melanocortin receptors 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 2026-07-31. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
Regulatory treatment varies by jurisdiction and has changed over time. In several countries the peptide is handled as an unapproved prescription medicine, and import or sale for human use is restricted, while elsewhere it falls under poisons or controlled-substance schedules. Enforcement activity against online vendors has been reported in Australia, New Zealand, the United Kingdom and the United States. Scholarly writing discusses melanotan-2 chiefly as an experimental tool and as a case study in unregulated peptide supply, and its precise legal position in any given country should be checked against current national schedules.
Lyophilised melanotan-2 is comparatively robust when kept dry, cold and dark, and a desiccated powder stored at minus twenty degrees Celsius or below is generally expected to retain its chemical integrity for extended periods. In solution the peptide is far less stable, with degradation proceeding through oxidation of tryptophan and histidine residues, hydrolysis adjacent to the lactam bridge, and aggregation at higher concentrations. Repeated freeze-thaw cycling accelerates loss of the parent peak. Working aliquots are therefore prepared once, held cold, and used without letting the stock return to ambient temperature.
Quality assessment of research-grade peptide rests mainly on reversed-phase high-performance liquid chromatography for purity and on mass spectrometry for identity confirmation. A single main peak above a stated threshold, commonly ninety-eight percent by peak area, is the usual release criterion applied by suppliers. Independent analyses commissioned by laboratories and consumer organisations have repeatedly reported discrepancies between label claims and measured content, including truncated sequences, residual trifluoroacetate, and lower-than-declared peptide mass. Those findings do not establish that every supplier is unreliable, but they indicate that purity figures printed on a vial are claims requiring verification rather than settled facts.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | Melanotan II; MT-II; N-acetyl-norleucyl-cyclo[Asp-His-D-Phe-Arg-Trp-Lys] amide | Naming follows peptide convention; the numeral distinguishes it from melanotan-1 |
| Molecular formula | C50H69N15O9 | Includes the lactam bridge; no counter-ion assumed |
| Monoisotopic mass | 1023.53 Da | Free base; salts and counter-ions shift the observed value |
| Appearance | White to off-white lyophilised powder | Batch-to-batch colour variation is not itself proof of impurity |
| Typical analytical method | RP-HPLC purity determination with ESI-MS identity confirmation | Retention time alone does not establish sequence identity |
The peptide acts as a non-selective agonist at melanocortin receptors, showing affinity for MC1R, MC3R, MC4R and MC5R. Activation of MC1R on melanocytes drives the conversion of tyrosine into melanin and shifts production toward the darker eumelanin form. MC4R signalling in the central nervous system is linked to appetite and energy balance, which helps explain why reduced food intake appeared in early human studies. Effects on MC4R and on vascular tone also account for the erectile responses recorded as unexpected findings in those same trials.
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 appears on the World Anti-Doping Agency prohibited list within the peptide hormone class, and several national regulators treat it as an unapproved prescription substance. Some countries restrict importation or sale for personal use. Because the compound is widely traded as a research chemical, the practical legal picture differs between jurisdictions and shifts over time. Human safety data covering long periods are limited, and whether repeated pigmentation changes carry any lasting risk to melanocytes remains an open question.
Freeze-dried melanotan-2 is normally kept as a desiccated powder at minus twenty degrees Celsius or lower, shielded from light and moisture. Peptides of this size degrade through hydrolysis, oxidation and deamidation, and each pathway accelerates as temperature and water activity rise. Repeated freeze-thaw cycles promote aggregation and loss of material, so aliquoting a stock solution before freezing is standard laboratory practice. Once dissolved, the solution is markedly less stable than the powder. In laboratory work, solutions are generally refrigerated and used within days rather than kept for months.
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.
Outside regulated medicine, melanotan II circulates through online vendors as a research chemical, often marketed for tanning. Products sold this way vary widely in purity, concentration, and labeling accuracy, and independent testing has documented discrepancies. Published reports describe both pigment effects and adverse reactions, including nausea, flushing, and darkening of existing moles. Long-term safety data are sparse, and no large controlled trial has established a risk profile. Questions about cumulative effects on melanocytes remain unresolved in the literature.
assimilatory process Any process by which chemical compounds containing biologically relevant elements (e.g. carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur, selenium, iron, cobalt, nickel, copper, zinc, molybdenum, etc.) are uptaken by microorganisms and incorporated into complex biomolecules in order to synthesize various cellular components. In contrast, a dissimilatory process uses the energy released by decomposing exogenous molecules to power the cell's metabolism and excretes residual or toxic compounds out of the cell, instead of reusing them to build new molecules.
Interstitial deletions: an intra-chromosomal deletion that removes a segment of DNA from a single chromosome, thereby apposing previously distant genes. For example, cells isolated from a human astrocytoma, a type of brain tumour, were found to have a chromosomal deletion removing sequences between the Fused in Glioblastoma (FIG) gene and the receptor tyrosine kinase (ROS), producing a fusion protein (FIG-ROS). The abnormal FIG-ROS fusion protein has constitutively active kinase activity that causes oncogenic transformation (a transformation from normal cells to cancer cells). Loss of heterozygosity: loss of one allele, either by a deletion or a genetic recombination event, in an organism that previously had two different alleles.
This experience has been described as "the most consequential mescaline trip of the sixties", as it caused Shulgin to redirect his focus and life's work to psychedelic chemistry. Starting in the 1960s, Shulgin synthesized and gradually described hundreds of novel synthetic psychedelics as well as entactogens in scientific publications and published books such as PiHKAL (1991) and TiHKAL (1997). Notable major examples of these drugs have included the DOx psychedelic DOM, the 2C psychedelic 2C-B, and the MDxx entactogen MDMA, among others. However, MDMA was not an original creation of Shulgin's but had previously been first synthesized in 1912 and had surfaced as a recreational drug related to MDA by the mid- to late-1960s. Instead, Shulgin had merely served to help popularize and spread awareness about MDMA and its unique effects. MDMA became outlawed in the mid-1980s. In response to this, the Multidisciplinary Association for Psychedelic Studies (MAPS) was founded by Rick Doblin in 1986 and began efforts to develop MDMA and other psychedelics as medicines. American chemist David E. Nichols has developed numerous novel psychedelics and entactogens from the 1970s to present. Swiss chemist Daniel Trachsel, sometimes referred to as the "German Shulgin", has also developed and published numerous novel psychedelics as well as entactogens since the 1990s. NBOMe psychedelics such as 25I-NBOMe, derived from structural modification of 2C psychedelics, were first described by Ralf Heim and colleagues by 2000.
=== Single unit transfusion === This refers to transfusing a single unit or bag of red blood cells to a person who is not bleeding and haemodynamically stable followed by an assessment to see if further transfusion is required. The benefits of single unit transfusion include reduced exposure to blood products. Each unit transfused increases the associated risks of transfusion such as infection, transfusion associated circulatory overload and other side effects. Transfusion of a single unit also encourages less wastage of red blood cells.
=== Immune system and infection === Hyperglycemia has been linked to increased susceptibility to a range of infectious diseases. This susceptibility can be attributed to the impairment of the immune system's response, which is often compromised in hyperglycemic conditions. Hyperglycemia also leads to biochemical changes in the body; both of these factors result in increased severity of respiratory infections and vulnerability to pathogens. Hyperglycemic individuals face the most pronounced risk from such types of ailments, including tuberculosis, the flu, and COVID-19. These risks can be compounded even further by the effects of physiological stress. Importantly, hyperglycemia affects the function of neutrophils, which are white blood cells responsible for responding to infection. In hyperglycemic individuals, the ability for neutrophils to move toward infection sites, ingest bacteria, and kill them are often impaired, leading to reduced effectiveness in combating infections. Hyperglycemia also creates microbiological changes within the body: hyperglycemia can lead to rapid changes in blood pH and cell viscosity, weakening the cells and making it more conducive for infectious agents to thrive and dampen inflammatory responses. This is because hyperglycemia impacts a few factors such as the microenvironment of immune cells, or even bacteria's supply of energy, adding on stress to the bacterial proliferation metabolism. The chronic inflammatory state induced by high glucose levels can also lead to dysfunction in various parts of the immune system.
Sources: en.wikipedia.org
Acting on the nuclear mineralocorticoid receptors (MR) within the principal cells of the distal tubule and the collecting duct of the kidney nephron, it upregulates and activates the basolateral Na+/K+ pumps, which pumps three sodium ions out of the cell, into the interstitial fluid and two potassium ions into the cell from the interstitial fluid. This creates a concentration gradient which results in reabsorption of sodium (Na+) ions and water (which follows sodium) into the blood, and secreting potassium (K+) ions into the urine (lumen of collecting duct). Aldosterone upregulates epithelial sodium channels (ENaCs) in the collecting duct and the colon, increasing apical membrane permeability for Na+ and thus absorption. Cl− is reabsorbed in conjunction with sodium cations to maintain the system's electrochemical balance. Aldosterone stimulates the secretion of K+ into the tubular lumen. Aldosterone stimulates Na+ and water reabsorption from the gut, salivary and sweat glands in exchange for K+. Aldosterone stimulates secretion of H+ via the H+/ATPase in the intercalated cells of the cortical collecting tubules Aldosterone upregulates expression of NCC in the distal convoluted tubule chronically and its activity acutely. Aldosterone is responsible for the reabsorption of about 2% of filtered sodium in the kidneys, which is nearly equal to the entire sodium content in human blood under normal glomerular filtration rates. Aldosterone, probably acting through mineralocorticoid receptors, may positively influence neurogenesis in the dentate gyrus.
=== ThermoFAD === Thermofluor variant specific for flavin-binding proteins. Analogous to Thermofluor binding assays, a small volume of protein solution is heated up and the fluorescence increase is followed as function of temperature. In contrast to Thermofluor, no external fluorescent dye is needed because the flavin cofactor is already present in the flavin-binding protein and its fluorescence properties change upon unfolding.
Ds,eff = aDs + b/ (1022Ds) = 8.051e−6Ds+0.999/(1022Ds), Eq. 3 where Ds = (1/(dC/dx))10−11 assuming a constant flux and taken as unity. The eq. (2) and assumption of unity is a matter of further investigation. Several commercial companies and university laboratories provide obsidian hydration services.
Heart failure - Giving 2.5 times of previous oral dose twice daily for those with acute decompensated heart failure is a reasonable strategy. However, daily assessment of clinical response is needed to adjust the subsequent doses. Edema - Volume overload associated with liver cirrhosis, heart failure, or nephrotic syndrome Cerebral edema - intravenous furosemide can be combined with mannitol to initiate rapid diuresis. However, the optimum duration of such treatment remains unknown. Frequent fluid status monitoring is required to prevent intravascular volume depletion which leads to reduced cerebral perfusion. A bolus intravenous dose of 10 or 20 mg of furosemide can be administered and then followed by intravenous bolus of 2 or 3% hypertonic saline to increase the serum sodium level. Pulmonary edema - Slow intravenous bolus dose of 40 to 80 mg furosemide at 4 mg per minute is indicated for patients with fluid overload and pulmonary edema. Such dose can be repeated after 20 minutes. After the bolus, a continuous intravenous infusion can be given at 5 to 10 mg per hour. For those with underlying renal impairment or severe heart failure, up to 160 to 200 mg bolus dose can be given. Hypertension - A systematic review by the Cochrane Hypertension group assessing the anti-hypertensive effects of loop diuretics found only a modest reduction in blood pressure when compared to placebo. According to Joint National Committee (JNC-8) guidelines, the first line treatment of hypertension is thiazide diuretics. The use of loop diuretics is not mentioned in this guideline.
Sources: en.wikipedia.org
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.
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.
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.
Solutions are best kept cold, protected from light, and buffered to a pH that limits hydrolysis. Dividing a stock into single-use aliquots avoids repeated freeze-thaw cycles, which measurably reduce the intact parent peak over time.