Maple PT-141 (bremelanotide, Ac-Nle-c[Asp-His-D-Phe-Arg-Trp-Lys]-OH) is a cyclic heptapeptide melanocortin receptor agonist derived from Melanotan II. Originally developed at Palatin Technologies, bremelanotide received FDA approval in 2019 under the brand name Vyleesi for treatment of hypoactive sexual desire disorder (HSDD) in premenopausal women. PT-141 is the only melanocortin receptor agonist approved for a CNS-mediated indication, making it a key reference compound in melanocortin pathway research.
Maple Research Labs supplies research-grade PT-141 to Canadian laboratories, universities, and documented research buyers. Every batch ships with an independent third-party Certificate of Analysis confirming identity and purity.
For research purposes only. Not for human consumption. Not for diagnostic or therapeutic use.
Molecular Profile
| Parameter | Value |
|---|---|
| Sequence | Ac-Nle-c[Asp-His-D-Phe-Arg-Trp-Lys]-OH |
| CAS Number | 189691-06-3 |
| Molecular Formula | C50H68N14O10 |
| Molecular Weight | 1025.2 Da |
| Structure | Cyclic heptapeptide (lactam bridge) |
| Primary Target | MC4R (melanocortin-4 receptor) |
| Purity | ≥99% (HPLC) |
| Storage | -20°C, lyophilized, desiccated, protected from light |
PT-141 differs from its parent compound Melanotan II by the removal of the C-terminal amide group (replaced with a free carboxyl). This seemingly minor structural modification shifts the receptor selectivity profile: while both compounds activate multiple melanocortin receptors, the free acid terminus of PT-141 was optimized to reduce MC1R-mediated melanogenic activity while preserving MC4R-mediated CNS effects. This selectivity optimization was the key design criterion in advancing from Melanotan II (a research tool) to bremelanotide (a clinical candidate).
Primary Research Mechanisms
MC4R Agonism and CNS-Mediated Signaling
PT-141’s primary mechanism involves activation of melanocortin-4 receptors (MC4R) in the CNS, particularly in the hypothalamus, paraventricular nucleus, and medial preoptic area. MC4R activation stimulates G-protein coupled signaling through the Gs/adenylyl cyclase/cAMP pathway, modulating downstream neuronal activity in circuits that regulate sexual arousal, appetite, and autonomic function. Unlike PDE5 inhibitors (which act peripherally on vascular smooth muscle), PT-141 acts centrally on hypothalamic circuits, representing a fundamentally different pharmacological approach.
Melanocortin Receptor Selectivity Profile
PT-141 retains activity at MC1R, MC3R, MC4R, and MC5R, but the relative potency profile differs from Melanotan II. The free acid C-terminus reduces MC1R-mediated melanogenic signaling while maintaining MC4R efficacy. In research settings, comparing the activity profiles of PT-141, Melanotan II, and selective MC4R agonists (such as setmelanotide) provides insight into structure-activity relationships within the cyclic melanocortin peptide scaffold.
Autonomic and Cardiovascular Effects
MC4R activation by PT-141 has been associated with transient increases in blood pressure in clinical studies. This effect is attributed to MC4R-mediated sympathetic nervous system activation, a pharmacological observation that has prompted research into the cardiovascular implications of melanocortin receptor signaling. The relationship between MC4R agonism, sympathetic tone, and hemodynamic responses is an active area of preclinical investigation.
PT-141 vs. Melanotan II: Structural and Functional Comparison
| Feature | PT-141 (Bremelanotide) | Melanotan II |
|---|---|---|
| C-terminus | Free acid (-OH) | Amide (-NH2) |
| MC1R activity | Reduced (by design) | High |
| MC4R activity | Preserved | High |
| Melanogenic effect | Reduced | Significant |
| CNS effects | Primary research focus | Secondary to melanogenesis |
| FDA status | Approved (Vyleesi, 2019) | Not approved |
| Research utility | MC4R pharmacology, CNS signaling | Multi-receptor MC research |
Product Specifications
| Specification | Detail |
|---|---|
| Peptide | PT-141 (Bremelanotide) |
| CAS Number | 189691-06-3 |
| Purity | ≥99% (HPLC verified) |
| Form | Lyophilized powder |
| COA | Third-party Certificate of Analysis included with every order |
| Storage | -20°C, desiccated, protected from light |
| Shipping | Same-day processing from Canada |
| Use | For research purposes only |
View PT-141 product page and COA | How to read a Certificate of Analysis
Frequently Asked Questions
What is PT-141 and how does it differ from Melanotan II?
PT-141 (bremelanotide) is a cyclic heptapeptide derived from Melanotan II with a free acid C-terminus replacing the amide group. This modification reduces MC1R-mediated melanogenic activity while preserving MC4R-mediated CNS effects. PT-141 received FDA approval in 2019 (Vyleesi), while Melanotan II remains an unapproved research compound. Both share the same cyclic core structure and melanocortin receptor agonist mechanism.
What receptor does PT-141 primarily target?
PT-141 primarily targets the melanocortin-4 receptor (MC4R), a G-protein coupled receptor expressed in the hypothalamus and other CNS regions. MC4R activation by PT-141 modulates neuronal circuits involved in sexual arousal, appetite regulation, and autonomic function. While PT-141 retains activity at other melanocortin receptors (MC1R, MC3R, MC5R), its design optimized for MC4R-mediated CNS effects over MC1R-mediated melanogenesis.
Can I purchase PT-141 for research in Canada?
Yes. Maple Research Labs supplies research-grade PT-141 verified at 99%+ purity via independent third-party HPLC analysis. Orders ship from within Canada with same-day processing and include a batch-specific Certificate of Analysis. PT-141 is sold exclusively for in-vitro and preclinical research use.
Related Research Resources
- Melanotan Research — MT-I vs MT-II and full MC receptor system overview
- Melanotan I vs Melanotan II — Detailed comparison
- Purity Testing Methods — HPLC and mass spectrometry explained
- All Research Peptides — Complete compound catalog
For research purposes only. Not for human consumption. Not for diagnostic or therapeutic use.