⚠ FOR LABORATORY RESEARCH USE ONLY · NOT FOR HUMAN CONSUMPTION · QUALIFIED RESEARCHERS 21+
// PB-0025 Peptide Melanocortin

Melanotan II

Cyclic α-MSH analog.

Melanotan II is a cyclic heptapeptide α-MSH analog developed at the University of Arizona in the 1980s. The cyclic structure confers high potency at melanocortin receptors. It is the direct precursor to bremelanotide (PT-141). Supplied as research-grade material with 3rd-party HPLC verification and full Certificate of Analysis per lot.

01

Compound profile.

// CHEMICAL & STRUCTURAL SPEC — MELANOTAN II
MOLECULAR FORMULA
C50H69N15O9
Peptide · melanocortin class.
MOLECULAR WEIGHT
1,024.2 Da
Monoisotopic / reported mass.
CHAIN LENGTH
7 aa
Primary structure residues.
ORIGIN
Synthetic · University of Arizona
Source or discovery context.
STUDIED PATHWAYS
MC1R · MC3R · MC4R · MC5R
Reported in published literature.
REPORTED HALF-LIFE
~30 min
Moderately short t½.
HPLC PURITY
99.8%
Minimum release spec · typical >99.9%.
APPEARANCE
White lyo.
White to off-white lyophilized form.
// PRIMARY STRUCTURE
Ac-Nle–cyclo[Asp–His–D-Phe–Arg–Trp–Lys]-NH₂

// Cyclic heptapeptide MSH analog. The Asp-Lys lactam bridge is the key structural feature — it constrains the peptide into the active β-turn conformation, increasing potency ~200-fold over linear α-MSH at melanocortin receptors.
02

What the literature reports.

Melanotan II is a cyclic heptapeptide α-MSH analog developed at the University of Arizona in the 1980s. The cyclic structure confers high potency at melanocortin receptors. It is the direct precursor to bremelanotide (PT-141).

Reported mechanism

Potent non-selective agonist of MC1R, MC3R, MC4R, and MC5R. The MC1R activity drives pigmentation effects; MC4R activity is implicated in the reported effects on sexual function and appetite suppression. Non-selectivity is a notable distinguishing feature from the later-developed PT-141 (which is modestly MC4R-selective).

Regulatory status

Never approved for any indication. Widely available as a research compound. Notable for a range of reported off-target effects due to non-selective melanocortin receptor agonism; documented reports of adverse skin pigmentation changes and atypical melanocytic lesions in research and self-administration contexts.

The above summarizes published research literature. This is not medical advice, a protocol, or a recommendation for use. This compound is supplied for laboratory research only.

03

Storage & release.

SHIP TEMP
Ambient
Lyophilized; stable at room temp in transit.
UNOPENED
Refrigerate
Lyophilized, protected from light.
RECONSTITUTED
~28 days
At 2–8°C; never freeze solutions.
RELEASE DOC
COA · per lot
3rd-party analytical · attached at ship.
lab@peptidebros:~$ cat release.melanotan-ii.MT2-26-Q2-0029.log
// lot release record
compound Melanotan II (C50H69N15O9)
lot.id MT2-26-Q2-0029
class peptide
mw.theoretical 1,024.2 Da
mw.observed 1,024.2 Da  [PASS]
purity.hplc 99.91%  [> 99.5% spec]
endotoxin < 0.125 EU/mL  [PASS]
sterility no growth  [PASS]
release.status RELEASED
04

Common questions.

What's the molecular profile?+

Melanotan II is a 7-residue peptide with molecular formula C50H69N15O9 and molecular weight of approximately 1,024.2 Da.

The full structural data and release specifications are in the Compound Profile section above. Every lot ships with an independently verified Certificate of Analysis.

How is purity verified?+

Each lot is independently verified by a 3rd-party analytical laboratory (STERIS Labs, Alcami Analytical, or equivalent) before release. Release specification is HPLC purity ≥ 99.5% (typical > 99.8%), mass spectrometry identity match within ±0.5 Da, water content < 5.0% Karl Fischer, and endotoxin < 0.25 EU/mL by LAL (USP <85>).

Look up the full COA for your lot at coa-lookup.html.

How is the compound shipped and stored?+

All compounds ship at ambient temperature in discreet, tamper-evident packaging. Lyophilized peptide powder is stable at room temperature for typical transit windows, which is why research-grade vendors ship this way. Tracked; signature not required.

Store unopened lyophilized product at 2–8°C protected from light. Once reconstituted, most peptides are stable at 2–8°C for approximately 28 days (compound-dependent).

Is this compound FDA-approved?+

Never approved for any indication. Widely available as a research compound. Notable for a range of reported off-target effects due to non-selective melanocortin receptor agonism; documented reports of adverse skin pigmentation changes and atypical melanocytic lesions in research and self-administration contexts.

All PeptideBros compounds are sold strictly as chemical reference materials for in-vitro laboratory research. They are not for human consumption.

Every lot,
on paper.

HPLC-verified. Mass-spec confirmed. Ambient-stable transit. The paperwork other vendors hope you never ask for.