What Are Melanocortin Peptides?
Melanocortin peptides are synthetic analogs of alpha-melanocyte stimulating hormone (α-MSH) studied for how they activate the melanocortin receptor family (MC1R–MC5R). This collection holds the three most-researched analogs — Melanotan I, Melanotan II, and PT-141 — supplied as lyophilized powder for laboratory research use only. These compounds are not approved for human use; regulatory agencies have publicly flagged unapproved melanotan products, and Vertex Peptide Lab supplies them strictly as research reference material.
MT-1 vs MT-2 vs PT-141
| Compound | Structure | Receptor profile studied |
|---|---|---|
| Melanotan I | Linear tridecapeptide | MC1R-preferential |
| Melanotan II | Cyclic lactam | Non-selective MC1R–MC5R |
| PT-141 | Cyclic heptapeptide | MC3R / MC4R-preferential |
Why Receptor Selectivity Matters in Research
The value of holding all three analogs is comparative: Melanotan I's linear structure gives it a more MC1R-selective binding profile, Melanotan II's cyclization broadens receptor coverage and metabolic stability, and PT-141 shifts preference toward the central MC3R/MC4R subtypes. Studies use these differences to isolate which receptor subtype drives a given signaling outcome.
Handling and Reconstitution
Each analog ships lyophilized and requires reconstitution before laboratory use — see our Supplies collection for bacteriostatic water and reconstitution kits. Store vials refrigerated after reconstitution to preserve peptide integrity.
Frequently Asked Questions
What is the difference between Melanotan I and Melanotan II? Melanotan I is a linear alpha-MSH analog with a more MC1R-selective profile, while Melanotan II is a cyclic analog that activates a broader range of melanocortin receptors. Both are research compounds only.
What receptors does Melanotan II act on in research models? Melanotan II is studied as a non-selective agonist across MC1R through MC5R, which is why it appears frequently in broad melanocortin-signaling research.
How is PT-141 different from Melanotan II? PT-141 is derived from Melanotan II but was developed for preferential MC3R/MC4R activity in central-nervous-system pathway research, rather than the broad receptor coverage of MT-2.
Are melanocortin peptides approved for human use? No. These are unapproved compounds supplied for laboratory research use only. Public health agencies have warned against non-research use of melanotan products.
How should melanocortin peptides be stored? As lyophilized powder before reconstitution and refrigerated afterward, handled only by qualified personnel in a laboratory setting.