The short version of cyclic heptapeptide fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
The compound was developed in the late 1980s and 1990s by academic researchers investigating photoprotection. The rationale held that stimulating melanin production might reduce ultraviolet damage to skin and lower skin cancer risk. Early work examined receptor binding, pigment response, and short-term tolerability in small studies. That program did not produce an approved drug, and formal development stalled after early-phase trials. Whether induced pigmentation confers meaningful photoprotection remains an open question.
Outside regulated medicine, melanotan II circulates through online vendors as a research chemical, often marketed for tanning. Products sold this way vary widely in purity, concentration, and labeling accuracy, and independent testing has documented discrepancies. Published reports describe both pigment effects and adverse reactions, including nausea, flushing, and darkening of existing moles. Long-term safety data are sparse, and no large controlled trial has established a risk profile. Questions about cumulative effects on melanocytes remain unresolved in the literature.
Melanotan II is a synthetic peptide analog modeled on alpha-melanocyte-stimulating hormone, a naturally occurring signaling peptide involved in pigmentation. Its structure is a cyclic heptapeptide containing two non-natural substitutions, norleucine at position four and D-phenylalanine at position seven. These modifications resist enzymatic breakdown and extend the molecule's activity relative to the native hormone. The compound binds melanocortin receptors and is studied mainly as a pharmacological tool rather than a therapeutic product. It has never received approval as a medicine in any major jurisdiction.
Melanotan II is a synthetic cyclic heptapeptide that acts as an agonist at melanocortin receptors. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous peptide involved in pigment production. The analogue carries a lactam bridge that constrains the ring and slows enzymatic breakdown relative to the native hormone. In research literature it appears under several abbreviations, and naming conventions are not fully standardized. Published descriptions usually place it within the broader melanocortin agonist family.
Receptor binding at MC1R on melanocytes raises intracellular cyclic AMP and increases expression of tyrosinase and related enzymes. The downstream result is greater synthesis of eumelanin, the dark pigment, without ultraviolet exposure acting as the trigger. The compound is not selective, however, and also engages MC3R, MC4R and MC5R, which are expressed in the central nervous system and elsewhere. That lack of selectivity is the explanation usually offered for effects reported outside pigmentation, including appetite suppression and nausea. Selectivity remains a central theme in comparative studies of related peptides.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Belongs to the melanocortin agonist family |
| Key substitutions | Nle4 and D-Phe7 | Improve resistance to enzymatic degradation |
| Molecular formula | C50H69N15O9 | Approximately 1024 g/mol |
| Regulatory status | Not approved as a medicine | Distributed as a research chemical |
| Common synonyms | Melanotan II, MT-II, MT-2 | Spelling varies across sources |
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.
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 II is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its structure substitutes a lactam bridge between side chains to increase stability relative to the native hormone. The compound is also known by the shorthand MT-II and by several non-proprietary synonyms used in research catalogues. It is not an approved therapeutic product in any major jurisdiction; material sold under this name is typically offered as a laboratory reagent rather than as a medicine.
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.
=== Pharmacokinetics === RO5203648 showed favorable pharmacokinetics orally and intravenously in mice, rats, and monkeys. However, it was found to be very rapidly metabolized in human hepatocytes in vitro.
The number of farms peaked in the late 1980s at more than 5,000 farms, but the number has declined steadily since, as individual farms grew in size. Danish mink farmers claim their business to be sustainable, feeding the mink food industry waste and using all parts of the dead animal as meat, bone meal and biofuel. Special attention is given to the welfare of the mink, and regular "Open Farm" arrangements are made for the general public. Mink thrive in, but are not a native to Denmark, and it is considered an invasive species. American Mink are now widespread in Denmark and continues to cause problems for the native wildlife, in particular waterfowl. Denmark also has a small production of fox, chinchilla and rabbit furs. Two hundred professional producers are responsible for the Danish egg production, which was 66 million kg in 2011. Chickens for slaughter are often produced in units with 40,000 broilers. In 2012, 100 million chickens were slaughtered. In the minor productions of poultry, 13 million ducks, 1.4 million geese and 5.0 million turkeys were slaughtered in 2012.
Column chromatography is a chromatography method used in analytical chemistry to separate the individual components (analytes) of a mixture. The mixture is carried by a solvent (the eluent) to form the mobile phase. The mobile phase moves through a column packed with solid particles (the stationary phase). The components adsorb to the stationary phase at different rates, so they pass out of the column at different times. This separates the components. The technique is widely applicable, as many different adsorbents (normal phase, reversed phase, or otherwise) can be used with a wide range of solvents. The technique can be used on scales from micrograms up to kilograms. The main advantage of column chromatography is its cost is relatively low, and the stationary phase can be replaced after use. The latter prevents cross-contamination and stationary phase degradation due to recycling. The mobile phase moves by gravity, compressed gas, or pressurized pumps (as in high-performance liquid chromatography). Before performing column chromatography, one usually performs thin-layer chromatography on a small amount of the sample first, to see how a mixture of compounds will behave when purified by column chromatography. This allows the experimenter to optimize the combination of mobile and stationary phases for this particular sample.
Sources: en.wikipedia.org
==== Metabolism ==== Gepirone is metabolized primarily by CYP3A4. Its major metabolites are 1-PP and 3'-OH-gepirone, both of which are pharmacologically active. These metabolites are present in the circulation at higher concentrations than gepirone.
=== As an electron pair donor === Acetonitrile has a free electron pair at the nitrogen atom, which can form many transition metal nitrile complexes. For example, bis(acetonitrile)palladium dichloride is prepared by heating a suspension of palladium chloride in acetonitrile:
=== Other actions === In addition to its GABA receptor agonism, GABA has been found to act as a histone deacetylase (HDAC) inhibitor, similarly to structurally related compounds like butyrate (butyric acid), β-hydroxybutyrate (BHB), and valproic acid (valproate). However, another group of researchers found that GABA did not detectably inhibit HDACs.
Sources: en.wikipedia.org
NATO categorizes ration packaging under three types: Primary packaging, which is in contact with or contains the food itself (e.g. a can containing food) Secondary packaging, which contains and groups several primary packages (e.g. a retort pouch containing food packages) Tertiary packaging, which contains and groups several secondary packages for storage, shipping, handling, and distribution (e.g. a box containing several rations for distribution)
Any individual member of the clinical trial team designated and supervised by the investigator at a trial site to perform critical trial-related procedures and/or to make important trial-related decisions (e.g., associates, residents, research fellows). (ICH E6) Subject Identification Code
A total of 51 cases of homozygotes or compound heterozygotes have been reported, most of them with double truncating MYBPC3 mutations and associated with severe cardiomyopathy, leading to heart failure and death within the first year of life.
Sources: en.wikipedia.org
It is a synthetic cyclic peptide designed as an analog of alpha-melanocyte-stimulating hormone. It acts on melanocortin receptors and is best known from research into pigmentation. It is not an approved pharmaceutical product.
No regulatory agency has approved it for any indication. It is encountered as a research chemical sold outside pharmaceutical supply chains. Products marketed this way are not subject to the manufacturing and labeling requirements that apply to approved drugs.
Reports describe increased skin pigmentation as well as side effects such as nausea, flushing, and changes to existing moles. Much of the evidence comes from small studies and case reports rather than large trials. The long-term safety profile is therefore uncertain.
It is a synthetic cyclic heptapeptide and a non-selective melanocortin receptor agonist. Structurally it is modelled on alpha-melanocyte-stimulating hormone, a peptide that occurs naturally in the body.