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Melanotan-2 Identity And Receptor Pharmacology — Practical Notes

By Editorial Desk · published 2026-07-18 · last reviewed 2026-08-01 · Topic

alpha-MSH analogue comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.

Last reviewed on 2026-08-01. Where a claim depends on a specific study, the study is described rather than over-claimed.

Melanotan-2 Identity and Receptor Pharmacology

Research interest has centred on photoprotection and pigmentation, with a smaller body of work on appetite and sexual function. Published human data remain limited to small, frequently uncontrolled studies, and the compound has never received marketing approval from a national medicines regulator. Most laboratory work treats it as a pharmacological tool for probing melanocortin signalling in cell culture or animal models. Whether pigmentation changes observed in people translate into measurable protection against ultraviolet-induced DNA damage remains an open question.

Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, the naturally occurring peptide involved in pigmentation signalling. Its sequence is conventionally written as Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, with a lactam bridge joining the aspartate side chain to the lysine side chain. The empirical formula is C50H69N15O9 and the monoisotopic mass lies near 1023.5 daltons. N-terminal acetylation and the D-configured phenylalanine both increase resistance to enzymatic breakdown compared with the parent hormone.

Pharmacologically, melanotan-2 behaves as a non-selective agonist across the melanocortin receptor family. Binding at MC1R on dermal melanocytes promotes eumelanin synthesis, which underlies the tanning response described in early human work. Activity at the centrally expressed MC4R receptor is associated with reported effects on appetite and erectile function. Because the peptide does not discriminate strongly among receptor subtypes, attributing any single observed effect to one receptor pathway is generally not possible without selective antagonists or receptor knockout models.

Peptide Identity and Structural Background

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.

Melanotan-2 at a glance

PropertyValueNotes
Common synonymsMelanotan II; MT-II; N-acetyl-norleucyl-cyclo[Asp-His-D-Phe-Arg-Trp-Lys] amideNaming follows peptide convention; the numeral distinguishes it from melanotan-1
Molecular formulaC50H69N15O9Includes the lactam bridge; no counter-ion assumed
Monoisotopic mass1023.53 DaFree base; salts and counter-ions shift the observed value
AppearanceWhite to off-white lyophilised powderBatch-to-batch colour variation is not itself proof of impurity
Typical analytical methodRP-HPLC purity determination with ESI-MS identity confirmationRetention time alone does not establish sequence identity

Chemistry and Receptor Pharmacology

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.

Published pharmacokinetic information is limited and comes mainly from small studies rather than registrational trials. Plasma half-life is usually described as short, on the order of tens of minutes, followed by rapid tissue distribution and clearance of the intact peptide. Metabolites and low concentrations of parent compound have been reported in urine, a detail relevant to anti-doping and forensic testing. Whether repeated exposure changes receptor sensitivity or clearance over time remains an open question. Values differ noticeably between analytical assays, so published numbers should be read as approximate rather than definitive.

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.

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Background and Receptor Mechanism

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.

Melanotan II is a synthetic cyclic heptapeptide analog derived from the core sequence of alpha-melanocyte-stimulating hormone. Researchers at the University of Arizona synthesized it during the 1980s while studying pigmentation and appetite signaling. The compound is not an approved medicine in any major jurisdiction and appears mainly in laboratory and research-chemical settings. Its structure incorporates a lactam bridge between side chains, which constrains the ring and slows enzymatic breakdown relative to the natural hormone.

Notes from published material

The four substrates of this enzyme are pyrrole-2-carboxylic acid, reduced nicotinamide adenine dinucleotide (NADH), oxygen, and a proton. Its products are 5-hydroxypyrrole-2-carboxylic acid, oxidised NAD+, and water. It is a flavoprotein that uses flavin adenine dinucleotide as a cofactor.

=== Computed tomography === Computed tomography angiography has a 98-100% sensitivity and specificity for diagnosing aortic dissections. It is the initial recommended test and also the most commonly used imaging test in the diagnosis of aortic dissections, being utilized in 74-77% of cases in population based studies.

All cells in animal body tissues are electrically polarized – in other words, they maintain a voltage difference across the cell's plasma membrane, known as the membrane potential. This electrical polarization results from a complex interplay between protein structures embedded in the membrane called ion pumps and ion channels. In neurons, the types of ion channels in the membrane usually vary across different parts of the cell, giving the dendrites, axon, and cell body different electrical properties. As a result, some parts of the membrane of a neuron may be excitable (capable of generating action potentials), whereas others are not. Recent studies have shown that the most excitable part of a neuron is the part after the axon hillock (the point where the axon leaves the cell body), which is called the axonal initial segment, but the axon and cell body are also excitable in most cases. Each excitable patch of membrane has two important levels of membrane potential: the resting potential, which is the value the membrane potential maintains as long as nothing perturbs the cell, and a higher value called the threshold potential. At the axon hillock of a typical neuron, the resting potential is around −70 millivolts (mV) and the threshold potential is around −55 mV. Synaptic inputs to a neuron cause the membrane to depolarize or hyperpolarize; that is, they cause the membrane potential to rise or fall. Action potentials are triggered when enough depolarization accumulates to bring the membrane potential up to threshold.

Parathyroid hormone is the principal regulator of serum calcium hemostasis. In response to subcutaneous doses of Preotact (100 micrograms), serum total calcium levels increase gradually and reach peak concentration at approximately 6 to 8 hours after dosing. In general, serum calcium levels return to normal within 24 hours.

=== 1.4 === DisplayPort version 1.4 was published 1 March 2016. No new transmission modes are defined, so HBR3 (32.4 Gbit/s) as introduced in version 1.3 still remains as the highest available mode. DisplayPort 1.4 adds support for Display Stream Compression 1.2 (DSC), Forward Error Correction, HDR10 metadata defined in CTA-861.3, including static and dynamic metadata and the Rec. 2020 color space, for HDMI interoperability, and extends the maximum number of inline audio channels to 32.

Sources: en.wikipedia.org

Background from the literature

Methenamine is provided in the form of 500 and 1,000 mg oral tablets. It is available both alone and in combination with the nonsteroidal anti-inflammatory drug (NSAID) sodium salicylate. Other combinations with other drugs, such as phenazopyridine, are also available. Methenamine is provided pharmaceutically alone as the hippuric acid (methenamine hippurate) and mandelic acid (methenamine mandelate) salts. The free base and other salts, including anhydromethylencitrate and sulfosalicylate, have also been marketed in some countries. Methenamine mandelate is provided as an enteric coated tablet and is taken four times daily, whereas methenamine hippurate is available only in non-coated tablet form and is taken twice daily. Non-coated methenamine tablets can have a chemical taste described as sweet, sour, and/or metallic. Methenamine is available both by prescription (by itself) and over the counter (in combinations). Over-the-counter formulations in combination with sodium salicylate (162.5 mg) contain a lower amount of methenamine of 162 mg methenamine free base per tablet compared to prescription formulations and are taken three times daily.

Completed in 2016, Cat Dreams is Ned Lagin's first music CD, and first public music, since 1975. Cat Dreams is formally a suite of composed pieces, and composed melodic, tonal, and rhythmic frameworks for improvisation. These are presented as solo, duo, small group, and band; acoustic, electric, electronic music. Originally composed and planned for a two CD release, Cat Dreams is the first of the two CDs that comprise the full suite of compositions. On Cat Dreams, Lagin plays electric piano, keyboard synths (including vocals, cello, acoustic guitar, electric guitar, pedal steel guitar, banjo, and others), Native American flutes, and softsynths: Ableton Live and Max for Live, Reason, Reaktor The other musicians performing on Cat Dreams:

Adrenomedullin (ADM) is a peptide hormone that plays an important role in various physiological processes throughout the human body. Initially discovered in 1993 from a pheochromocytoma, a tumor of the adrenal medulla, this 52-amino acid peptide is now recognized for its diverse effects, including vasodilation, regulation of blood pressure, and maintenance of the vascular system. ADM is widely expressed in tissues and also found in the circulation, exerting its influence on the cardiovascular, lymphatic, and endocrine systems, as well as demonstrating anti-inflammatory and tissue-protective properties. In humans, ADM is encoded by the ADM gene. A similar peptide named adreomedullin2 was reported in rats in 2004, which exhibits a similar function.

==== Neural ==== Oxytocin secretion in response to suckling or vagino-cervical stimulation is mediated by some of these pathways; vasopressin secretion in response to cardiovascular stimuli arising from chemoreceptors in the carotid body and aortic arch, and from low-pressure atrial volume receptors, is mediated by others. In the rat, stimulation of the vagina also causes prolactin secretion, and this results in pseudo-pregnancy following an infertile mating. In the rabbit, coitus elicits reflex ovulation. In the sheep, cervical stimulation in the presence of high levels of estrogen can induce maternal behavior in a virgin ewe. These effects are all mediated by the hypothalamus, and the information is carried mainly by spinal pathways that relay in the brainstem. Stimulation of the nipples stimulates release of oxytocin and prolactin and suppresses the release of LH and FSH. Cardiovascular stimuli are carried by the vagus nerve. The vagus also conveys a variety of visceral information, including for instance signals arising from gastric distension or emptying, to suppress or promote feeding, by signalling the release of leptin or gastrin, respectively. Again, this information reaches the hypothalamus via relays in the brainstem. In addition, hypothalamic function is responsive to—and regulated by—levels of all three classical monoamine neurotransmitters, noradrenaline, dopamine, and serotonin (5-hydroxytryptamine), in those tracts from which it receives innervation.

Sources: en.wikipedia.org

Further detail

=== Jan Vikalp Morcha / AIHCP === Soon after he left the Indian National Congress, he launched a new outfit called Jan Vikalp Morcha with Parthesh Patel ahead of 2017 Gujarat Legislative Assembly election. As the application for registration of Jan Vikalp Morcha was not approved by the elections were announced by the Election Commission, his outfit fielded 95 candidates under the symbol and banner of Jaipur-based All India Hindustan Congress Party to contest election. AIHCP garnered only 0.3% (83,922) of total votes and did not win any seat.

Some people, however, can continue to lose potassium while on an ACE inhibitor. Hyperkalemia may decrease the velocity of impulse conduction in the nerves and muscles, including cardiac tissues. This leads to cardiac dysfunction and neuromuscular consequences, such as muscle weakness, paresthesia, nausea, diarrhea, and others. Close monitoring of potassium levels is required in patients receiving treatment with ACE inhibitors who are at risk of hyperkalemia. Another possible adverse effect specific for ACE inhibitors, but not for other RAAS blockers, is an increase in bradykinin level. Additional research on this topic is required. A persistent dry cough is a common adverse effect produced by ACE inhibitors in 10% to 20% of patients. People who experience coughing are often switched to angiotensin II receptor antagonists. Between 0.1% and 0.7% of patients develop angioedema or swelling. A genetic predisposition may exist.

=== Early observational studies === From the 1890s onwards, associations of tobacco use with cancers and vascular disease were regularly reported. In 1930, Fritz Lickint of Dresden, Germany, published a meta-analysis citing 167 other works to link tobacco use to lung cancer. Lickint showed that people with lung cancer were likely to be smokers. He also argued that smoking tobacco was the best way to explain the fact that lung cancer struck men four or five times more often than women (since women smoked much less), and discussed the causal effect of smoking on cancers of the liver and bladder.

A point mutation is a genetic mutation where a single nucleotide base is changed, inserted or deleted from a DNA or RNA sequence of an organism's genome. Point mutations have a variety of effects on the downstream protein product—consequences that are moderately predictable based upon the specifics of the mutation. These consequences can range from no effect (e.g. synonymous mutations) to deleterious effects (e.g. frameshift mutations), with regard to protein production, composition, and function.

Bergamot essential oil has been used in cosmetics, aromatherapy, and as a flavoring in food and beverages. Its citrus scent makes it a natural flavoring and deodorizing agent. The volatile oils of the bergamot orange are described as flavoring agents in the USP Food Chemicals Codex and are generally recognized as safe for human consumption by the US Food and Drug Administration. For example, Earl Grey tea is a type of black tea that may contain bergamot essential oil as a flavoring agent. Historically, bergamot essential oil was an ingredient in Eau de Cologne, a perfume originally concocted by Johann Maria Farina at the beginning of the 18th century. The first record of bergamot oil used as a fragrance in perfume is from 1714, found in the Farina Archive in Cologne.

Sources: en.wikipedia.org

Frequently asked questions

What is melanotan-2 chemically?

It is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, containing seven amino acids with a lactam ring and a D-configured phenylalanine residue. It is supplied as a lyophilised powder for laboratory research.

How does it differ from the natural hormone?

The natural hormone is a linear tridecapeptide that is rapidly degraded in circulation. Melanotan-2 is shortened, cyclised, N-terminally acetylated, and carries a D-amino acid substitution, all of which slow enzymatic breakdown.

Does it hold any regulatory approval?

No national medicines regulator has approved melanotan-2 for therapeutic or cosmetic use. In several jurisdictions it is treated as an unapproved prescription medicine, and its legal classification differs from country to country.

What is Melanotan-2 chemically?

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.

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