GHK (Glycyl-Histidyl-Lysine)
/ Native tripeptide glycyl-histidyl-lysine (GHL); copper-free formALIAS · GHK · GHL · Glycyl-Histidyl-Lysine · Native GHL tripeptide
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Tier 3. The metal-free native tripeptide is foundational in the copper-peptide / wound-healing literature originating with Loren Pickart's group in the 1970s. Mechanistic and in-vitro / preclinical studies span five decades; controlled human trials of free GHK (as opposed to GHK-Cu) are sparse. The copper-bound form GHK-Cu has its own Open Assay page; this entry covers the metal-free native peptide.
Glycyl-L-histidyl-L-lysine (GHK) is a tripeptide originally isolated from human plasma by Loren Pickart in the early 1970s. The native peptide binds copper(II) with high affinity (apparent Kd in the nanomolar to picomolar range depending on conditions) and is generally considered to circulate predominantly as the copper-bound complex in plasma. The metal-free GHK form has been studied in cell-culture models for effects on collagen synthesis, fibroblast proliferation, and gene expression patterns associated with wound repair and antioxidant defence; many of the reported biological effects are stronger or only present when copper is supplied, leading to the focus on GHK-Cu as the canonical bioactive species.
Tier 3. Decades of in-vitro and rodent literature describe GHK and GHK-Cu effects on fibroblast biology, collagen and glycosaminoglycan synthesis, and wound healing in animal models. Pickart 2015 (Biomedical Research International review) summarises the gene-expression and clinical-context literature. Controlled human trials specifically of the metal-free GHK tripeptide are limited; most published human work uses topical GHK-Cu cosmetic formulations.
Topical GHK / GHK-Cu in cosmetic formulations has a long market history without a major safety signal in published surveillance. The metal-free form has been generally well tolerated in cell culture and in topical preclinical work. Systemic dosing of synthetic GHK has not been characterised in a formal Phase 1 trial database.
Regulatory status
- FDA status:
- Not FDA-approved
The metal-free GHK and the copper-bound GHK-Cu are pharmacologically distinct, and vendor product-labelling sometimes conflates them. Most cited biological activities require copper in the experimental system, and reproducibility across laboratories has been mixed in non-Pickart settings. The cosmetic-marketing claims for topical GHK serums exceed what the controlled-trial literature supports, and the bulk of human evidence comes from cosmetic-industry studies of specific finished formulations rather than from regulatory-grade clinical pharmacology.