Melanotan II | CAS 121062-08-6 | Melanocortin Receptor Agonist (Research Use Only) | Knowlux

Document Type: Research-Use Product Specification
Version: 2026-11

Product Description

Melanotan II, CAS 121062-08-6, is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone (alpha-MSH) supplied by Knowlux for laboratory research use. It is a lactam-bridged peptide with the sequence Ac-Nle-Asp-His-D-Phe-Arg-Trp-Lys-NH2, cyclised between Asp2 and Lys7. The molecular formula is C50H69N15O9 and the molecular weight is 1024.18 g/mol. Each lot is released with a lot-specific COA, MSDS and analytical traceability.

CAS Clarification: CAS 121062-08-6 is the free base registry for Melanotan II. The acetate salt form is frequently listed under the same CAS by suppliers; Knowlux declares the counter-ion and salt basis per lot on the COA. Buyers should confirm whether pricing and specification are quoted on a free-peptide or acetate-salt basis before procurement. Molecular weight calculations and receptor-study dosing must reconcile to the declared basis.

Product Parameters

Product Details

1. Overview

Melanotan II is a synthetic analogue of alpha-MSH engineered for enhanced metabolic stability and broader melanocortin receptor engagement. It was developed as a research tool to investigate melanocortin signalling, particularly at MC1R, MC3R, MC4R and MC5R. Unlike the linear afamelanotide (Melanotan I), Melanotan II is cyclic and non-selective, which distinguishes its pharmacological profile in receptor studies. Knowlux supplies Melanotan II as a research-grade peptide; it is not approved as a therapeutic or cosmetic product in any jurisdiction, and supply is restricted to laboratory research channels.

2. Structural Profile

The peptide backbone contains seven amino acids with a lactam bridge cyclising Asp2 to Lys7. The Nle4 substitution (norleucine in place of methionine) reduces oxidation susceptibility relative to the native alpha-MSH sequence, though it does not eliminate oxidation entirely. The D-Phe7 residue contributes to receptor binding affinity and metabolic stability. The C-terminal amide protects against carboxypeptidase degradation. These modifications collectively yield a peptide with a substantially longer half-life than native alpha-MSH in preclinical models.

3. Receptor Pharmacology

Melanotan II binds and activates multiple melanocortin receptor subtypes. In recombinant receptor assays, reported Ki values are approximately 0.67 nM (MC1R), 34 nM (MC3R), 6.6 nM (MC4R) and 46 nM (MC5R). This non-selective profile contrasts with more subtype-selective agonists and is the basis for its use in studies examining integrated melanocortin signalling. Downstream effects observed in published preclinical models include MC4R-mediated modulation of energy balance and MC1R-mediated melanogenesis. These descriptions are derived from published research and are provided for scientific reference only.

4. Research Applications

• Reference standard for melanocortin receptor agonist analytical methods

• MC1R, MC3R, MC4R and MC5R binding and functional assay development

• Melanocortin signalling research in energy balance and pigmentation models

• Analytical method validation for HPLC and LC-MS platforms

These findings are derived from in vitro and preclinical investigations and do not establish clinical efficacy or safety.

Quality Control

Solubility and Handling

Solubility: The acetate salt form is soluble in water at approximately 5 mg/mL. DMSO is suitable for stock solution preparation at higher concentrations. Prepare solutions fresh and aliquot to avoid repeated freeze-thaw cycles.

Handling Precautions: Use powder-handling containment (glove box or fume hood with particulate control). Avoid inhalation of fine powder. Wear nitrile gloves, lab coat, and eye protection. Follow institutional chemical hygiene plans for research peptides.

Storage and Stability

Storage recommendations align with supplier technical sheets and independent procurement guidance. The lyophilized powder is hygroscopic; equilibrate vials to room temperature before opening to prevent condensation. Protect from light.

Packaging and Shipping

Lyophilized powder: amber glass vial under nitrogen headspace, sealed with butyl stopper and aluminium crimp. Secondary packing: tamper-evident, light-protected carton with desiccant. Cold-chain shipping with validated gel packs and temperature logger. COA, MSDS, packing list and certificate of origin issued with each shipment. Note that Melanotan II is a named customs enforcement target in several jurisdictions, including Australia and the UK; buyers must confirm local import requirements before ordering.

Documentation Support

Per lot: COA, MSDS, certificate of origin, HPLC chromatogram, and mass spectrometry data. Regulatory packages (specification summaries, audit support) and third-party inspection available on a project basis.

About Knowlux

Knowlux Biotechnology is a GMP-oriented manufacturer and supplier of peptides, APIs and fine-chemical research compounds, operating from Hubei, China. We serve research groups, CDMOs and distributors in more than 40 countries, and support contract synthesis, custom packaging and technical documentation requests.

Compliance Statement

FOR RESEARCH USE ONLY. NOT FOR HUMAN USE. NOT FOR DIAGNOSTIC OR THERAPEUTIC USE.

This product is supplied for laboratory research use only. It is not for human or animal administration, not for diagnostic or therapeutic use, not for retail sale, and not for personal use. Melanotan II is not approved as a medicinal product in any jurisdiction. It is prohibited under WADA category S0 (non-approved substances). The purchaser is responsible for verifying product specifications against their specific research requirements and for compliance with all applicable institutional, local, and national regulations governing research chemical acquisition, storage, and use. Research context statements are for scientific reference only and do not constitute medical advice, promotional claims, or dosing guidance.