Melanotan II is a cyclic lactam α-MSH analogue with its own CAS and PubChem entry — not a catalog SKU here.
Melanotan II (MT-II) is a synthetic cyclic lactam analogue of α-melanocyte-stimulating hormone (α-MSH). Purchasing teams see the name on forums, PO templates, and third-party COAs even when the molecule is not on a given storefront. This note exists so the name is not mixed with KPV (α-MSH 11–13), with afamelanotide (Melanotan I), or with any cream or “tanning” product language. It is an identity and documentation article for laboratory buyers — not a protocol.
Document the check shown above before moving to the next figure — label fields, lot paper, and pack notes belong on the same receiving record.
Research use only. Do not treat storefront nicknames as a substitute for sequence, CAS, or observed mass on the certificate.
Lab hands check: label sequence and lot paper must agree before a reagent is booked into inventory.
What Melanotan II is (and is not)
MT-II is commonly described as the cyclic heptapeptide amide Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2. Structural marks relative to native α-MSH include norleucine in place of methionine, a D-phenylalanine residue, a C-terminal amide, and an Asp–Lys lactam bridge. Those marks change formula and mass. They also create a different CAS Registry Number from the parent hormone and from short melanocortin fragments.
What it is not: it is not KPV (the free-acid or amidated tripeptide Lys-Pro-Val). It is not afamelanotide (Melanotan I / [Nle4, D-Phe7]-α-MSH). It is not a cosmetic, not a tanning kit, and not a BioLabs Research catalog SKU. Absence from this catalog is a scope decision, not a purity claim about any other vendor’s lot.
Public identifiers
| Field | Public listing |
|---|---|
| Common name | Melanotan II; MT-II |
| Sequence (common) | Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2 |
| CAS | 121062-08-6 |
| PubChem | CID 92432 |
| Formula (PubChem) | C50H69N15O9 |
| MW (approx.) | ~1024.2 g/mol |
| This catalog | Not listed |
Confirm identifiers against PubChem CID 92432 (CAS 121062-08-6). If a COA cites a different CAS against an “MT-II” nickname, treat identity as unresolved until sequence, formula, and observed mass agree.
Identity is confirmed on lot paper and MS/HPLC methods — not by a storefront nickname alone.
How it differs from KPV and afamelanotide
| Name seen on paper | What it usually means | Catalog status here |
|---|---|---|
| Melanotan II / MT-II | Cyclic α-MSH analogue, CAS 121062-08-6 | Not listed |
| KPV / α-MSH 11–13 | Tripeptide fragment (see KPV note) | Listed as KPV |
| Afamelanotide / Melanotan I | Linear [Nle4,D-Phe7]-α-MSH analogue | Not listed |
Related catalog peptide in the melanocortin neighborhood: KPV. See also Catalog SKUs vs research analogues for how this storefront treats names that circulate without a card.
Purchasing and documentation checklist
- Require the COA to print sequence (or structure), formula or exact mass, and observed MS — not only “Melanotan II.”
- Match CAS 121062-08-6 only when the structure on the certificate is the cyclic lactam analogue above.
- Do not map an MT-II PO line onto the KPV SKU. Different residue count, different CAS, different mass.
- Reject “tanning,” “cosmetic,” or dosing language on laboratory paperwork. This site’s language is RUO only.
- If the molecule is not on our catalog, do not expect a BioLabs lot COA for it.
For listed reagents, lot HPLC area percent is still a UV ratio under one method — not net peptide content. Read HPLC area percent vs net peptide content and Lot COA is not a purity percentage before treating any percentage as a weighing factor.
Why this site does not list it
Catalog scope is deliberate: we publish cards we can support with named identity fields and lot paper on request. A molecule may be well indexed in PubChem and still absent from the storefront. An identity note is not a sales listing. Current catalog: sixteen listed reagents. Melanotan II is not one of them.
Receiving language that keeps MT-II out of the wrong bin
Laboratories that already stock KPV sometimes inherit purchase requests that say “the melanocortin one” or “MT.” That shorthand is how Melanotan II ends up booked against the wrong SKU. Receiving should require the full common name plus CAS or PubChem CID on the inbound packing list. If the inbound paper cites 121062-08-6, it is not the KPV listing. If it cites the KPV CAS from the product card, it is not Melanotan II.
Train purchasing templates to reject free-text nicknames without a registry number. A rejected line item is cheaper than a mis-binned reagent that later appears in an audit trail under the wrong identity. When a collaborator insists the names are “close enough,” point them at the residue count and the lactam bridge: those are not optional footnotes.
Finally, keep marketing PDFs out of the lot folder. If a third-party flyer discusses pigmentation or cosmetic outcomes, it does not belong with RUO receiving records. Store only the certificate, SDS if supplied, and the PO/line that names the molecule. This site will not sell Melanotan II; the documentation habit still matters whenever the name appears on shared lab paperwork.
Current catalog
Sixteen listed reagents. Melanotan II is not one of them. Research use only.
Open the catalog →Related notes
References
- PubChem CID 92432, melanotan-II. CAS 121062-08-6. https://pubchem.ncbi.nlm.nih.gov/compound/92432
- PubChem compound record fields (formula C50H69N15O9) as published on the CID page above — verify before booking inventory.