Everything below concerns Melanotan II. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-09-11. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Compound class | Synthetic cyclic heptapeptide | Alpha-MSH analogue containing a D-phenylalanine residue |
| Molecular formula | C50H69N15O9 | Average molecular mass approximately 1024.2 g/mol |
| Appearance | White to off-white lyophilised powder | Normally supplied as a freeze-dried solid in a sealed vial |
| Solubility | Freely soluble in water and polar solvents | Dissolves readily in aqueous buffers and in alcohol-water mixtures |
| Receptor targets | MC1R, MC3R, MC4R, MC5R | Acts as a non-selective melanocortin receptor agonist |
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.
== Medical uses == Ampicillin/sulbactam has a wide array of medical use for many different types of infectious disease. It is usually reserved as a second-line therapy in cases where bacteria have become beta-lactamase resistant, rendering traditional penicillin-derived antibiotics ineffective. It is effective against certain gram positive bacteria, gram-negative bacteria, and anaerobes.
Paul Berg, a Nobel laureate in chemistry, wrote to the Senate that "Quackery will always prey on the gullible and uninformed, but we should not provide it with cover from the NIH," and called the office "an embarrassment to serious scientists". Allen Bromley, then-president of the American Physical Society, similarly wrote to Congress that the OAM had "emerged as an undiscriminating advocate of unconventional medicine. It has bestowed the considerable prestige of the NIH on a variety of highly dubious practices, some of which clearly violate basic laws of physics". Leon Jaroff, writing for The New York Times in 1997, described the OAM as "Tom Harkin's folly". In 1995, Wayne Jonas, a promoter of homeopathy and political ally of Harkin, became the director of the OAM, and continued in that role until 1999. In 1997, the NCCAM budget was increased from $12 million to $20 million annually. From 1990 to 1997, use of alternative medicine in the US increased by 25%, with a corresponding 50% increase in expenditures. The OAM drew increasing criticism from eminent members of the scientific community with letters to the Senate Appropriations Committee when discussion of renewal of funding OAM came up. In 1998, the President of the North Carolina Medical Association publicly called for shutting down the OAM. In 1998, NIH director and Nobel laureate Harold Varmus came into conflict with Harkin by pushing to have more NIH control of alternative medicine research. The NIH Director placed the OAM under stricter scientific NIH control.
== Mechanism == Pyridoxine is in the vitamin B family of vitamins. It is required by the body to make amino acids, carbohydrates, and lipids. Sources in the diet include fruit, vegetables, and grain. It is also required for muscle phosphorylase activity associated with glycogen metabolism.
== Transportation == SST class blimp Supersonic transport, aircraft Training Submarines, (US Navy hull classification symbol: SST) Mitsubishi SST, a concept car by Mitsubishi Twin Clutch SST, a twin-clutch transmission developed by Mitsubishi Safe Secure Trailer, see US Office of Secure Transportation SST, the National Rail station code for Stansted Mountfitchet railway station, Essex, England
Sources: en.wikipedia.org
=== Articles === Rosen, DR; Siddique, T; Patterson, D; Figlewicz, DA; Sapp, P; Hentati, A; Donaldson, D; Goto, J; O'Regan, JP; Deng, HX; et al. (1993). "Mutations in Cu/Zn superoxide dismutase gene are associated with familial amyotrophic lateral sclerosis". Nature. 364 (6435): 362. Bibcode:1993Natur.364..362R. doi:10.1038/364362c0. PMID 8332197. Gusella, JF; Wexler, NS; Conneally, PM; Naylor, SL; Anderson, MA; Tanzi, RE; Watkins, PC; Ottina, K; Wallace, MR; Sakaguchi, AY; Young, AB; Shoulson, I; Bonilla, E; Martin, JB (1983). "A polymorphic DNA marker genetically linked to Huntington's Disease". Nature. 306 (5940): 234–238. Bibcode:1983Natur.306..234G. doi:10.1038/306234a0. PMID 6316146. S2CID 4320711. Tanzi, RE; Gusella, JF; Watkins, PC; Bruns, GAP; St; George-Hyslop, PH; Van Keuren, ML; Patterson, D; Pagan, S; Kurnit, DM; Neve, RL. (1987). "The amyloid beta protein gene: cDNA cloning, mRNA distribution, and genetic linkage near the Alzheimer locus". Science. 235 (4791): 880–884. Bibcode:1987Sci...235..880T. doi:10.1126/science.2949367. PMID 2949367. Tanzi, RE; McClatchey, AI; Lamperti, ED; V-Komaroff, L; Gusella, JF; Neve, R (1988). "Protease inhibitor domain encoded by an amyloid protein precursor mRNA associated with Alzheimer's disease". Nature. 331 (6156): 528–530. Bibcode:1988Natur.331..528T. doi:10.1038/331528a0. PMID 2893290. S2CID 4277294.
Napoleon's Wars: An International History, 1803–1815. Penguin Books. ISBN 978-0-14-311628-8. Ferguson, Niall (2008). The Ascent of Money: A Financial History of the World: 10th Anniversary Edition. Penguin. ISBN 978-1-4406-5402-2. Fremont-Barnes, Gregory (2014). The Napoleonic Wars (3): The Peninsular War 1807–1814. Bloomsbury Publishing. ISBN 978-1-4728-0975-9. Gates, David (1986). The Spanish Ulcer: A History of the Peninsular War. Allen & Unwin. ISBN 978-0-04-940079-5. Glover, Michael (1963). Wellington's Peninsular Victories: Busaco, Salamanca, Vitoria, Nivelle. Macmillan. Götz, Norbert (6 June 2014). "The Good Plumpuddings' Belief: British Voluntary Aid to Sweden During the Napoleonic Wars". The International History Review. 37 (3): 519–539. doi:10.1080/07075332.2014.918559. ISSN 0707-5332. Grab, Alexander (2003). Napoleon and the Transformation of Europe. Macmillan International Higher Education. ISBN 978-1-4039-3757-5. Grainger, John D. (2004). The Amiens Truce: Britain and Bonaparte, 1801–1803. Boydell Press. ISBN 978-1-84383-041-2. Gray, Colin S. (2007). War, Peace and International Relations: An Introduction to Strategic History. Routledge. ISBN 978-1-134-16951-1. Halévy, Elie (1924). A History of the English People ...: England in 1815. Harcourt, Brace. Haythornthwaite, Philip; et al. (Illustrations and graphics by Peter Dennis) (20 September 2012). Cowper, Marcus (ed.). Borodino 1812: Napoleon's great gamble. Campaign. Vol. 246. London, England, United Kingdom of Great Britain: Bloomsbury Publishing. ISBN 9781849086974.
== Monitoring glutathione reductase activity == The activity of glutathione reductase is used as indicator for oxidative stress. The activity can be monitored by the NADPH consumption, with absorbance at 340 nm, or the formed GSH can be visualized by Ellman's reagent. Alternatively the activity can be measured using roGFP (redox-sensitive Green Fluorescent Protein).
PF-219,061 is a drug that was under development by Pfizer which acts as a potent and highly selective agonist for the dopamine D3 receptor. It was under development as a potential medication for the treatment of female sexual dysfunction. It did not advance into clinical trials.
For the correction of male breast defects and deformities, the pectoral implant is the breast prosthesis used for the reconstruction and the aesthetic repair of a man's chest wall (see: gynecomastia and mastopexy).
Sources: en.wikipedia.org
No. It is a laboratory-made peptide, while the natural hormone is alpha-melanocyte-stimulating hormone, a longer peptide produced by the pituitary gland and by skin cells. Melanotan-2 mimics only a short active region of that hormone and contains non-natural residues such as D-phenylalanine.
No approved regulatory indication exists in major markets. An approval exists for a different peptide, afamelanotide, which is used for a rare photosensitivity disorder called erythropoietic protoporphyria. Melanotan-2 itself remains a research compound with no cleared clinical role.
Melanocortin-1 receptors on melanocytes are the receptor most closely linked to pigment production. The peptide is not selective, however, and also activates melanocortin-3, melanocortin-4, and melanocortin-5 receptors. That lack of selectivity is the usual explanation offered for both its range of observed effects and its off-target effects.
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.