Cosmetic Peptides

Glycyl-L-histidyl-L-lysine Copper

GHK-Cu is the copper(II) complex of the human tripeptide Gly-His-Lys, first identified in plasma by Loren Pickart in 1973. Peer-reviewed evidence is strongest for TOPICAL use — controlled human studies of ~2% creams show improvements in photoaged skin (fine lines, firmness, density). Microarray work by Pickart and colleagues reports modulation of thousands of genes involved in tissue repair, DNA repair, antioxidant defense, and anti-inflammation. Subcutaneous injection is a grey-market practice without controlled human trial support; community SubQ protocols typically use 1–2 mg but have no clinically validated dose. Researchers monitoring SubQ use often track serum copper, ceruloplasmin, and ferritin.

MT-2

Melanotan II (MT-II) is a cyclic heptapeptide analog of alpha-melanocyte-stimulating hormone (α-MSH) — Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2 — developed at the University of Arizona in the 1980s by Hruby, Hadley, and colleagues as a candidate photoprotection / sunless-tanning agent. It has never been approved by the FDA or any other regulator for any indication; clinical development was abandoned and it is sold only via grey-market research-chemical channels. Genuine safety signals have been reported, including darkening of existing moles, eruptive atypical nevi, and case reports of new primary melanoma in young tanning-seeking users.

AHK Copper Peptide

AHK-Cu is a copper-binding tripeptide (Ala-His-Lys-Cu) structurally related to GHK-Cu, studied in dermatological research for its role in extracellular matrix remodeling and hair follicle signaling.

Afamelanotide

Melanotan I (Afamelanotide) is a synthetic analog of alpha-MSH that selectively activates MC1R. FDA-approved as Scenesse for erythropoietic protoporphyria (EPP), it is distinct from Melanotan II and is studied for melanogenesis and photoprotection.

Glycyl-L-Histidyl-L-Lysine

GHK is the parent tripeptide Gly-His-Lys, originally isolated from human plasma by Loren Pickart (1973) as an activity that caused aged hepatocytes to synthesize proteins like younger tissue. It is DISTINCT from GHK-Cu, the 1:1 copper(II) complex tracked as a separate entry — but GHK binds copper readily in vivo, so in physiological environments the bare peptide rapidly associates with available Cu(II). Not FDA-approved for any indication; used in cosmetic and research contexts only.

Acetyl Octapeptide-3

SNAP-8 is a topical cosmetic peptide derived from SNAP-25, marketed as an alternative to topical Argireline for expression-line reduction.