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 2026-05-18. 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.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its sequence incorporates modified residues that increase potency and extend biological activity relative to the native hormone. The compound binds receptors of the melanocortin family and is examined mainly in laboratory research. It does not occur naturally and exists only as a manufactured chemical entity produced by solid-phase synthesis.
The peptide was developed during the 1980s by researchers investigating melanocortin signalling and skin pigmentation pathways. Early work focused on analogues of alpha-melanocyte-stimulating hormone that would resist enzymatic breakdown more effectively than the parent molecule. Melanotan-2 emerged from that programme as a shortened, cyclised variant. Reports describing its synthesis and receptor activity later appeared in the scientific literature. Commercial availability grew through unregulated channels rather than through pharmaceutical approval.
| 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-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.
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.
6 July – One child dies, while 16 are injured after a Land Rover hits a primary school in Wimbledon, south-west London. The crash is not treated as terror-related, but the driver is arrested on suspicion of causing death by dangerous driving. The UK Health Security Agency and Met Office issue a yellow heat health alert for six regions of England, effective from 12pm on 7 July to 9am on 9 July, when temperatures are expected to reach 28 °C–30 °C in some areas. RMT workers on the London Underground announce six days of strikes from Sunday 23 July to Friday 28 July. 7 July – British cinema chain Empire Cinemas collapses into administration with the immediate loss of 150 jobs, citing the impact of the COVID-19 pandemic and the ongoing cost-of-living crisis as the main reasons. The closures leave Sunderland and Wigan with no main cinema. 8 July – The Union Chain Bridge, which spans the River Tweed, linking England and Scotland, is named as an International Historic Civil Engineering Landmark. 9 July – A second child dies of injuries sustained in the crash at a school in Wimbledon, south London. 10 July – A teenage boy is arrested on suspicion of attempted murder after a teacher is stabbed at Tewkesbury School in Gloucestershire. The school, along with neighbouring schools, are locked down during the incident. The teacher is hospitalised. He is charged with attempted wounding with intent and possession of bladed article the next day.
=== Indirect separation of enantiomer === Indirect enantiomer separation involves the interaction between the chiral analyte (CA) of interest and the suitable reactive CS (in this case it is an enantiopure chiral derivatizing agent, CDA) leading to the formation of a covalent diastereomeric complex that can be separated with an achiral chromatographic technique. Therapeutic agents often contain reactive functional groups (amino, hydroxyl, epoxy, carbonyl and carboxylic acid, etc.) in their structures. They are converted into covalently bonded diastereomeric derivatives using enantiomerically pure chiral derivatizing agent. The diastereomers thus formed unlike enantiomers, exhibit different physicochemical properties in an achiral environment and are eventually separated as a result of differential retention time on a stationary phase. The success of this approach depends on the availability of stable enantiopure chiral derivatizing agent (CDA) and on the presence of a suitable reactive functional group in the chiral drug molecule for covalent formation of diastereomeric derivative. The reaction of a racemic, (R,S)- Drug with a chirally and chemically pure chiral derivatizing agent, (R')-CDA, will afford diastereomeric products, (R)-Drug-(R')-CDA + (S)-Drug-(R')- CDA. The chiral derivatization reaction scheme is illustrated in the box on the right hand side. In contrast to enantiomers, diastereomers have different physicochemical properties that make them separable on regular achiral stationary phases.
The NRD pathway for the 40S subunit may be independent or separate from the NRD pathway for the 60S subunit. It has been observed that certain genes were able to affect degradation of certain pre-RNAs, but not others. Numerous proteins are involved in the NRD pathway, such as Mms1p and Rtt101p, which are believed to complex together to target ribosomes for degradation. Mms1p and Rtt101p are found to bind together and Rtt101p is believed to recruit a ubiquitin E3 ligase complex, allowing for the non-functional ribosomes to be ubiquinated before being degraded. Prokaryotes lack a homolog for Mms1, so it is unclear how prokaryotes are able to degrade non-functional rRNAs. The growth rate of eukaryotic cells did not seem to be significantly affected by the accumulation of non-functional rRNAs.
Sources: en.wikipedia.org
Experimental gene therapy exists to treat hereditary spherocytosis in lab mice; however, this treatment has not yet been tried on humans due to all of the risks involved in human gene therapy. Bone marrow transplant. Paradoxical endurance-based athleticism associated with hereditary spherocytosis. Evolution of spherocytic erythrocyte adaptation in those of Northern European and Japanese descent. Increased ability to defend against viral infections in hereditary spherocytosis patients.
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== History == RO5203648 was first described by 2012. It was the first selective TAAR1 partial agonist to be developed. The drug followed the first TAAR1 antagonist EPPTB and the first TAAR1 full agonist RO5166017. It was under investigation for potential clinical use in humans, but showed indication of very rapid human metabolism in vitro. As a result, it was deselected from development, and other compounds, such as the TAAR1 partial agonist RO5263397, were pursued instead.
Sources: en.wikipedia.org
=== Diagnosis === Radiometric assays include the radioallergosorbent test (RAST test) method, which uses IgE-binding (anti-IgE) antibodies labeled with radioactive isotopes for quantifying the levels of IgE antibody in the blood. The RAST methodology was invented and marketed in 1974 by Pharmacia Diagnostics AB, Uppsala, Sweden, and the acronym RAST is actually a brand name. In 1989, Pharmacia Diagnostics AB replaced it with a superior test named the ImmunoCAP Specific IgE blood test, which uses the newer fluorescence-labeled technology. American College of Allergy Asthma and Immunology (ACAAI) and the American Academy of Allergy Asthma and Immunology (AAAAI) issued the Joint Task Force Report "Pearls and pitfalls of allergy diagnostic testing" in 2008, and is firm in its statement that the term RAST is now obsolete:
Likewise, the saturated zone of a soil frequently has a higher radon content than the unsaturated zone because of diffusional losses to the atmosphere. In 1971, Apollo 15 passed 110 km (68 mi) above the Aristarchus plateau on the Moon, and detected a significant rise in alpha particles thought to be caused by the decay of 222Rn. The presence of 222Rn has been inferred later from data obtained from the Lunar Prospector alpha particle spectrometer. Radon is found in some petroleum. Because radon has a similar pressure and temperature curve to propane, and oil refineries separate petrochemicals based on their boiling points, the piping carrying freshly separated propane in oil refineries can become contaminated because of decaying radon and its products. Residues from the petroleum and natural gas industry often contain radium and its daughters. The sulfate scale from an oil well can be radium rich, while the water, oil, and gas from a well often contains radon. Radon decays to form solid radioisotopes that form coatings on the inside of pipework.
=== Chronic === Assessment of the effects of stimulants is relevant given the large population currently taking stimulants. A 2022 meta-analysis with a sample size of just under four million people found no association between the use of prescription stimulants and the development of cardiovascular disease in any age group. A review of a year long period of prescription stimulant use in those with attention deficit hyperactivity disorder (ADHD) found that cardiovascular side effects were limited to transient increases in blood pressure only. However, a 2024 systematic review of the evidence found that stimulants overall improve ADHD symptoms and broadband behavioral measures in children and adolescents, though they carry risks of side effects like appetite suppression and other adverse events. Initiation of stimulant treatment in those with ADHD in early childhood appears to carry benefits into adulthood in social and cognitive functioning, and appears to be relatively safe. Abuse of prescription stimulants (not following physician instruction) or of illicit stimulants carries many negative health risks. Abuse of cocaine, depending upon route of administration, increases risk of cardiorespiratory disease, stroke, and sepsis.
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.
It is a synthetic cyclic heptapeptide and an analogue of alpha-melanocyte-stimulating hormone. The molecule is produced by chemical synthesis rather than extracted from a biological source.