If you have been reading about afamelanotide 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 2026-01-17. Where a claim depends on a specific study, the study is described rather than over-claimed.
Melanotan-2 is a synthetic linear peptide built from seven amino acids arranged in a short chain. Its sequence is commonly written as Ac-Nle-Asp-His-D-Phe-Arg-Trp-Lys-NH2, which includes a modified N-terminus and an amidated C-terminus. The molecule belongs to the melanocortin family and acts as a receptor agonist. Structural features such as the D-phenylalanine residue and the Nle substitution are associated with increased stability against enzymatic degradation relative to the natural parent peptide.
The compound emerged from research programs in the 1980s that examined analogues of alpha-melanocyte-stimulating hormone for pigmentation and photoprotection. Investigators modified the native sequence to extend activity duration and potency. A related analogue, afamelanotide, was developed within the same broad line of inquiry and eventually gained approval in certain jurisdictions for a rare light-sensitivity condition. Melanotan-2 itself did not progress through the same regulatory route and has no approved therapeutic indication.
Melanocortin receptors comprise five subtypes with distinct tissue distributions and functions. Melanotan-2 is described in the literature as a non-selective agonist that engages several of these subtypes, including MC1R, MC3R, MC4R, and MC5R. MC1R is the subtype most directly linked to melanin production in skin cells. Because the compound is not subtype-selective, its observed effects in experimental settings are generally attributed to activity across multiple receptor pathways rather than to a single target.
The peptide acts as a non-selective agonist at melanocortin receptors, showing affinity for MC1R, MC3R, MC4R and MC5R. Activation of MC1R on melanocytes drives the conversion of tyrosine into melanin and shifts production toward the darker eumelanin form. MC4R signalling in the central nervous system is linked to appetite and energy balance, which helps explain why reduced food intake appeared in early human studies. Effects on MC4R and on vascular tone also account for the erectile responses recorded as unexpected findings in those same trials.
Melanotan-2 is frequently confused with afamelanotide, a linear analogue authorised in the European Union for erythropoietic protoporphyria. The two compounds differ in chain length, ring structure and receptor selectivity, so findings for one cannot be transferred directly to the other. Published controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports. Questions about effect size, dose-response behaviour and long-term safety therefore remain unresolved.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence incorporates a lactam bridge that constrains the peptide into a ring, which increases resistance to enzymatic breakdown relative to the natural hormone. Researchers at the University of Arizona synthesised the compound in the late 1980s and early 1990s while studying pigmentation pathways. It has never received marketing approval from any national medicines regulator. In the scientific literature it is usually described as a laboratory research reagent rather than a therapeutic product.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Free base; salt forms differ |
| Molecular weight | Approximately 1024 g/mol | Calculated for the free base |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water and polar solvents | Poorly soluble in non-polar solvents |
| Typical storage | -20 degrees Celsius, dry, protected from light | Refers to the solid form |
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.
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.
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.
== Diagnosis == A seroma may be diagnosed based on signs on the skin. On CT scans, seromas have a radiodensity of 0–20 Hounsfield units, generally in the lower part of this range, consistent with clear fluid.
The dependence of osteosarcoma cells on NMNAT1-derived NAD for the PARP1-dependent DNA repair and survival is not restricted to cisplatin-treated cancer cells but has also been reported to occur in actinomycine D-treated tumor cell lines, as well. These data suggest that nuclear NAD synthesis by NMNAT1 may represent a therapeutic target in osteosarcoma and possibly in other tumors, as well.
=== Sources === Chapple, Christopher Key (1993), Nonviolence to Animals, Earth, and Self in Asian Traditions, State University of New York Press Cort, John E., ed. (1998), Open Boundaries: Jain Communities and Cultures in Indian History, SUNY Press, ISBN 0-7914-3785-X Cort, John E. (2001a), Jains in the World: Religious Values and Ideology in India, Oxford University Press, ISBN 978-0-19-513234-2 Dundas, Paul (2002) [1992], The Jains (Second ed.), London and New York: Routledge, ISBN 978-0-415-26605-5 Jaini, Padmanabh S. (1998) [1979], The Jain Path of Purification, Delhi: Motilal Banarsidass, ISBN 978-81-208-1578-0 Laidlaw, James (1995), Riches and Renunciation. Religion, economy, and society among the Jains, Oxford, ISBN 978-0-19-828031-6 Sangave, Vilas Adinath (1980), Jain Community: A Social Survey (2nd ed.), Bombay: Popular Prakashan, ISBN 978-0-317-12346-3 Shah, Umakant Premanand (1987), Jaina-rūpa-maṇḍana: Jaina iconography, Abhinav Publications, ISBN 81-7017-208-X Vallely, Anne (2002), Guardians of the Transcendent: An Ethnography of a Jain Ascetic Community, University of Toronto Press, ISBN 978-0-8020-8415-6 Wiley, Kristi L. (2009) [1949], The A to Z of Jainism, vol. 38, Scarecrow Press, ISBN 978-0-8108-6337-8
== Animal welfare == Pizza Hut was the target of criticism by a World Animal Protection assessment in 2018, which claimed that it demonstrated "limited evidence" of concern with the humane handling of livestock in its operations. In 2021, Yum! Brands, the owner of Pizza Hut, committed to using only cage-free eggs in the majority of its locations by 2026, and in all locations globally by 2030. The commitment came following the "largest public cage-free campaign" at that time.
Sources: en.wikipedia.org
Alpha cells are endocrine cells, meaning they secrete a hormone, in this case glucagon. Alpha cells store this glucagon in secretory vesicles that typically have an electron dense core and a grayish outer edge. It is believed that alpha cells make up approximately 20% of endocrine cells within the pancreas. Alpha cells are most commonly found on the dorsal side of the pancreas and are very rarely found on the ventral side of the pancreas. Alpha cells are typically found in compact Islets of Langerhans, which are themselves typically found in the body of the pancreas. Alpha cells function in the maintenance of blood glucose levels. Alpha cells are stimulated to produce glucagon in response to hypoglycemia, epinephrine, amino acids, other hormones, and neurotransmitters.
An ion-exchange membrane is a semi-permeable membrane that transports certain dissolved ions, while blocking other ions or neutral molecules. Ion-exchange membranes are therefore electrically conductive. They are often used in desalination and chemical recovery applications, moving ions from one solution to another with little passage of water. Important examples of ion-exchange membranes include the proton-exchange membranes, that transport H+ cations, and the anion exchange membranes used in certain alkaline fuel cells to transport OH− anions.
=== Official discovery and later history === The discovery of element 43 was finally confirmed in a 1937 experiment at the University of Palermo in Sicily by Carlo Perrier and Emilio Segrè. In mid-1936, Segrè visited the United States, first Columbia University in New York and then the Lawrence Berkeley National Laboratory in California. He persuaded cyclotron inventor Ernest Lawrence to let him take back some discarded cyclotron parts that had become radioactive. Lawrence mailed him a molybdenum foil that had been part of the deflector in the cyclotron. Segrè enlisted his colleague Perrier to attempt to prove, through comparative chemistry, that the molybdenum activity was indeed from an element with the atomic number 43, which they did. University of Palermo officials wanted them to name their discovery panormium, after the Latin name for Palermo, Panormus. In 1947, element 43 was named after the Greek word technetos (τεχνητός), meaning 'artificial', since it was the first element to be artificially produced. Segrè returned to Berkeley and met Glenn T. Seaborg. They isolated the metastable isotope technetium-99m, which is now used in some ten million medical diagnostic procedures annually. In 1952, the astronomer Paul W. Merrill detected the spectral signature of technetium (specifically wavelengths of 403.1 nm, 423.8 nm, 426.2 nm, and 429.7 nm) in light from S-type red giants. The stars were near the end of their lives but were rich in the short-lived element, which indicated that it was being produced in the stars by nuclear reactions.
=== Type 2 diabetes === In the BEGIN Basal-Bolus Type 2 trial, insulin degludec was studied as an alternative to insulin glargine in participants with type 2 diabetes. 995 participants were randomized to receive either insulin degludec (n=755) or insulin glargine (n=251), in addition to either mealtime insulin aspart, metformin, and/or pioglitazone. Participants in this trial had an average HbA1c of 8.3–8.4%, and 49–50% were on a regimen consisting of basal-bolus insulin plus oral antidiabetic medications. After 52 weeks, insulin degludec was found to be noninferior to insulin glargine, providing a similar HbA1c lowering effect (−1.10 vs. −1.18%). Overall rates of hypoglycemia were significantly lower with insulin degludec (11.09 vs. 13.63%/yr, p=0.0359), including cases of nocturnal hypoglycemia (1.39 vs. 1.84%/yr, p=0.0399).
=== National acceptance and symbolic meaning === By the period leading to independence, the name "Ghana" was accepted and adopted as a symbol of precolonial prestige, cultural unity, and national legitimacy.
Sources: en.wikipedia.org
No. Melanotan-2 is manufactured synthetically. The naturally occurring peptide in the same family is alpha-melanocyte-stimulating hormone, which the body produces as part of normal endocrine and neural signalling.
Both are synthetic analogues derived from the same parent hormone. Reference descriptions usually characterise afamelanotide as more selective for the MC1R subtype, whereas melanotan-2 is reported to interact with a wider range of melanocortin receptors.
Early studies explored melanocortin signalling and pigmentation, which later led to informal use of the label tanning peptide. That label is not a regulatory category and does not imply approved status for any purpose.
It is a synthetic cyclic heptapeptide modelled on alpha-melanocyte-stimulating hormone. A lactam bridge links two side chains, forming a ring that stabilises the molecule against proteolysis. It belongs to the broader melanocortin peptide family.