If you have been reading about eumelanin and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-03-22. Where a claim depends on a specific study, the study is described rather than over-claimed.
Melanotan II binds several melanocortin receptor subtypes rather than a single target. MC1R on melanocytes drives melanin synthesis, while MC3R and MC4R participate in energy balance, appetite, and sexual response pathways. This lack of selectivity explains why reported effects extend beyond skin darkening. Substitutions at positions four and seven, including norleucine and D-phenylalanine, increase potency and resistance to peptidases. Understanding which receptor mediates which effect remains an active area of investigation.
Published human data come mostly from small, short studies rather than large controlled trials. Reported outcomes include increased skin pigmentation and, in some reports, effects on appetite and libido, but sample sizes are small and follow-up is limited. Whether long-term use produces durable pigment changes or adverse effects is not established. Because products sold outside pharmacies are not standardized, the actual content of any given vial is often unknown. Independent testing of such material is uncommon.
No regulatory authority has approved melanotan-2 for human use, and several countries classify it as a prescription-only or controlled substance, which restricts lawful supply. Material sold online is generally labelled as a research chemical and is not required to meet pharmaceutical standards of identity or purity. Published human data consist mainly of small uncontrolled studies, case reports and adverse-event notifications, so the evidence base is descriptive rather than confirmatory. Whether repeated melanocyte stimulation alters long-term naevus behaviour remains an open question that no completed trial has resolved.
Melanotan-2 is a synthetic cyclic heptapeptide designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous tridecapeptide that regulates pigment production. Two modifications distinguish it from the natural hormone: norleucine replaces methionine at the N-terminus, which limits oxidation, and a D-phenylalanine substitution raises receptor affinity. The ring is closed through an aspartate-lysine lactam bridge, giving the molecule a constrained conformation. The free base has a molecular mass near 1024 daltons, and commercial material is usually supplied as an acetate salt. It appears in the literature as a research peptide rather than an approved therapeutic agent.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Analog of alpha-melanocyte-stimulating hormone |
| Primary receptor family | Melanocortin receptors MC1R through MC5R | Binding is not subtype-selective |
| Development period | 1980s | Synthesized during pigmentation and appetite research |
| Regulatory status | Not an approved medicine | No major regulator has authorized human use |
| Related compound | Afamelanotide | Linear analog studied for photoprotection |
Two structural changes distinguish the synthetic peptide from the natural hormone. A norleucine residue replaces methionine at one position, and a D-configured phenylalanine replaces the natural L-form at another. Both substitutions slow enzymatic breakdown, which extends the molecule's persistence relative to the parent hormone. The lactam bridge further constrains the backbone into a stable conformation. These features are standard design strategies in peptide chemistry and are not unique to this compound; they appear across many research peptides built for improved stability.
The compound was developed in the late 1980s and early 1990s by academic researchers investigating melanocortin signaling and pigmentation. Early work explored whether synthetic analogs could reproduce effects of the natural hormone under controlled conditions. The molecule never advanced through the full regulatory pathway required for approval as a medicine. From the mid-2000s onward it appeared in unregulated consumer markets, often distributed through informal channels. That gap between research origins and commercial availability shapes how the compound is discussed today.
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.
Receptor-binding studies classify melanotan II as a non-selective melanocortin agonist. It interacts with MC1R, MC3R, MC4R and MC5R, with reported affinities in the low nanomolar range and no strong subtype preference. Activation of MC1R on dermal melanocytes shifts pigment synthesis toward eumelanin, the dark polymer deposited in melanosomes and transferred to keratinocytes. Because the same peptide engages MC4R in the hypothalamus, it also appears in animal work on food intake and erectile response, which is why it is discussed in both pigment and metabolic research. Which receptor populations dominate after systemic exposure in humans is not fully established.
Melanotan II is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its structure substitutes a lactam bridge between side chains to increase stability relative to the native hormone. The compound is also known by the shorthand MT-II and by several non-proprietary synonyms used in research catalogues. It is not an approved therapeutic product in any major jurisdiction; material sold under this name is typically offered as a laboratory reagent rather than as a medicine.
Activity is attributed to agonism at melanocortin receptors, particularly MC1R and MC4R. Activation of MC1R on melanocytes increases melanin synthesis, which underlies the reported tanning effect. MC4R engagement in the central nervous system is linked to appetite suppression and to effects on sexual arousal reported in early clinical studies. Those studies were small and were not designed to establish efficacy or long-term safety. Receptor selectivity among the melanocortin subtypes is not absolute, which complicates attribution of any effect to a single pathway.
Regulatory treatment varies between countries. Several national medicines agencies have classified the peptide as unapproved, and customs authorities in some jurisdictions seize shipments on that basis. A few jurisdictions channel supply through prescription-only frameworks that do not list the substance by name. Because the material circulates mainly through online vendors, composition and purity are rarely verified before sale. Surveys of unapproved peptide products have reported labels that did not match measured content in a substantial fraction of samples.
== Veröffentlichungen == Qualität im analytischen Labor. Wiley-VCH, Weinheim 1995, ISBN 978-3-527-28683-6 HPLC-Tips, Band 1 – Die schnelle Hilfe für jeden Anwender. WEKA BUSINESS MEDIEN, Kissing, (3. Auflage) 2000, ISBN 3-935772-02-5 erweiterte Version (englisch): Practical Problem Solving in HPLC, Wiley-VCH, Weinheim 2000, ISBN 3-527-29842-8 erschienen in Persisch, übersetzt von Maliheh Ghassemi & Proshat Mazhar, 2005, FDCRL Handbuch Validierung in der Analytik. Wiley-VCH, Weinheim (2. Auflage) 2011, ISBN 3-527-32938-2 Validierung in der Analytik. Wiley-VCH, Weinheim (2. Auflage) 2011, ISBN 3-527-32939-0 Eigenschaften von kommerziellen HPLC-RP-Säulen im Vergleich. Pirrot Verlag, Saarbrücken 2002, ISBN 978-3-930714-78-0 HPLC-Tipps, Band 2 – Die schnelle Hilfe für jeden Anwender. WEKA BUSINESS MEDIEN, Kissing 2004, ISBN 3-935772-07-6 erweiterte Version (englisch): More Practical Problem Solving in HPLC, Wiley-VCH, Weinheim 2005, ISBN 3-527-31113-0 (Hrsg.): HPLC richtig optimiert. Wiley-VCH, Weinheim 2006, ISBN 3-527-31470-9 erweiterte Version (englisch): HPLC Made to Measure, Wiley-VCH, Weinheim 2007, ISBN 3-527-31377-X mit H.J. Kuss (Hrsg.): Chromatogramme richtig integrieren und bewerten. Wiley-VCH, Weinheim 2008, ISBN 978-3-527-31774-5 erweiterte Version (englisch): Quantification in LC and GC – A practical guide to Good Chromatographic Data, Wiley-VCH, Weinheim 2009, ISBN 978-3-527-32301-2 chinesische Version: 液相与气相色谱定量分析使用指南 [平装], ISBN 978-7-117-13370-8
Das Ångström [ˈɔŋstrø:m] (nach dem schwedischen Physiker Anders Jonas Ångström) ist eine Maßeinheit der Länge. Das Einheitenzeichen ist Å (A mit Ring). Ein Ångström entspricht dem zehnmillionsten Teil eines Millimeters. Das Ångström ist keine SI-Einheit.
1 Å = 100 pm = 0,1 nm = 10−10 m Das Ångström wird insbesondere in der Kristallographie und der Chemie benutzt, um mit „einfachen“ Zahlenwerten arbeiten zu können. So ist 1 Å die typische Größenordnung für Atomradien sowie Abstände von Atomen in Kristallstrukturen und Bindungslängen in Molekülen. Der Radius isolierter neutraler Atome beträgt zwischen 0,3 und 3 Å. Daher wird das Ångström oft als Einheit für Abstände in atomaren Größenordnungen verwendet, z. B. für die Dicke sehr dünner Schichten, für die Angabe der Wellenlänge der Röntgenstrahlung bei Röntgenbeugungsexperimenten wie der Kristallstrukturanalyse, sowie für die Porengröße von stationären Phasen in flüssigchromatographischen Säulen für die Hochleistungsflüssigkeitschromatographie (HPLC). In der Thermodynamik wird die mittlere freie Weglänge der sich bewegenden Moleküle häufig in Ångström angegeben. Auch in der Optik und der Astronomie wird es zur Angabe einer Wellenlänge genutzt (allerdings weniger in deutschsprachigen, sondern eher in englischsprachigen Fachpublikationen). Da das Ångström nicht in der Einheitenrichtlinie aufgeführt wird, ist es in der EU keine gesetzliche Einheit, nach der schweizerischen Einheitenverordnung auch nicht in der Schweiz. In DIN 1301-3 ist sie ausdrücklich als nicht mehr zugelassene Einheit aufgelistet.
== Geschichte == Um die Jahrhundertwende 1900 benutzte Michelson eine rote Spektrallinie von Cadmium als Referenz für andere Messungen, weil diese experimentell besonders gut zugänglich und stabil war. Im Jahr 1907 setzte die Internationale Astronomische Union diese Wellenlänge als 6438,4696 Ångström fest und definierte damit eine Längenmaßeinheit, die sehr nahe, aber nicht exakt bei 10−10 m lag. Für Präzisionsmessungen in diesem Längenbereich war es einfacher, diese mikroskopisch definierte Maßeinheit zu benutzen, als den Meter um zehn Größenordnungen „herunterzubrechen“. Einen ähnlichen Versuch, zu einfach handhabbaren Zahlenwerten zu kommen, unternahm 1925 Manne Siegbahn mit der Definition der X-Einheit, die etwa 10−13 Meter entsprach. Das Ångström setzte sich aber durch. Als 1960 der Meter über eine Wellenlänge (des Kryptons) neu definiert wurde, bot die „mikroskopische“ Definition des Ångström keinen Vorteil mehr, und es bekam seine heutige Definition. 1965 führte der amerikanische Atomphysiker Joyce Alvin Bearden die Einheit Ångström Stern (Einheitenzeichen: Å*) für die Messung der Wellenlänge von Röntgenstrahlen und Kristallgittern ein, die die X-Einheit ersetzen sollte. Dabei wählte er als Definition die Kα1-Linie des chemischen Elements Wolfram, die dann 0.2090100 Å* entsprach. Der aktuelle CODATA-Wert ist 1 Å* = 1.00001495(90)e-10 m.
Sources: de.wikipedia.org
No regulator in a major market has approved it for human use. It appears in research settings and in products marketed outside pharmacy channels. Legal status for personal possession varies by country.
Afamelanotide is a linear analog that has received approval in some jurisdictions for a specific photoprotection indication. Melanotan II is cyclic and less selective across melanocortin receptors. The two are related but are not interchangeable in regulatory or clinical terms.
A compound that activates several receptor subtypes may produce effects beyond pigmentation. Selectivity influences which tissues respond and shapes the side-effect profile described in reports. Designing subtype-selective analogs is a stated goal of melanocortin research.
No regulatory agency has authorised melanotan-2 as a medicine for any indication. It circulates mainly as a research chemical or through unregulated channels. As a result, identity, purity and content are not independently guaranteed.