If you have been reading about melanotan-2 and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
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.
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.
| 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 |
No regulatory authority has approved melanotan-2 for human use, and several countries classify it as a prescription-only or controlled substance, which restricts lawful supply. Material sold online is generally labelled as a research chemical and is not required to meet pharmaceutical standards of identity or purity. Published human data consist mainly of small uncontrolled studies, case reports and adverse-event notifications, so the evidence base is descriptive rather than confirmatory. Whether repeated melanocyte stimulation alters long-term naevus behaviour remains an open question that no completed trial has resolved.
Melanotan-2 is a synthetic cyclic heptapeptide designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous tridecapeptide that regulates pigment production. Two modifications distinguish it from the natural hormone: norleucine replaces methionine at the N-terminus, which limits oxidation, and a D-phenylalanine substitution raises receptor affinity. The ring is closed through an aspartate-lysine lactam bridge, giving the molecule a constrained conformation. The free base has a molecular mass near 1024 daltons, and commercial material is usually supplied as an acetate salt. It appears in the literature as a research peptide rather than an approved therapeutic agent.
Receptor studies place melanotan-2 among non-selective melanocortin agonists, binding MC1R, MC3R, MC4R and MC5R rather than a single subtype. Activation of MC1R on cutaneous melanocytes raises tyrosinase activity and shifts pigment synthesis toward eumelanin, which is darker and more photostable than pheomelanin. Central receptors, particularly MC4R, are associated with appetite suppression and with reported effects on sexual function. Because subtype selectivity is low, the same molecule engages pigment, metabolic and vascular pathways at once, and this breadth is a common explanation offered for the range of adverse events described in user reports.
Eighteen isotopes and four nuclear isomers are known for einsteinium, with mass numbers 240–257. All are radioactive; the most stable one, 252Es, has half-life 471.7 days. The next most stable isotopes are 254Es (half-life 275.7 days), 255Es (39.8 days), and 253Es (20.47 days). All the other isotopes have half-lives shorter than 40 hours, most shorter than 30 minutes. Of the five isomers, the most stable is 254mEs with a half-life of 39.3 hours.
In biochemistry, the Corey–Pauling rules are a set of three basic statements that govern the secondary nature of proteins, in particular, the CO-NH peptide link. They were originally proposed by Robert Corey and Linus Pauling. The rules are as follows:
== Sources == Bingham, Jonathan Brewster (1953). Shirt-Sleeve Diplomacy: Point 4 in Action. John Day & Co. Brown, William Adams Jr.; Opie, Redvers (1953). American Foreign Assistance. Washington, DC: The Brookings Institution. Butterfield, Samuel Hale (2004). U.S. Development Aid – An Historic First: Achievements and Failures in the Twentieth Century. Westport, CN: Praeger. ISBN 0-313-31910-3. Glick, Philip M. (1957). The Administration of Technical Assistance: Growth in the Americas. Chicago: University of Chicago Press. Haviland, H. Field (1958). "Foreign Aid and the Policy Process: 1957". The American Political Science Review. 52 (3): 689–724. doi:10.2307/1951900. JSTOR 1951900. S2CID 144564474. Hayes, Samuel J., ed. (1971). The Beginnings of American Aid to Southeast Asia: The Griffin Mission of 1950. Lexington, MA: Heath Lexington Books. Jolly, Richard; Emmerji, Louis; Ghai, Dharam; Lapeyre, Frederic (2004). UN Contributions to Development Thinking and Practice. Bloomington: Indiana University Press. Kaufman, B. Ira (1982). Trade and aid : Eisenhower's foreign economic policy, 1953–1961. Baltimore, MD: Johns Hopkins University Press. p. 82. ISBN 978-0-8018-2623-8. Nowels, Larry Q. (February 1987). Economic Security Assistance As a Tool of American Foreign Policy: The Current Dilemma and Future Options (PDF) (Report). National War College. Archived from the original (PDF) on 2017-10-11. Retrieved 2017-06-20 – via Development Experience Clearinghouse. Ruttan, Vernon W. (1996). United States Development Assistance Policy: The Domestic Politics of Foreign Economic Aid.
Aptamers are oligomers of artificial ssDNA, RNA, XNA, or peptide that bind a specific target molecule, or family of target molecules. They exhibit a range of affinities (KD in the pM to μM range), with variable levels of off-target binding and are sometimes classified as chemical antibodies. Aptamers and antibodies can be used in many of the same applications, but the nucleic acid-based structure of aptamers, which are mostly oligonucleotides, is very different from the amino acid-based structure of antibodies, which are proteins. This difference can make aptamers a better choice than antibodies for some purposes (see antibody replacement). Aptamers are used in biological lab research and medical tests. If multiple aptamers are combined into a single assay, they can measure large numbers of different proteins in a sample. They can be used to identify molecular markers of disease, or can function as drugs, drug delivery systems and controlled drug release systems. They also find use in other molecular engineering tasks. Most aptamers originate from SELEX, a family of test-tube experiments for finding useful aptamers in a massive pool of different DNA sequences. This process is much like natural selection, directed evolution or artificial selection. In SELEX, the researcher repeatedly selects for the best aptamers from a starting DNA library made of about a quadrillion different randomly generated pieces of DNA or RNA.
Sources: en.wikipedia.org
=== Diagnosis of infections === Clinical features of a respiratory tract infection may include initial symptoms of an upper respiratory tract infection mimicking a viral infection, usually associated with low-grade fevers. This may progress to the lower respiratory tract within a few days, with features often resembling those of wheezy bronchitis. Sputum may be difficult to expectorate and is often grey or creamy in color. The cough may persist for weeks without appropriate treatment. Many cases are diagnosed after presenting chest infections that do not respond to penicillins or first-generation cephalosporins. A chest X-ray can identify alveolar consolidation. Clinical diagnosis of invasive H. influenzae infection (infection that has spread to the bloodstream and internal tissues) is typically confirmed by bacterial culture, latex particle agglutination tests, or polymerase chain reaction tests on clinical samples obtained from an otherwise sterile body site. In this respect, H. influenzae cultured from the nasopharyngeal cavity or throat would not indicate H. influenzae disease, because these sites are colonized in disease-free individuals. Although highly specific, bacterial culture of H. influenzae lacks sensitivity. Use of antibiotics prior to sample collection greatly reduces the isolation rate by killing the bacteria before identification is possible. Recent work has shown that H. influenzae uses a highly specialized spectrum of nutrients where lactate is a preferred carbon source.
The shape of the ends of the bones — Some joints normally have a large range of movement, such as the shoulder and hip. Both are ball-and-socket joints. The joint ends of bones finish their growth last, so children tend to have more flexible joints than adults; children may "grow out of" hypermobility as their bone ends fully develop. A shallow socket will lead to a relatively large range of movement. If the hip socket is particularly shallow, then the hip may dislocate easily. Ligament problems— Ligaments are made of several types of protein fiber, including elastin and collagen. Gymnasts and athletes can voluntarily acquire hypermobility in some joints by stretching healthy ligaments over time. However, weak or abnormally long ligaments can cause unstable hypermobile joints. Protein deficiencies may weaken ligaments. Some hormones may alter the structure of collagen proteins. For example, in late pregnancy, relaxin allows the ligaments of the pelvis to lengthen so the head of the baby can pass. Muscle tone—Opposing sets of muscles are attached to bones to move joints in various directions. The tone of muscles—a mild basic level of contraction that protects joints and organs—is controlled by the nervous system. Neuromuscular problems can cause loss of muscle tone, increasing the range of movement possible and removing the muscles' protection of the joint. Lack of exercise also weakens the muscles that support and anchor highly flexible joints such as the shoulder, hip, wrist, and ankle.
However, action potentials may end prematurely in certain places where the safety factor is low, even in unmyelinated neurons; a common example is the branch point of an axon, where it divides into two axons. Some diseases degrade myelin and impair saltatory conduction, reducing the conduction velocity of action potentials. The most well-known of these is multiple sclerosis, in which the breakdown of myelin impairs coordinated movement.
Through various studies in which functional derivatives of ribosomes were mixed with puromycin (an analog of the 3' end of an aa-tRNA) it was determined that adding LepA to a post transcriptionally modified ribosome prevents dipeptide formation as it inhibits the binding of aa-tRNA to the A site.
Wolverine is killed again, along with Nightcrawler and others. However, he, along with the other X-Men who have been recently killed, are then resurrected in the Arbor Magus' hatchery on the Pacific island of Krakoa using a new 48 hour cloning process. In this new era, the X-Men have learned how to resurrect any mutant who has died. Wolverine enters into a violent conflict with Beast, who has become aggressive and paranoid in his defense of Krakoa.
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 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.