AHK-Cu

AHK‑Cu is a peptide composed of alanine, histidine and lysine, with the copper ion coordinated by moieties of these three amino acids.⁽¹⁾ This peptide appears to occur naturally in blood and has been proposed as a potential agent for regulating the growth, development and apoptosis of vascular endothelial cells.

AHK‑Cu, also known as Copper‑AHK, has been investigated for its potential in hair growth and the maintenance of skin tissue integrity. The peptide is thought to exert its effects primarily on fibroblasts, which are responsible for producing and maintaining components of the extracellular matrix (ECM) surrounding cells. Fibroblasts also secrete a variety of biologically active substances, including vascular endothelial growth factor (VEGF), which is recognised to facilitate the formation of new blood vessels.

The copper ion within AHK‑Cu is believed to be involved in the activity of enzymes associated with collagen and elastin synthesis. These two proteins are key components of the extracellular matrix and play an essential role in sustaining the structural integrity of skin tissue. Copper ions are also reported to possess antioxidant properties.

Chemical Composition⁽²⁾

Molecular Formula: C₁₅H₂₅CuN₆O₄ Molecular Weight: 416.9 g/mol Other Designations: ALA‑HIS‑LYS‑CU, L‑Alanyl‑κN‑L‑histidyl‑κN,κN³‑L‑lysinato(2‑)]copper monohydrochloride

Research and Clinical Studies

Copper Peptides and Antioxidant Potential

Owing to its unique amino‑acid structure, AHK‑Cu is considered to exhibit potent antioxidant properties. Based on these antioxidant characteristics, studies indicate that it may have the capacity to enlarge hair‑follicle size and thereby promote hair growth. Multiple in‑vitro investigations focusing on the hair‑growth effects of this peptide have consistently demonstrated its potential to support hair‑follicle development. Beyond hair‑growth applications, researchers have suggested that AHK‑Cu may have broader uses covering cellular senescence, wound healing and other fields. It is hypothesised to stimulate the proliferation and survival of skin cells, a process critical for collagen biosynthesis. Collagen is an essential substance for maintaining skin‑cell renewal and function, and enhanced cellular activity triggered by AHK‑Cu may accelerate this process.⁽³⁾

Copper Peptides and Hair‑Follicle Development

Researchers hypothesise that the tripeptide AHK‑Cu is capable of stimulating the proliferation of dermal fibroblasts. These cells secrete mediators such as vascular endothelial growth factor (VEGF), a key regulator of blood‑vessel formation. AHK‑Cu may also reduce the secretion of transforming growth factor‑beta 1 (TGF‑β1) by skin fibroblasts.

In a recent study⁽⁴⁾, the hair‑growth‑promoting potential of AHK‑Cu was evaluated. Findings suggested the peptide could lengthen hair follicles and induce proliferation of dermal papilla cells (DPCs), specialised fibroblasts that drive hair‑follicle growth and maturation. In addition, the authors reported that AHK‑Cu treatment appeared to lower the number of apoptotic dermal papilla cells. Further analysis revealed that the peptide may raise the Bcl‑2/Bax ratio and decrease levels of cleaved caspase‑3 and PARP, two well‑established markers of cell death. The Bcl‑2/Bax ratio is a vital modulator of apoptosis: Bcl‑2 functions as an anti‑apoptotic protein that suppresses cell death, whereas Bax acts as a pro‑apoptotic protein that promotes apoptosis. A higher Bcl‑2/Bax ratio indicates dominance of anti‑apoptotic signalling, which can inhibit programmed cell death and improve cell survival. Ultimately, the investigators concluded that AHK‑Cu “stimulated […] hair‑follicle elongation and the proliferation of DPCs in‑vitro”. Based on these observations, the authors commented, “This study proposes that AHK‑Cu promotes […] hair‑follicle growth, and this stimulatory effect may be mediated by triggering DPC proliferation and counteracting apoptosis.”⁽⁴⁾ Other researchers reviewing this work noted that AHK‑Cu may interact with VEGF and transforming growth factor‑beta 1 (TGF‑β1). TGF‑β1 has been widely studied for its roles in cell proliferation, differentiation and apoptosis, and participates in multiple biological processes including immune regulation and wound repair. By potentially down‑regulating TGF‑β1, AHK‑Cu can modulate these cellular pathways, consequently influencing cell growth and immune responses at the cellular level. Meanwhile, VEGF is famous for its function in angiogenesis — the formation of new blood vessels from pre‑existing vasculature. Up‑regulation of VEGF induced by AHK‑Cu may enhance angiogenic activity, improving nutrient and oxygen delivery at the cellular level⁽⁵⁾. In particular, VEGF encourages vascular development around hair follicles; this effect facilitates the transport of nutrients and oxygen to follicles and consequently supports hair growth.

AHK‑Cu Peptide and Alopecia Research

One study assessed the biological potential of two formulations containing growth factors and peptides, including vascular endothelial growth factor, basic fibroblast growth factor, insulin‑like growth factor‑1, keratinocyte growth factor, copper tripeptide‑1, and related peptides such as AHK‑Cu, suspended within a sterile carrier system. In‑vitro keratinocyte and fibroblast assays were performed to test the potential cytotoxicity of these agents. The formulations were further evaluated for their capacity to boost hair growth and preserve follicle viability in cases of secondary alopecia⁽¹⁾.

The authors reported that both formulations yielded positive hair‑growth responses in animal models. Activity was also observed when the formulations were tested alongside agents linked to hair loss. As stated by researcher Rinky Kapoor et al., “The results appear sufficiently encouraging to warrant trials in […] secondary alopecia.”⁽¹⁾

Copper Peptides and Skin Tissue Integrity

Preliminary laboratory investigations have demonstrated that the core peptide molecule AHK can stimulate fibroblast growth and collagen production. Notably, AHK improves the survival and proliferation of dermal fibroblasts, cells renowned for synthesising key structural skin proteins such as collagen. In experiments conducted on healthy skin fibroblasts, AHK significantly enhanced cellular growth, viability and type‑I collagen synthesis. This conclusion was reached by quantifying type‑I collagen concentrations secreted by fibroblasts in cell cultures after exposure to different AHK concentrations. Research showed that AHK supplementation could triple type‑I collagen production relative to untreated control groups. These outcomes indicate that AHK possesses the potential to regenerate the extracellular matrix and restore normal skin function.⁽⁶⁾