If you have been reading about alpha-MSH analogue 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 2025-09-28. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Analog of alpha-melanocyte-stimulating hormone |
| Primary receptor family | Melanocortin receptors MC1R through MC5R | Binding is not subtype-selective |
| Development period | 1980s | Synthesized during pigmentation and appetite research |
| Regulatory status | Not an approved medicine | No major regulator has authorized human use |
| Related compound | Afamelanotide | Linear analog studied for photoprotection |
== Thermodynamics == The thermodynamics of metal ion complex formation provides much significant information. In particular it is useful in distinguishing between enthalpic and entropic effects. Enthalpic effects depend on bond strengths and entropic effects have to do with changes in the order/disorder of the solution as a whole. The chelate effect, below, is best explained in terms of thermodynamics. An equilibrium constant is related to the standard Gibbs free energy change for the reaction
The majority of early research suggested that the translocation of polycationic CPPs across biological membranes occurred via an energy-independent cellular process. It was believed that translocation could progress at 4 °C and most likely involved a direct electrostatic interaction with negatively charged phospholipids. Researchers proposed several models in attempts to elucidate the biophysical mechanism of this energy-independent process. Although CPPs promote direct effects on the biophysical properties of pure membrane systems, the identification of fixation artifacts when using fluorescent labeled probe CPPs caused a reevaluation of CPP-import mechanisms. These studies promoted endocytosis as the translocation pathway. An example of direct penetration has been proposed for TAT. The first step in this proposed model is an interaction with the unfolded fusion protein (TAT) and the membrane through electrostatic interactions, which disrupt the membrane enough to allow the fusion protein to cross the membrane. After internalization, the fusion protein refolds due to the chaperone system. This mechanism was not agreed upon, and other mechanisms involving clathrin-dependent endocytosis have been suggested. Many more detailed methods of CPP uptake have been proposed including transient pore formation.
Functional KORs are present on nerve terminals of both oxytocin and vasopressin neurons in the rat neurohypophysis, where agonists inhibit potassium-evoked hormone release. Both dynorphin1-8 and (1–17) suppress stimulated oxytocin release from isolated neurosecretory endings, with effects on the initial and secondary peaks of hormone secretion, while exerting no influence on vasopressin release under similar conditions. These interactions extend to plasma hormone levels, where KOR agonists decrease circulating oxytocin concentrations, while antagonists increase oxytocin release, suggesting that KOR signaling mediates negative regulation of oxytocin secretion during stress or physiological challenges.
The small-pox so fatal and so general amongst us is here entirely harmless by the invention of ingrafting (which is the term they give it). There is a set of old women who make it their business to perform the operation. Every autumn in the month of September, when the great heat is abated, people send to one another to know if any of their family has a mind to have the small-pox. They make parties for this purpose, and when they are met (commonly fifteen or sixteen together) the old woman comes with a nutshell full of the matter of the best sort of small-pox and asks what veins you please to have opened. She immediately rips open that you offer to her with a large needle (which gives you no more pain than a common scratch) and puts into the vein as much venom as can lye upon the head of her needle, and after binds up the little wound with a hollow bit of shell, and in this manner opens four or five veins. ... The children or young patients play together all the rest of the day and are in perfect health till the eighth. Then the fever begins to seize them and they keep their beds two days, very seldom three. They have very rarely above twenty or thirty in their faces, which never mark, and in eight days time they are as well as before the illness. ... There is no example of any one that has died in it, and you may believe I am very well satisfied of the safety of the experiment since I intend to try it on my dear little son.
Take anticoagulants ('blood thinners') such as warfarin (Coumadin), diabetes medications, digoxin (Lanoxin), theophylline (Theobid, Theo-Dur), and vitamins Have ever had any blood disease, such as decreased white blood cells (leukopenia), decreased platelets (thrombocytopenia) or aplastic anemia, or liver disease (hepatitis, jaundice)
Sources: en.wikipedia.org
Table 2. Protein interactions found using BioGrid. All interactions were physical interactions and had very confident significant scores. A STRING protein association search yielded no confident results, or ones that seem significant based on previous findings.
Especially the case of the community of Sarayaku has become well known among the Kichwa of the lowlands, who after years of struggle were able to successfully resist expropriation and exploitation of the rain forest for petroleum recovery.
A physical or emotional change, occurring after a substance is taken or administered, that is not the result of any special property of the substance. The change may be beneficial, reflecting the expectations of the participant and, often, the expectations of the person giving the substance. (NLM) Placebo therapy
=== Livestock feed === One of the major uses of soybeans globally is as livestock feed, predominantly in the form of soybean meal. In the European Union, for example, though it does not make up most of the weight of livestock feed, soybean meal provides around 60% of the protein fed to livestock. In the United States, 70 percent of soybean production is used for animal feed, with poultry being the number one livestock sector of soybean consumption. The American Soybean Association estimates that over 90% of U.S. soybeans are used as animal feed and 97% of soybean meal feeds livestock and poultry. Spring grasses are rich in omega-3 fatty acids, whereas soy is predominantly omega-6. The soybean hulls, which mainly consist of the outer coats of the beans removed before oil extraction, can also be fed to livestock and whole soybean seeds after processing.
Sources: en.wikipedia.org
Acrosin is a digestive enzyme that acts as a protease. In humans, acrosin is encoded by the ACR gene. Acrosin is released from the acrosome of spermatozoa as a consequence of the acrosome reaction. It aids in the penetration of the Zona Pellucida.
The experiences reported by women living with HIV suggest that stigma and discrimination within healthcare settings plays a large role in coercive and forced sterilization. These women are particularly vulnerable when accessing maternal health services.
Prucalopride, sold under brand names Resolor and Motegrity among others, is a medication acting as a selective, high affinity 5-HT4 receptor agonist which targets the impaired motility associated with chronic constipation, thus normalizing bowel movements. Prucalopride was approved for medical use in the European Union in 2009, in Canada in 2011, and in the United States in December 2018.
Sources: en.wikipedia.org
No regulator in a major market has approved it for human use. It appears in research settings and in products marketed outside pharmacy channels. Legal status for personal possession varies by country.
Afamelanotide is a linear analog that has received approval in some jurisdictions for a specific photoprotection indication. Melanotan II is cyclic and less selective across melanocortin receptors. The two are related but are not interchangeable in regulatory or clinical terms.
A compound that activates several receptor subtypes may produce effects beyond pigmentation. Selectivity influences which tissues respond and shapes the side-effect profile described in reports. Designing subtype-selective analogs is a stated goal of melanocortin research.
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.