Melanotan II vs PT-141: How Two Melanocortin Peptides Differ
PT-141 is derived from Melanotan II, and the two differ by a single structural change. They act on the same family of melanocortin receptors, but they followed different research paths, and that history decides which one fits a given study. Here is how they compare.
At a glance
| Melanotan II | PT-141 (bremelanotide) | |
|---|---|---|
| Parent hormone | α-MSH (alpha-melanocyte-stimulating hormone) | Derived from Melanotan II |
| Structure | Cyclic lactam heptapeptide, C-terminal amide | Cyclic heptapeptide; C-terminal amide replaced by a free acid |
| Receptor profile | Non-selective: MC1R, MC3R, MC4R, MC5R | Also non-selective (MC1R, MC3R, MC4R, MC5R); studied mainly for MC4R-mediated central effects |
| Main research areas | Melanogenesis (MC1R), broad melanocortin signaling | Central MC4R signaling, structure–activity comparisons |
The melanocortin system in brief
Melanocortin receptors (MC1R–MC5R) respond to peptides derived from pro-opiomelanocortin, including α-MSH. They do different jobs: MC1R is best known for controlling pigment production in melanocytes, while MC3R and MC4R are mainly found in the brain and are involved in energy balance and other central signaling. A compound’s receptor profile decides which of these systems it reaches.
Melanotan II: the broad agonist
Melanotan II is a cyclic analogue of α-MSH. Ring-closing the peptide through a lactam bridge makes it far more stable than the native hormone. It activates most melanocortin receptors, which makes it a strong tool for MC1R and melanogenesis research in melanocyte models, and a broad probe of melanocortin signaling overall. Melanotan II research profile.
PT-141: the centrally focused derivative
PT-141 is Melanotan II with the C-terminal amide replaced by a free carboxylic acid. It still activates several melanocortin receptors, including MC1R, but its research program has centered on MC4R signaling in the brain rather than on pigmentation. Researchers use it for central melanocortin studies and in structure–activity work comparing it directly with Melanotan II. PT-141 research profile.
Choosing between them
Pigmentation, MC1R or broad melanocortin studies: Melanotan II.
Central MC4R-focused studies: PT-141.
Structure–activity studies: both side by side show what the C-terminal change does in your model.
Related: KPV, the C-terminal tripeptide of α-MSH, is studied for the hormone’s anti-inflammatory activity rather than its receptor-agonist effects.
Testing
Because the two compounds differ by so little, mass-spectrometry identity testing is what confirms you received the one on the label. Every lot we sell is tested by Bioviridian Labs (ISO/IEC 17025, Texas) for HPLC purity, mass-spec identity, endotoxin and heavy metals. See the COA Library.
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For laboratory research use only. Not for human or veterinary use. This article summarizes published research for educational purposes and does not provide medical advice.