The short version of Melanotan II fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-08-07 and is reviewed periodically as new material appears.
Melanotan-2 is handled in the laboratory as a lyophilised powder that dissolves readily in water, dimethyl sulfoxide and dimethylformamide, with limited solubility in ethanol. Stock solutions prepared in an organic solvent often precipitate when diluted into aqueous buffer, so gradual dilution with mixing is standard practice. The peptide carries a tryptophan residue and a histidine residue, both sensitive to oxidation and to alkaline conditions. Working solutions are therefore kept near neutral to slightly acidic pH, protected from light, and consumed within the same working session whenever that is practical.
Solid peptide kept dry at minus twenty degrees Celsius, shielded from light and moisture, is generally considered stable for extended periods. Solutions are divided into single-use aliquots and held at minus twenty or minus eighty degrees Celsius, because repeated freeze-thaw cycles promote aggregation and loss of material to container surfaces. Hydrolysis of the backbone and oxidation of tryptophan are the principal degradation routes in aqueous solution, and both accelerate at ambient temperature. Hygroscopic uptake after a vial is opened can also shift the actual mass weighed, which affects any concentration calculated from it.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilised material may be hygroscopic |
| Solubility class | Soluble in water, DMSO and DMF | Dilution into aqueous buffer can cause precipitation |
| Storage of solid | Minus 20 degrees C, desiccated, dark | Aliquot to limit repeated opening of the vial |
| Storage of solution | Minus 20 to minus 80 degrees C, aliquoted | Avoid repeated freeze-thaw cycles |
| Identity method | Reversed-phase HPLC with mass spectrometry | Retention time and mass are checked together |
Identity testing for a synthetic peptide relies on several complementary methods. Reversed-phase high-performance liquid chromatography separates the target from related impurities and reports purity as a percentage of total peak area. Mass spectrometry confirms molecular mass and can reveal deletions or truncations. Amino acid analysis and peptide mapping provide sequence-level confirmation, while counter-ion content and residual solvents are measured separately. A purity figure alone does not establish identity, so a complete dataset combines chromatographic and spectrometric evidence.
Lyophilized peptide powder is generally stored frozen, protected from light and moisture. Tryptophan residues are susceptible to oxidation, and the lactam bridge can hydrolyze under strongly acidic or basic conditions. Solutions prepared for laboratory work degrade faster than dry powder, and repeated freeze-thaw cycles accelerate loss. Common practice is to aliquot solutions before freezing and to avoid alkaline buffers. Reported stability windows vary with concentration, buffer, and temperature, so exact shelf lives are method-specific rather than universal.
Regulatory status differs by country, and in many places supplying the compound for human consumption is unlawful. Vendors frequently label material as intended for research use only, a designation that shifts stated purpose but does not create a legal pathway for personal use. Certificates of analysis accompanying such products vary widely in detail and provenance. Third-party testing exists but is voluntary, and results are rarely linked to a specific lot in a publicly verifiable way.
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.
Lyophilised melanotan-2 is supplied as a solid, which is more stable than a solution. The material is hygroscopic, so weighing is done quickly, in low humidity, with the container kept sealed. Reconstitution usually uses water for injection or bacteriostatic water, added down the wall of the vial to limit foaming. A reconstituted solution is held at 2 to 8 °C and kept away from light. Repeated freezing and thawing of the same vial is avoided because ice crystal formation and concentration effects degrade the peptide.
Reversed-phase high-performance liquid chromatography is the routine method for purity assessment. Peptides absorb near 214 nm because of the peptide bond, and a gradient of acetonitrile in water separates the intact peptide from deletion sequences, oxidised products, and earlier-eluting fragments at neutral pH. Electrospray ionisation mass spectrometry provides an orthogonal check: the measured mass must agree with the theoretical value. Amino acid analysis and peptide mapping confirm structure but are used less often. Reference standards remain scarce because the peptide is not described in any pharmacopoeia.
Activity is attributed to agonism at melanocortin receptors, particularly MC1R and MC4R. Activation of MC1R on melanocytes increases melanin synthesis, which underlies the reported tanning effect. MC4R engagement in the central nervous system is linked to appetite suppression and to effects on sexual arousal reported in early clinical studies. Those studies were small and were not designed to establish efficacy or long-term safety. Receptor selectivity among the melanocortin subtypes is not absolute, which complicates attribution of any effect to a single pathway.
Regulatory treatment varies between countries. Several national medicines agencies have classified the peptide as unapproved, and customs authorities in some jurisdictions seize shipments on that basis. A few jurisdictions channel supply through prescription-only frameworks that do not list the substance by name. Because the material circulates mainly through online vendors, composition and purity are rarely verified before sale. Surveys of unapproved peptide products have reported labels that did not match measured content in a substantial fraction of samples.
Depending on the marker, it can take between 2 and 24 hours for the level to increase in the blood. Additionally, determining the levels of cardiac markers in the laboratory - like many other lab measurements - takes substantial time. Cardiac markers are therefore not useful in diagnosing a myocardial infarction in the acute phase. The clinical presentation and results from an ECG are more appropriate in the acute situation. However, in 2010, research at the Baylor College of Medicine revealed that, using diagnostic nanochips and a swab of the cheek, cardiac biomarker readings from saliva can, with the ECG readings, determine within minutes whether someone is likely to have had a heart attack.
Some fish species have humps, with their makeup varying. The nuchal hump of a humpback chub (from which the species gets its name) is made up almost entirely of skeletal muscle, and may exist to reduce the chub's vulnerability to predators. The flowerhorn cichlid is an ornamental aquarium fish which is bred for its very large nuchal hump. Some breeders may artificially increase the hump's size by injecting it with hormones or feeding the flowerhorn a hormone-rich diet. Male salmon of the Oncorhynchus genus have dorsal humps, which were once thought to consist of cartilage, but is now known to be formed by increases in connective tissues and neural spine growth. Of this genus, sockeye and pink salmon develop the biggest humps, which are mostly made of connective tissue and which decrease in lipid content with age. In contrast, the closely related masu and chum salmon have smaller humps that are mostly formed by bone tissue.
=== Mechanism of toxicity in humans === After FIAU is converted to FIAU-TP, it is not only available to viral polymerase, in humans it can also be taken up into mitochondria and used by mitochondrial DNA polymerase γ (POLG). When FIAU is incorporated into mitochondrial DNA (mtDNA), it disrupts mtDNA replication, which leads to mtDNA depletion. With less mtDNA, cells can make fewer proteins for the electron transport chain, so oxidative phosphorylation fails. The consequences are lactic acidosis (shift to anaerobic metabolism) and microvascular steatosis (impaired fatty-acid oxidation), especially in the liver
A few incidents have occurred when radioactive material was disposed of improperly, shielding during transport was defective, or when it was simply abandoned or even stolen from a waste store. In the Soviet Union, waste stored in Lake Karachay was blown over the area during a dust storm after the lake had partly dried out. In Italy, several radioactive waste deposits let material flow into river water, thus contaminating water for domestic use. In France in the summer of 2008, numerous incidents happened: in one, at the Areva plant in Tricastin, it was reported that, during a draining operation, liquid containing untreated uranium overflowed out of a faulty tank and about 75 kg of the radioactive material seeped into the ground and, from there, into two rivers nearby; in another case, over 100 staff were contaminated with low doses of radiation. There are ongoing concerns around the deterioration of the nuclear waste site on the Enewetak Atoll of the Marshall Islands and a potential radioactive spill. Scavenging of abandoned radioactive material has been the cause of several other cases of radiation exposure, mostly in developing nations, which may have less regulation of dangerous substances (and sometimes less general education about radioactivity and its hazards) and a market for scavenged goods and scrap metal. The scavengers and those who buy the material are almost always unaware that the material is radioactive and it is selected for its aesthetics or scrap value.
Sources: en.wikipedia.org
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After the Avar Khaganate collapsed in the 790s, the First Bulgarian Empire became the dominant power of the region, occupying lands as far as the river Tisa. The First Bulgarian Empire had a mixed population consisting of the Bulgar conquerors, Slavs and Vlachs (or Romanians) but the Slavicisation of the Bulgar elite had already begun in the 9th century. Following the conquest of southern Transylvania around 830, people from the Bulgar Empire mined salt at the local salt mines. The Council of Preslav declared Old Church Slavonic the language of liturgy in the country in 893. The Vlachs also adopted Old Church Slavonic as their liturgical language. The Magyars (or Hungarians) took control of the steppes north of the Lower Danube in the 830s, but the Bulgarians and the Pechenegs forced them to abandon this region for the lowlands along the Middle Danube around 894. Centuries later, the Gesta Hungarorum wrote of the invading Magyars' wars against three dukes—Glad, Menumorut and the Vlach Gelou—for Banat, Crișana and Transylvania. The Gesta also listed many peoples—Slavs, Bulgarians, Vlachs, Khazars, and Székelys—inhabiting the same regions. The reliability of the Gesta is debated. Some scholars regard it as a basically accurate account, others describe it as a literary work filled with invented details. The Pechenegs seized the lowlands abandoned by the Hungarians to the east of the Carpathians. Byzantine missionaries proselytised in the lands east of the Tisa from the 940s and Byzantine troops occupied Dobruja in the 970s.
The state runs most public universities in Croatia. Students who perform well academically pay only administrative fees which are less than €100 per year. Students who fail multiple classes in a year must retake the courses and pay a partial or full tuition fee.
Sources: en.wikipedia.org
== Description == Calvatia gigantea grows up to 10–50 centimetres (4–19+1⁄2 in) wide and high. It can grow to 80 cm diameter and weigh several kilograms. A specimen weighing over 23 kg (51 lb) was recorded in Thunder Bay, Ontario, Canada. The interior of an immature puffball is white, while that of a mature specimen is greenish brown. The fruiting body of a puffball mushroom develops within a few weeks and soon begins to decompose and rot, at which point it becomes dangerous to eat. Unlike most mushrooms, all the spores of the giant puffball are created inside the fruiting body; large specimens can easily contain several trillion. The spores are yellowish, smooth, and 3–6 μm in size. They produce a white spore print when young, while it is olive with an unpleasant smell in age. Prof. John Lindley has calculated that C. gigantea grows at a rate of sixty million new cells per minute on its way to making seven quintillion (7 × 1018) spores.
In patients with non-severe asymptomatic aortic valve stenosis, increased age- and sex adjusted N-terminal pro-brain natriuretic peptide (NT-proBNP) levels alone and combined with a 50% or greater increase from baseline had been found associated with increased event rates of aortic valve stenosis related events (cardiovascular death, hospitalization with heart failure due to progression of aortic valve stenosis, or aortic valve replacement surgery). In patients with non-severe asymptomatic aortic valve stenosis and no overt coronary artery disease, the increased troponin T (above 14 pg/mL) was found associated with an increased 5-year event rate of ischemic cardiac events (myocardial infarction, percutaneous coronary intervention, or coronary artery bypass surgery).
== History == Reduction of biomolecules with trialkyphosphines received little attention for decades because historically available phosphines were extremely malodorous and/or insoluble in water. In 1969, TCEP was reported as an odorless and water-soluble trialkyphosphine suitable for biochemical use, however the potential use of TCEP for biochemical applications was almost totally ignored for decades. In 1991, Burns reported a new convenient synthetic procedure for TCEP, which set off TCEP becoming more widely available and marketed as a "new" reducing agent for biochemical use, & thus TCEP came into more widespread use throughout the 1990s.
Sources: en.wikipedia.org
Purity is normally stated as an area percentage from high-performance liquid chromatography, for example ninety-five or ninety-eight percent. That figure describes the proportion of ultraviolet-absorbing material eluting as the main peak. It says nothing about water content, counterions, residual solvents or mass fraction of the peptide itself.
Peptides are commonly isolated as acetate or trifluoroacetate salts, and the counterion contributes to total mass. Two vials with identical peptide content can therefore differ in weight and in measured response. Residual trifluoroacetate is also relevant in cell-based work because it can influence membrane behaviour.
Degradation products are often closely related to the parent molecule, making them hard to resolve with a single method. Counterion variability adds a further source of scatter between laboratories. Because no pharmacopoeial monograph exists for melanotan-2, groups rely on method-specific validation rather than a shared reference standard.
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.