Skin and cosmetic

GHK-Cu is a natural copper-binding tripeptide (glycyl-histidyl-lysine plus copper) the body uses in tissue repair, and levels fall with age. In plain terms: applied to skin it signals collagen and healing, which is why it is a popular anti-aging skincare ingredient.

Melanotan I (afamelanotide) is an analog of alpha-MSH, the hormone that tells skin to make the pigment melanin. In plain terms: it builds a slow, even, protective tan and shifts your skin toward real sun defense. It is FDA-approved (as Scenesse) for a rare light-sensitivity disorder.

Argireline (acetyl hexapeptide-8) is a cosmetic peptide that mildly limits the release of the signal muscles use to contract. In plain terms: applied topically, it softens fine expression lines a bit like a gentle, needle-free version of Botox.

SNAP-8 (acetyl octapeptide-3) is a longer cousin of Argireline used in skincare. In plain terms: applied to the skin, it relaxes the tiny muscles under expression lines to soften forehead and eye wrinkles.

Matrixyl (palmitoyl pentapeptide-4) is a cosmetic peptide that signals skin to rebuild collagen. In plain terms: used in serums over time, it firms skin and smooths fine lines.

Palmitoyl Tripeptide-1 is a cosmetic collagen-signal peptide, often paired with Matrixyl. In plain terms: applied to skin, it tells the skin to make more collagen to firm and smooth.

Tetrapeptide-21 is a cosmetic peptide that boosts skin's production of collagen and hyaluronic acid. In plain terms: used topically, it helps skin look firmer and plumper.

PTD-DBM is a peptide designed to switch a hair-growth signal back on. Your body uses a pathway called Wnt to decide when follicles grow, and a protein called CXXC5 acts as a brake on it. PTD-DBM gets in the way of that brake. In plain terms: it is meant to take the handbrake off hair growth. Everything published about it is from mice, and almost all of it comes from the one laboratory that invented it.

AHK-Cu is a copper peptide, the same family as GHK-Cu. It is three amino acids holding a copper atom, and copper is genuinely needed for building skin and blood vessels. It is sold mostly for hair rather than skin. In plain terms: it is the same idea as GHK-Cu with far less research behind it.

Acetyl Tetrapeptide-3 is a four amino acid peptide used almost entirely in scalp and hair products. It is meant to strengthen the tissue that anchors a hair follicle by prompting cells to make more of the surrounding matrix, particularly collagen and laminin.

Biotinoyl Tripeptide-1 is the same three amino acid sequence as GHK, the copper peptide, with a biotin molecule attached instead of copper. It is used almost exclusively in hair, eyelash and eyebrow products.

Palmitoyl Tetrapeptide-7 is a four amino acid sequence taken from immunoglobulin G, an immune protein, with a fatty palmitoyl tail added so it can cross the skin barrier. It is used for its calming effect rather than as a collagen builder.

Palmitoyl Tripeptide-5 is a three amino acid sequence with a fatty palmitoyl tail, sold under the trade name Syn-Coll. Unlike Matrixyl, which mimics a collagen fragment, this one is described as activating a growth factor that in turn drives collagen production.

SYN-AKE is a small synthetic peptide designed to imitate waglerin-1, a component of temple viper venom. It is sold for expression lines, working on the receiving side of the nerve-to-muscle junction rather than the sending side that Argireline targets.

GHK is the three amino acid sequence glycyl-histidyl-lysine, found naturally in human plasma. Sold without a copper ion attached, it is a different product from GHK-Cu, and the copper is not an inert addition.

Vialox is the trade name for pentapeptide-3, a five-amino-acid cosmetic peptide. In plain terms: it is meant to soften expression lines by blocking the signal that tells a facial muscle to contract.

Leuphasyl is the trade name for pentapeptide-18, a five-amino-acid cosmetic peptide modelled on enkephalin. In plain terms: it is meant to quiet the nerve that tells a facial muscle to contract, softening expression lines.

Progeline is the trade name for trifluoroacetyl tripeptide-2, a three-amino-acid cosmetic peptide. In plain terms: it targets slackness along the jaw and neck rather than fine lines, by acting on a protein linked to cell aging.

Decapeptide-12 is a ten-amino-acid cosmetic peptide sold as Lumixyl. In plain terms: it slows the enzyme that makes skin pigment, so it is used on dark spots and uneven tone.

Nonapeptide-1 is a nine-amino-acid cosmetic peptide sold as Melanostatine-5. In plain terms: it blocks the hormone signal that tells skin cells to make pigment, so it is used on dark spots and uneven tone.

Hexapeptide-11 is a six-amino-acid cosmetic peptide originally identified in yeast extract and now made synthetically. In plain terms: it is sold for skin elasticity and firmness, with little published to back it.

Acetyl tetrapeptide-5 is a four-amino-acid cosmetic peptide sold as Eyeseryl. In plain terms: it is used in eye creams for puffiness and bags rather than for wrinkles.

Myristoyl pentapeptide-17 is a cosmetic peptide with a fatty acid attached, used in eyelash and eyebrow serums. In plain terms: it is meant to make lashes look longer and thicker by supporting keratin production.

Oligopeptide-1 is the cosmetic name for epidermal growth factor, a 53-amino-acid human protein made by recombinant methods. In plain terms: it is a genuine growth signal used in repair-focused skincare, and it is not a small peptide like the rest of this category.

Melanotan III is a name that appears on vendor shelves alongside Melanotan I and II. In plain terms: no published source describes what molecule the name refers to.