Everything below concerns melanotan-2. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-04-26. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Melanocortin receptors comprise five subtypes with distinct tissue distributions and functions. Melanotan-2 is described in the literature as a non-selective agonist that engages several of these subtypes, including MC1R, MC3R, MC4R, and MC5R. MC1R is the subtype most directly linked to melanin production in skin cells. Because the compound is not subtype-selective, its observed effects in experimental settings are generally attributed to activity across multiple receptor pathways rather than to a single target.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Free base; salt forms differ |
| Molecular weight | Approximately 1024 g/mol | Calculated for the free base |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water and polar solvents | Poorly soluble in non-polar solvents |
| Typical storage | -20 degrees Celsius, dry, protected from light | Refers to the solid form |
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.
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.
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.
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.
=== Safety === In humans, there is no evidence for riboflavin toxicity produced by excessive intakes and absorption becomes less efficient as dosage increases. Any excess riboflavin is excreted via the kidneys into urine, resulting in a bright yellow color known as flavinuria. During a clinical trial on the effectiveness of riboflavin for treating the frequency and severity of migraines, subjects were given up to 400 mg of riboflavin orally per day for periods of 3–12 months. Abdominal pains and diarrhea were among the side effects reported.
Drug administration via the nasal cavity yields rapid drug absorption and therapeutic effects. This is because drug absorption through the nasal passages does not go through the gut before entering capillaries situated at tissue cells and then systemic circulation and such absorption route allows transport of drugs into the central nervous system via the pathways of olfactory and trigeminal nerve. Intranasal absorption features low lipophilicity, enzymatic degradation within the nasal cavity, large molecular size, and rapid mucociliary clearance from the nasal passages, which explains the low risk of systemic exposure of the administered drug absorbed via intranasal.
== Discovery == Lariocidin was identified as part of a natural-product screening program led by researchers at McMaster University. The producer organism, Paenibacillus sp. M2, was isolated from a backyard soil sample from the garden in Hamilton, ON, Canada; researchers cultivated soil bacteria under conditions intended to enrich slower-growing organisms and screened culture extracts for antibacterial activity.
== Mitigation == The "CDC Clinical Practice Guideline for Prescribing Opioids for Pain-United States, 2022" provides recommendations related to opioid misuse, OUD, and opioid overdoses. It reports a lack of clinical evidence that "abuse-deterrent" opioids (e.g., OxyContin), as labeled by the U.S. Food and Drug Administration, are effective for OUD risk mitigation. CDC guidance suggests the prescription of immediate-release opioids instead of opioids that have a long duration (long-acting) or opioids that are released over time (extended-release). Other recommendations include prescribing the lowest opioid dose that successfully addresses the pain in opioid-naïve patients and collaborating with patients who already take opioid therapy to maximize the effect of non-opioid analgesics. While receiving opioid therapy, patients should be periodically evaluated for opioid-related complications and clinicians should review state prescription drug monitoring program systems. The latter should be assessed to reduce the risk of overdoses in patients due to their opioid dose or medication combinations. For patients receiving opioid therapy in whom the risks outweigh the benefits, clinicians and patients should develop a treatment plan to decrease their opioid dose incrementally. Compartmental models are mathematical frameworks used to assess and describe complex topics such as the opioid crisis. Applied compartmental models are used in public health to assess the effectiveness of interventions in opioid use disorder.
Sources: en.wikipedia.org
=== Comorbidities === The condition is strongly associated with or caused by type 2 diabetes, insulin resistance, and metabolic syndrome (defined as at least three of the five following medical conditions: abdominal obesity, high blood pressure, high blood sugar, high serum triglycerides, and low serum high-density lipoprotein). It is also associated with:
== Diagnosis == In addition to the usual routine haematologic and biochemical investigations, the serum calcium, phosphorus, magnesium, alkaline phosphatase, calcitonin and parathyroid hormone should also be measured. The cerebrospinal fluid (CSF) should be examined to exclude bacteria, viruses and parasites. The Ellsworth Howard test (a 10–20 fold increase of urinary cyclic AMP excretion following stimulation with 200 micromoles of parathyroid hormone) may be worth doing also. Serology for toxoplasmosis is also indicated. Brain CT scan is the preferred method of localizing and assessing the extent of cerebral calcifications. Elevated levels of copper, iron, magnesium and zinc but not calcium have been reported in the CSF but the significance of this finding—if any—is not known. The diagnosis requires the following criteria be met:
=== March === 4 March – Banco Master scandal: The Supreme Federal Court orders the arrest of former Banco Master president and major shareholder Daniel Vorcaro in a potential fraud case worth up to 12 billion reais. The Federal Senate ratifies the EU–Mercosur Partnership Agreement. 5 March – A nursing home collapses in Belo Horizonte, killing eight people and leaving four missing. 10 March – Ski racer Cristian Ribera becomes the first athlete representing Brazil to win a medal in the Paralympics after achieving silver in the para-cross-country skiing men's seated sprint at the 2026 Winter Paralympics in Italy. 14 March – President Lula revokes the visa of US diplomat Darren Beattie after the latter tries to visit former president Jair Bolsonaro in prison. Three Israeli nationals are arrested after clashing with pro-Palestine demonstrators in Itacare. 17 March – A law restricting access to social media by minors comes into effect. 18 March – Eight people, including Comando Vermelho commander Claudio Augusto dos Santos, are killed in police raids across Rio de Janeiro. 20 March – Fernando Haddad resigns as finance minister after announcing that he would run for governor of Sao Paulo.
== Evolutionary origins == The lungs of today's terrestrial vertebrates and the gas bladders of today's fish are believed to have evolved from simple sacs, as outpocketings of the oesophagus, that allowed early fish to gulp air under oxygen-poor conditions. These outpocketings first arose in the bony fish. In most of the ray-finned fish, the sacs evolved into closed off gas bladders, while a number of carp, trout, herring, catfish, and eels have retained the physostome condition with the sac being open to the oesophagus. In more basal bony fish, such as the gar, bichir, bowfin and the lobe-finned fish, the sacs have evolved to primarily function as lungs. The lobe-finned fish gave rise to the land-based tetrapods. Thus, the lungs of vertebrates are homologous to the gas bladders of fish (but not to their gills).
Microfluidics refers to a system that manipulates a small amount of fluids (10−9 to 10−18 liters) using small channels with sizes of ten to hundreds of micrometres. It is a multidisciplinary field that involves molecular analysis, molecular biology, and microelectronics. It has practical applications in the design of systems that process low volumes of fluids to achieve multiplexing, automation, and high-throughput screening. Microfluidics emerged in the beginning of the 1980s and is used in the development of inkjet printheads, DNA chips, lab-on-a-chip technology, micro-propulsion, and micro-thermal technologies. Typically microfluidic systems transport, mix, separate, or otherwise process fluids. Various applications rely on passive fluid control using capillary forces, in the form of capillary flow modifying elements, akin to flow resistors and flow accelerators. In some applications, external actuation means are additionally used for a directed transport of the media. Examples are rotary drives applying centrifugal forces for the fluid transport on the passive chips. Active microfluidics refers to the defined manipulation of the working fluid by active (micro) components such as micropumps or microvalves. Micropumps supply fluids in a continuous manner or are used for dosing. Microvalves determine the flow direction or the mode of movement of pumped liquids. Often, processes normally carried out in a lab are miniaturised on a single chip, which enhances efficiency and mobility, and reduces sample and reagent volumes.
Sources: en.wikipedia.org
No. Melanotan-2 is manufactured synthetically. The naturally occurring peptide in the same family is alpha-melanocyte-stimulating hormone, which the body produces as part of normal endocrine and neural signalling.
Both are synthetic analogues derived from the same parent hormone. Reference descriptions usually characterise afamelanotide as more selective for the MC1R subtype, whereas melanotan-2 is reported to interact with a wider range of melanocortin receptors.
Early studies explored melanocortin signalling and pigmentation, which later led to informal use of the label tanning peptide. That label is not a regulatory category and does not imply approved status for any purpose.
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.