Everything below concerns reversed-phase HPLC. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-06-07. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, which separates the target peptide from truncated or oxidised impurities. Mass spectrometry, most often coupled to liquid chromatography, confirms molecular mass and detects substitutions that chromatography alone may miss. Amino acid analysis and peptide mapping supply additional structural evidence, while nuclear magnetic resonance is reserved for full structural confirmation. Laboratories that examine samples sold online report wide variation in actual content, with some vials containing little or none of the labelled material.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Cyclic heptapeptide, C-terminally amidated |
| Approximate molecular mass | 1024 Da | Monoisotopic mass of the free peptide |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility class | Soluble in water and polar solvents | Also dissolves in neutral aqueous buffer |
| Common synonyms | Melanotan II, MT-II, MT-2 | Described as a melanocortin agonist in early literature |
Melanotan II binds several melanocortin receptor subtypes rather than a single target. MC1R on melanocytes drives melanin synthesis, while MC3R and MC4R participate in energy balance, appetite, and sexual response pathways. This lack of selectivity explains why reported effects extend beyond skin darkening. Substitutions at positions four and seven, including norleucine and D-phenylalanine, increase potency and resistance to peptidases. Understanding which receptor mediates which effect remains an active area of investigation.
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.
Regulatory treatment varies by country. In the United States, melanotan-2 is not approved for any indication, and products marketed for human use fall outside the approved drug framework. Some other jurisdictions have placed it under prescription controls or listed it as a prohibited or restricted substance. Online listings frequently describe the material as a research chemical, a category that does not carry the same manufacturing and labelling requirements as approved medicines.
Solid peptide material is generally stable when kept cold and dry. Common practice is storage at -20 degrees Celsius or lower, with desiccant and protection from light. Repeated freeze-thaw cycles and exposure to moisture are associated with degradation, aggregation, or loss of material. Once dissolved, stability depends on solvent, concentration, and temperature, and solutions are usually treated as short-lived unless stability data support longer periods. Handling notes typically emphasise minimising time at ambient temperature.
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.
) is a pharmacokinetic parameter representing the efficiency of drug elimination. This is the rate of elimination of a substance divided by its concentration. The parameter also indicates the theoretical volume of plasma from which a substance would be completely removed per unit time. Usually, clearance is measured in L/h or mL/min. Excretion, on the other hand, is a measurement of the amount of a substance removed from the body per unit time (e.g., mg/min, μg/min, etc.). While clearance and excretion of a substance are related, they are not the same thing. The concept of clearance was described by Thomas Addis, a graduate of the University of Edinburgh Medical School. Substances in the body can be cleared by various organs, including the kidneys, liver, lungs, etc. Thus, total body clearance is equal to the sum clearance of the substance by each organ (e.g., renal clearance + hepatic clearance + pulmonary clearance = total body clearance). For many drugs, however, clearance is solely a function of renal excretion. In these cases, clearance is almost synonymous with renal clearance or renal plasma clearance. Each substance has a specific clearance that depends on how the substance is handled by the nephron. Clearance is a function of 1) glomerular filtration, 2) secretion from the peritubular capillaries to the nephron, and 3) reabsorption from the nephron back to the peritubular capillaries.
=== Personal life === Humphreys married Nancy Wallace, a woman from a prominent Tulsa family, in 1960. The couple had two children, Claire and David. In 1974, Humphreys came out as a gay man during a discussion at a conference session at the ASA. Humphreys was a co-founder of the Sociologists' Gay Caucus (now the Committee on the Status of Lesbian, Gay, Bisexual, Transgender, and Queer People in Sociology), established in 1974 as a response to a presentation by Edward Sagarin that criticized homosexual sociologists as hiding in the closet. Humphreys separated from his wife in 1980 and began living with Brian Miller, a graduate student at the University of Alberta. With Miller, he co-authored articles about gay subcultures and victims of violent homophobia. Humphreys died of lung cancer on August 23, 1988, aged 57.
Soft balancing was developed in the 2000s to account for the contemporary anomaly of the unipolar unbalanced world. Thomas Mowle and David Sacko describe "soft balancing" as "balancing that does not balance at all." These theoretical efforts are counter-productive, since Realism and unipolarity are compatible and structural realism should rather develop a set of hypotheses for a unipolar world: "Scholars do not need to desperately search for signs of balancing, they do not need to soften balancing beyond recognition, and they do not need to stand to watch for the first glimmering of a new multipolar dawn." Campbell Craig explained the development of soft balancing theory on the Thomas Kuhn's three-stage model how scholarly communities respond to anomalies that seem clearly to defy their core theoretical predictions:
==== Polymer and peptide vectors ==== Cationic polymers can be mixed with mRNA to generate protective coatings called polyplexes. These protect the recombinant mRNA from ribonucleases and assist its penetration in cells. Protamine is a natural cationic peptide and has been used to encapsulate mRNA for vaccination.
CLE peptides (CLAVATA3/Embryo Surrounding Region-Related) are a group of peptides found in plants that are involved with cell signaling. Production is controlled by the CLE genes. Upon binding to a CLE peptide receptor in another cell, a chain reaction of events occurs, which can lead to various physiological and developmental processes. This signaling pathway is conserved in diverse land plants.
Sources: en.wikipedia.org
==== The riddle in popular culture ==== In Jean Cocteau's retelling of the Oedipus legend, The Infernal Machine, the Sphinx tells Oedipus the answer to the riddle in order to kill herself so that she did not have to kill any more, and also to make him love her. He leaves without ever thanking her for giving him the answer to the riddle. The scene ends when the Sphinx and Anubis ascend back to the heavens. There are mythic, anthropological, psychoanalytic and parodic interpretations of the Riddle of the Sphinx, and of Oedipus's answer to it. Sigmund Freud describes "the question of where babies come from" as a riddle of the Sphinx.
A sequential deterministic wallet utilizes a simple method of generating addresses from a known starting string or "seed". This would utilize a cryptographic hash function, e.g. SHA-256 (seed + n), where n is an ASCII-coded number that starts from 1 and increments as additional keys are needed.
P-type calcium channels are voltage-dependent calcium channels that are classified under the high voltage activated class channel, along with L-, N-, Q- and R-type channels. These channels require a strong depolarization in order to be activated. They are found at axon terminals, as well as in somatodendritic areas of neurons within the central and peripheral nervous system. P-type calcium channels are also critical to vesicle release, specifically neurotransmitters and hormones at synaptic terminals of excitatory and inhibitory synapses. Voltage-gated P-type calcium channels consist of a main pore-forming α1 subunit (which is more specifically referred to as CaV2.1), an α2δ subunit and a β subunit. There can be γ subunits found in calcium channels of skeletal muscles. The α1 subunit is encoded specifically by the CACNA1A gene and is composed of four domains, each containing six transmembrane (S1-S6) spanning α helices. The S1-S2 loop and the S6 region are thought to be responsible for the channel's inactivation, the S4 region serves as the voltage sensor and S5-S6 loop forms the pore. There are seven subunits within the α1 subunit. The A subunit, called α1ACa2+, corresponds to what is functionally defined as the P-type and Q-type isoforms. P-type and Q-type calcium channels are closely related as they are produced from the same gene via alternative splicing. As a complication of the alternative splicing, P-type and Q-type channels may have different subunit compositions. The β subunit regulates the kinetics and expression of the channel, along with the α2δ subunit.
In the absence of suitable plate culture techniques, some microbes require culture within live animals. Bacteria such as Mycobacterium leprae and Treponema pallidum can be grown in animals, although serological and microscopic techniques make the use of live animals unnecessary. Viruses are also usually identified using alternatives to growth in culture or animals. Some viruses may be grown in embryonated eggs. Another useful identification method is Xenodiagnosis, or the use of a vector to support the growth of an infectious agent. Chagas disease is the most significant example, because it is difficult to directly demonstrate the presence of the causative agent, Trypanosoma cruzi in a patient, which therefore makes it difficult to definitively make a diagnosis. In this case, xenodiagnosis involves the use of the vector of the Chagas agent T. cruzi, an uninfected triatomine bug, which takes a blood meal from a person suspected of having been infected. The bug is later inspected for growth of T. cruzi within its gut.
Sources: en.wikipedia.org
The southern districts of Le Havre are mainly used for industrial and port activities. There are buildings in brick from the 19th century, large developments (Chicago, Les Neiges), worker estates, SMEs, warehouses, dock and port facilities, and transport infrastructure. The southern districts have for some years experienced profound change due to European funding. It is revitalizing areas neglected by industrial and port activities by developing tertiary activities. Thus, the docks have been completely transformed into sports and entertainment complexes (Dock Océane), a mall (Docks Vauban), and an exhibition hall (Docks Café). Les Bains Des Docks was designed by the architect Jean Nouvel. At the end of 2012 students from Sciences Po's Europe-Asia undergraduate college campus and from INSA integrated new buildings next to the ISEL (Higher Institute of logistics studies) and the future ENSM (Ecole Nationale Supérieure Maritime). The new medical axis around the new Clinic des Ormeaux was built in the neighbourhoods where many homes are planned with the aim of promoting social mix. The City of the Sea and of Sustainable Development (Odyssey 21) will be organized around a metal tower one hundred metres high designed by Jean Nouvel: the project was suspended in 2007 but the work should finally begin in 2013. The municipality has to attract some 300,000 visitors per year.
An advantage of the bacterial one-hybrid system over the yeast one-hybrid system (Y1H) lies in the higher transformation efficiency of plasmids into bacteria which allows for more complex “prey” libraries to be examined.
=== Water treatment === Several destructive and non-destructive technologies can be applied to drinking water supplies, groundwater, industrial wastewater, surface water, and other applications such as landfill leachate, including: Non-destructive methods
=== 4 June === One person was killed in a Russian attack in Kherson Oblast. Another was killed by shelling in Sumy Oblast. The SBU arrested a man in Zaporizhzhia Oblast on suspicion of plotting an attack against a military enlistment office on behalf of Russia. Russia "vehemently denied" any involvement in an event in which five coffins draped in French flags were placed under the Eiffel Tower in Paris with the inscription "French soldiers of Ukraine". French media claimed that it was a Kremlin attempt to weaken French support for Ukraine. Ukraine announced plans to establish a "decentralised energy system" using "mini-power plants" to reduce vulnerability to Russian attacks after the country's generating capacity was found to have been reduced to below 20 gigawatts from its previous capacity of 55 gigawatts.
In 1994, HCFA stated that in vitro fertilization was categorized as a therapeutic procedure, not a diagnostic procedure, and therefore not covered under CLIA. As such, AAB/ABB took the position that IVF laboratory tests are covered under CLIA, while ASRM and SART took the opposing position. On September 16, 1998, the Clinical Laboratory Improvement Advisory Committee (CLIAC) made a non-binding recommendation that CLIA coverage apply to embryology laboratories and suggested the College of American Pathologists (CAP) and ASRM accreditation checklist. However, the United States Secretary of Health and Human Services Donna Shalala did not implement the recommendation prompting the AAB to sue HHS to force a decision on March 16, 1999. In response, ASRM filed an amicus brief opposing AAB's lawsuit. On March 8, 2000, the lawsuit was dismissed by Thomas F. Hogan due to lack of standing. In 1994, the American Board of Bioanalysis (ABB) created the first CLIA-approved HCLD board exam for andrologists and embryologists.
Sources: en.wikipedia.org
No. It is a synthetic analogue carrying four amino acid changes, a lactam ring and an amidated C-terminus. The natural hormone is a linear thirteen-amino-acid peptide processed from proopiomelanocortin.
Afamelanotide is the linear analogue [Nle4-D-Phe7]-alpha-MSH, sometimes called melanotan I, while melanotan II is cyclic and carries three further substitutions. The two are distinct molecules and are not interchangeable in analytical testing.
Binding to the four melanocortin receptor subtypes is well documented in vitro. The relative contribution of each subtype to whole-body effects in humans is far less certain.
The lyophilised solid is best kept cold, dry and dark, typically at minus twenty degrees Celsius. Moisture and repeated warming cycles are the main causes of degradation. Solutions prepared from the powder are less stable and are normally used quickly.