Cosmetic & Dermal — 8 Compounds Compared

What this category covers

Cosmetic and dermal research compounds fall into three mechanistically distinct groups, and conflating them is the most common source of confusion in this category.

Copper-binding tripeptides — GHK-Cu and AHK-Cu — carry a copper(II) ion and are studied in the context of extracellular-matrix remodelling, collagen and glycosaminoglycan synthesis, and follicular research. Their activity is inseparable from the bound copper; the apo-peptide is a different subject of study.

Cosmetic signal peptides — Matrixyl, Argireline and SNAP-8 — are studied almost exclusively in topical formulation research. Argireline and SNAP-8 are SNARE-complex-targeting sequences investigated for their effect on neurotransmitter vesicle docking, a mechanistically different question from Matrixyl's matrix-signalling research.

Melanocortin receptor agonists — Melanotan I and Melanotan II — are alpha-MSH analogs studied in melanogenesis research. Melanotan I is the more receptor-selective earlier-generation compound; Melanotan II is a shorter cyclic analog with broader melanocortin-receptor activity, which is why the two appear in different research literatures despite the shared name.

Context matters as much as mechanism. The signal peptides are studied in topical formulations, where penetration through the stratum corneum is itself a research variable and molecular weight largely determines whether a sequence is a plausible topical candidate. The copper tripeptides appear in both topical and injected research contexts. The melanocortin analogs appear in systemic contexts only. Reading a study without noting which context applies is the fastest way to draw a wrong conclusion here.

Every entry in this category, side by side

All 8 compounds PeptiDex documents under Cosmetic & Dermal, on the specifications that actually separate one entry from another. Values are reproduced from each entry's own record; follow any name for the full research overview.

Every Cosmetic & Dermal entry in the PeptiDex library, compared on compound class, residue count, molecular weight and reported half-life.
Entry	Compound class	Length (aa)	Molecular weight	Reported half-life
GHK-Cu	Copper-binding tripeptide	3	340.4 Da	Not listed
Melanotan II	Melanocortin receptor agonist	7	~1024 g/mol	~30-60 minutes (plasma, subcutaneous)
SNAP-8	Cosmetic signal peptide	8	~1075 Da	Not listed
Matrixyl	Cosmetic signal peptide	5	~802 Da	Not listed
Argireline	Cosmetic signal peptide	6	~889 g/mol	Not listed
AHK-Cu	Copper-binding tripeptide	3	~354 Da	Not listed
Melanotan I	Melanocortin receptor agonist	13	~1646 g/mol	~0.8-1.7 h (free peptide, SC beta-phase); ~15 h apparent for the Scenesse implant
GLOW Blend (BPC-157 + TB-500 + GHK-Cu)	Multi-component research blend	Not listed	Not listed	Not listed

Of the 8 compounds above, 7 carry a published molecular weight, 2 have a reported half-life, 7 have a documented residue count and 7 have a published amino-acid sequence. No half-life is recorded for GHK-Cu, SNAP-8, Matrixyl, Argireline and 2 others.

A cell reading "Not listed" is a gap in the published record, not an omission on this page. PeptiDex records a specification only where a source documents it. Some entries here are blends or multi-component preparations, which have no single molecular weight to report at all. Where a value has never been established in the published literature the cell says so, rather than carrying an estimate — a plausible-looking number would make the table read as complete while making it wrong.

Mechanisms represented in this category

The 8 compounds here resolve into 4 compound classes, 3 of which are shared by more than one entry. Entries inside a group carry the same stated class; entries in different groups are not interchangeable, however similar their research context looks.

Cosmetic signal peptide 3 entries

SNAP-8 — SNAP-8 is a topically applied peptide reported to mimic a segment of the SNAP-25 protein, competing with SNAP-25 in the SNARE complex that mediates neurotransmitter (catecholamine) vesicle docking and release.
Matrixyl — Matrixyl couples a matrikine pentapeptide (KTTKS, a fragment derived from type I collagen) to a palmitoyl group that improves skin penetration.
Argireline — Argireline is a topical hexapeptide modeled on the N-terminus of SNAP-25, a component of the SNARE complex that mediates vesicle docking and neurotransmitter release.

Copper-binding tripeptide 2 entries

GHK-Cu — GHK has a high affinity for copper(II) and is understood to act partly as a copper-delivery molecule, facilitating copper transport relevant to enzymatic and remodeling processes.
AHK-Cu — Like other copper tripeptides, AHK-Cu binds copper(II) and is used to deliver copper in cosmetic applications.

Melanocortin receptor agonist 2 entries

Melanotan II — Melanotan II is a cyclic heptapeptide that acts as a non-selective agonist across melanocortin receptors, including MC1R and MC4R.
Melanotan I — Melanotan I is a superpotent, more metabolically stable analog of alpha-MSH that acts as an agonist at melanocortin receptors, with high activity at MC1R.

Multi-component research blend

GLOW Blend (BPC-157 + TB-500 + GHK-Cu) — As a blend, GLOW combines the documented properties of its components: BPC-157's angiogenesis and growth-factor-related repair signaling, TB-500's actin regulation and cell-migration activity, and GHK-Cu's copper-delivery and extracellular-matrix remodeling signaling.

Each line is the opening sentence of that entry's own mechanism record, reproduced verbatim. The full mechanism, the research areas behind it and the evidence level sit on the entry's page.

How the compounds in this category differ

Sharing a category does not make two compounds substitutes. Each note below is the differentiator recorded on that entry — the property that separates it from the others in the table.

GHK-Cu

A copper-binding tripeptide studied in dermal-research and tissue-remodeling contexts.

GHK-Cu is the most established copper tripeptide in cosmetic use, distinguished from AHK-Cu by its sequence and from repair peptides like BPC-157 by its remodeling and copper-delivery focus.

Melanotan II

A synthetic analog of α-MSH studied in melanogenesis research.

Melanotan II is a cyclic, non-selective melanocortin agonist (MC1R and MC4R), distinguishing it from the linear, more MC1R-focused Melanotan I and from the MC4R-selective PT-141.

SNAP-8

An octapeptide studied in cosmetic-research and topical formulation contexts.

SNAP-8 is an elongated (octapeptide) analog of the hexapeptide Argireline, marketed for greater SNAP-25 mimicry, versus collagen-signaling matrikines like Matrixyl.

Matrixyl

A palmitoyl pentapeptide studied in collagen-research and topical applications.

Matrixyl works via matrikine collagen-stimulation signaling rather than the neurotransmitter/SNARE modulation attributed to Argireline and SNAP-8.

Argireline

A hexapeptide studied in cosmetic muscle-relaxation research.

Argireline is the original SNAP-25-mimicking hexapeptide; SNAP-8 is its elongated analog, and both differ from collagen-signaling matrikines like Matrixyl.

AHK-Cu

A copper-binding tripeptide studied alongside GHK-Cu in dermal and follicular research contexts.

AHK-Cu differs from GHK-Cu by a single amino acid and is more often associated with hair-related cosmetic applications, with a comparatively limited evidence base.

Melanotan I

A synthetic analog of α-MSH studied in melanogenesis research, the earlier-generation counterpart to Melanotan II.

Unlike Melanotan II, Melanotan I (afamelanotide) is a linear alpha-MSH analog with an approved clinical form (Scenesse) and comparatively MC1R-focused pigmentation activity.

GLOW Blend (BPC-157 + TB-500 + GHK-Cu)

A research-supplier blend combining BPC-157, TB-500, and GHK-Cu, three peptides referenced in dermal and tissue-repair research contexts.

GLOW is oriented toward combined skin and tissue-repair research, adding the copper tripeptide GHK-Cu to the BPC-157/TB-500 pairing found in simpler blends.

Commonly co-studied pairs

Pairings documented on the entries themselves, with the reason each is co-referenced. Cross-referencing research context is not a combination recommendation, and PeptiDex gives no protocol, ratio or dosing guidance.

Within Cosmetic & Dermal

GHK-Cu + Matrixyl — Both are collagen-fragment-derived signaling peptides studied together in topical anti-aging formulation research.
Melanotan II + Melanotan I — The sibling alpha-MSH analog; frequently compared side-by-side in pigmentation research for receptor selectivity and duration.
SNAP-8 + Argireline — The parent hexapeptide SNAP-8 was extended from; frequently combined or compared in topical expression-line research.
SNAP-8 + Matrixyl — Commonly paired in cosmetic formulations, combining SNAP-8's neuro-signaling analogy with Matrixyl's collagen-stimulating mechanism.
Matrixyl + Argireline — Complementary mechanisms (collagen signaling vs expression-line relaxation) make them a classic topical anti-aging pairing.
AHK-Cu + GHK-Cu — The closely related copper tripeptide; frequently compared and sometimes combined in skin- and hair-focused copper-peptide research.
AHK-Cu + Matrixyl — Pairs a copper-signaling peptide with a collagen-stimulating peptide in topical cosmetic formulations.
GLOW Blend (BPC-157 + TB-500 + GHK-Cu) + GHK-Cu — A core GLOW component; contributes copper delivery and collagen/matrix remodeling within the blend.

Reaching into other categories

GHK-Cu + BPC-157 — Co-studied in tissue-repair blends where GHK-Cu contributes matrix remodeling alongside BPC-157's angiogenic activity.
GHK-Cu + TB-500 — Paired in recovery-oriented research blends (e.g. GLOW) combining cell-migration and copper-peptide remodeling effects.
Melanotan II + PT-141 (Bremelanotide) — PT-141 is a melanocortin metabolite of MT-II studied specifically for sexual-response pathways, making the two closely related in melanocortin research.
GLOW Blend (BPC-157 + TB-500 + GHK-Cu) + BPC-157 — A core GLOW component; contributes angiogenic tissue-repair signaling within the blend.

2 further pairings are documented on the individual entries. Each note is reproduced from the entry that records the pairing.

What this category is studied for

Research areas drawn from the 8 compounds in this category, deduplicated and ordered by how many entries list them. A further 12 research areas are listed across the individual entries.

Listing a research area records where a compound has been studied. It is not a claim of efficacy, an indication, or a suggestion of human use.

Category questions

How many compounds does PeptiDex list under Cosmetic & Dermal?

8: GHK-Cu, Melanotan II, SNAP-8, Matrixyl, Argireline, AHK-Cu, Melanotan I and GLOW Blend (BPC-157 + TB-500 + GHK-Cu). Each has its own research overview covering compound class, mechanism, studied research areas, specifications and entry-specific questions.

Why do some entries show "Not listed" instead of a molecular weight or half-life?

Because PeptiDex records a specification only where a source documents it. In this category 7 of 8 entries have a published molecular weight and 2 have a reported half-life. Some entries here are blends or multi-component preparations, which have no single molecular weight to report; for the rest, the value has simply not been established in the published literature. An estimate there would look like data and function as a guess, so the gap is shown instead.

What compound classes are represented in this category?

4 distinct classes across the 8 compounds: Copper-binding tripeptide, Melanocortin receptor agonist, Cosmetic signal peptide and Multi-component research blend. Entries sharing a class are grouped together in the mechanisms section; the comparison table lists each entry's full class verbatim, qualifiers included.

Which entries in this category are studied together?

GHK-Cu and Matrixyl are cross-referenced on each other's entries: Both are collagen-fragment-derived signaling peptides studied together in topical anti-aging formulation research. The co-studied pairs section lists the rest. Co-reference describes how the literature groups compounds; it is not a combination recommendation and no ratios or protocols are given.

Are the compounds in this category approved for human use?

PeptiDex documents all 8 entries strictly for research and educational purposes and provides no dosing, protocol or human-use guidance. Regulatory status differs from entry to entry and is stated in the regulatory note on each entry's own page. Nothing here is medical advice or a therapeutic claim.

Where should I start in this category?

The comparison table gives the fastest orientation, then the differentiator notes explain why two entries with similar research contexts are not interchangeable. GHK-Cu is the entry PeptiDex features here. The glossary defines the vocabulary the entries are written in.

Answers summarise what the catalog records for this category. They are educational context, not medical advice. See the Research Library, the Glossary and each entry's own page for detail.