If you have been reading about alpha-MSH analogue 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 2025-12-09. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Regulatory status differs by country, and in many places supplying the compound for human consumption is unlawful. Vendors frequently label material as intended for research use only, a designation that shifts stated purpose but does not create a legal pathway for personal use. Certificates of analysis accompanying such products vary widely in detail and provenance. Third-party testing exists but is voluntary, and results are rarely linked to a specific lot in a publicly verifiable way.
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.
| 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 |
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.
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.
No regulatory authority has approved melanotan-2 for human use, and several countries classify it as a prescription-only or controlled substance, which restricts lawful supply. Material sold online is generally labelled as a research chemical and is not required to meet pharmaceutical standards of identity or purity. Published human data consist mainly of small uncontrolled studies, case reports and adverse-event notifications, so the evidence base is descriptive rather than confirmatory. Whether repeated melanocyte stimulation alters long-term naevus behaviour remains an open question that no completed trial has resolved.
Melanotan-2 is a synthetic cyclic heptapeptide designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous tridecapeptide that regulates pigment production. Two modifications distinguish it from the natural hormone: norleucine replaces methionine at the N-terminus, which limits oxidation, and a D-phenylalanine substitution raises receptor affinity. The ring is closed through an aspartate-lysine lactam bridge, giving the molecule a constrained conformation. The free base has a molecular mass near 1024 daltons, and commercial material is usually supplied as an acetate salt. It appears in the literature as a research peptide rather than an approved therapeutic agent.
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.
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.
=== In U.S. drinking water === In 2000, perchlorate contamination beneath the former flare manufacturing plant Olin Corporation Flare Facility, Morgan Hill, California was first discovered several years after the plant had closed. The plant had used potassium perchlorate as one of the ingredients during its 40 years of operation. By late 2003, the State of California and the Santa Clara Valley Water District had confirmed a groundwater plume currently extending over nine miles through residential and agricultural communities. The California Regional Water Quality Control Board and the Santa Clara Valley Water District have engaged in a major outreach effort, a water well testing program has been underway for about 1,200 residential, municipal, and agricultural wells. Large ion exchange treatment units are operating in three public water supply systems which include seven municipal wells with perchlorate detection. The potentially responsible parties, Olin Corporation and Standard Fuse Incorporated, have been supplying bottled water to nearly 800 households with private wells, and the Regional Water Quality Control Board has been overseeing cleanup efforts. The source of perchlorate in California was mainly attributed to two manufacturers in the southeast portion of the Las Vegas Valley in Nevada, where perchlorate has been produced for industrial use.
A kitten is a juvenile cat. After being born, kittens display primary altriciality and are fully dependent on their mothers for survival. They normally do not open their eyes for seven to ten days. After about two weeks, kittens develop quickly and begin to explore the world beyond their nest. After a further three to four weeks, they begin to eat solid food and grow baby teeth. Domestic kittens are highly social animals and usually enjoy human companionship.
== Landmark designations == Bryant Park and the New York Public Library Main Branch were jointly listed on the National Register of Historic Places (NRHP) in 1966. Its listing on the NRHP is distinct from the "New York Public Library" on the same day, which covered just the main branch building. In addition, in 1974, the New York City Landmarks Preservation Commission designated the park as a New York City scenic landmark.
== Other Branded Generics == Biqi is the brand name for its generic OTC anti-diarrhea pharmaceutical. The Company obtained approval to manufacture and sell Biqi in November 1999. Zaiqi is the brand name for the company's azithromycin granules antibiotics for the treatment of infections. Zaike is the brand name for its cefaclor in dry suspension antibiotics for the treatment of infections. Simcere Kechuanning is the brand name for Simcere Pharmaceutical's OTC herbal medicine used for the treatment of coughs. It comes in oral liquid and tablet formulations. Zaikang is the brand name for its OTC compound zinc gluconate and ibuprofen granules for the treatment of cold symptoms, such as fever, nasal congestion, running nose and sneezing. Faneng is the brand name for the company's alfacalcidol soft capsules for the treatment of osteoporosis.
Physical side effects included pupil dilation, tingling, trembling, numbness, sweating, lightheadedness, athetosis, slight nausea, and increased heart rate and blood pressure. In addition to parenteral DMT, Shulgin described the effects of oral DMT plus harmaline or in some cases Peganum harmala seeds in TiHKAL. The effects were reported to include closed-eye imagery such as colors, infinitely repeated and wavy sheets of patterns, and kaleidoscopic images, visual changes like brighter colors and patterns and distortions, music enhancement, time distortion, clarity, insights, intoxication, emotional changes, feeling alive and excited, depression, despair, and feeling psychotic. Other effects included difficulty focusing on thoughts, short-term memory disruption, feeling cold, nausea, gait impairment or difficulty walking, and an afterglow. The preceding effects are variably due to both DMT and harmaline, with harmaline also producing its own hallucinogenic effects at sufficiently doses, for instance 150 mg or more.
Sources: en.wikipedia.org
== Biochemical structure == It is a low-molecular-weight neurotoxin which has highly functional polar groups: free phenolic OH and amine and guanidine residues. It also possesses arginine (free NH2) connected to a -NH (CH)3 NH (C ~) 3NH (CH) 5-NH- one through a peptide bond polyamine. The polyamine is connected to the asparagine's α-carboxyl group. The amino group of this aminoacid is linked to 2,4-dihydroxyphenyl acetic acid. Its structure was established using spectroscopy 1H, 13C-RMN, mass spectrometry, and elemental aminoacid analysis. A complete synthesis strategy of argiotoxin and derivatives was developed in order to make biological tests in different living beings. A noted type of argiotoxin, the Arg-636, which molecular formula is C29H52N10O6 [3], has a molecular weight of 636.78658 g/mol. It has a formal charge of 0. Its IUPAC name is: (2S) - N- { 5 - [ 3 - ( 3 - [ [ (2S)-2-amino-5-(diaminomethylideneamino) pentanoyl ] amino ] propylamino ) propylamino ] pentyl } -2- { [ 2 - (2,4-dihydroxyphenyl) acetyl ] amino } butanediamide
(Feb 2011) found that, "The increase in zeaxanthin appears to surpass the decrease in violaxanthin in spinach" and commented that the discrepancy could be explained by "a synthesis of zeaxanthin from beta-carotene", however they noted further study is required to explore this hypothesis.
== Fabrication of porous silicon == Anodization and stain-etching are the two most common methods used for fabrication of porous silicon; however, there are almost twenty other methods to fabricate this material. Drying and surface modification might be needed afterwards. If anodization in an aqueous solution is used to form microporous silicon, the material is commonly treated in ethanol immediately after fabrication, to avoid damage to the structure that results due to the stresses of the capillary effect of the aqueous solution.
== Contraindications == Labetalol is contraindicated in people with overt cardiac failure, greater-than-first-degree heart block, severe bradycardia, cardiogenic shock, severe hypotension, anyone with a history of obstructive airway disease including asthma, and those with hypersensitivity to the drug.
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.
Dry powder is usually held frozen, shielded from light, and kept away from moisture. Desiccant packaging limits hydrolysis during storage. Solutions are typically aliquoted and frozen once, because repeated thawing shortens useful life.