Melanotan II
MT-II · MT2 · Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2 · C50H69N15O9 · monoisotopic 1023.5402 Da. The index holds 77 assay reports on this compound across 19 batches from 13 suppliers.
Analytical fingerprint
Hand-authored chemistry. These properties describe the substance and do not change when a record is added.
Melanotan II is a head-to-side-chain lactam cyclic heptapeptide, and the defining impurity is the uncyclised linear precursor at +18 Da, which elutes 0.74 min early. Incomplete cyclisation is the commonest process failure and levels above 1.5 % are a reliable indicator of a rushed macrolactamisation step. The [L-Phe7] diastereomer is mass-identical and matters because the D-Phe configuration is what confers the receptor affinity; RG-2 resolves it to about 60 % valley, which is enough to see but not enough to integrate reliably. Records report it as "co-eluting diastereomer, estimated" where applicable.
- Compound class
- Melanocortin-receptor peptides
- Molecular formula
- C50H69N15O9
- Monoisotopic mass
- 1023.5402Da
- Average mass
- 1024.18Da
- Residues
- 7
- Nominal retention (RG-2, 30 min)
- 9.84min
- Retention window
- 0.25min
- Counter-ion as usually shipped
- acetate
- Typical label claims
- 10 mg
- Analytical difficulty (index scale)
- 0.90 — straightforward
- Purity is a defined quantity
- YES
Representative chromatogram
Drawn from this page's own medians. Not a scan, not an illustration, and not any single report.
What the index has observed
Arithmetic over the 77 records the index holds. Aggregates on this page are computed over the records the index holds, which are not a random sample of the material on the market. Lots that get tested are lots someone chose to test. Read every figure here as a description of this dataset rather than as an estimate of a population.
By supplier
Suppliers with fewer than two purity records on this compound are omitted from the figure rather than drawn as a line. The full table, including the thin cells, is on the by-supplier page.
Characteristic impurities and degradants
The left three columns are authored chemistry — what this molecule characteristically carries and where it elutes. The right three are what the index has actually reported.
| Named species | ΔRT (min, RG-2) | Δ mass (Da) | Seen in | Median % area | Max % area |
|---|---|---|---|---|---|
| linear (open-lactam) precursor (+18 Da) | -0.74 | +18.011 | 91% | 0.17 | 0.99 |
| des-acetyl MT-II (−42 Da) | -0.48 | -42.011 | 88% | 0.08 | 0.45 |
| oxidised Trp (+16 Da) | -0.36 | +15.995 | 79% | 0.08 | 1.55 |
| [L-Phe7]-diastereomer | -0.16 | mass-identical | 78% | 0.05 | 0.64 |
| MT-II dimer (head-to-tail) | +2.35 | +1023.540 | 64% | 0.06 | 0.74 |
Degradation pathways
- Trp oxidation
- lactam hydrolysis reopening the ring
Full impurity profile, with what each named species implies about the synthesis →