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THEPeptide Academy
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LESSON 2 OF 2

Skin and immune peptides

By the end you can

  • Describe the main skin peptides and their evidence
  • Describe the main immune peptides and their evidence
  • Separate approved branded drugs from research products

Skin and pigmentation

GHK-Cu is a copper-binding peptide found naturally in blood. Small human studies looked at it in cosmetic skin formulations (grade C); all other GHK-Cu research is animal-only (D). SNAP-8 is an eight-amino-acid peptide studied in cosmetic research on expression wrinkles.

MT-1 (afamelanotide) is approved only as a branded implant, Scenesse, for a rare light-sensitivity disorder. MT-2 is a broader-acting relative with small early human studies; PT-141 was developed from it.

Immune peptides

Thymosin alpha-1 comes from the thymus. As thymalfasin (Zadaxin) it is approved in about 35 countries outside the US, including for hepatitis B (grade B). LL-37 is the body's own antimicrobial peptide; it reached a phase 2b trial in leg ulcers (B). KPV is a three-amino-acid piece of α-MSH, a natural skin-pigment hormone, studied in animal models of gut inflammation (D). FDA advisers voted 8–6–1 in July 2026 to recommend allowing it in pharmacy compounding.

Thymalin, a thymus extract used in Russia, has small open-label human studies (C). VIP (aviptadil) has reached larger human trials, including a lung-failure trial that missed its main goal, and is approved outside the US in a combination product for an unrelated use (B). The GLOW and KLOW blends have never been studied as combinations (D).

  • MT-1 (as Scenesse)

    Grade A

  • Thymosin alpha-1

    Grade B

  • VIP

    Grade B

  • GHK-Cu (cosmetic)

    Grade C

  • SNAP-8 (cosmetic)

    Grade C

  • MT-2

    Grade C

  • LL-37

    Grade C

  • Thymalin

    Grade C

  • GHK-Cu (other)

    Grade D

  • KPV

    Grade D

  • GLOW / KLOW blends

    Grade D
Evidence grade by product.

Key terms

GHK-Cu
A natural copper peptide studied in skin and collagen research.
Afamelanotide
MT-1, approved only as the Scenesse implant.
Thymalfasin
The approved form of thymosin alpha-1, sold outside the US as Zadaxin.
Open-label
A study where everyone knows who got what, which makes bias more likely.

Remember

  • GHK-Cu evidence depends on the research: cosmetic C, all other D.
  • Thymosin alpha-1 is approved abroad and LL-37 reached phase 2b (both B); Thymalin has small human studies (C).
  • KPV is animal-only, and VIP's trials missed their goals.