This is a working overview of MC1R, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-07-15 and is reviewed periodically as new material appears.
Melanotan II is a synthetic cyclic heptapeptide that acts as an agonist at melanocortin receptors. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous peptide involved in pigment production. The analogue carries a lactam bridge that constrains the ring and slows enzymatic breakdown relative to the native hormone. In research literature it appears under several abbreviations, and naming conventions are not fully standardized. Published descriptions usually place it within the broader melanocortin agonist family.
Receptor binding at MC1R on melanocytes raises intracellular cyclic AMP and increases expression of tyrosinase and related enzymes. The downstream result is greater synthesis of eumelanin, the dark pigment, without ultraviolet exposure acting as the trigger. The compound is not selective, however, and also engages MC3R, MC4R and MC5R, which are expressed in the central nervous system and elsewhere. That lack of selectivity is the explanation usually offered for effects reported outside pigmentation, including appetite suppression and nausea. Selectivity remains a central theme in comparative studies of related peptides.
Human data remain limited and mostly short-term. Reports describe small trials and observational accounts rather than large controlled studies, so questions about dose-response relationships and long-term effects on melanocytes stay open. Whether repeated exposure alters naevus behaviour is not settled in the published record. Researchers also note that self-administered use outside clinical settings makes actual exposure difficult to quantify. Statements about efficacy and safety should therefore be read as preliminary rather than established.
Identity testing for a synthetic peptide relies on several complementary methods. Reversed-phase high-performance liquid chromatography separates the target from related impurities and reports purity as a percentage of total peak area. Mass spectrometry confirms molecular mass and can reveal deletions or truncations. Amino acid analysis and peptide mapping provide sequence-level confirmation, while counter-ion content and residual solvents are measured separately. A purity figure alone does not establish identity, so a complete dataset combines chromatographic and spectrometric evidence.
Lyophilized peptide powder is generally stored frozen, protected from light and moisture. Tryptophan residues are susceptible to oxidation, and the lactam bridge can hydrolyze under strongly acidic or basic conditions. Solutions prepared for laboratory work degrade faster than dry powder, and repeated freeze-thaw cycles accelerate loss. Common practice is to aliquot solutions before freezing and to avoid alkaline buffers. Reported stability windows vary with concentration, buffer, and temperature, so exact shelf lives are method-specific rather than universal.
Regulatory status differs by country, and in many places supplying the compound for human consumption is unlawful. Vendors frequently label material as intended for research use only, a designation that shifts stated purpose but does not create a legal pathway for personal use. Certificates of analysis accompanying such products vary widely in detail and provenance. Third-party testing exists but is voluntary, and results are rarely linked to a specific lot in a publicly verifiable way.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Melanocortin receptor agonist |
| Molecular formula | C50H69N15O9 | Neutral form, mass near 1024.2 g/mol |
| Primary targets | MC1R, MC3R, MC4R, MC5R | Binding is non-selective across subtypes |
| Related compounds | Alpha-MSH, melanotan I, afamelanotide | Structurally or functionally related peptides |
| Common abbreviations | MT-II, MT-2 | Naming in the literature is not uniform |
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.
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.
Identification in laboratories relies on reversed-phase liquid chromatography coupled with tandem mass spectrometry, with product-ion spectra compared against a certified reference standard. High-resolution mass spectrometry supplies accurate mass confirmation, and peptide mapping after enzymatic digestion separates melanotan II from closely related analogues. Quantitation of seized material is complicated by unknown counter-ions and residual trifluoroacetate left from purification. Immunoassays raised against alpha-melanocyte-stimulating hormone can cross-react, so chromatographic confirmation is normally required. Urinary detection windows are short, and reported limits of detection differ substantially between laboratories.
We have quoted this data to show not only how groundless but also how dangerous these operations were. We are unable to explain how their author, holder of a degree in medicine, could bring himself to carry them out ... The authors neglected to mention, however, that in 1910 Puusepp himself had performed surgery on the brains of three mentally ill patients, sectioning the cortex between the frontal and parietal lobes. He had abandoned these attempts because of unsatisfactory results, and this experience probably inspired the invective that was directed at Burckhardt in the 1912 article. By 1937, Puusepp, despite his earlier criticism of Burckhardt, was increasingly persuaded that psychosurgery could be a valid medical intervention for the mentally disturbed. In the late 1930s, he worked closely with the neurosurgical team of the Racconigi Hospital near Turin to establish it as an early and influential centre for the adoption of leucotomy in Italy.
Pulpal core, which is in the center of the pulp chamber, with many cells and an extensive vascular supply; except for its location, it is very similar to the cell-rich zone. Cell-rich zone, which contains fibroblasts and undifferentiated mesenchymal cells. Cell-free zone (zone of Weil, which is rich in both capillaries and nerve networks. Odontoblastic layer, the outermost layer which contains odontoblasts and lies next to the predentin and mature dentin. Cells found in the dental pulp include fibroblasts (the principal cell), odontoblasts, defence cells like histiocytes, macrophages, granulocytes, mast cells, and plasma cells. The nerve plexus of Raschkow is located central to the cell-rich zone.
12 June – The Green Party launches its manifesto, with key points including increasing taxes for the better off, and higher spending on healthcare, housing and climate change. Sky News presenter Beth Rigby presents an election debate from Grimsby Town Hall, where Sunak and Starmer face questions from an audience. Craig Williams, who served as Sunak's Parliamentary Private Secretary, is being investigated by the Gambling Commission after placing a bet on the date of the general election. Williams subsequently describes the bet as a "huge error of judgement". Dr Anne McCloskey, an independent general election candidate for Foyle, is sentenced to 14 days in prison for non-payment of a COVID-19 related fine by Derry Magistrates. Police say they are aware of YouTuber and internet prankster Niko Omilana, who has registered himself as a general election candidate in 11 different constituencies. 13 June – Keir Starmer unveils the Labour Party's general election manifesto. He says that wealth creation is the "number one priority" and that Labour will focus on economic growth. The Green Party is forced to temporarily remove its manifesto from its website after facing criticism for using an image of an ill man to illustrate its policy on HIV. Plaid Cymru launches its 2024 election manifesto, which includes plans for Welsh independence, 500 extra GPs and funding from rail improvements.
Sources: en.wikipedia.org
== Evidence == It has been demonstrated in animal experiments that there is an improvement in sorbitol levels and Na+/K+ ATPase activity leading to improved nerve conduction velocity. Diabetic rats treated with epalrestat showed improvement in morphological abnormalities of nerves. In a placebo controlled double blind trial of 196 patients, it was shown that Epalrestat in a dose of 150 mg/day improved the effects of diabetic neuropathy like upper limb spontaneous pain, motor nerve conduction velocity, thresholds of vibratory sensation and autonomic nerve function as compared to a placebo. These effects were significantly better in those with poorer control of diabetes. A systematic review and metaanalysis showed that based on the results of 10 articles, it can be concluded that Epalrestat has some benefit in the control of diabetic cardiovascular autonomic neuropathy but only in the early or mild cases. It also doesn't influence glycaemic control.
== External links == Glutamate+Aspartate+Transporter+1 at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Overview of all the structural information available in the PDB for UniProt: P43003 (Excitatory amino acid transporter 1) at the PDBe-KB.
The proteome can be used in order to comparatively analyze different cancer cell lines. Proteomic studies have been used in order to identify the likelihood of metastasis in bladder cancer cell lines KK47 and YTS1 and were found to have 36 unregulated and 74 down regulated proteins. The differences in protein expression can help identify novel cancer signaling mechanisms. Biomarkers of cancer have been found by mass spectrometry based proteomic analyses. The use of proteomics or the study of the proteome is a step forward in personalized medicine to tailor drug cocktails to the patient's specific proteomic and genomic profile. The analysis of ovarian cancer cell lines showed that putative biomarkers for ovarian cancer include "α-enolase (ENOA), elongation factor Tu, mitochondrial (EFTU), glyceraldehyde-3-phosphate dehydrogenase (G3P), stress-70 protein, mitochondrial (GRP75), apolipoprotein A-1 (APOA1), peroxiredoxin (PRDX2) and annexin A (ANXA)". Comparative proteomic analyses of 11 cell lines demonstrated the similarity between the metabolic processes of each cell line; 11,731 proteins were completely identified from this study. Housekeeping proteins tend to show greater variability between cell lines. Resistance to certain cancer drugs is still not well understood. Proteomic analysis has been used in order to identify proteins that may have anti-cancer drug properties, specifically for the colon cancer drug irinotecan. Studies of adenocarcinoma cell line LoVo demonstrated that 8 proteins were unregulated and 7 proteins were down-regulated.
Sources: en.wikipedia.org
=== May 2005 === A Pentagon order is mentioned in a military report filed on May 16, 2005 ordering U.S. personnel to turn a blind eye to Iraqi torture by refraining from investigating instances of apparent detainee abuse by Iraqi personnel, unless the investigation is first approved by U.S. headquarters: "Provided the initial report confirms US forces were not involved in the detainee abuse, no further investigation will be conducted unless directed by HHQ." Such approval was rarely granted.
== Habitat degradation == Human activities such as urban development, agriculture, and dam construction lead to habitat degradation, posing significant threats to aquatic plants. Urbanization increases impervious surfaces, leading to higher runoff volumes that carry pollutants and sediments into water bodies. This runoff can smother aquatic plants and alter water chemistry. Agricultural practices contribute to nutrient loading and pesticide contamination, further stressing aquatic vegetation. Dam construction and water diversion projects alter natural flow regimes, affecting sediment transport and water temperature. These changes can disrupt the life cycles of aquatic plants and the species that depend on them. Aquatic plants are integral to healthy aquatic ecosystems, but they face numerous threats from invasive species, nutrient pollution, climate change, and habitat degradation. Addressing these challenges requires integrated management approaches, including controlling invasive species, reducing nutrient inputs, mitigating climate change impacts, and protecting and restoring aquatic habitats.
channel protein A type of transmembrane protein whose shape forms an aqueous pore in a membrane, permitting the passage of specific solutes, often small ions, across the membrane in either or both directions.
Secondary structure prediction is a set of techniques in bioinformatics that aim to predict the local secondary structures of proteins based only on knowledge of their amino acid sequence. For proteins, a prediction consists of assigning regions of the amino acid sequence as likely alpha helices, beta strands (often termed extended conformations), or turns. The success of a prediction is determined by comparing it to the results of the DSSP algorithm (or similar e.g. STRIDE) applied to the crystal structure of the protein. Specialized algorithms have been developed for the detection of specific well-defined patterns such as transmembrane helices and coiled coils in proteins. The best modern methods of secondary structure prediction in proteins were claimed to reach 80% accuracy after using machine learning and sequence alignments; this high accuracy allows the use of the predictions as feature improving fold recognition and ab initio protein structure prediction, classification of structural motifs, and refinement of sequence alignments. The accuracy of current protein secondary structure prediction methods is assessed in weekly benchmarks such as LiveBench and EVA.
Sources: en.wikipedia.org
It is a synthetic cyclic heptapeptide and a non-selective melanocortin receptor agonist. Structurally it is modelled on alpha-melanocyte-stimulating hormone, a peptide that occurs naturally in the body.
Activation of MC1R increases pigment synthesis independently of ultraviolet exposure, which is the mechanism usually cited for darkening without sun exposure. Ultraviolet light still influences skin response through separate biological pathways.
Because the peptide binds several melanocortin receptor subtypes, its effects are not confined to pigmentation. This complicates interpretation of both intended and unintended outcomes reported in studies.
Dry powder is usually held frozen, shielded from light, and kept away from moisture. Desiccant packaging limits hydrolysis during storage. Solutions are typically aliquoted and frozen once, because repeated thawing shortens useful life.