This is a working overview of melanocortin receptor, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-12-03 and is reviewed periodically as new material appears.
Melanotan-2 is frequently confused with afamelanotide, a linear analogue authorised in the European Union for erythropoietic protoporphyria. The two compounds differ in chain length, ring structure and receptor selectivity, so findings for one cannot be transferred directly to the other. Published controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports. Questions about effect size, dose-response behaviour and long-term safety therefore remain unresolved.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence incorporates a lactam bridge that constrains the peptide into a ring, which increases resistance to enzymatic breakdown relative to the natural hormone. Researchers at the University of Arizona synthesised the compound in the late 1980s and early 1990s while studying pigmentation pathways. It has never received marketing approval from any national medicines regulator. In the scientific literature it is usually described as a laboratory research reagent rather than a therapeutic product.
Identity and purity are assessed with chromatographic and mass spectrometric techniques. Reversed-phase high-performance liquid chromatography separates the target peptide from related impurities and degradation products, and the resulting retention time is compared against a reference standard. Mass spectrometry, often coupled to liquid chromatography, confirms molecular mass. Amino acid analysis or peptide mapping can provide additional sequence-level confirmation when required. Results are only as reliable as the reference materials used alongside them.
Regulatory treatment varies by country. In the United States, melanotan-2 is not approved for any indication, and products marketed for human use fall outside the approved drug framework. Some other jurisdictions have placed it under prescription controls or listed it as a prohibited or restricted substance. Online listings frequently describe the material as a research chemical, a category that does not carry the same manufacturing and labelling requirements as approved medicines.
Solid peptide material is generally stable when kept cold and dry. Common practice is storage at -20 degrees Celsius or lower, with desiccant and protection from light. Repeated freeze-thaw cycles and exposure to moisture are associated with degradation, aggregation, or loss of material. Once dissolved, stability depends on solvent, concentration, and temperature, and solutions are usually treated as short-lived unless stability data support longer periods. Handling notes typically emphasise minimising time at ambient temperature.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Alpha-MSH analogue with a lactam ring |
| Molecular formula | C50H69N15O9 | Commonly cited value for the neutral peptide |
| Molecular weight | 1024.18 g/mol | Calculated for the free molecule |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water, DMSO and ethanol | Dissolution in pure water is often slow |
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.
Regulatory status varies by jurisdiction, and the substance is frequently described as unapproved for therapeutic use. Some authorities classify it alongside prescription-only medicines or controlled categories, while others address it through general consumer protection rules. Analytical surveys have reported mismatches between label claims and measured content in products sold online, although the scope of such testing is limited. Whether these discrepancies are widespread remains an open question. Discussion in the literature therefore tends to combine chemistry, supply-chain observation and policy analysis.
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.
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.
Structurally, Melanotan-2 retains the core recognition motif of alpha-melanocyte-stimulating hormone while adding a lactam bridge that links two side chains and constrains the molecule into a ring. This modification lowers susceptibility to enzymatic degradation. The compound acts as an agonist at melanocortin receptors, particularly subtypes associated with melanin production. Because the same receptor family influences several physiological processes, researchers note that its activity is not confined to pigmentation alone. Receptor selectivity continues to be examined in published studies.
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.
Gag-onc fusion protein Bcr-abl fusion protein Tpr-met fusion protein Antibodies are fusion proteins produced by V(D)J recombination. There are also rare examples of naturally occurring polypeptides that appear to be a fusion of two clearly defined modules, in which each module displays its characteristic activity or function, independent of the other. Two major examples are: double PP2C chimera in Plasmodium falciparum (the malaria parasite), in which each PP2C module exhibits protein phosphatase 2C enzymatic activity, and the dual-family immunophilins that occur in a number of unicellular organisms (such as protozoan parasites and Flavobacteria) and contain full-length cyclophilin and FKBP chaperone modules. The evolutionary origin of such chimera remains unclear.
On 18 October 2011, the European Commission adopted the following definition of a nanomaterial for regulatory purpose:A natural, incidental or manufactured material containing particles, in an unbound state or as an aggregate or as an agglomerate and for 50% or more of the particles in the number size distribution, one or more external dimensions is in the size range 1 nm – 100 nm. In specific cases and where warranted by concerns for the environment, health, safety or competitiveness the number size distribution threshold of 50% may be replaced by a threshold between 1% to 50%.
The 75th Infantry Regiment was a Regular infantry regiment in the United States Army, briefly active during World War I as part of the 13th Division. It was reconstituted on paper during World War II and disbanded in the early 1950s.
The metabolism of xenobiotics is often divided into three phases: modification, conjugation, and excretion. These reactions act in concert to detoxify xenobiotics and remove them from cells. For some chemicals, they may instead lead to an increase in toxicity (toxication).
Sources: en.wikipedia.org
The nucleotide sequence of the human gene for proopiomelanocortin (POMC) was characterized in 1980. The POMC gene codes for endogenous opioids such as β-endorphin and γ-endorphin. The human gene for the enkephalins was isolated and its sequence described in 1982. The human gene for dynorphins (originally called the "Enkephalin B" gene because of sequence similarity to the enkephalin gene) was isolated and its sequence described in 1983. The PNOC gene encoding prepronociceptin, which is cleaved into nociceptin and potentially two additional neuropeptides. Adrenorphin, amidorphin, and leumorphin were discovered in the 1980s. The endomorphins were discovered in the 1990s. Opiorphin and spinorphin, enkephalinase inhibitors (i.e., prevent the metabolism of enkephalins). Hemorphins, hemoglobin-derived opioid peptides, including hemorphin-4, valorphin, and spinorphin, among others. While not peptides, codeine and morphine are also produced in the human body.
== Contraindications and precautions == Amitriptyline/chlordiazepoxide should not be taken if the patient has recently had a heart attack. It may induce a mixed-manic episode in patients with a history of bipolar disorder or who have had manic or hypomanic episodes in the past. Amitriptyline/chlordiazepoxide may worsen seizures in patients with a previous history of them. Patients older than 65 years of age may be more sensitive to amitriptyline/chlordiazepoxide. It may also have stronger effects on patients with kidney or liver disease due to slowed filtering from the bloodstream. It may also cause adverse effects in patients with a thyroid condition such as hyperthyroidism. Use of amitriptyline/chlordiazepoxide later in pregnancy can cause sedation or symptoms of withdrawl in the infant after delivery. The safety of amitriptyline/chlordiazepoxide for breastfeeding or pediatric patients is unknown.
== External links == "Paclitaxel". National Cancer Institute. 5 October 2006. "Paclitaxel". NCI Drug Dictionary. 2 February 2011. Molecule of the Month: TAXOL by Neil Edwards, University of Bristol. A Tale of Taxol from Florida State University. Berenson A (1 October 2006). "Hope, at $4,200 a Dose". The New York Times. Retrieved 31 March 2007.
=== Economic extraction and digital sovereignty === Economists such as Mariana Mazzucato argue that the UK's reliance on US-dominated AI infrastructure risks creating a form of "digital colonialism" or "digital feudalism", where economic value is systematically extracted from the UK and repatriated to the United States.
=== Counseling psychology === Counseling psychologists undergo the same level of rigor in study and use many of the same interventions and tools as clinical psychologists, including psychotherapy and assessment. Traditionally, counseling psychologists helped people with what might be considered normal or moderate psychological problems—such as the feelings of anxiety or sadness resulting from major life changes or events. However, that distinction has faded over time, and of the counseling psychologists who do not go into academia (which does not involve treatment or diagnosis), the majority of counseling psychologists treat mental illness alongside clinical psychologists. Many counseling psychologists also receive specialized training in career assessment, group therapy, and relationship counseling. Counseling psychology as a field values multiculturalism and social advocacy, often stimulating research in multicultural issues. There are fewer counseling psychology graduate programs than those for clinical psychology and they are more often housed in departments of education rather than psychology. Counseling psychologists tend to be more frequently employed in university counseling centers compared to hospitals and private practice for clinical psychologists. However, counseling and clinical psychologists can be employed in a variety of settings, with a large degree of overlap (prisons, colleges, community mental health, non-profits, corporations, private practice, hospitals and Veterans Affairs).
Sources: en.wikipedia.org
== Pharmacology == The drug is a selective KOR antagonist and shows approximately 10- to 20-fold higher affinity for the KOR (Ki = 1–3 nM) over the μ-opioid receptor (MOR) (Ki = 10–64 nM) and has negligible affinity for the δ-opioid receptor (DOR) (Ki > 4,000 nM). It is a "short-acting" or non-inactivating antagonist of the KOR (as opposed to irreversible antagonists like JDTic). Although originally characterized as a KOR neutral antagonist however, subsequent research revealed in 2020 that PF-04455242 is actually only a moderately efficacious partial antagonist of the KOR (Imax ≈ 50%). In any case, the drug reversed the analgesic and prolactin-elevating effects of the KOR agonist spiradoline in animals, showed efficacy in animal models predictive of antidepressant activity, and reversed stress-induced reinstatement of cocaine-seeking behavior. However, PF-04455242 also showed a variety of other weak off-target activities.
McGregor divides his time between Los Angeles, California, and St John's Wood, London. McGregor enjoys travelling and is a fan of Manchester City F.C.. In 2007, on an episode of Parkinson, McGregor said he had been a teetotaller for the last seven years. He also mentioned this in an interview with the Irish Independent in 2008, stating that he would often turn up to sets drunk or hung over in the late 1990s, and that he decided to stop altogether to avoid spiralling down further. In 2008, McGregor had a cancerous mole removed from below his right eye. In September 2020, after travelling through Chile for the documentary Long Way Up, he revealed that one of his great-grandfathers, John "Juan" Charles McIndoe, was born in Chile to Scottish parents while his father worked with the American engineers in the construction of the railways at the end of the 19th century. Later, John went to Glasgow and worked as a wine importer and diplomat. McGregor became a naturalised US citizen after 2016 so he would be able to vote in the 2020 US presidential election. During his journey on Long Way Up, he travelled entirely on his US passport. He is a fan of the Fremantle Dockers in the Australian Football League. In 2025, McGregor rejoined his youth pipe band the Morrison's Academy; he invited the band to his estate in Carse of Gowrie, where he alongside the band played a special show for his parents.
===== Behavioral treatments ===== A 2018 systematic review and network meta-analysis of 50 trials involving 12 different psychosocial interventions for amphetamine, methamphetamine, or cocaine addiction found that combination therapy with both contingency management and community reinforcement approach had the highest efficacy (i.e., abstinence rate) and acceptability (i.e., lowest dropout rate). Other treatment modalities examined in the analysis included monotherapy with contingency management or community reinforcement approach, cognitive behavioral therapy, 12-step programs, non-contingent reward-based therapies, psychodynamic therapy, and other combination therapies involving these. Additionally, research on the neurobiological effects of physical exercise suggests that daily aerobic exercise, especially endurance exercise (e.g., marathon running), prevents the development of drug addiction and is an effective adjunct therapy (i.e., a supplemental treatment) for amphetamine addiction. Exercise leads to better treatment outcomes when used as an adjunct treatment, particularly for psychostimulant addictions. In particular, aerobic exercise decreases psychostimulant self-administration, reduces the reinstatement (i.e., relapse) of drug-seeking, and induces increased dopamine receptor D2 (DRD2) density in the striatum. This is the opposite of pathological stimulant use, which induces decreased striatal DRD2 density.
== Medical uses == This glue is used as a supportive treatment in surgery (such as liver surgery) for the improvement of hemostasis where standard surgical techniques are insufficient or impractical. It is also used for repairing dura mater tears and bronchial fistulas and for achieving hemostasis after spleen and liver trauma, in "no sutures" corneal transplantation, pterygium excision with amniotic membrane or conjunctival autograft, and in eye trauma for corneal or conjunctival defects, as well as for skin graft donor site wounds to reduce postoperative pain. It can also be used to treat pilonidal sinus disease but it is of unclear benefit as of 2017, due to insufficient research.
=== Adverse effects === The most common adverse effects of medicinal nicotinic acid (500–3000 mg) are flushing (e.g., warmth, redness, itching or tingling) of the face, neck and chest, headache, abdominal pain, diarrhea, dyspepsia, nausea, vomiting, rhinitis, pruritus and rash. These can be minimized by initiating therapy at low dosages, increasing dosage gradually, and avoiding administration on an empty stomach. The acute adverse effects of high-dose nicotinic acid therapy (1–3 grams per day) – which is commonly used in the treatment of hyperlipidemias – can further include hypotension, fatigue, glucose intolerance and insulin resistance, heartburn, blurred or impaired vision, and macular edema. With long-term use, the adverse effects of high-dose nicotinic acid therapy (750 mg per day) also include liver failure (associated with fatigue, nausea, and loss of appetite), hepatitis, and acute liver failure; these hepatotoxic effects of nicotinic acid occur more often when extended-release dosage forms are used. The long-term use of nicotinic acid at greater than or equal to 2 grams per day also significantly increases the risk of cerebral hemorrhage, ischemic stroke, gastrointestinal ulceration and bleeding, diabetes, dyspepsia, and diarrhea.
Sources: en.wikipedia.org
It is a synthetic cyclic heptapeptide modelled on alpha-melanocyte-stimulating hormone. A lactam bridge links two side chains, forming a ring that stabilises the molecule against proteolysis. It belongs to the broader melanocortin peptide family.
No national medicines agency has approved melanotan-2 for clinical use. Afamelanotide, a related but distinct peptide, holds a marketing authorisation in the European Union for a rare photosensitivity disorder. Melanotan-2 itself is handled as a laboratory chemical.
Its broad activity across melanocortin receptors makes it a tool for probing pigmentation, appetite and vascular signalling. Early trials recorded skin darkening and other effects that were not the original focus of the work. Those observations generated hypotheses that later studies have examined.
Laboratory confirmation typically combines retention time matching on a chromatographic system with mass measurement. A reference standard of known identity is needed for a meaningful comparison. Sequence-level techniques can add further confirmation.