Melanotan II 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.
Updated 2025-08-22. Numbers and descriptions here follow the published literature rather than marketing material.
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 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.
| 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 |
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.
Melanotan II binds several melanocortin receptor subtypes rather than a single target. MC1R on melanocytes drives melanin synthesis, while MC3R and MC4R participate in energy balance, appetite, and sexual response pathways. This lack of selectivity explains why reported effects extend beyond skin darkening. Substitutions at positions four and seven, including norleucine and D-phenylalanine, increase potency and resistance to peptidases. Understanding which receptor mediates which effect remains an active area of investigation.
Identity and purity are assessed mainly by reversed-phase high-performance liquid chromatography with ultraviolet detection, often paired with mass spectrometry. Retention time supports identity, while the mass spectrum confirms the molecular weight of the intact peptide. Purity is frequently reported as a percentage of total peak area, a figure that depends on the wavelength, column and gradient used. Impurity profiling may also look for truncated sequences, oxidised forms and residual counterions. Amino acid analysis and peptide mapping provide orthogonal confirmation when required.
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.
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.
== Notes == ^ α: GLA-domainless protein C is produced by selective proteolysis between residues 82 and 83 to remove the N-terminal portion of the protein that includes essentially all of the GLA domain (residues 47–88). The N-terminus was removed in order to make crystallization of the protein easier. ^ β: In hypereosinophilia, excess eosinophil-specific granule proteins (such as major basic protein, erythropoietin and eosinophil cationic protein) on the endothelial surface bind to thrombomodulin and inhibit its participation in the activation of protein C by electrostatic interaction on the surface of thrombomodulin.
== History == Natural enzymes catalyze chemical reactions with high selectivity and efficiency. Catalysis occurs in the enzyme's active site, where substrates bind near functional groups, enabling proximity effects. Artificial enzymes mimic this by combining substrate-binding sites (e.g., cyclodextrins, crown ethers, or calixarenes) with catalytic groups in small molecules. Advances include artificial enzymes based on amino acids or peptides, such as scaffolded histidine residues mimicking metalloproteins like hemocyanin, tyrosinase, and catechol oxidase. Computational design using tools like Rosetta has enabled de novo creation of artificial enzymes. In 2014, enzymes were created from non-natural molecules. A 2016 book chapter discussed future directions in artificial enzymes.
Phenylpiracetam, also known as fonturacetam (INNTooltip International nonproprietary name) and sold under the brand names Phenotropil, Actitropil, and Carphedon among others, is a stimulant and nootropic medication used in Russia and certain other Eastern European countries in the treatment of cerebrovascular deficiency, depression, apathy, attention, and memory problems, among other indications. It is also used in Russian cosmonauts to improve physical, mental, and cognitive abilities. The drug is taken by mouth. Side effects of phenylpiracetam include sleep disturbances among others. The mechanism of action of phenylpiracetam was originally unknown. However, it was discovered that (R)-phenylpiracetam is a selective atypical dopamine reuptake inhibitor in 2014. In addition, phenylpiracetam interacts with certain nicotinic acetylcholine receptors. Chemically, phenylpiracetam is a racetam and phenethylamine and is structurally related to piracetam. Phenylpiracetam was first described in 1983 by Bobkov Iu, et al. It was approved for medical use in Russia in 2003. Development of (R)-phenylpiracetam (code name MRZ-9547) in the West as a potential treatment for fatigue related to Parkinson's disease began by 2014. In addition to its medical use, phenylpiracetam is sold online as a nootropic.
=== Pharmacokinetics === After injection into a vein, 14% of the circulating ioxaglic acid is bound to blood plasma proteins, which is unusually high for a water-soluble iodinated contrast agent. The substance is distributed in the body with a half-life of 12 minutes (range 4 to 17 minutes) and eliminated in unmetabolized (unchanged) form via the kidneys with a half-life of 92 minutes (range 61 to 140 minutes). In people with kidney failure, it is eliminated via the bile duct, saliva or sweat.
Sources: en.wikipedia.org
Ritanserin, also known by its developmental code name R-55667, is a serotonin receptor antagonist which was under development for the treatment of anxiety disorders and major depressive disorder but was never marketed. It was also investigated for treatment of insomnia, especially to enhance sleep quality by significantly increasing slow wave sleep by virtue of potent and concomitant serotonin 5-HT2A and 5-HT2C receptor antagonism. The drug is taken orally.
In March 2008, AFRL's Human Effectiveness Directorate located at Wright-Patterson AFB was merged with the Air Force School of Aerospace Medicine and the Human Performance Integration Directorate from the 311th Human Systems Wing both located at Brooks City-Base, Texas to form the 711th Human Performance Wing. In its vision statement, the wing includes the goals of improving aerospace medicine, science and technology, and human systems integration. The current Commander of the 711th is Brig. Gen. Timothy Jex. One practical application of its work is ensuring and advancing the safety of ejection systems for pilots. With the increasing number of females in the Air Force ranks, anthropometry is of greater import now than ever, and 711th's WB4 'whole-body scanner' enables swift and accurate acquisition of anthropometric data which may be used to design pilot equipment with a better fit for comfort and safety.
The mass number of this isotope was not clearly established (possibly 258 or 259) at the time. In 1965, 256Lr was synthesized by Flyorov et al. from 243Am and 18O. Thus IUPAC recognized the nuclear physics teams at Dubna and Berkeley as the co-discoverers of lawrencium.
== In the heart == In the heart, A1 receptors play roles in electrical pacing (chronotropy and dromotropy), fluid balance, local sympathetic regulation, and metabolism. When bound by adenosine, A1 receptors inhibit impulses generated in supraventricular tissue (SA node, AV node) and the Bundle of His/Purkinje system, leading to negative chronotropy (slowing of the heart rate). Specifically, A1 receptor activation leads to inactivation of the inwardly rectifying K+ current and inhibition of the inward Ca2+ current (ICa) and the 'funny' hyperpolarization-activated current (If). Adenosine agonism of A1ARs also inhibits release of norepinephrine from cardiac nerves. Norepinephrine is a positive chronotrope, inotrope, and dromotrope, through its agonism of β adrenergic receptors on pacemaker cells and ventricular myocytes. Collectively, these mechanisms lead to an myocardial depressant effect by decreasing the conduction of electrical impulses and suppressing pacemaker cells function, resulting in a decrease in heart rate. This makes adenosine a useful medication for treating and diagnosing tachyarrhythmias, or excessively fast heart rates. This effect on the A1 receptor also explains why there is a brief moment of cardiac standstill when adenosine is administered as a rapid IV push during cardiac resuscitation. The rapid infusion causes a momentary myocardial stunning effect. In normal physiological states, this serves as protective mechanisms.
=== Stagnation and a forfeited World Cup (1976–1986) === Runners-up status brought no lasting improvement. Colombia failed to win any of their four matches in the 1978 qualifiers, managing one goal across the group and losing 6–0 in Rio de Janeiro. At the 1979 Copa América they again finished level on points with Chile after beating them 1–0 in Bogotá and putting four past Venezuela, only to be eliminated on goal difference following a 2–0 defeat in Santiago. The 1982 campaign, overseen by the Argentine Carlos Bilardo, yielded two points from four matches and no victories, Hernán Darío Herrera scoring three of Colombia's four goals. A second-place group finish behind Peru ended the 1983 Copa América campaign.
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.
Regulatory treatment varies by country. In the United States, the European Union and Australia it is an unapproved drug and its sale is restricted, while some other jurisdictions list it as prescription-only or controlled. The applicable rules depend on the country of import.