This is a working overview of melanocortin receptor, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-09-04 and is reviewed periodically as new material appears.
Published pharmacokinetic information is limited and comes mainly from small studies rather than registrational trials. Plasma half-life is usually described as short, on the order of tens of minutes, followed by rapid tissue distribution and clearance of the intact peptide. Metabolites and low concentrations of parent compound have been reported in urine, a detail relevant to anti-doping and forensic testing. Whether repeated exposure changes receptor sensitivity or clearance over time remains an open question. Values differ noticeably between analytical assays, so published numbers should be read as approximate rather than definitive.
Melanotan II is a synthetic cyclic heptapeptide with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, corresponding to a molecular formula of C50H69N15O9 and a monoisotopic mass near 1024 daltons. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, a peptide hormone produced by cleavage of proopiomelanocortin. A lactam bridge between the aspartate and lysine side chains closes the ring, and the C-terminal amide removes a free carboxyl group. Both modifications increase resistance to enzymatic degradation compared with the linear parent hormone. Four substitutions distinguish it from afamelanotide, the linear analogue studied under the name melanotan I.
Outside regulated medicine, melanotan II circulates through online vendors as a research chemical, often marketed for tanning. Products sold this way vary widely in purity, concentration, and labeling accuracy, and independent testing has documented discrepancies. Published reports describe both pigment effects and adverse reactions, including nausea, flushing, and darkening of existing moles. Long-term safety data are sparse, and no large controlled trial has established a risk profile. Questions about cumulative effects on melanocytes remain unresolved in the literature.
Melanotan II is a synthetic peptide analog modeled on alpha-melanocyte-stimulating hormone, a naturally occurring signaling peptide involved in pigmentation. Its structure is a cyclic heptapeptide containing two non-natural substitutions, norleucine at position four and D-phenylalanine at position seven. These modifications resist enzymatic breakdown and extend the molecule's activity relative to the native hormone. The compound binds melanocortin receptors and is studied mainly as a pharmacological tool rather than a therapeutic product. It has never received approval as a medicine in any major jurisdiction.
The compound was developed in the late 1980s and 1990s by academic researchers investigating photoprotection. The rationale held that stimulating melanin production might reduce ultraviolet damage to skin and lower skin cancer risk. Early work examined receptor binding, pigment response, and short-term tolerability in small studies. That program did not produce an approved drug, and formal development stalled after early-phase trials. Whether induced pigmentation confers meaningful photoprotection remains an open question.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Cyclic heptapeptide, C-terminally amidated |
| Approximate molecular mass | 1024 Da | Monoisotopic mass of the free peptide |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility class | Soluble in water and polar solvents | Also dissolves in neutral aqueous buffer |
| Common synonyms | Melanotan II, MT-II, MT-2 | Described as a melanocortin agonist in early literature |
Melanocytes are the pigment-producing cells of the skin, and they carry melanocortin-1 receptors on their surface. When the receptor is activated, cyclic adenosine monophosphate rises inside the cell and raises the activity of enzymes such as tyrosinase, which increases melanin output. Melanotan-2 binds melanocortin-1 receptors in vitro and in animal models, and this binding is generally described as the basis for the tanning effect. Other receptors account for different effects: melanocortin-4 receptors contribute to appetite and erectile signalling, while melanocortin-3 and melanocortin-5 receptors contribute to energy balance and exocrine function.
Early published reports described melanotan-2 as a tanning agent without sun protection, which means darkening is not the same as protection against ultraviolet radiation. Later studies explored the peptide in erectile dysfunction, hemorrhagic shock, and some skin conditions. No regulator in the United States or Europe has approved it for clinical use. Many products labelled melanotan-2 are sold without approval and their identity and purity are unverified. Its long-term safety in humans remains an open question.
Melanotan-2, also written Melanotan II, is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, and the lactam bridge between the aspartate and lysine side chains constrains the peptide into a ring. This structural change increases receptor affinity and metabolic stability relative to the native hormone. The compound was created in the 1980s as a research tool for studying pigmentation biology.
== Duelle == Wie bereits im Vorjahr fanden auch dieses Jahr wieder Duelle in der „Duell-Arena“ zwischen den Bereichen statt. „Big Brother“ bestimmte jeweils einen oder mehrere Bewohner vom Bereich „Haus“ und „Kanal“, die in der Duell-Arena antreten müssen. In der Duell-Arena absolvierten die beiden Teams ein Spiel und der Verlierer musste mit Konsequenzen für seinen Wohnbereich rechnen. Bei einem Unentschieden gewannen immer die Bewohner im „Haus“. Die Duelle hatten jeweils positive Auswirkungen auf den Gewinnerbereich bzw. die Gewinner und negative Auswirkungen für den Verliererbereich bzw. die Verlierer.
== Nominierungen == Ab dem 9. September 2016 nominierten in der Regel die Teilnehmer einen anderen Teilnehmer für das Zuschauervoting. Die Zuschauer bestimmen am Ende des Tages, wer von der Nominierungsliste das Haus verlassen muss. Am 13. September 2016 bzw. in der fünften Runde nominierten die Bewohner einen anderen Teilnehmer, der Nominierungsschutz bekommen soll. Die Kandidaten, die die wenigsten Stimmen hatte, wurden nominiert.
Das Ausstrahlungsschema der Show war dasselbe wie in den bisherigen Staffeln. Die fast vierstündige Einzugsshow wurde am Freitag, den 2. September 2016 ausgestrahlt. Am Freitag, den 9. September 2016 wurde eine weitere große Liveshow ausgestrahlt. Das Finale wurde am Freitag, den 16. September 2016 gesendet. An den restlichen Tagen wurden jeweils eine Tageszusammenfassung um 22:15 Uhr ausgestrahlt, wobei die Folgen gegen Mitternacht endeten, und nicht wie eigentlich geplant um ca. 23:15 Uhr.
Die Moderation übernahm Jochen Schropp zum dritten Mal. Am 1. Juli 2016 wurde bekannt, dass Cindy aus Marzahn nicht mehr als „Mother of Big Brother“ auftreten wird. Stattdessen kommentierte die Teilnehmerin aus der dritten Staffel Désirée Nick als Sidekick das Geschehen. Des Weiteren berichtete der Gewinner der zweiten Staffel Aaron Troschke aus der „Web Lounge“, was in den sozialen Netzwerken über die Show gepostet wurde. Diese Staffel wurde ebenfalls im Coloneum der MMC Studios Köln produziert. Rebellen von Juno17 wurde als Titelsong der Staffel und als Übergang zu den Werbepausen genutzt. Als Sprecher der Trailer und zusammenfassenden Kommentare war erneut Pat Murphy zu hören. Phil Daub übernahm erneut die menschliche Stimme von „Big Brother“. Die Zeitung Bild bot über den Weblink stream.bild.de einen 24-Stunden-Livestream für die Bildplus-Nutzer an.
Sources: de.wikipedia.org
No. It is a synthetic analogue carrying four amino acid changes, a lactam ring and an amidated C-terminus. The natural hormone is a linear thirteen-amino-acid peptide processed from proopiomelanocortin.
Afamelanotide is the linear analogue [Nle4-D-Phe7]-alpha-MSH, sometimes called melanotan I, while melanotan II is cyclic and carries three further substitutions. The two are distinct molecules and are not interchangeable in analytical testing.
Binding to the four melanocortin receptor subtypes is well documented in vitro. The relative contribution of each subtype to whole-body effects in humans is far less certain.
It is a synthetic cyclic peptide designed as an analog of alpha-melanocyte-stimulating hormone. It acts on melanocortin receptors and is best known from research into pigmentation. It is not an approved pharmaceutical product.