The short version of Melanotan II fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-12-23. Anything still debated is marked as such rather than presented as settled.
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.
Receptor-binding studies classify melanotan II as a non-selective melanocortin agonist. It interacts with MC1R, MC3R, MC4R and MC5R, with reported affinities in the low nanomolar range and no strong subtype preference. Activation of MC1R on dermal melanocytes shifts pigment synthesis toward eumelanin, the dark polymer deposited in melanosomes and transferred to keratinocytes. Because the same peptide engages MC4R in the hypothalamus, it also appears in animal work on food intake and erectile response, which is why it is discussed in both pigment and metabolic research. Which receptor populations dominate after systemic exposure in humans is not fully established.
Published pharmacokinetic information is limited and comes mainly from small studies rather than registrational trials. Plasma half-life is usually described as short, on the order of tens of minutes, followed by rapid tissue distribution and clearance of the intact peptide. Metabolites and low concentrations of parent compound have been reported in urine, a detail relevant to anti-doping and forensic testing. Whether repeated exposure changes receptor sensitivity or clearance over time remains an open question. Values differ noticeably between analytical assays, so published numbers should be read as approximate rather than definitive.
| 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.
Melanocytes are the pigment-producing cells of the skin, and they carry melanocortin-1 receptors on their surface. When the receptor is activated, cyclic adenosine monophosphate rises inside the cell and raises the activity of enzymes such as tyrosinase, which increases melanin output. Melanotan-2 binds melanocortin-1 receptors in vitro and in animal models, and this binding is generally described as the basis for the tanning effect. Other receptors account for different effects: melanocortin-4 receptors contribute to appetite and erectile signalling, while melanocortin-3 and melanocortin-5 receptors contribute to energy balance and exocrine function.
Early published reports described melanotan-2 as a tanning agent without sun protection, which means darkening is not the same as protection against ultraviolet radiation. Later studies explored the peptide in erectile dysfunction, hemorrhagic shock, and some skin conditions. No regulator in the United States or Europe has approved it for clinical use. Many products labelled melanotan-2 are sold without approval and their identity and purity are unverified. Its long-term safety in humans remains an open question.
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.
=== General === In Christian iconography, some works of art depict women with their breasts in their hands or on a platter, signifying that they died as a martyr by having their breasts severed; one example of this is Saint Agatha of Sicily.
MDMA, also known as 3,4-methylenedioxy-N-methylamphetamine or as 1-(1,3-benzodioxol-5-yl)-N-methylpropan-2-amine, is a chemical compound of the phenethylamine, amphetamine, and methylenedioxyphenethylamine (MDxx) families. It is a derivative of various related compounds including phenethylamine, amphetamine, methamphetamine, homopiperonylamine (MDPEA), and 3,4-methylenedioxyamphetamine (MDA). MDMA is a racemic mixture of two enantiomers, (R)-MDMA and (S)-MDMA.
=== Melamine adulteration and contamination in the U.S. === On 31 May 2007, the International Herald Tribune reported that melamine has also been purposely added as a binder to fish and livestock feed manufactured in the United States and traced to suppliers in Ohio and Colorado. In autumn 2008, the Food and Drug Administration detected traces of melamine in one top-selling brand of infant formula and traces of cyanuric acid in another brand. Separately, a third major formula maker said that in-house tests had detected trace levels of melamine in its infant formula. The three firms manufacture more than 90 percent of all infant formula produced in the United States. The FDA and other experts said the melamine contamination in U.S.-made formula had occurred unintentionally during the manufacturing process and were not a safety concern.
He also served as a member of the executive committee of the American Society for Testing and Materials (A.S.T.M.) Committee E-19 on Chromatography (1966–1973); as a foreign member of the executive committee of the (British) Chromatographic Society (1992–1997); and as an executive committee member of the Chromatography Subdivision of the Division of Analytical Chemistry of the American Chemical Society (A.C.S.).
Sources: en.wikipedia.org
=== Prescription drug history === Antibiotics first arrived on the medical scene in 1932 thanks to Gerhard Domagk; and were coined the "wonder drugs". The introduction of the sulfa drugs led to the mortality rate from pneumonia in the U.S. to drop from 0.2% each year to 0.05% (i.e., 1⁄4 as much) by 1939. Antibiotics inhibit the growth or the metabolic activities of bacteria and other microorganisms by a chemical substance of microbial origin. Penicillin, introduced a few years later, provided a broader spectrum of activity compared to sulfa drugs and reduced side effects. Streptomycin, found in 1942, proved to be the first drug effective against the cause of tuberculosis and also came to be the best known of a long series of important antibiotics. A second generation of antibiotics was introduced in the 1940s: aureomycin and chloramphenicol. Aureomycin was the best known of the second generation. Lithium was discovered in the 19th century for nervous disorders and its possible mood-stabilizing or prophylactic effect; it was cheap and easily produced. As lithium fell out of favor in France, valpromide came into play. This antibiotic was the origin of the drug that eventually created the mood stabilizer category. Valpromide had distinct psychotrophic effects that were of benefit in both the treatment of acute manic states and in the maintenance treatment of manic depression illness. Psychotropics can either be sedative or stimulant; sedatives aim at damping down the extremes of behavior. Stimulants aim at restoring normality by increasing tone.
=== Mass spectrometry === Deuterated (i.e. where all or some hydrogen atoms are replaced with deuterium) compounds are often used as internal standards in mass spectrometry. Like other isotopically labeled species, such standards improve accuracy, while often at a much lower cost than other isotopically labeled standards. Deuterated molecules are usually prepared via hydrogen isotope exchange reactions.
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In 2023, the most opioid overdose deaths were among White Americans (47,754), followed by African Americans (16,481), Latinos (11,310), Native Americans (1,170), and Asians (695). While media attention has often focused on the uptick of deaths among middle class White Americans, the heroin overdose death rate among African Americans has gone up more than 200 percent since 2010. Among Latinos, it climbed nearly 140 percent. The prevalence of rural opioid overdose deaths per 100,000 within the USA was highest for Native Americans, followed by non-Hispanic Whites, Black, Hispanic, and Asian/Pacific Islander individuals. During the first and second wave of the opioid epidemic, White American people were most affected by opioid overdose. While all groups were affected in the third and fourth wave of the epidemic, White Americans and non-Hispanic Black individuals saw the greatest rise in deaths. Native Americans and Alaska Natives experienced a five-fold increase in opioid-overdose deaths between 1999 and 2015, with Native Americans having the highest increase of any demographic group. With the belief that there would be a low risk of addiction, Indian Health Service physicians, like doctors nationwide, readily prescribed opioids. In addition, structural health care deficiencies from the provider and cultural beliefs against receiving care from the patient, as well as inadequate community support structures for substance misuse, contributed to high mortality rates. In 2015, American Indians/Alaska Natives had the greatest drug overdose mortality rates of any U.S.
In March 2021, Charles River announced the acquisition of Retrogenix for $48 million. In May 2021, Charles River announced the acquisition of Vigene Biosciences, a gene therapy contract development and manufacturing organization (CDMO), for $292.5 million. In October 2021, a Japanese subsidiary of Charles River was acquired by Jackson Laboratory for $63M. In April 2022, the company announced it would acquire Explora BioLabs. In January 2023, the business announced it would acquire SAMDI Tech, Inc.
Sources: en.wikipedia.org
Nucleotides are made from amino acids, carbon dioxide and formic acid in pathways that require large amounts of metabolic energy. Consequently, most organisms have efficient systems to salvage preformed nucleotides. Purines are synthesized as nucleosides (bases attached to ribose). Both adenine and guanine are made from the precursor nucleoside inosine monophosphate, which is synthesized using atoms from the amino acids glycine, glutamine, and aspartic acid, as well as formate transferred from the coenzyme tetrahydrofolate. Pyrimidines, on the other hand, are synthesized from the base orotate, which is formed from glutamine and aspartate.
==== Nuts ==== A species of hard nut is gaining popularity as a replacement for ivory, although its size limits its usability. It is sometimes called vegetable ivory, or tagua, and is the seed endosperm of the ivory nut palm commonly found in coastal rainforests of Ecuador, Peru and Colombia.
=== Fibronectin glomerulopathy === Fibronectin glomerulopathy is a rare form of glomerulopathy characterised by enlarged glomeruli with deposits in the mesangium and subendothelial space. The deposits have been shown to be fibronectin. This condition is inherited in an autosomal dominant fashion. About 40% of cases are due to mutations in the fibronectin (FN1) gene located on chromosome 2 (2q34).
The part instead went to Martin Landau. Culp co-starred in The Greatest American Hero as tough veteran FBI Special Agent Bill Maxwell, who teams up with a high-school teacher who receives superpowers from extraterrestrials. He wrote and directed the second-season finale episode "Lilacs, Mr. Maxwell", with free rein to do the episode as he saw fit. The show lasted three years from 1981 to 1983. He reprised the role in the spin-off pilot The Greatest American Heroine. During that time, Culp was rumored to replace Larry Hagman as J. R. Ewing in Dallas. However, Culp firmly denied this, insisting he would never leave his role as Bill Maxwell. Culp reunited with Cosby on The Cosby Show in the episode "Bald and Beautiful" (1987), playing Dr. Cliff Huxtable's old friend Scott Kelly. The name was a combination of their I Spy characters' names. In I Spy Returns (1994), a nostalgic television movie, Culp and Cosby reprised their roles as Robinson and Scott for the first time since 1968. Culp and Cosby reunited one last time on the television show Cosby in an episode entitled "My Spy" (1999), in which Cosby's character, Hilton Lucas, dreams he is Alexander Scott on a mission with Kelly Robinson. Culp appeared on episodes of other television programs, including The Golden Girls where he played Simon, Blanche's beau, in the episode titled "Like the Beep Beep Beep of My Tom Tom" (1990), as well as Murder, She Wrote, Matlock, Who's the Boss?, Dr. Quinn, Medicine Woman, The Nanny, and Wings.
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.
No. It is a synthetic analogue carrying four amino acid changes, a lactam ring and an amidated C-terminus. The natural hormone is a linear thirteen-amino-acid peptide processed from proopiomelanocortin.