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.
Last reviewed on 2026-04-05. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
| 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 |
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.
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.
Insects have two types of "blood sugar", the monosaccharide glucose and the disaccharide trehalose. Trehalose is the major carbohydrate used by insects for flight. The concentrations of the carbohydrates trehalose and glucose in the insect hemolymph are tightly controlled by multiple enzymes and hormones, including trehalase, insulin-like peptides (ILPs and DILPs), adipokinetic hormone (AKH), leucokinin (LK), octopamine and other mediators, thereby maintaining carbohydrate homeostasis by endocrine and metabolic feedback mechanisms.
The neptunium antimonide compound NpSb was produced in 1971 by placing equal quantities of both elements in a vacuum tube, heating them to the melting point of antimony, and then heating it further to 1000 °C for sixteen days. This procedure also produced trace amounts of an additional antimonide compound Np3Sb4. One neptunium-bismuth compound, NpBi, has also been reported. The neptunium carbides NpC, Np2C3, and NpC2 (tentative) have been reported, but have not characterized in detail despite the high importance and utility of actinide carbides as advanced nuclear reactor fuel. NpC is a non-stoichiometric compound, and could be better labelled as NpCx (0.82 ≤ x ≤ 0.96). It may be obtained from the reaction of neptunium hydride with graphite at 1400 °C or by heating the constituent elements together in an electric arc furnace using a tungsten electrode. It reacts with excess carbon to form pure Np2C3. NpC2 is formed from heating NpO2 in a graphite crucible at 2660–2800 °C.
=== Later work === In 1965, Zuckerkandl moved back to France to direct in Montpellier, the "Centre de Recherche de Biochimie Macromoléculaire" of the Centre National de Recherche Scientifique. In 1971, he became the founding editor of the Journal of Molecular Evolution, and in the late 1970s became President of the Linus Pauling Institute (then in 1992 of its successor, the Institute of Molecular Medical Sciences). His recent work includes criticism of social constructionism and intelligent design.
Starting in 2007, Jimmy John's began sponsoring NASCAR, first with Steven Wallace in 2007 and 2008. In 2009 and 2010, Jimmy John's sponsored Kevin Harvick in the NASCAR Nationwide Series. In 2011, Jimmy John's and Richard Childress Racing reached a multi-year agreement to sponsor Harvick for the Sprint Cup Series. The 2014 sponsorship continued with Harvick and the Stewart–Haas Racing team. On September 13, 2014, Jimmy John's became the title sponsor of the Jimmy John's Freaky Fast 300 at Chicagoland Speedway. Harvick won the 2014 NASCAR Sprint Cup Championship, giving Jimmy John's their first championship. From 2010 to 2019, Jimmy John's entered into an Ultimate Fighting Championship sponsorship with Brock Lesnar with logos appearing on his trunks. This sponsorship extended to WWE upon Lesnar's return to that company in 2012, making him the only WWE performer in history to be permitted such a deal. In 2015, Jimmy John's co-sponsored the RCH Factory Racing Supercross and Motocross team featuring Ken Roczen. The team contested both the Monster Energy AMA Supercross and the Lucas Oil Pro Motocross championships. In June, Jimmy John's sponsored former NASCAR champion Rusty Wallace for his Speed Energy Formula Off-Road debut at the 2015 X Games.
Sources: en.wikipedia.org
In countercurrent flow, the two flows move in opposite directions. Two tubes have a liquid flowing in opposite directions, transferring a property from one tube to the other. For example, this could be transferring heat from a hot flow of liquid to a cold one, or transferring the concentration of a dissolved solute from a high concentration flow of liquid to a low concentration flow. The counter-current exchange system can maintain a nearly constant gradient between the two flows over their entire length of contact. With a sufficiently long length and a sufficiently low flow rate this can result in almost all of the property transferred. So, for example, in the case of heat exchange, the exiting liquid will be almost as hot as the original incoming liquid's heat.
Blumofe (1930), producer of Bound for Glory, nominated for the Academy Award for Best Picture Ben Maddow (1930), screenwriter for The Asphalt Jungle, God's Little Acre and The Mephisto Waltz Albert Maltz (1930), screenwriter for Destination Tokyo and one of the Hollywood Ten Arnold M. Auerbach (1932), Primetime Emmy Award-winning American comedy writer William Ludwig (1932), Academy Award-winning screenwriter, Interrupted Melody Martin Manulis (1935), CBS television and movie producer, Days of Wine and Roses, The Best of Broadway, Climax!, Suspense; creator of Playhouse 90; former president of 20th Century Fox Television Charles H. Schneer (1940), film producer known for his collaboration with Ray Harryhausen I.A.L. Diamond (1941), screenwriting partner of Billy Wilder; co-author of Some Like It Hot; co-winner of the Academy Award for Best Original Screenplay for The Apartment Don M.
== Sources == Ovington LG (October 2002). "The evolution of wound management: ancient origins and advances of the past 20 years". Home Healthc Nurse. 20 (10): 652–6. doi:10.1097/00004045-200210000-00009. PMID 12394337. Sipos P, Gyõry H, Hagymási K, Ondrejka P, Blázovics A (February 2004). "Special wound healing methods used in ancient egypt and the mythological background". World J Surg. 28 (2): 211–6. doi:10.1007/s00268-003-7073-x. PMID 14708054. S2CID 1210892. "Dressing and Bandage Types." Wound Care. N.p., n.d. Web. 23 Nov. 2015.
== Export == Sinokrot holding has expanded their businesses of medjoul dates (Pal Gardens Agriculture Company) to the european markets. Building relationships with big European Dates distributors such as Dadelskopen.
== Co-culture composition and conditions == Based on the desired product of the SCOBY, different species of bacteria and yeast are used. Such cultures generally include aerobic, gram negative AAB species such as Acetobacter, Gluconobacter and Komagataeibacter, aerobic, gram positive LAB such as Lactobacillus, as well as various yeasts such as Saccharomyces and Zygosaccharomyces. Strains are pre-screened for viability under compatible conditions, increased yield of desired product, and indisposition to compete; once chosen, various culture conditions are modified for optimal growth and productivity. For kombucha SCOBYs, the first step is yeast fermentation of sugars such as glucose from black or green tea into ethanol and carbon dioxide. Zygosaccharomyces is reported to be involved in 84.1% of all kombucha SCOBY fermentation processes due to its improved stability in high sugar and halophilic conditions, while Saccharomyces is predominantly used for its efficient fermentation rates and resistance to high temperature and alcohol content. Different variations of yeast can also be added as either a supplemental means to introduce different flavors and aromas or ensure reaction completion by utilizing different niches. While these niches vary yeast to yeast, certain fermentation conditions remain consistent. Such conditions include but are not limited to high substrate concentration, sufficient oxygen levels, temperatures of 20–30 °C (68–86 °F), and a pH between 4–4.5.
Sources: en.wikipedia.org
== Sources == Espy, Richard (1981). The Politics of the Olympic Games: With an Epilogue, 1976–1980. University of California Press. ISBN 9780520043954. Retrieved 16 June 2013. Honey, Andrew (2000). "South Africa and the Olympic Movement" (PDF). In K.B. Wamsley; S.G. Martyn; G. H. MacDonald; R.K. Barney (eds.). Bridging Three Centuries: Intellectual Crossroads and the Modern Olympic Movement. International Symposium for Olympic Research. pp. 177–184. Retrieved 17 June 2013. Killanin, Michael Morris, Lord (1983). "V: South Africa". My Olympic Years. New York: Morrow. pp. 33–45. ISBN 978-0-688-02209-9 – via Internet Archive. Ramsamy, Sam (1991). "Apartheid and Olympism: on the Abolishment of Institutionalized Discrimination in International Sport". In Fernand Landry; Marc Landry; Magdeleine Yerlès (eds.). Sport, the Third Millennium: Proceedings of the International Symposium, Quebec City, Canada, May 21-25, 1990. Presses Université Laval. pp. 539–548. ISBN 9782763772677. Retrieved 17 June 2013.
However, as Liebling began to make his first attempts at recovery, the filmmakers started to see potential in his journey. Shaping Last Days Here into a coherent narrative proved to be a challenge. Liebling's personality was more erratic than the documentary ultimately portrayed. "Many times we had to finesse the rapid shifts in Bobby's life so the viewer wouldn't be left confused. Over the three years we were shooting, we saw the many different faces of Bobby Liebling. The delusional crack-smoking hustler, the arrogant '70s rock star, and the really cool loveable uncle. When boiling the footage down to 90 minutes, we really wanted to exemplify a balance of those personalities. That balance is sometimes tough to maintain," stated Fenton.
Bukele's popularity as mayor of San Salvador led some journalists to believe that he would run for president in 2019, but he denied that he would. He eventually expressed interest in running for president with the FMLN, but the party did not consider him as its vice-presidential nominee. He wrote on social media that the FMLN had purged him, and portrayed himself as an independent politician who rejected the country's political system. On 15 October 2017, Bukele announced his intention to run for president in 2019 and form a new political party. He announced the establishment of the Nuevas Ideas party on 25 October 2017 on social media, saying that Nuevas Ideas would seek to remove ARENA and the FMLN from power. During his presidential campaign, Bukele and a network of YouTubers, bloggers, and internet trolls attempted to discredit ARENA and the FMLN. Bukele tried to associate the two parties with the governments of previous presidents that were marred by corruption, using slogans such as "There's enough money when nobody steals" and "Return what was stolen". His campaign promises included the creation of an international commission to combat corruption, the development of a trans-national railroad and a new airport, job opportunities for Salvadorans, and reduced crime.
=== Half-Life 3 === Half-Life 3 was in development between 2013 and 2014. Valve planned to use procedurally generated levels alongside a "crafted experience", similar to the Left 4 Dead series; the game would generate different routes through environments each time it was played. The team took new scans of the face of Frank Sheldon, whose likeness was used for the G-Man character in Half-Life 2. The Source 2 engine was still unfinished and the project was canceled early in development.
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 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.