If you have been reading about melanocortin receptor 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 2026-05-07. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
Regulatory status varies by jurisdiction, and the substance is frequently described as unapproved for therapeutic use. Some authorities classify it alongside prescription-only medicines or controlled categories, while others address it through general consumer protection rules. Analytical surveys have reported mismatches between label claims and measured content in products sold online, although the scope of such testing is limited. Whether these discrepancies are widespread remains an open question. Discussion in the literature therefore tends to combine chemistry, supply-chain observation and policy analysis.
The material is commonly handled as a lyophilized powder in sealed vials. The solid dissolves readily in water and in polar organic solvents, producing a clear solution after reconstitution. Light, heat and repeated freeze-thaw cycles are the concerns most often raised in handling guidance, because peptide bonds and the constrained ring can degrade. Working solutions are generally prepared fresh, and material left in solution is treated as less stable than the dry form. These properties shape how laboratories store and aliquot reference material.
Identity and purity are assessed mainly by reversed-phase high-performance liquid chromatography with ultraviolet detection, often paired with mass spectrometry. Retention time supports identity, while the mass spectrum confirms the molecular weight of the intact peptide. Purity is frequently reported as a percentage of total peak area, a figure that depends on the wavelength, column and gradient used. Impurity profiling may also look for truncated sequences, oxidised forms and residual counterions. Amino acid analysis and peptide mapping provide orthogonal confirmation when required.
| 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 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.
Human data remain limited and mostly short-term. Reports describe small trials and observational accounts rather than large controlled studies, so questions about dose-response relationships and long-term effects on melanocytes stay open. Whether repeated exposure alters naevus behaviour is not settled in the published record. Researchers also note that self-administered use outside clinical settings makes actual exposure difficult to quantify. Statements about efficacy and safety should therefore be read as preliminary rather than established.
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.
Regulatory treatment varies by country. In the United States the peptide is not approved as a medicine, and products offered for human use may be treated as unapproved new drugs; some states also restrict sale. Australia, the United Kingdom, and European Union member states apply comparable restrictions to unapproved peptide products. Border agencies have seized shipments labelled as research chemicals. Classification may change over time, and the legal position for personal importation is not clearly settled in most published guidance.
Lyophilised melanotan-2 is supplied as a solid, which is more stable than a solution. The material is hygroscopic, so weighing is done quickly, in low humidity, with the container kept sealed. Reconstitution usually uses water for injection or bacteriostatic water, added down the wall of the vial to limit foaming. A reconstituted solution is held at 2 to 8 °C and kept away from light. Repeated freezing and thawing of the same vial is avoided because ice crystal formation and concentration effects degrade the peptide.
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.
Identity testing for a synthetic peptide relies on several complementary methods. Reversed-phase high-performance liquid chromatography separates the target from related impurities and reports purity as a percentage of total peak area. Mass spectrometry confirms molecular mass and can reveal deletions or truncations. Amino acid analysis and peptide mapping provide sequence-level confirmation, while counter-ion content and residual solvents are measured separately. A purity figure alone does not establish identity, so a complete dataset combines chromatographic and spectrometric evidence.
Lyophilized peptide powder is generally stored frozen, protected from light and moisture. Tryptophan residues are susceptible to oxidation, and the lactam bridge can hydrolyze under strongly acidic or basic conditions. Solutions prepared for laboratory work degrade faster than dry powder, and repeated freeze-thaw cycles accelerate loss. Common practice is to aliquot solutions before freezing and to avoid alkaline buffers. Reported stability windows vary with concentration, buffer, and temperature, so exact shelf lives are method-specific rather than universal.
== History == Ubrogepant, also known as MK-1602, was discovered by scientists at Merck in 2020. The effectiveness of ubrogepant for the acute treatment of migraine was demonstrated in two randomized, double-blind, placebo-controlled trials. In these studies, 1,439 adult patients with a history of migraine, with and without aura, received the approved doses of ubrogepant to treat an ongoing migraine. In both studies, the percentages of patients achieving pain relief two hours after treatment (defined as a reduction in headache severity from moderate or severe pain to no pain) and whose most bothersome migraine symptom (nausea, light sensitivity or sound sensitivity) stopped two hours after treatment were significantly greater among patients receiving ubrogepant (19–21% depending on the dose) compared to those receiving placebo (12%). Patients were allowed to take their usual acute treatment of migraine at least two hours after taking ubrogepant. 23% of patients were taking a preventive medication for migraine. In December 2019, the US Food and Drug Administration approved Ubrelvy produced by Allergan USA, Inc. for treatment of migraine after onset.
=== Behavioral changes in humans === Restlessness, apprehension, and anxiety were reported effects after the use of various beta-agonists, particularly after oral or parenteral treatment. In pilot clinical trials with ractopamine, four patients showed little evidence for central nervous system stimulation. Whether long-term treatment with these drugs results in the development of tolerance to these adverse effects is unclear.
== Other uses == Ghotuo language (ISO 639-3 code: AAA) Adopt-An-Alleyway Youth Empowerment Project, San Francisco, California AAA or 3A, the middle level of the Tourist Attraction Rating Categories of China
Libya suffered a humiliating defeat as it was completely expelled from Chad and its commander Khalifa Haftar captured, along with 600-700 Libyan soldiers. Gaddafi disavowed Haftar and the other prisoners; one possible contributing factor to this repudiation may have been that Gaddafi had signed an agreement to withdraw Libyan forces, and Haftar's operations had been in violation of this. An embittered Haftar then joined the anti-Gaddafi National Front for the Salvation of Libya, became a CIA asset, and was given refuge in the US. Many African nations were tired of Libya's interference in their affairs; by 1980, nine African states had severed diplomatic relations, while in 1982 the OAU cancelled its scheduled conference in Tripoli to prevent Gaddafi gaining chairmanship. Some African states, however, such as Jerry Rawlings's Ghana and Thomas Sankara's Burkina Faso, had warm relations with Libya during the 1980s. Proposing political unity with Morocco, in August 1984, Gaddafi and Moroccan monarch Hassan II signed the Oujda Treaty, forming the Arab–African Union; such a union was considered surprising due to the political differences and longstanding enmity that existed between the two. In a sign of warming relations, Gaddafi promised to stop funding the Polisario Front and Hassan II extradited former RCC member Umar Muhayshi to Libya, where he was immediately killed. But relations deteriorated, particularly due to Morocco's friendship with the US and Israel; in August 1986, Hassan abolished the union.
=== Bacillus subtilis === Bacillus subtilis (B. subtilis) is a gram-positive, non-pathogenic organism that does not produce lipopolysaccharides (LPS). LPS, found in gram negative bacteria, is known to cause many degenerative disorders in humans and animals and affects the production of proteins in E. coli. Therefore, although it is deemed potentially safe, B. subtilis has not been officially categorized as generally regarded by the FDA as safe (GRAS). B. subtilis has genetic characteristics that readily transform it with bacteriophages and plasmids. Additionally, it can facilitate more purification steps through direct secretion into the culture medium, and can easily be scaled up because of its ability to non-specifically secrete these proteins. To date, B. subtilis has been used to successfully study different biological mechanisms including metabolism, gene regulation, differentiation, and protein expression and generation of bioactive products. It is also the most well studied gram-positive bacteria in the world, with the genomic information being widely available. Drawbacks of this host system include reduced or non-expression of the protein of interest and production of degradative extracellular proteases that target heterologous proteins. Finally, despite B. subtilis' attractive properties, these limitations result in E.coli being the default host system over B. subtilis. However, with more research and optimization, B. subtilis has the potential to produce membrane proteins in large scales.
Sources: en.wikipedia.org
=== Plasma cortisol concentration === Resting plasma cortisol may be slightly elevated in affected horses, but is commonly within normal limits or below normal. Additionally, elevations may occur secondary to stress, concurrent disease, and due to individual variation. Therefore, resting cortisol levels alone are not adequate to diagnose or rule out the presence of PPID.
Common: aPTT, PT (also used to determine INR), fibrinogen testing (often by the Clauss fibrinogen assay), platelet count, platelet function testing (often by PFA-100), thrombodynamics test. Other: TCT, bleeding time, mixing test (whether an abnormality corrects if the patient's plasma is mixed with normal plasma), coagulation factor assays, antiphospholipid antibodies, D-dimer, genetic tests (e.g. factor V Leiden, prothrombin mutation G20210A), dilute Russell's viper venom time (dRVVT), miscellaneous platelet function tests, thromboelastography (TEG or Sonoclot), euglobulin lysis time (ELT). The contact activation (intrinsic) pathway is initiated by activation of the contact activation system, and can be measured by the activated partial thromboplastin time (aPTT) test. The tissue factor (extrinsic) pathway is initiated by release of tissue factor (a specific cellular lipoprotein), and can be measured by the prothrombin time (PT) test. PT results are often reported as ratio (INR value) to monitor dosing of oral anticoagulants such as warfarin. The quantitative and qualitative screening of fibrinogen is measured by the thrombin clotting time (TCT). Measurement of the exact amount of fibrinogen present in the blood is generally done using the Clauss fibrinogen assay. Many analysers are capable of measuring a "derived fibrinogen" level from the graph of the Prothrombin time clot.
=== Guidance on interpretation of BPE scores === A myriad of factors, which are patient specific, can affect the BPE scores derived. Hence, dental professionals should use their expertise, knowledge and experience to form a reasonable decision when interpreting BPE scores. The BPE scores should be taken into account alongside other factors when being interpreted. A general guideline is:
The most common adverse effects of tramadol include nausea, dizziness, dry mouth, indigestion, abdominal pain, vertigo, vomiting, constipation, drowsiness, and headache. Other side effects may result from interactions with other medications. Tramadol has the same dose-dependent adverse effects as morphine including respiratory depression.
Sources: en.wikipedia.org
== Workflow == A typical bottom-up proteomics workflow is described by (Yates, 2014). Protein samples are enzymatically digested by a protease to produce peptides. Each digested experimental sample is derivative from a set with a different isotopic variant of the tag. The samples are mixed in typically equal ratios and analyzed simultaneously in one MS run. Since the tags are isobaric and have identical chemical properties, the isotopic variants of the tags appear as a single composite peak at the same m/z value in an MS1 scan with identical liquid chromatography (LC) retention times. During the MS2 analysis and upon fragmentation, each isotopic variant of the tag produces sequence-specific product ions. These product ions are used to determine the peptide sequence and the reporter tags whose abundances reflect the relative ratio of the peptide in the combined samples. The use of MS/MS is required to detect the tags, therefore, unlabeled peptides are not quantified.
In fact, while ONJ was demonstrated in the RCTs of the two IV bisphosphonates dosed at higher dose and more frequently in patients with cancer, ONJ was not seen in meta-analysis of all of the osteoporosis RCTs that comprised the Fosamax clinical development program, or in an FDA analysis of all of the RCTs of 2–10 years in duration comprising almost 100,00 patient-years of RCT data from the clinical development programs for alendronate sodium (Fosamax), risedronate sodium (Actonel) ibandronate sodium (oral Boniva), ibandronic acid (IV Boniva), and zoledronic acid (Reclast). Bone: alendronate has been linked in long-term users to the development of low-impact femoral fractures. Further, studies suggest that users of alendronate have an increase in the numbers of osteoclasts and develop giant, more multinucleated osteoclasts; the significance of this development is unclear. Fosamax has been linked to a rare type of leg fracture that cuts straight across the upper thigh bone after little or no trauma (subtrochanteric fractures).
Calories consumed (food, drink) = Calories expended (basal metabolic rate, physical activity, thermogenic effect of food, acute illness) Outcome: Weight remains unchanged Calories consumed > Calories expended Also known as Positive Energy Balance Outcome: Weight increases Calories consumed < Calories expended Also known as Negative Energy Balance Outcome: Weight decreases The calories a person consumes come from food and drink intake. The calories a person expends comes from their basal metabolic rate and their daily physical activity. The human body is very good at maintaining a neutral energy balance, particularly with a diet composed of fruits, vegetables, and meats so that calories consumed do not substantially exceed calories expended in a given time period and vice versa. This energy balance is regulated by hormones like Leptin (suppresses), Ghrelin (stimulates), and Cholecystokinin (suppresses) which either suppress or stimulate appetite.
These CSPs are compatible with NP/RP and SFC and also used for analytical, semi-preparative and preparative separations. Many screening research studies conducted at different labs go to suggest that the four CSPs namely Chiralcel OD, Chiralcel OJ, Chiralpak AD, and Chiralpak As are capable of resolving more than 80% of the chiral separations due to their adaptability and high loading capacity. These four polysaccharide chiral stationary stationary phases are referred to as the "golden four". Polysaccharide CSPs are prepared with high quality silica support on to which the polymeric chiral selector (amylose/cellulose dr.) is physically coated (coated CSP) or chemically immobilized (immobilized CSP). Separations can be done in normal phase, reversed-phase, and polar organic mode. While working with coated polysaccharide CSP solvent selection should be done with caution. One should not use drastic solvents such as dichloromethane, chloroform, toluene, ethyl acetate, THF; 1,4-dioxane; acetone; DMSO, etc. These so called "non-standard" solvents will dissolve the silica and irreversibly destroy the stationary phase. The limited resistance of these coated phases to many solvents lead to the development of immobilized polysaccharide CSP. The table below presents some of the immobilized CSP commercially available and with the alternates wherever accessible.
The ruby laser was developed in 1960 by Theodore Maiman (1927-2007) as the first laser based on the ruby maser. Soon after, the dangers of lasers were discovered, especially for the eyes and skin, due to the laser's low penetration depth. Lasers have numerous applications in technology and research as well as in everyday life, from simple laser pointers to distance measuring devices, cutting and welding tools, reproduction of optical storage media such as CDs, DVDs and Blu-ray discs, communication, laser scalpels and other devices using laser light in everyday medical practice. The Radiation Protection Commission requires that laser applications on human skin be performed only by a specially trained physician. Lasers are also used for show effects in discotheques and at events.
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.
The dry powder is more stable during transport and storage than a solution. It also allows a known amount of material to be reconstituted at a chosen concentration.