PT-141 (Bremelanotide) vs Melanotan II
PT-141 (bremelanotide) and Melanotan II are both melanocortin receptor agonists derived from the alpha-melanocyte-stimulating hormone (alpha-MSH) scaffold. However, they differ in receptor selectivity and the breadth of their studied effects.
Side-by-Side Comparison
| Property | PT-141 (Bremelanotide) | Melanotan II |
|---|---|---|
| Category | Melanocortin receptor agonist (selective MC3R/MC4R) | Non-selective melanocortin receptor agonist (MC1R-MC5R) |
| Mechanism of Action | Cyclic heptapeptide; preferentially activates MC3R and MC4R in the central nervous system, modulating hypothalamic signaling | Cyclic lactam analog of alpha-MSH; activates multiple melanocortin receptors including MC1R (pigmentation) and MC4R (central effects) |
| Molecular Weight | ~1,025 Da (7 amino acids, cyclic) | ~1,024 Da (7 amino acids, cyclic lactam) |
| Primary Research Focus | Sexual dysfunction research, central nervous system melanocortin pathways | Skin pigmentation, photoprotection, appetite regulation research |
| Receptor Target | MC3R and MC4R (selective) | MC1R, MC3R, MC4R, MC5R (non-selective) |
| Half-Life | ~2.5 hours | ~1-2 hours (estimated) |
| Key Research Citations | Molinoff et al. (2003), Ann N Y Acad Sci; Kingsberg et al. (2019), Obstet Gynecol | Dorr et al. (1996), Life Sci; Hadley et al. (2005), Peptides |
Key Differences
- PT-141 is receptor-selective, primarily targeting MC3R and MC4R in the CNS. Melanotan II is non-selective, activating MC1R through MC5R, which accounts for its broader range of observed effects.
- Melanotan II activates MC1R, the primary melanocortin receptor responsible for melanogenesis (skin pigmentation). PT-141 has minimal MC1R activity.
- PT-141 was developed specifically by modifying the Melanotan II structure to remove pigmentation activity while retaining CNS melanocortin effects.
- Both peptides share nearly identical molecular weights (~1,024-1,025 Da) and are cyclic heptapeptides, but their amino acid substitutions produce markedly different receptor selectivity profiles.
Research Summary
PT-141 and Melanotan II share a common structural origin in the alpha-MSH scaffold, but represent different pharmacological strategies. Melanotan II is a broad-spectrum melanocortin agonist studied for pigmentation and multiple CNS effects. PT-141 was engineered from Melanotan II through structural modifications that shifted receptor selectivity toward MC3R/MC4R while eliminating significant MC1R activation, making it a more targeted tool for melanocortin CNS pathway research.
What is the difference between PT-141 and Melanotan II?
PT-141 (bremelanotide) is a selective MC3R/MC4R agonist engineered from Melanotan II to target central nervous system melanocortin pathways without significant pigmentation effects. Melanotan II is a non-selective melanocortin agonist that activates MC1R through MC5R, producing both pigmentation and CNS effects. PT-141 was specifically designed to remove the MC1R-mediated melanogenesis activity of Melanotan II.
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Disclaimer: All compounds referenced on this page are sold for research and laboratory use only. The comparisons presented are based on published scientific literature and are intended for educational and informational purposes. This content does not constitute medical advice. Researchers should consult primary literature and applicable regulations before designing study protocols.