If you have been reading about MC1R 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.
Updated 2026-02-15. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
The material is commonly handled as a lyophilized powder in sealed vials. The solid dissolves readily in water and in polar organic solvents, producing a clear solution after reconstitution. Light, heat and repeated freeze-thaw cycles are the concerns most often raised in handling guidance, because peptide bonds and the constrained ring can degrade. Working solutions are generally prepared fresh, and material left in solution is treated as less stable than the dry form. These properties shape how laboratories store and aliquot reference material.
Identity and purity are assessed mainly by reversed-phase high-performance liquid chromatography with ultraviolet detection, often paired with mass spectrometry. Retention time supports identity, while the mass spectrum confirms the molecular weight of the intact peptide. Purity is frequently reported as a percentage of total peak area, a figure that depends on the wavelength, column and gradient used. Impurity profiling may also look for truncated sequences, oxidised forms and residual counterions. Amino acid analysis and peptide mapping provide orthogonal confirmation when required.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Belongs to the melanocortin agonist family |
| Key substitutions | Nle4 and D-Phe7 | Improve resistance to enzymatic degradation |
| Molecular formula | C50H69N15O9 | Approximately 1024 g/mol |
| Regulatory status | Not approved as a medicine | Distributed as a research chemical |
| Common synonyms | Melanotan II, MT-II, MT-2 | Spelling varies across sources |
Melanotan II is a synthetic cyclic heptapeptide analog derived from the core sequence of alpha-melanocyte-stimulating hormone. Researchers at the University of Arizona synthesized it during the 1980s while studying pigmentation and appetite signaling. The compound is not an approved medicine in any major jurisdiction and appears mainly in laboratory and research-chemical settings. Its structure incorporates a lactam bridge between side chains, which constrains the ring and slows enzymatic breakdown relative to the natural hormone.
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.
Melanotan II holds no marketing authorisation from the Food and Drug Administration, the European Medicines Agency, the UK Medicines and Healthcare products Regulatory Agency or Australia's Therapeutic Goods Administration. Products sold under that name are treated as unapproved new drugs, and their sale or import is prohibited in several jurisdictions. Other countries classify the peptide as a prescription-only medicine or place it among controlled substances, so the legal position changes with the destination market. No pharmacopoeial monograph supplies an official specification, because the material is not a licensed pharmaceutical. Consequently, products offered online are not manufactured to a shared public standard.
The peer-reviewed record is dominated by small early-phase studies, case reports and pharmacovigilance summaries rather than large randomised trials. Papers typically examine tanning response, receptor selectivity or patterns of reported adverse events. Many note that participants obtained the peptide outside a clinical setting, which limits verification of composition and administered amount. Reported events vary widely, and causality is frequently unclear because the identity and purity of self-sourced material are unknown. Open questions include whether repeated melanocortin receptor stimulation produces cumulative effects, and how often label claims match actual content.
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.
Delayed stomach emptying creates especially favorable conditions for the shock lactic acidosis, because the digestive system may meanwhile still inhibit fatty acid release and oxidation, helping more muscles to run out of glycogen in those persons, who are otherwise still able to maintain its stores between meals. It has been experimentally demonstrated, that delayed gastric emptying prolongs the duration of the GLP-1 signal. Notably, a small quantity of dietary fructose does not produce this effect (the lactic acidosis), as it is captured by liver and may be fully expended for replenishing liver glycogen. Once all AMP has been recharged to ATP, and glycogen stores allowed to replenish, the cell transitions back to the unmodified original state. If carbohydrate-rich food is not consumed in this state, AMP elimination from the cell eventually completes, glycogen stores can be replenished again, and the cell transitions back to the original state but with reduced ATP pool and an up-regulated citric acid cycle. It may be especially important to have adequate dietary iodine in the glycogen-less state, so that stomach emptying is not excessively delayed, the up-regulation of the citric acid cycle in muscle cells in response to a load increment is not too slow, and the muscles can each time accept a bigger load increment relative to the perceived effort.
=== Mycorrhizal associations === Boletus edulis is mycorrhizal—it is in a mutualistic relationship with the roots of plants (hosts), in which the fungus exchanges nitrogen and other nutrients extracted from the environment for fixed carbon from the host. Other benefits for the plant are evident: in the case of the Chinese chestnut, the formation of mycorrhizae with B. edulis increases the ability of plant seedlings to resist water stress, and increases leaf succulence, leaf area, and water-holding ability. The fungus forms a sheath of tissue around terminal, nutrient-absorbing root tips, often inducing a high degree of branching in the tips of the host, and penetrating into the root tissue, forming, to some mycologists, the defining feature of ectomycorrhizal relationships, a hartig net. The ectomycorrhizal fungi are then able to exchange nutrients with the plant, effectively expanding the root system of the host plant to the furthest reaches of the symbiont fungi. Compatible hosts may belong to multiple families of vascular plants that are widely distributed throughout the Northern Hemisphere; according to one 1995 estimate, there are at least 30 host plant species distributed over more than 15 genera. Examples of mycorrhizal associates include Chinese red pine, Mexican weeping pine, Scots pine, Norway spruce, Coast Douglas-fir, mountain pine, and Virginia pine. The fungus has also been shown to associate with gum rockrose, a pioneer early stage shrub that is adapted for growth in degraded areas, such as burned forests.
1975: Indian geneticist Archana Sharma received the Shanti Swarup Bhatnagar Prize, the first female recipient in the Biological Sciences category. 1975: Female officers of the British Geological Survey no longer had to resign upon getting married. 1975: Chien-Shiung Wu became the first female president of the American Physical Society. 1976: Filipino-American microbiologist Roseli Ocampo-Friedmann traveled to the Antarctic with Imre Friedmann and discovered micro-organisms living within the porous rock of the Ross Desert. These organisms – cryptoendoliths – were observed surviving extremely low temperatures and humidity, assisting scientific research into the possibility of life on Mars. 1976: Margaret Burbidge was named the first female president of the American Astronomical Society. 1977: American medical physicist Rosalyn Yalow received the Nobel Prize in Physiology or Medicine "for the development of radioimmunoassays of peptide hormones" along with Roger Guillemin and Andrew V. Schally who received it "for their discoveries concerning the peptide hormone production of the brain". 1977: Austrian naturalist, artist and author Joy Adamson was awarded the Austrian Cross of Honour for Science and Art. Her book, Born Free, an international bestseller, describes her experiences raising a lion cub named Elsa. It was made into an Academy Award-winning film of the same name. 1977: The Association for Women Geoscientists was founded.
Sources: en.wikipedia.org
Attempts are being made to restore many of the city's best-maintained examples of pre-Soviet architecture. These restored structures are distinguished by bright colors and particularly clean façades. There are also a few examples of Soviet avant-garde work, such as the house of the architect Konstantin Melnikov in the Arbat area. Many of these restorations were criticized for allegedly disrespecting historical authenticity. In addition, facadism is widely practiced. Later examples of Soviet architecture are usually distinguished by large size and semi-Modernist styles. An example is the Novy Arbat project—informally called the "false teeth of Moscow"—and known for widespread disruption of the project's historic area in central Moscow.
== Further reading == Goldsmith, WM (1945). "Trepanation and the 'CatlinMark'". American Antiquity. 10 (4): 348–52. doi:10.2307/275576. JSTOR 275576. S2CID 163518652. Guerra Doce, E (2006). "Evidencias del consumo de drogas en Europa durante la Prehistoria". Trastornos Adictivos (in Spanish). 8 (1): 53–61. doi:10.1016/S1575-0973(06)75106-6. Archived from the original on 15 May 2008. Retrieved 14 November 2010. Gurlt, EJ (1898). "VI: Volkschirurgie in Japan in alter und neuerer". Geschichte der Chirurgie und ihrer Ausübung (in German). Vol. 1. Berlin: Verlag von August Hirschwald. p. 83. Retrieved 14 November 2010. Hrdlicka, A (1939). "Trepanation among prehistoric people, especially in America". Ciba Foundation Symposium. 1 (6): 170–7. Matsuki, A (2005). "A brief history of the biographical study of Seishu Hanaoka". Nihon Ishigaku Zasshi (in Japanese). 51 (3): 355–84. ISSN 0549-3323. PMID 16450478. Retrieved 14 November 2010. Matsuki, A (2006). "Why did Hanaoka's Method of Anesthesia Decay Rapidly at the End of the Edo Period?". Nihon Ishigaku Zasshi (in Japanese). 52 (1): 40–1. ISSN 0549-3323. Ruffer, MA (1918). "Studies in paleopathology. Some recent researches on prehistoric trephining". Journal of Pathology and Bacteriology. 22: 90–104. doi:10.1002/path.1700220109. Stewart, TD (1958). "Stone Age skull surgery. A general review with emphasis on the New World". Smithsonian Annual Report of the Board of Regents, 1957. pp. 469–91.
His 1964 publication of The Jargon of Authenticity took aim at the halo such writers had attached to words like "angst," "decision," and "leap." He also disapproved of Ernest Hemingway's works, agreeing with his friend Reinhard Baumgart that Hemingway's idyll of a life of simple pleasures was an unrealistic fantasy. This set him against many in the German literary elite, such as Hemingway's translators Ernst Rowohlt and Annemarie Horschitz-Horst and Adorno's own friend Annemarie Seidel. After seven years of work, Adorno completed Negative Dialectics in 1966, after which, during the summer semester of 1967 and the winter semester of 1967–68, he offered regular philosophy seminars to discuss the book chapter by chapter. Among the students at these seminars were the Americans Angela Davis and Irving Wohlfarth. One objection, which would soon take on ever greater importance, was that critical thought must adopt the standpoint of the oppressed, to which Adorno replied that negative dialectics was concerned "with the dissolution of standpoint thinking itself."
Sources: en.wikipedia.org
== Dosing considerations == The recommended intravenous dosage in adults is 500 mg every 6 hours or 1000 mg every 12 hours, with modification to achieve a therapeutic range as needed. The recommended oral dosage in the treatment of antibiotic-induced pseudomembranous enterocolitis is 125 to 500 mg every 6 hours for 7 to 10 days. Dose optimization and target attainment of vancomycin in children involves adjusting the dosage to maximize effectiveness while minimizing the risk of adverse effects, specifically acute kidney injury. Dose optimization is achieved by therapeutic drug monitoring (TDM), which allows measurement of vancomycin levels in the blood. TDM using area under the curve (AUC)-guided dosing, preferably with Bayesian forecasting, is recommended to ensure that the AUC0-24h/minimal inhibitory concentration (MIC) ratio is maintained above a certain threshold (400–600) associated with optimal efficacy.
Peptides and proteins are often described by the number of amino acids in their chain, e.g. a protein with 158 amino acids may be described as a "158 amino-acid-long protein". Peptides of specific shorter lengths are named using IUPAC numerical multiplier prefixes:
S. divinorum (0.89 mg/g to 3.70 mg/g). S. recognita (212.9 μg/g). S. cryptantha (51.5 μg/g). S. glutinosa (38.9 μg/g). Salvinorin B has been detected in S. potentillifolia and S. adenocaulon, however these species do not contain a measureable amount of salvinorin A.
Sources: en.wikipedia.org
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.
No regulatory agency has approved it for any indication. It is encountered as a research chemical sold outside pharmaceutical supply chains. Products marketed this way are not subject to the manufacturing and labeling requirements that apply to approved drugs.
Reports describe increased skin pigmentation as well as side effects such as nausea, flushing, and changes to existing moles. Much of the evidence comes from small studies and case reports rather than large trials. The long-term safety profile is therefore uncertain.
The dry powder is more stable during transport and storage than a solution. It also allows a known amount of material to be reconstituted at a chosen concentration.