alpha-MSH 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 2026-03-29. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Melanotan-2, also written Melanotan II, is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, and the lactam bridge between the aspartate and lysine side chains constrains the peptide into a ring. This structural change increases receptor affinity and metabolic stability relative to the native hormone. The compound was created in the 1980s as a research tool for studying pigmentation biology.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Analogue of alpha-melanocyte-stimulating hormone |
| Common synonyms | MT-II; melanotan 2 | No internationally accepted non-proprietary name |
| Typical presentation | Lyophilised powder in a sealed vial | Often supplied alongside a separate diluent |
| Regulatory status | Unapproved therapeutic substance | Customs seizure reported in several jurisdictions |
| Reported route in use | Subcutaneous injection | Self-administered outside clinical settings |
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.
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.
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.
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 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.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence incorporates a lactam bridge that constrains the peptide into a ring, which increases resistance to enzymatic breakdown relative to the natural hormone. Researchers at the University of Arizona synthesised the compound in the late 1980s and early 1990s while studying pigmentation pathways. It has never received marketing approval from any national medicines regulator. In the scientific literature it is usually described as a laboratory research reagent rather than a therapeutic product.
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.
== Clinical relevance == IGF-2 is sometimes produced in excess in islet cell tumors and non-islet hypoglycemic cell tumors, causing hypoglycemia. Doege-Potter syndrome is a paraneoplastic syndrome in which hypoglycemia is associated with the presence of one or more non-islet fibrous tumors in the pleural cavity. Loss of imprinting of IGF-2 is a common feature in tumors seen in Beckwith-Wiedemann syndrome. As IGF-2 promotes development of fetal pancreatic beta cells, it is believed to be related to some forms of diabetes mellitus. Preeclampsia induces a decrease in methylation level at IGF-2 demethylated region, and this might be among the mechanisms behind the association between intrauterine exposure to preeclampsia and high risk for metabolic diseases in the later life of the infants. In animals it has been shown that toxins such as PCB (polychlorinated biphenyls) affects IGF II expression.
== Veterinary uses == Eflornithine is effective in mice. Bacchi et al. 1980 found the drug to be curative in T. b. brucei infection of mouse and it is generally without toxicity. Klug et al. 2016 are of the opinion that this demonstrates good promise for oral treatment. However although Jansson et al. 2008 also effectively treated mice with it they found the pharmacokinetics of oral administration in rats very negative. Brun et al. 2010 are of the opinion that Jansson's results have killed the prospects for oral treatment.
== Further reading == Arms, Thomas S. Encyclopedia of the Cold War (1994). Brune, Lester H. Chronology of the Cold War, 1917–1992 (Routledge, 2006) 720 pp of brief facts Hanes, Sharon M. and Richard C. Hanes. Cold War Almanac (2 vol 2003), 1460pp of brief facts Parrish, Thomas. The Cold War Encyclopedia (1996) Trahair, Richard C.S. and Robert Miller. Encyclopedia of Cold War Espionage, Spies, and Secret Operations (2012). excerpt Tucker, Spencer C. and Priscilla Mary Roberts, eds. The Encyclopedia of the Cold War: A Political, Social, and Military History (5 Vol., 2007). excerpt van Dijk, Ruud, ed. Encyclopedia of the Cold War (2 vol. 2017) excerpt
Sources: en.wikipedia.org
Brain-derived neurotrophic factor (Bdnf), or abrineurin, is a protein that, in humans, is encoded by the BDNF gene. BDNF is a member of the neurotrophin family of growth factors, which are related to the canonical nerve growth factor (NGF), a family which also includes NT-3 and NT-4/NT-5. Neurotrophic factors are found in the brain and the periphery. BDNF was first isolated from a pig brain in 1982 by Yves-Alain Barde and Hans Thoenen. BDNF activates the TrkB tyrosine kinase receptor.
Alcohol has traditionally been viewed as possessing aphrodisiac-like qualities owing to its effect as a central nervous system depressant, as depressants can increase sexual desire and sexual behavior through disinhibition. Alcohol affects people both physiologically and psychologically, and it is therefore difficult to determine exactly how people experience its aphrodisiac effects (aphrodisiac qualities or the expectancy effect). Alcohol taken in moderate quantities can elicit a positive increase in sexual desire, whereas larger quantities are associated with difficulties in reaching sexual pleasure. Chronic alcohol consumption is related to sexual dysfunction.
gwrthddatgysylltiadaeth (antidisestablishmentarianism) microgyfrifiaduron (microcomputers) gwrthgyfansoddiaethwyr (anticonstitutionalists) lled-ddargludyddion (semiconductors) tra-arglwyddiaethasant (they tyrannised) cyfrwngddarostynedigaeth (intercession) (-au can be added to form the plural, and the word can be further lengthened slightly by initial mutation: fy nghyfrwngddarostynedigaethau, "my intercessions")
Sources: en.wikipedia.org
=== Solvent process === The process involves transesterification of sucrose and triglycerides under a basic condition at 90 °C. DMF was used as a solvent at first, but was later substituted with dimethyl sulfoxide or DMSO, which is less hazardous and cheaper. This process produces a mixture of sucrose monoesters and more substituted esters at about a 5:1 ratio.
Endocytosis is another mechanism for cellular internalization. Endocytosis is the process of cellular ingestion by which the plasma membrane folds inward to bring substances into the cell. During this process cells absorb material from the outside of the cell by imbibing it with their cell membrane. The classification of cellular localization using fluorescence or by endocytosis inhibitors is the basis of most examination. However, the procedure used during preparation of these samples creates questionable information regarding endocytosis. Moreover, studies show that cellular entry of penetratin by endocytosis is an energy-dependent process. This process is initiated by polyarginines interacting with heparan sulphates that promote endocytosis. Research has shown that TAT is internalized through a form of endocytosis called macropinocytosis. Studies have illustrated that endocytosis is involved in the internalization of CPPs, but it has been suggested that different mechanisms could transpire at the same time. This is established by the behavior reported for penetratin and transportan wherein both membrane translocation and endocytosis occur concurrently.
==== United States ==== In the United States, buprenorphine and buprenorphine with naloxone were approved for opioid use disorder by the Food and Drug Administration in October 2002. The DEA rescheduled buprenorphine from a schedule V drug to a schedule III drug just before approval. The ACSCN for buprenorphine is 9064, and being a schedule III substance, it does not have an annual manufacturing quota imposed by the DEA. The salt in use is hydrochloride, which has a free-base conversion ratio of 0.928. In the years before buprenorphine/naloxone was approved, Reckitt Benckiser had lobbied Congress to help craft the Drug Addiction Treatment Act of 2000, which gave authority to the Secretary of Health and Human Services to grant a waiver to physicians with certain training to prescribe and administer schedule III, IV, or V narcotic drugs for the treatment of addiction or detoxification. Before this law was passed, such treatment was permitted only in clinics designed specifically for drug addiction. The waiver, which can be granted after the completion of an eight-hour course, was required for outpatient treatment of opioid addiction with buprenorphine from 2000 to 2021. Initially, the number of people each approved physician could treat was limited to 10. This was eventually modified to allow approved physicians to treat up to 100 people with buprenorphine for opioid addiction in an outpatient setting. This limit was increased by the Obama administration, raising the number of patients to which doctors can prescribe to 275.
=== Mechanism of action === Bisoprolol is cardioprotective because it selectively and competitively blocks catecholamine (adrenaline) stimulation of β1 adrenergic receptors (adrenoreceptors), which are mainly found in the heart muscle cells and heart conduction tissue (cardiospecific), but also found in juxtaglomerular cells in the kidney. Normally, adrenaline and noradrenaline stimulation of the β1 adrenoreceptor activates a signalling cascade (Gs protein and cAMP) which ultimately leads to increased myocardial contractility and increased heart rate of the heart muscle and heart pacemaker, respectively. Bisoprolol competitively blocks the activation of this cascade, so decreases the adrenergic tone/stimulation of the heart muscle and pacemaker cells. Decreased adrenergic tone shows less contractility of heart muscle and lowered heart rate of pacemakers.
Sources: en.wikipedia.org
No. No major regulatory agency has granted a marketing authorisation for melanotan II as a medicine. Products sold under this name are generally presented as laboratory reagents and are not subject to the batch-release testing applied to approved drugs.
It was developed in the 1980s by researchers investigating analogues of alpha-melanocyte-stimulating hormone for pigmentation and related endpoints. Early work included small human studies during the 1990s. Development did not progress to licensing, and the compound remained a research and grey-market item.
Peptides are prone to truncation, oxidation and aggregation during synthesis and handling. Without independent testing, a buyer cannot confirm the identity or the content of a vial. Analytical surveys of unapproved peptide products have repeatedly found discrepancies between label claims and measured composition.
No. It is a laboratory-made peptide, while the natural hormone is alpha-melanocyte-stimulating hormone, a longer peptide produced by the pituitary gland and by skin cells. Melanotan-2 mimics only a short active region of that hormone and contains non-natural residues such as D-phenylalanine.