This is a working overview of cyclic heptapeptide, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-03-21 and is reviewed periodically as new material appears.
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.
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.
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 |
|---|---|---|
| Common synonyms | Melanotan II; MT-II; N-acetyl-norleucyl-cyclo[Asp-His-D-Phe-Arg-Trp-Lys] amide | Naming follows peptide convention; the numeral distinguishes it from melanotan-1 |
| Molecular formula | C50H69N15O9 | Includes the lactam bridge; no counter-ion assumed |
| Monoisotopic mass | 1023.53 Da | Free base; salts and counter-ions shift the observed value |
| Appearance | White to off-white lyophilised powder | Batch-to-batch colour variation is not itself proof of impurity |
| Typical analytical method | RP-HPLC purity determination with ESI-MS identity confirmation | Retention time alone does not establish sequence identity |
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.
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.
Belizean Creoles are primarily mixed-raced descendants of West and Central Africans who were brought to the British Honduras (modern Belize along the Bay of Honduras) as well as the English and Scottish log cutters, known as the Baymen. Over the years they have also intermarried with Miskito from Nicaragua, Jamaicans and other Caribbean people, Mestizos, Europeans, Garifunas, Maya, etc. The majority of Creoles trace their ancestry to several of the aforementioned groups. The creole and African slaves came to British Honduras (modern day Belize) from Jamaica, as Jamaica was the closest British colony administering British Honduras at the time and it was the slave ships' final destination. It is also mentioned that many slaves brought to Belize were trouble makers and resisters from Jamaican sugar cane plantations. Belize town was the epicentre of the colony and many slaves ended up in the logwood and timber industry. Women and children stayed doing domestic and farm work. Slaves in Belize were more free to travel and roam around the colony due to their work. This caused the rapid integration of African slaves from different tribes and parts of Africa to mingle with the free coloureds and sons and daughters of slave owners with slaves. Some predominant coloured or light-skinned creole communities were in the Belize river valley: Crooked Tree, Isabela Bank, Bermudian Landings and Lemonal, among others. Most of them have light or blue eyes and light skin.
== Specialty facilities == East Carolina Endoscopy Center East Carolina Heart Institute James & Connie Maynard Children's Hospital at ECU Health Medical Center Marion L. Shepard Cancer Center Onslow Radiation Oncology Service League of Greenville Inpatient Hospice ECU Health Behavioral Crisis Center ECU Health Cancer Care at the Eddie and Jo Allison Smith Tower in Greenville ECU Health Cardiovascular & Pulmonary Rehabilitation ECU Health Health Foundation ECU Health Home Health & Hospice ECU Health Medical Group Practices ECU Health Minor Emergency ECU Health Outpatient Rehabilitation ECU Health Pain Management Centers ECU Health Radiation Oncology ECU Health Sleep Centers ECU Health SurgiCenter ECU Health Wellness Centers ECU Health Wound Healing Centers
Some traditional Mexican open-air markets called tianguis, such as the Mercado Margarita Maza de Juárez in Oaxaca, are separated into a fresh food section (zona húmeda) and a dry goods section (zona seca). A 2002 study observed a trend that Mexican consumers, especially those in the middle class, increasingly prefer supermarkets for beef purchases as opposed to traditional markets. In 2014, a study of Mexican beef retail also noted an ongoing transition from traditional full-service markets to self-service meat display cases in supermarkets. In Mexico, conflicts between traditional and modern retailers are handled at the municipal and state levels. Some local zoning rules, such as those in the central districts of Mexico City and Morelia, have prohibited traditional markets from operating in urban districts without providing further assistance to the retailers.
Cannabis has been used in traditional medicine over centuries. Today, cannabis is subjected to medical research mostly concentrating on the cannabinoids THC and CBD. The cannabis varieties used for the production of the hemp juice such as cannabis sativa are high in CBD content. Hemp juice can also be added into crèmes and gels, and used as an eczema treatment.
== Myelin clearance == Myelin is a phospholipid membrane that wraps around axons to provide them with insulation. It is produced by Schwann cells in the PNS, and by oligodendrocytes in the CNS. Myelin clearance is the next step in Wallerian degeneration following axonal degeneration. The cleaning up of myelin debris is different for PNS and CNS. PNS is much faster and efficient at clearing myelin debris in comparison to CNS, and Schwann cells are the primary cause of this difference. Another key aspect is the change in permeability of the blood-tissue barrier in the two systems. In PNS, the permeability increases throughout the distal stump, but the barrier disruption in CNS is limited to just the site of injury.
Sources: en.wikipedia.org
transactivation An experimental approach to artificially control gene expression by introducing a transactivator gene under the control of an inducible promoter into a genome. The transactivator encodes a transcription factor capable of acting in trans upon one or more other genes by recognizing and specifically binding their promoters; thus by inducing the transactivator gene, the expression of many other genes can be experimentally manipulated.
== Fatty acid oxidation inhibition by malonyl-CoA == Malonyl-CoA signals glucose utilization and it controls the entry and oxidation of long-chain fatty acids (LCFA) in the mitochondria. Circulating glucose in the liver stimulates its uptake. Glucose oxidation produces citrate which can be converted to malonyl-CoA by acetyl-CoA carboxylase. Malonyl-CoA inhibits the carnitine palmitoyltransferase (CPT) that controls the entry and oxidation of LCFA. The glucose-derived malonyl-CoA prevents the oxidation of fatty acids and favors fatty acid esterification.
=== Razin and Pugachev Rebellions === As a largely independent nation, the Cossacks had to defend their liberties and democratic traditions against the ever-expanding Muscovy, succeeded by the Russian Empire. Their tendency to act independently of the Tsardom of Russia increased friction. The Tsardom's power began to grow in 1613, with the ascension of Mikhail Romanov to the throne following the Time of Troubles. The government began attempting to integrate the Cossacks into the Russian Tsardom by granting elite status and enforcing military service, thus creating divisions among the Cossacks themselves as they fought to retain their traditions. The government's efforts to alter their traditional nomadic lifestyle resulted in the Cossacks being involved in nearly all the major disturbances in Russia over 200 years, including the rebellions led by Stepan Razin and Yemelyan Pugachev.
=== Biomaterials and nanotechnology === Mechler engaged in the design and characterization of biomaterials, nanostructures as well as in the development of novel nanotechnologies throughout his career. He used multimodal atomic force microscopy to map charge transfer properties of the conductive copolymer poly(ethyldioxythiophene)–poly(styrenesulfonic acid), showing that efficient charge injection occurs at lamellar edges and can be improved by controlling lamellar orientation. In a collaborative project, he also presented a method utilizing surface acoustic waves to produce monodispersed submicron poly-ε-caprolactone particles, demonstrating how acoustic forces and evaporative processes influence particle size and morphology. In a joint study, Mechler established that 14-helical N-acetyl β3-peptides self-assemble into nanofibers and that their morphology, such as nano-beams and dendritic structures, can be tuned by adjusting the solvent and inter-fibril interactions, enabling new bio- and nanomaterial applications. By using far-IR spectroscopy and DFT modeling, he confirmed the structure of self-assembled fibrous nano-materials from unnatural tripeptides, showing that far-IR spectroscopy can effectively characterize bioinspired materials where crystallographic methods fall short. He further showcased that using two binding motifs in supramolecular assemblies creates metallosupramolecular frameworks with controlled nanorod and two-dimensional structures, with copper ions forming polynuclear metal complexes.
Sources: en.wikipedia.org
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.
The natural hormone is a linear tridecapeptide that is rapidly degraded in circulation. Melanotan-2 is shortened, cyclised, N-terminally acetylated, and carries a D-amino acid substitution, all of which slow enzymatic breakdown.
No national medicines regulator has approved melanotan-2 for therapeutic or cosmetic use. In several jurisdictions it is treated as an unapproved prescription medicine, and its legal classification differs from country to country.
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.