Overview of Melanotan II Bulk Powder
Melanotan II is a synthetic peptide developed as a stable analog of α-melanocyte-stimulating hormone (α-MSH), a neuropeptide involved in the regulation of pigmentation, energy balance, and central nervous system signaling. Its design incorporates a lactam bridge that confers greater resistance to enzymatic degradation compared to the linear native hormone, making it a valuable tool in receptor pharmacology and cellular signaling research. The compound is supplied as a lyophilized powder, facilitating long-term storage and precise reconstitution under controlled laboratory conditions. Researchers and pharmaceutical entities procure Melanotan II in bulk quantities to support large-scale binding studies, in vitro assays, and in vivo modeling without the interruptions of frequent reordering.
Every shipment of Melanotan II bulk powder is manufactured under strictly controlled processes to meet the analytical demands of academic and industrial laboratories. The lyophilized format minimizes residual water, preserving molecular integrity during transit and storage. Laboratories reconstruct the peptide with sterile, research-grade solvents immediately before experimental use, ensuring consistency across parallel investigations. This preparation aligns with accepted best practices for peptide handling and supports reproducible outcomes in projects ranging from receptor profiling to metabolic pathway dissection. In all instances, the material is intended solely for scientific inquiry; no aspect of its packaging or documentation suggests suitability for clinical or self-administered contexts.
Chemical and Physical Properties
The molecular architecture of Melanotan II is characterized by a cyclic heptapeptide core that features an amide bond between the side-chain carboxyl group of aspartic acid and the ε-amino group of lysine. The full sequence is Ac-Nle-cyclo(Asp-His-D-Phe-Arg-Trp-Lys)-NH₂, with the N-terminus acetylated and the C-terminus amidated to enhance stability. This cyclization, coupled with the substitution of L-norleucine for methionine, produces a compact structure with a calculated monoisotopic mass near 1,024 daltons (Da). The molecular formula is often cited as C₅₀H₆₈N₁₄O₁₀, corresponding to an exact mass of approximately 1,024.5 Da. These attributes are routinely verified during batch release testing.
- Purity: ≥98% as determined by reversed-phase high-performance liquid chromatography (RP-HPLC) at 214 and 280 nm; no single impurity typically exceeds 1.0%.
- Appearance: White to off-white lyophilized cake or powder, free of particulate contamination.
- Solubility: Freely soluble in water, 0.9% saline, phosphate-buffered saline (PBS), and other aqueous buffers commonly used in research settings. Gentle vortexing or brief sonication may aid complete dissolution.
- CAS number: 121062-08-6 — a unique identifier used to track the peptide across regulatory and literature databases.
Analytical characterization routinely confirms backbone cyclization, correct mass, and absence of deletion or truncated sequences. Mass spectrometry (typically electrospray ionization or MALDI-TOF) provides a precise mass-to-charge ratio consistent with the theoretical value, while amino acid analysis or Edman sequencing can further corroborate the primary structure. The combination of a highly pure peptide with a well-defined solubility profile permits dependable dosing in cell culture and animal models, provided that researchers prepare solutions according to institutional protocols for sterile technique.
Applications de la recherche
Melanocortin Receptor Binding and Signaling
Melanotan II acts as a non-selective agonist at several melanocortin receptor subtypes, with significant affinity for MC1R, MC3R, MC4R, and MC5R. Competitive binding assays using radiolabeled ligands (e.g., [¹²⁵I]NDP-α-MSH) demonstrate that the cyclic peptide displaces the tracer at low nanomolar concentrations in transfected cell lines. These observations make it a favored reference compound for characterizing novel receptor ligands and for dissecting downstream Gαₛ-mediated cAMP accumulation and ERK1/2 phosphorylation. Studies frequently employ Melanotan II in parallel with receptor-specific antagonists to map the signal transduction cascade in HEK293 cells, melanocytes, and neuronal cultures.
Pigmentation and Melanogenesis
In laboratory models of pigmentation, Melanotan II stimulates melanin synthesis via MC1R activation on melanocyte membranes. Rodent studies, as well as ex vivo skin explant cultures, have documented increased tyrosinase activity and eumelanin deposition following peptide exposure. Researchers utilize these systems to explore the molecular regulation of microphthalmia-associated transcription factor (MITF) and the post-translational processing of pigmentary enzymes. Such work contributes to fundamental understanding of melanocyte biology and the interplay between UV-independent signaling and skin adaptation responses, always within the boundaries of experimental models rather than clinical application.
Central Nervous System and Energy Homeostasis
The role of central melanocortin circuits in feeding behavior and energy expenditure is another area where Melanotan II bulk powder finds extensive use. Acute or repeated administration in rodents suppresses food intake and increases metabolic rate via hypothalamic MC4R, a finding that has been replicated across multiple independent laboratories. Related behavioral paradigms examine effects on sexual response and grooming — endpoints that are quantifiably linked to melanocortin receptor engagement. By applying this peptide alongside receptor antagonists or genetic knockouts, researchers parse the individual contributions of MC3R and MC4R to body weight regulation and sympathetic nervous system outflow. All such applications remain strictly within preclinical research frameworks, with no extrapolation to human or therapeutic use.
Quality and Purity Standards
A rigorous quality assurance program underpins every lot of Melanotan II bulk powder destined for the research supply chain. Following solid-phase peptide synthesis and cyclization, the crude product undergoes preparative HPLC purification before lyophilization. Final release testing includes:
- Analytical HPLC: A single sharp peak integrating to ≥98% of total area, confirming chemical purity.
- Spectrométrie de masse : ESI-MS or MALDI-TOF spectra matched to the theoretical monoisotopic mass within ±1.0 Da, validating molecular identity.
- Peptide Content Quantification: Amino acid analysis or UV spectrophotometry to determine net peptide weight, accounting for any residual water or counterions.
- Solubility and Appearance: Visual inspection and dissolution testing to confirm consistency.
Each batch is accompanied by a Certificate of Analysis (COA) that documents these metrics and chronicles the storage conditions during shipment. The COA allows receiving institutions to correlate analytical data with their own internal quality checks, facilitating traceability and publication-quality reporting. Lyophilization further protects the peptide by reducing molecular mobility; when stored under recommended conditions, the powder retains its specified purity for years.
Storage and Handling Guidelines
Maintaining the structural fidelity of Melanotan II bulk powder depends on adherence to established cold-chain protocols. Upon receipt, the sealed container should be stored at −20 °C or colder, ideally in a frost-free freezer that protects against ambient humidity. Desiccated, light-resistant packaging is essential to prevent photo-oxidation of the tryptophan residue and hydrolysis of the lactam bridge. Short-term transport at ambient temperature (e.g., 2–8 °C) is generally acceptable for a few days, but prolonged exposure to warmth or moisture accelerates degradation.
- Long-term storage: −20 °C or below, with desiccant, in the original amber glass vial.
- Reconstitution: Use sterile, endotoxin-free water, 0.9% sodium chloride, or a suitable buffer (pH 5–7) immediately before experimentation. A concentration of 1–5 mg/mL is typical for stock solutions, though actual dilution depends on the assay.
- Post-reconstitution stability: Working solutions should be kept on ice and used within the same day. If storage of aliquots is necessary, single-use portions can be snap-frozen at −80 °C and thawed once; repeated freeze-thaw cycles should be avoided as they promote aggregate formation and loss of bioactivity.
Laboratories that process large quantities often aliquot the bulk powder itself under inert gas, reserving individual vials for later reconstitution. This practice minimizes the number of times the master container is opened and helps sustain batch-to-batch consistency across lengthy study timelines.
Questions fréquemment posées
What purity level is standard for Melanotan II bulk powder?
The accepted industry benchmark is ≥98% purity, as measured by analytical HPLC. Many commercial lots exceed 99%, but specifications vary among manufacturers. Any COA provided with the product will state the exact percentage and the chromatographic conditions used to derive it.
How should the powder be stored for long-term stability?
Store the lyophilized powder at −20 °C or below, in a tightly sealed, light-protected container, along with a desiccant pack. When these conditions are met, the peptide can retain full activity for multiple years. Inspect the vial periodically for signs of moisture ingress or discoloration, and avoid condensation by equilibrating the container to room temperature before opening.
Is this product intended for human or veterinary use?
No. Melanotan II bulk powder is supplied exclusively for laboratory research and preclinical investigation. It is not manufactured, tested, or labeled for administration to humans or animals outside of controlled, institutional review board–approved studies that assess toxicity, pharmacokinetics, or mechanism of action. Any handling must be conducted by qualified personnel using appropriate personal protective equipment and in accordance with institutional safety policies.
Research use only: The information and product described herein are provided solely for scientific inquiry in laboratory settings. No statement should be interpreted as suggesting suitability for clinical, diagnostic, therapeutic, or any other in‑human or in‑veterinary application.
Réservé à la recherche. Ne pas utiliser chez l'homme ni chez les animaux.
