of mid-2026.

AHK-Cu is primarily a cosmetic ingredient. Its documented use appears in multi-peptide topical formulations, where it is typically combined with GHK-Cu or other copper-chelating peptides. The cosmetics industry sometimes references AHK-Cu alongside GHK-Cu as a "copper tripeptide complex" without distinguishing between the two compounds. Researchers and formulators should note that the evidence supporting GHK-Cu (Copper Tripeptide-1) does not automatically transfer to AHK-Cu (Copper Tripeptide-3). The two compounds have different amino acid sequences and different primary research records.

1. [1] Pyo 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. Archives of Pharmacal Research. 2007;30(7):834–9. PubMed ↗