TL;DR — Melanotan II (MT-II) is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone (α-MSH). It is one of the most widely researched melanocortin receptor agonists, with published studies investigating its effects on melanogenesis, appetite regulation, and central nervous system pathways associated with arousal. B.A.B.E LABS supplies Melanotan II via BRONZED, and in multi-peptide research bundles ADONIS, SPRINGBREAK, and THE GOLD RITUAL.
What is Melanotan II?
Melanotan II is a cyclic heptapeptide derived from the melanocortin-family hormone α-MSH. The sequence is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂ — a seven-residue cyclised structure designed for improved metabolic stability and non-selective melanocortin receptor agonism compared to native α-MSH.
It was originally developed at the University of Arizona in the late 1980s and early 1990s, where researchers were investigating whether a stable α-MSH analogue could be used to induce a protective tan response.
Melanocortin receptor pharmacology:
Melanotan II binds and activates five known melanocortin receptors (MC1R through MC5R).
| MC1R | Melanocytes, skin | Melanogenesis, eumelanin production |
| MC2R | Adrenal cortex | ACTH-mediated cortisol axis (MT-II affinity low here) |
| MC3R | CNS, periphery | Energy homeostasis, inflammation |
| MC4R | CNS (hypothalamus) | Appetite, sexual function, weight regulation |
| MC5R | Exocrine glands | Thermoregulation, lipid production |
This non-selective receptor profile is what gives MT-II its characteristic breadth of observed effects across rodent and primate studies.
What research has investigated:
Melanogenesis (MC1R pathway)
The original research interest. MT-II binds MC1R on melanocytes, triggering tyrosinase activation and eumelanin synthesis. This is the basis for MT-II's characterisation in the 1990s "synthetic tanning" research program at Arizona.
Central arousal and sexual function (MC4R)
A substantial body of work has investigated MT-II's actions at MC4R in the hypothalamus, reporting effects on central arousal pathways. PT-141 is an MT-II analogue that was further developed specifically for this pharmacology.
Appetite and energy balance (MC3R/MC4R)
Melanocortin signalling in the hypothalamus is a central node of the satiety network. Rodent studies have reported anorexigenic (appetite-suppressing) effects following MT-II administration.
Inflammation and immunology (MC3R)
More recent work has examined melanocortin signalling in inflammatory and autoimmune models — MC3R in particular is of interest in this area.
Why MT-II often appears in multi-peptide research bundles:
MT-II's melanocortin pharmacology is orthogonal to most other peptide classes, which is why it turns up in research bundles pairing unrelated mechanisms.
- ADONIS pairs MT-II (BRONZED) with the GH-secretagogue blend HULK — studies the intersection of somatotropic and melanocortin axes.
- SPRINGBREAK pairs MT-II with SHRED — incretin/glucagon + melanocortin in parallel.
- THE GOLD RITUAL pairs MT-II with tissue-repair and antioxidant chemistry.
Purity and testing:
Every Bronzed batch is:
- HPLC ≥99% purity
- Mass-spec verified against expected molecular weight (~1024.18 Da for cyclic MT-II)
- Documented with a Certificate of Analysis
Low-purity MT-II research compounds sometimes contain linear (uncyclised) contaminants — these behave very differently at melanocortin receptors. Purity verification matters for any MC-pathway study.
Storage and reconstitution:
- Lyophilised: –20°C, light-protected
- Reconstituted: 2–8°C, use per COA window
Research-use disclaimer:
Melanotan II is supplied strictly for in-vitro and laboratory research. Not TGA-approved. Not for human consumption.
FAQs:
What is the difference between Melanotan I and Melanotan II?
Melanotan I (afamelanotide) is a linear peptide that has received regulatory approval in some jurisdictions for a specific rare photosensitivity disorder. Melanotan II is the cyclic heptapeptide — structurally more stable, non-selective across all five melanocortin receptors, and studied more broadly in the research literature.
Is Melanotan II the same as Bremelanotide?
No. Bremelanotide (PT-141) is a structurally related but distinct MT-II derivative developed specifically for MC4R-mediated central arousal research.
Why is MT-II often supplied in 10mg vials?
Most published research protocols work on a per-milligram basis, and 10mg represents a commonly-used size for in-vitro and animal study series.