Melanotan I
10 mg
Linear alpha-MSH analogue, 10 mg per vial.
- Storage
- Refrigerated
Comparison
Melanotan I vs Melanotan II
Both are analogues of alpha-melanocyte-stimulating hormone. The difference is receptor selectivity, and it is the whole reason both exist.
What is the difference between Melanotan I and Melanotan II?
Melanotan I is the selective one: it isolates MC1R, so pigmentation research can be done without the other melanocortin receptors confounding the result. Melanotan II is non-selective and therefore reaches MC3R and MC4R as well, which is why its metabolite PT-141 became a separate compound studied for central melanocortin signalling.
Side by side
| Property | Melanotan I | Melanotan II |
|---|---|---|
| Structure | Linear peptide | Cyclic lactam |
| Receptor selectivity | Selective for MC1R | Non-selective across melanocortin receptors |
| Molar mass | 1646.9 g/mol | 1024.2 g/mol |
| Also called | Afamelanotide | MT-2 |
| Research emphasis | Pigmentation pathways in isolation | Broader melanocortin signalling |
| Related compound | None in this catalogue | PT-141, a metabolite with MC3R and MC4R activity |
| Price | $78.00 · 10 mg | $72.00 · 10 mg |
Both compounds
Melanotan II
10 mg
Cyclic alpha-MSH analogue, 10 mg per vial.
- CAS
- 121062-08-6
- Storage
- Refrigerated
Questions
Which is more selective?
Melanotan I. It is selective for MC1R, whereas Melanotan II acts across melanocortin receptors including MC3R and MC4R.
How is PT-141 related?
PT-141, bremelanotide, is a metabolite of Melanotan II. It retains MC3R and MC4R activity while having minimal pigmentation signalling, which is what made it a compound in its own right.
Why does structure differ between them?
Melanotan II is a cyclic lactam, which constrains the molecule into a fixed conformation. Melanotan I is linear and considerably larger. The conformational difference is a major part of why their receptor selectivity differs.
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