This is a working overview of melanocortin receptor, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-06-11 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-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.
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.
| 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 II is a synthetic cyclic heptapeptide with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, corresponding to a molecular formula of C50H69N15O9 and a monoisotopic mass near 1024 daltons. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, a peptide hormone produced by cleavage of proopiomelanocortin. A lactam bridge between the aspartate and lysine side chains closes the ring, and the C-terminal amide removes a free carboxyl group. Both modifications increase resistance to enzymatic degradation compared with the linear parent hormone. Four substitutions distinguish it from afamelanotide, the linear analogue studied under the name melanotan I.
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.
== Habitat == The Turkestan cockroach is primarily an outdoor insect, not known as an aggressive indoor pest, unlike some cockroach species such as the German and brown-banded cockroaches, though it will inhabit areas around dwellings where shelter can be found. However, in specific localities or tropical locations, it can become a significant indoor pest. Of occasional indoor interlopers, males are more commonly encountered than females, due to their ability to fly and an attraction to lights. In Arabia, it lives beneath stones in damp hollows, desert farms, and wadis, feeding primarily at night.
=== Medical imaging === In people with myasthenia gravis, older forms of iodinated contrast used for medical imaging have caused an increased risk of exacerbation of the disease, but modern forms have no immediate increased risk.
1993/267) Local Government Act 1988 (Defined Activities) (Specified Period) (Woking Borough Council) Regulations 1993 (S.I. 1993/268) Education (Further Education Corporations) Order 1993 (S.I. 1993/269) Education (St Austell Sixth Form College and Mid-Cornwall College) (Dissolution) Order 1993 (S.I. 1993/270) St Austell College (Government) Regulations 1993 (S.I. 1993/271) Hereford and Worcester and Warwickshire (County Boundaries) Order 1993 (S.I. 1993/272) Housing and Planning Act 1986 (Commencement No. 18 and Transitional Provisions) (Scotland) Order 1993 (S.I. 1993/273) Environmental Protection Act 1990 (Commencement No. 13) Order 1993 (S.I. 1993/274) Planning and Compensation Act 1991 (Commencement No. 15) (Scotland) Order 1993 (S.I. 1993/275) River Tay Catchment Area Protection (Renewal) Order 1993 (S.I. 1993/276) Council Tax (Transitional Reduction Scheme) (Scotland) Regulations 1993 (S.I. 1993/277) Removal and Disposal of Vehicles (Amendment) Regulations 1993 (S.I. 1993/278) Guaranteed Minimum Pensions Increase Order 1993 (S.I. 1993/279) Social Security (Contributions) (Re-rating) Order 1993 (S.I. 1993/280) Social Security (Contributions) Amendment (No. 2) Regulations 1993 (S.I. 1993/281) Social Security (Contributions) Amendment (No. 3) Regulations 1993 (S.I. 1993/282) A63 Trunk Road (Selby Bypass) Order 1993 (S.I. 1993/286) A1041 Trunk Road (The Crescent to Brayton Lane) (De-trunking) Order 1993 (S.I. 1993/287) A63 Trunk Road (Whinny Hagg Lane to Magazine Road) (De-trunking) Order 1993 (S.I.
Sources: en.wikipedia.org
The lower respiratory tract is part of the respiratory system, and consists of the trachea and the structures below this including the lungs. The trachea receives air from the pharynx and travels down to a place where it splits (the carina) into a right and left primary bronchus. These supply air to the right and left lungs, splitting progressively into the secondary and tertiary bronchi for the lobes of the lungs, and into smaller and smaller bronchioles until they become the respiratory bronchioles. These in turn supply air through alveolar ducts into the alveoli, where the exchange of gases take place. Oxygen breathed in, diffuses through the walls of the alveoli into the enveloping capillaries and into the circulation, and carbon dioxide diffuses from the blood into the lungs to be breathed out. Estimates of the total surface area of lungs vary from 50 to 75 square metres (540 to 810 sq ft); although this is often quoted in textbooks and the media being "the size of a tennis court", it is actually less than half the size of a singles court. The bronchi in the conducting zone are reinforced with hyaline cartilage in order to hold open the airways. The bronchioles have no cartilage and are surrounded instead by smooth muscle. Air is warmed to 37 °C (99 °F), humidified and cleansed by the conducting zone. Particles from the air being removed by the cilia on the respiratory epithelium lining the passageways, in a process called mucociliary clearance.
A compound is a pure chemical substance composed of more than one element. The properties of a compound bear little similarity to those of its elements. The standard nomenclature of compounds is set by the International Union of Pure and Applied Chemistry (IUPAC). Organic compounds are named according to the organic nomenclature system. The names for inorganic compounds are created according to the inorganic nomenclature system. When a compound has more than one component, then they are divided into two classes, the electropositive and the electronegative components. In addition the Chemical Abstracts Service (CAS) has devised a method to index chemical substances. In this scheme each chemical substance is identifiable by a number known as its CAS registry number.
Following the July 2009 Ürümqi riots, Xi was put in charge to restore order, aided by security chief Zhou Yongkang. Xi also took active part in diplomacy, visiting various countries as vice president.
Sources: en.wikipedia.org
Source: INCB Red List (14th Edition, January 2015) The list of 23 substances is identical to list of EU-controlled drug precursors, except for the different categorization and inclusion of stereoisomers in EU Category 1.
== Uses == Chemical analyses have shown that the plant parts are rich in compounds such as amentoflavone, cupressuflavone, and isoorientin. Its extracts are traditionally believed to be antibacterial, anti-inflammatory, antioxidant, antitumor, radioprotective, chemoprotective, antiangiogenetic, wound-healing, immunomodulatory, anti-diabetic, and cardioprotective in nature.
=== Food rotation === Food rotation is important to preserve freshness. When food is rotated, the oldest food is used first. As food is used, new food is added to the pantry to replace it; the essential rationale is to use the oldest food as soon as possible so that nothing is in storage too long and becomes unsafe to eat. Labeling food with paper labels on the storage container, marking the date the container is placed in storage, can simplify this practice.
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.
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.