MC1R is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2025-11-17. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Receptor studies place melanotan-2 among non-selective melanocortin agonists, binding MC1R, MC3R, MC4R and MC5R rather than a single subtype. Activation of MC1R on cutaneous melanocytes raises tyrosinase activity and shifts pigment synthesis toward eumelanin, which is darker and more photostable than pheomelanin. Central receptors, particularly MC4R, are associated with appetite suppression and with reported effects on sexual function. Because subtype selectivity is low, the same molecule engages pigment, metabolic and vascular pathways at once, and this breadth is a common explanation offered for the range of adverse events described in user reports.
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 peptide designed as an analog of alpha-melanocyte-stimulating hormone, a signaling molecule produced in the pituitary and skin. Its structure is a linear chain of seven amino acids that folds into a ring through an internal lactam bridge joining two side chains. The compound is sometimes written as MT-II or MEL-2 in informal and commercial contexts. It belongs to the melanocortin peptide family, a group of short signaling molecules that share a conserved core sequence recognized by melanocortin receptors.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Free base; salt forms add to total mass |
| Molecular mass | About 1024 daltons | Calculated for the free base |
| Structural class | Cyclic heptapeptide | Contains D-phenylalanine and norleucine |
| Parent hormone | Alpha-melanocyte-stimulating hormone | Endogenous tridecapeptide of 13 residues |
| Receptor profile | Non-selective melanocortin agonist | Interacts with MC1R, MC3R, MC4R and MC5R |
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.
== Criticisms == Yu managed to become a household name in China because she abridged the works of Confucius (551-479 B.C.) and Zhuangzi (369-286 B.C.) to make it appear relevant to laymen with "colloquial re-wordings and vivid short stories". In an interview with New York Times, Yu attributed the popularity of her work to the stresses of life in the fast-changing nation and to historical factors (paraphrased): "Traditional thought has been criticized for so many years that there is genuine interest in rediscovering it." On the Baidu (《百度》) portal alone, there are over 20,000 posts on the "bulletin board" named after her. "White collar workers, college students, professors, migrant workers, community guards and retired grannies all had something to say." Christian Caryl, writing in Hong Kong's Muse Magazine, has criticised Yu's book Confucius from the heart: Ancient Wisdom for Today's World: 'New-Agers in the West have made an industry out of freeze-drying non-Western religions until they're tasteless enough for the indiscriminate modern palate. Yu's book is the first time I've seen a non-Westerner up to the same sort of thing.'
Tánaiste Micheál Martin announces Irish government plans to "initiate an inter-State case against the United Kingdom under the European Convention on Human Rights" over provisions in the Northern Ireland Troubles (Legacy and Reconciliation) Act 2023 which offers immunity from prosecution for certain Troubles-era related offences. Junior doctors in England begin another three-day strike over their long-running pay dispute. A number of ballet dancers are reported to have come forward to make claims about incidents of "body shaming" at UK ballet schools following a BBC investigation into the subject earlier in the year. COVID-19 in the UK: JN.1 is reported as a new variant of interest, following a recent, rapid rise in COVID-19 cases. A teenage boy and girl who shared an obsession with violence and torture are convicted of the murder of Brianna Ghey. Lawrence Bierton is sentenced to a whole life order for the murder of his neighbour, 73-year-old Pauline Quinn, who he battered to death with a coffee table while out on parole following his conviction for two previous murders in 1996. The Scottish Government confirms it will abandon its legal challenge against the UK government's veto of the Gender Recognition Reform (Scotland) Bill. Eight-year-old girl, Bodhana Sivanandan from Harrow, London is crowned best female player at the European blitz chess championships in Zagreb, Croatia. The three men convicted of attempted murder for shooting two children on 14 December are jailed for 23 years.
1940: Turkish archaeologist, Sumerologist, Assyriologist, and writer Muazzez İlmiye Çığ received her degree and began a multi-decade career at Museum of the Ancient Orient, one of three such institutions comprising Istanbul Archaeology Museums, as a resident specialist in the field of cuneiform tablets, thousands of which were being stored untranslated and unclassified in the facility's archives. In the intervening years, due to her efforts in the deciphering and publication of the tablets, the museum became a Middle Eastern languages learning center attended by ancient history researchers from every part of the world. 1941: American scientist Ruth Smith Lloyd became the first African-American woman to receive a PhD in anatomy. 1942: Austrian-American actress and inventor Hedy Lamarr and composer George Antheil developed a radio guidance system for Allied torpedoes that used spread spectrum and frequency hopping technology to defeat the threat of jamming by the Axis powers. Although the US Navy did not adopt the technology until the 1960s, the principles of their work are incorporated into Bluetooth technology and are similar to methods used in legacy versions of CDMA and Wi-Fi. This work led to their induction into the National Inventors Hall of Fame in 2014. 1942: American geologist Marguerite Williams became the first African-American woman to receive a PhD in geology in the United States. She completed her doctorate, entitled A History of Erosion in the Anacostia Drainage Basin, at Catholic University.
Sources: en.wikipedia.org
Synthetic oxytocin, sold under the brand name Pitocin among others, is a medication made from the peptide oxytocin. As a medication, it is used to cause contraction of the uterus to start labor, increase the speed of labor, and to stop bleeding following delivery. For this purpose, it is given by injection either into a muscle or into a vein. Oxytocin is also available in intranasal spray form for psychiatric, endocrine and weight management use as a supplement. Intranasal oxytocin works on a different pathway than injected oxytocin, primarily along the olfactory nerve crossing the blood–brain barrier to the olfactory lobe in the brain, where dense magnocellular oxytocin neurons receive the nerve impulse quickly. The natural occurrence of oxytocin was discovered in 1906. It is on the World Health Organization's List of Essential Medicines.
== Awards == Phillips has been honored by Paul Newman and by John F. Kennedy Jr. as one of America's most generous business leaders when EAS was honored in 1999 with a Newman's Own/George Award. The United States Junior Chamber of Commerce honored Phillips in January 2000 as one of the Ten Outstanding Young Americans. Phillips was also chosen to help carry the Olympic torch on its relay across the United States for the 2002 Winter Olympics in Salt Lake City. Bill Phillips has donated over $5 million to the Make-A-Wish Foundation. Over the past 20 years Bill Phillips has granted over 600 wishes to kids facing life-threatening medical conditions through the Make-A-Wish Foundation. All the proceeds that would have gone to Phillips from the sale of his book Body-for-LIFE were donated to the Make-A-Wish Foundation. Phillips was awarded with The Ernst & Young Entrepreneur of the Year Award in 1997. On June 24, 2014, Bill Phillips was inducted into the Fitness Hall of Fame along with Jack LaLanne, Arnold Schwarzenegger, and Jillian Michaels.
1993/3229) Milk Marketing Board Scheme of Reorganisation (Extension of Period for Application) Order 1993 (S.I. 1993/3230) Merchant Shipping (Musters and Training) (Amendment) Regulations 1993 (S.I. 1993/3231) Merchant Shipping (Pilot Ladders and Hoists) (Amendment) Regulations 1993 (S.I. 1993/3232) Dairy Produce Quotas (Amendment) Regulations 1993 (S.I. 1993/3234) Pensions Increase (Approved Schemes) (National Health Service) (Scotland) Amendment Regulations 1993 (S.I. 1993/3235) Council Tax (Transitional Reduction Scheme) (Scotland) (No.2) Regulations 1993 (S.I. 1993/3236) Railways Act 1993 (Commencement No. 1) Order 1993 (S.I. 1993/3237) Road Traffic Act 1991 (Commencement No. 9 and Transitional Provisions) Order 1993 (S.I. 1993/3238) Road Traffic (Special Parking Areas) (London Boroughs of Richmond upon Thames and Southwark) Order 1993 (S.I. 1993/3239) Act of Sederunt (Sheriff Court Summary Application Rules) 1993 (S.I. 1993/3240) Insurance Accounts Directive (Miscellaneous Insurance Undertakings) Regulations 1993 (S.I. 1993/3245) Companies Act 1985 (Insurance Companies Accounts) Regulations 1993 (S.I. 1993/3246) Animals and Animal Products (Import and Export) Regulations 1993 (S.I. 1993/3247) Artificial Breeding of Sheep and Goats Regulations 1993 (S.I. 1993/3248) Importation of Bees (Amendment) Order 1993 (S.I. 1993/3249) Specified Animal Pathogens Order 1993 (S.I. 1993/3250) Parliamentary Pensions (Additional Voluntary Contributions Scheme) Regulations 1993 (S.I. 1993/3252) Parliamentary Pensions (Consolidation and Amendment) Regulations 1993 (S.I.
Sources: en.wikipedia.org
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.
Melanotan-1, also called afamelanotide, is a linear analogue with greater selectivity for MC1R and has received approval in some jurisdictions for a specific photosensitivity disorder. Melanotan-2 is cyclic, less selective, and reaches central receptors more readily. The two are often confused in online discussion despite different pharmacology and regulatory status.
Alpha-MSH is an endogenous tridecapeptide derived from pro-opiomelanocortin. Melanotan-2 reproduces its core receptor-binding sequence inside a shortened, stabilised ring. The result is a molecule with a longer effective half-life and higher potency than the parent hormone.
It is a synthetic seven-amino-acid peptide modeled on alpha-melanocyte-stimulating hormone. It carries two non-natural substitutions and a cyclic bridge that increase its stability relative to the natural hormone. It circulates as a research chemical and is not an approved medicine.