The short version of melanocortin receptors fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-07-10 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.
Regulatory treatment varies by jurisdiction and has changed over time. In several countries the peptide is handled as an unapproved prescription medicine, and import or sale for human use is restricted, while elsewhere it falls under poisons or controlled-substance schedules. Enforcement activity against online vendors has been reported in Australia, New Zealand, the United Kingdom and the United States. Scholarly writing discusses melanotan-2 chiefly as an experimental tool and as a case study in unregulated peptide supply, and its precise legal position in any given country should be checked against current national schedules.
Lyophilised melanotan-2 is comparatively robust when kept dry, cold and dark, and a desiccated powder stored at minus twenty degrees Celsius or below is generally expected to retain its chemical integrity for extended periods. In solution the peptide is far less stable, with degradation proceeding through oxidation of tryptophan and histidine residues, hydrolysis adjacent to the lactam bridge, and aggregation at higher concentrations. Repeated freeze-thaw cycling accelerates loss of the parent peak. Working aliquots are therefore prepared once, held cold, and used without letting the stock return to ambient temperature.
Quality assessment of research-grade peptide rests mainly on reversed-phase high-performance liquid chromatography for purity and on mass spectrometry for identity confirmation. A single main peak above a stated threshold, commonly ninety-eight percent by peak area, is the usual release criterion applied by suppliers. Independent analyses commissioned by laboratories and consumer organisations have repeatedly reported discrepancies between label claims and measured content, including truncated sequences, residual trifluoroacetate, and lower-than-declared peptide mass. Those findings do not establish that every supplier is unreliable, but they indicate that purity figures printed on a vial are claims requiring verification rather than settled facts.
| 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 |
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.
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 appears on the World Anti-Doping Agency prohibited list within the peptide hormone class, and several national regulators treat it as an unapproved prescription substance. Some countries restrict importation or sale for personal use. Because the compound is widely traded as a research chemical, the practical legal picture differs between jurisdictions and shifts over time. Human safety data covering long periods are limited, and whether repeated pigmentation changes carry any lasting risk to melanocytes remains an open question.
Freeze-dried melanotan-2 is normally kept as a desiccated powder at minus twenty degrees Celsius or lower, shielded from light and moisture. Peptides of this size degrade through hydrolysis, oxidation and deamidation, and each pathway accelerates as temperature and water activity rise. Repeated freeze-thaw cycles promote aggregation and loss of material, so aliquoting a stock solution before freezing is standard laboratory practice. Once dissolved, the solution is markedly less stable than the powder. In laboratory work, solutions are generally refrigerated and used within days rather than kept for months.
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.
== Properties and production == The characteristics of dark meat from poultry (such as its color, low plasticity, and high fat content) are caused by myoglobin, a pigmented chemical compound found in muscle tissue that undergoes frequent use. Because domestic poultry rarely fly, the flight muscles in the breast contain little myoglobin and appear white. Dark meat which is high in myoglobin is less useful in industry, especially fast food, because it is difficult to mold into shapes. Processing dark meat into a slurry makes it more like white meat, easier to prepare. The meat is first finely ground and mixed with water. The mixture is then used in a centrifuge or with an emulsifier to separate the fats and myoglobin from the muscle. The product is then allowed to settle into three layers: meat, excess water, and fat. The remaining liquefied meat is then flash-frozen and packaged.
=== Pests === Common tomato pests include the tomato bug, stink bugs, cutworms, tomato hornworms and tobacco hornworms, aphids, cabbage loopers, whiteflies, tomato fruitworms, flea beetles, red spider mite, Tuta absoluta (tomato leafminer), slugs, and Colorado potato beetles. The tomato russet mite, Aculops lycopersici, feeds on foliage and young fruit of tomato plants, causing shrivelling and necrosis of leaves, flowers, and fruit, possibly killing the plant. After an insect attack tomato plants produce systemin, a plant peptide hormone. This activates defensive mechanisms, such as the production of protease inhibitors to slow the growth of insects. The hormone was first identified in tomatoes.
Muscle cells work by detecting a flow of electrical impulses from the brain which signals them to contract through the release of calcium by the sarcoplasmic reticulum. Fatigue (reduced ability to generate force) may occur due to the nerve, or within the muscle cells themselves.
Diversity of odourant binding proteins revealed by an expressed sequence tag project on male Manduca sexta moth antennae. Insect Mol Biol. 1999; 8: 501-518. 49. Picimbon JF, Regnault-Roger C 2008. Composés sémiochimiques volatils, phytoprotection et olfaction : cibles moléculaires de la lutte intégrée. In: Eds: C. Regnault-Roger C, B. Philogène B, and Vincent C (Eds.), Biopesticides d’origine végétale, Lavoisier Tech and Doc, Paris, France, 2008, pp. 383–415. 50. Einhorn E, Imler JL. Insect immunity; from systemic to chemosensory organs protection. In: Picimbon JF (Ed.), Olfactory Concepts of Insect Control-Alternative to Insecticides. vol. 2 Springer Nature, Switzerland, 2019, pp. 205–229.
structural formula A graphical representation of the molecular structure and geometry of a particular chemical compound, showing how the atoms are arranged in real, three-dimensional space. Chemical bonding within the molecule is also shown, either implicitly or explicitly. When known with certainty, structural formulas are very useful because they allow chemists to visualize the molecules and the structural changes that occur in them during chemical reactions.
Sources: en.wikipedia.org
The Rocky Mountains, west of the Great Plains, extend north to south across the country, peaking at over 14,000 feet (4,300 m) in Colorado. The supervolcano underlying Yellowstone National Park in the Rocky Mountains, the Yellowstone Caldera, is the continent's largest volcanic feature. Farther west are the rocky Great Basin and the Chihuahuan, Sonoran, and Mojave deserts. In the northwest corner of Arizona, carved by the Colorado River, is the Grand Canyon, a steep-sided canyon and popular tourist destination known for its overwhelming visual size and intricate, colorful landscape. The Cascade and Sierra Nevada mountain ranges run close to the Pacific coast. The lowest and highest points in the contiguous United States are in the state of California, about 84 miles (135 km) apart. Alaska is a state in the northwestern regions of North America. It is a semi-exclave and separated from the contiguous United States. At an elevation of 20,310 feet (6,190.5 m), Alaska's Denali (also called Mount McKinley) is the highest peak in the country and on the continent. Active volcanoes in the U.S. are common throughout Alaska's Alexander and Aleutian Islands, while Hawaii has six active volcanoes, including Kilauea and Mauna Loa. Located entirely outside North America, the Hawaiian archipelago consists of volcanic islands, all physiographically and ethnologically part of the Polynesian subregion of Oceania.
=== Privacy of health data === Phones that can track one's whereabouts, steps and more can serve as medical devices, and medical devices have much the same effect as these phones. According to one study, people were willing to share personal data for scientific advancements, although they still expressed uncertainty about who would have access to their data. People are naturally cautious about giving out sensitive personal information. Phones add an extra level of threat. Mobile devices continue to increase in popularity each year. The addition of mobile devices serving as medical devices increases the chances for an attacker to gain unauthorized information. In 2015 the Medical Access and CHIP Reauthorization Act (MACRA) was passed, pushing towards electronic health records. In the article "Health Information Technology: Integration, Patient Empowerment, and Security", K. Marvin provided multiple different polls based on people's views on different types of technology entering the medical field most answers were responded with somewhat likely and very few completely disagreed on the technology being used in medicine. Marvin discusses the maintenance required to protect medical data and technology against cyber attacks as well as providing a proper data backup system for the information. Patient Protection and Affordable Care Act (ACA) also known as Obamacare and health information technology health care is in the digital era. Although this technology needs to be protected.
== Regulation and policy == In the United States, there are approximately 1,500 methadone clinics that are federally certified opioid treatment programs. There are generally two types of methadone clinics, public and private. The public clinics are generally cheaper to attend. However, there is usually a waiting list due to limited funding. The private clinics are more expensive to attend but usually have either a short or no waiting list. In many parts of the United States, methadone clinics are few and far between, which presents problems for addicts seeking methadone treatment who live far from a clinic. All methadone clinics must register as an accredited opioid treatment program with the Substance Abuse and Mental Health Service Administration and renew yearly or every three years based on the accreditation time frame awarded. Additionally, methadone clinics must register with the Drug Enforcement Administration before methadone can be dispensed. While not restricted to adults, this treatment method is generally not considered for people under the age of 18. Methadone clinics in the United States operate under strict regulations by state and federal laws. Before entering treatment, a patient must be given adequate information to provide informed consent about starting treatment. This information includes reasons for treatment and recommendations, the side effects and risks of treatment, and rules that must be followed to receive methadone treatment.
=== Vascular malformations === Sirolimus is used to treat vascular malformations. Treatment with sirolimus can decrease pain and the fullness of vascular malformations, improve coagulation levels, and slow the growth of abnormal lymphatic vessels. Sirolimus is a relatively new medical therapy for the treatment of vascular malformations in recent years, sirolimus has emerged as a new medical treatment option for both vascular tumors and vascular malformations, as a mammalian target of rapamycin (mTOR), capable of integrating signals from the PI3K/AKT pathway to coordinate proper cell growth and proliferation. Hence, sirolimus is ideal for "proliferative" vascular tumors through the control of tissue overgrowth disorders caused by inappropriate activation of the PI3K/AKT/mTOR pathway as an antiproliferative agent.
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.
Solutions are best kept cold, protected from light, and buffered to a pH that limits hydrolysis. Dividing a stock into single-use aliquots avoids repeated freeze-thaw cycles, which measurably reduce the intact parent peak over time.