If you have been reading about LC-MS 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 2025-11-04. Where a claim depends on a specific study, the study is described rather than over-claimed.
Because the substance circulates mainly through informal markets, verification is a recurring theme in technical discussion. Independent analyses have found that labeled content and actual content can diverge, and that purity varies between samples. Analytical laboratories use reversed-phase chromatography to separate components and mass spectrometry to confirm identity. Isotope-labeled internal standards improve quantification in complex matrices. Such methods describe what a sample contains but say nothing about its sterility, lawful status, or suitability for any use. Open questions remain about how consistently testing is applied across the supply chain.
Regulatory treatment of this peptide varies by country. It holds no marketing authorization as a medicine in the United States, the European Union, or most other jurisdictions. Some countries classify products containing it as prescription-only or unlicensed medicines, which restricts lawful supply. Authorities have issued public notices warning that unregulated products may contain undeclared or incorrect ingredients. The molecule also appears on prohibited lists for competitive sport. These measures address supply oversight rather than any approved therapeutic role.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Regulatory status | Not approved as a medicine | No marketing authorization in major jurisdictions |
| Scheduling example | Prescription-only supply in some countries | Handled as an unlicensed medicine where restricted |
| Sports classification | Prohibited peptide | Appears on anti-doping prohibited lists |
| Reported presentation | Lyophilized vial | Nominal content varies between vendors |
| Detection approach | Liquid chromatography–tandem mass spectrometry | Used in anti-doping and forensic testing |
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.
Structurally, Melanotan-2 retains the core recognition motif of alpha-melanocyte-stimulating hormone while adding a lactam bridge that links two side chains and constrains the molecule into a ring. This modification lowers susceptibility to enzymatic degradation. The compound acts as an agonist at melanocortin receptors, particularly subtypes associated with melanin production. Because the same receptor family influences several physiological processes, researchers note that its activity is not confined to pigmentation alone. Receptor selectivity continues to be examined in published studies.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its sequence incorporates modified residues that increase potency and extend biological activity relative to the native hormone. The compound binds receptors of the melanocortin family and is examined mainly in laboratory research. It does not occur naturally and exists only as a manufactured chemical entity produced by solid-phase synthesis.
The peptide was developed during the 1980s by researchers investigating melanocortin signalling and skin pigmentation pathways. Early work focused on analogues of alpha-melanocyte-stimulating hormone that would resist enzymatic breakdown more effectively than the parent molecule. Melanotan-2 emerged from that programme as a shortened, cyclised variant. Reports describing its synthesis and receptor activity later appeared in the scientific literature. Commercial availability grew through unregulated channels rather than through pharmaceutical approval.
Verification of a purchased sample requires documentation linking a batch to a certificate of analysis, and that document should be read for the methods used rather than the headline purity figure. A single chromatographic percentage does not establish identity. Independent laboratories can perform identity and content assays, but no such test establishes that a product is suitable for human use. Claims about efficacy rest largely on small, early studies rather than on replicated controlled trials, and that gap remains open.
Identity testing for a cyclic peptide of this size usually relies on reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The mass spectrum confirms molecular weight, while the chromatographic trace indicates the proportion of related impurities. Tandem mass spectrometry can provide sequence-level information when fragmentation data are compared against a reference standard. Nuclear magnetic resonance is sometimes used to confirm the lactam bridge, although it requires more material and greater operator expertise than routine chromatographic methods.
Lyophilised peptide powder is comparatively stable when kept dry, cold and protected from light. Once dissolved, the molecule is exposed to hydrolysis, oxidation and microbial growth, and degradation accelerates at higher temperatures and in alkaline solution. Repeated freeze-thaw cycles concentrate solutes and promote aggregation. Handling guidance for research peptides commonly clusters around freezer temperatures for powder and short refrigerated use for reconstituted solutions, with pH control and sterile technique applied throughout.
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.
Receptor studies place melanotan-2 among non-selective melanocortin agonists, binding MC1R, MC3R, MC4R and MC5R rather than a single subtype. Activation of MC1R on cutaneous melanocytes raises tyrosinase activity and shifts pigment synthesis toward eumelanin, which is darker and more photostable than pheomelanin. Central receptors, particularly MC4R, are associated with appetite suppression and with reported effects on sexual function. Because subtype selectivity is low, the same molecule engages pigment, metabolic and vascular pathways at once, and this breadth is a common explanation offered for the range of adverse events described in user reports.
== Habitat == It is found in the Himalayan region from Ladakh Kashmir to Sikkim at an elevation of 2700–4500 m and in Nepal, found abundantly between 3500 and 4800 m. It has been reported that Picrorhiza has been harvested to near extinction.
NAD+ kinase (EC 2.7.1.23, NADK) is an enzyme that converts nicotinamide adenine dinucleotide (NAD+) into NADP+ through phosphorylating the NAD+ coenzyme. NADP+ is an essential coenzyme that is reduced to NADPH primarily by the pentose phosphate pathway to provide reducing power in biosynthetic processes such as fatty acid biosynthesis and nucleotide synthesis. The structure of the NADK from the archaean Archaeoglobus fulgidus has been determined. Since NADP(H) cannot cross subcellular membranes, eukaryotic cells have separate NADP(H) pools that are maintained by specific NAD kinases:
=== Membrane protein databases === TCDB - Transporter Classification database, a comprehensive classification of transmembrane transporter proteins Orientations of Proteins in Membranes (OPM) database - 3D structures of integral and peripheral membrane proteins arranged in the lipid bilayer Protein Data Bank of Transmembrane Proteins - 3D models of transmembrane proteins approximately arranged in the lipid bilayer. TransportDB - Genomics-oriented database of transporters from TIGR Membrane PDB Archived 2020-08-03 at the Wayback Machine - Database of 3D structures of integral membrane proteins and hydrophobic peptides with an emphasis on crystallization conditions Mpstruc database Archived 2013-12-25 at the Wayback Machine - A curated list of selected transmembrane proteins from the Protein Data Bank MemProtMD - a database of membrane protein structures simulated by coarse-grained molecular dynamics Membranome database provides information about bitopic proteins from several model organisms
Quantities of liquids are measured in units of volume. These include the SI unit cubic metre (m3) and its divisions, in particular the cubic decimeter, more commonly called the litre (1 dm3 = 1 L = 0.001 m3), and the cubic centimetre, also called millilitre (1 cm3 = 1 mL = 0.001 L = 10−6 m3). The volume of a quantity of liquid is fixed by its temperature and pressure. Liquids generally expand when heated, and contract when cooled. Water between 0 °C and 4 °C is a notable exception. On the other hand, liquids have little compressibility. Water, for example, will compress by only 46.4 parts per million for every unit increase in atmospheric pressure (bar). At around 4000 bar (400 megapascals or 58,000 psi) of pressure at room temperature water experiences only an 11% decrease in volume. Incompressibility makes liquids suitable for transmitting hydraulic power, because a change in pressure at one point in a liquid is transmitted undiminished to every other part of the liquid and very little energy is lost in the form of compression. However, the negligible compressibility does lead to other phenomena. The banging of pipes, called water hammer, occurs when a valve is suddenly closed, creating a huge pressure-spike at the valve that travels backward through the system at just under the speed of sound. Another phenomenon caused by liquid's incompressibility is cavitation. Because liquids have little elasticity they can literally be pulled apart in areas of high turbulence or dramatic change in direction, such as the trailing edge of a boat propeller or a sharp corner in a pipe.
After the initial interaction, the final serpin complex is formed and the heparin moiety is released. This interaction is physiologically important. For example, after injury to the blood vessel wall, heparin is exposed, and antithrombin is activated to control the clotting response. Understanding of the molecular basis of this interaction enabled the development of Fondaparinux, a synthetic form of Heparin pentasaccharide used as an anti-clotting drug.
Sources: en.wikipedia.org
Anthelmintics: Used for treating certain parasitic infections; includes praziquantel Buprenorphine: Metabolized into norbuprenorphine by CYP3A4 Buspirone (Buspar): Grapefruit juice increased peak and AUC plasma concentrations of buspirone 4.3- and 9.2-fold, respectively, in a randomized, 2-phase, ten-subject crossover study. Codeine is a prodrug that produces its analgesic properties following metabolism to morphine entirely by CYP2D6. Ciclosporin (cyclosporine, Neoral): Blood levels of ciclosporin are increased if taken with grapefruit juice, orange juice, or apple juice. A plausible mechanism involves the combined inhibition of enteric CYP3A4 and MDR1, which potentially leads to serious adverse events (e.g., nephrotoxicity). Blood levels of tacrolimus (Prograf) can also be equally affected for the same reason as ciclosporin, as both drugs are calcineurin inhibitors. Dihydropyridines including felodipine (Plendil), nicardipine (Cardene), nifedipine, nisoldipine (Sular) and nitrendipine (Bayotensin) Erlotinib (Tarceva) Exemestane, aromasin, and by extension all estrogen-like compounds and aromatase inhibitors that mimic estrogen in function will be increased in effect, causing increased estrogen retention and increased drug retention. Etoposide interferes with grapefruit, orange, and apple juices. Fexofenadine (Allegra) concentrations are decreased rather than increased as is the case with most grapefruit–drug interactions.
=== Pharmacodynamics === Like other barbiturates, pentobarbital binds to the barbiturate-binding site on the GABAA receptor. This action increases the duration of ion-channel opening. At high doses, pentobarbital is capable of opening the ion channel in the absence of GABA.
Rapid and simple – simple contact for 10–120 minutes and constructs spontaneously and stably incorporate – no washing required. Replicable – same variables (time, temperature, concentration) equals the same result. Toxicity – FSL constructs are biocompatible, disperse into biological solutions without solvents, detergents. They label non-covalently and are non-genetic. Normal vitality and functionality is maintained in modified cells/virions/organisms. Toxicity/vitality experiments in small laboratory animals, zebrafish, cell cultures, spermatozoa and embryos find no toxic effects within physiological ranges. Amphiphilic – the amphiphilic nature of the FSL Kode construct makes them water dispersible (clear solution of micelles), yet once interacted with a membrane they insert/coat and become water resistant Variable design – a single F can be presented in more than 100 ways by varying the spacer and lipid. High biovisibility – as the spacer holds the F moiety away for the membrane it is able to achieve increased sensitivity, specificity and reactivity can be optimized by use of multiple and variable biomarker presentations on the same surface. Additive – FSL modification is compatible with other technologies allowing users to add additional features to cells/viruses/organisms/surfaces already modified by more traditional methods. Multiple FSL constructs may be added to a surface simultaneously by simply creating a mix of FSL Kode constructs. Constructs insert into living or fixed cell (glutaraldehyde) membranes.
Plecanatide, sold under the brand name Trulance, is a medication for the treatment of chronic idiopathic constipation (CIC) and irritable bowel syndrome with constipation. It is available in India under the brand name Plectide (OQM Div, MSN Laboratories, India). Plecanatide is an agonist of guanylate cyclase-C. Plecanatide increases intestinal transit and fluid through a buildup of cGMP.
Under established doping control protocols, the athlete will be asked to provide a urine sample, which will be divided into two, each portion to be preserved within sealed containers bearing the same unique identifying number and designation respectively as A- and B-samples. An athlete whose A-sample has tested positive for a prohibited substance is requested an analysis of his or her B-sample after a confirmation test on sample A that delivered the same results. If the B-sample test results match the A-sample results, then the athlete is considered to have a positive test, otherwise, the test results are negative. This confirmation process ensures the safety of the individual.
Sources: en.wikipedia.org
Only a small number of early-stage human studies have been reported, and most were limited in size and duration. No large late-stage program has established a general efficacy or safety profile. The evidence base is therefore thin compared with approved medicines.
The peptide is listed as prohibited in competitive sport, so laboratories develop detection methods and monitor for its presence. Its appearance in enforcement reports reflects that classification rather than any approved athletic use. Analytical work in this area focuses on identifying the molecule and its breakdown products in biological samples.
Chromatographic separation combined with mass spectrometry identifies the peptide and estimates its amount in a sample. Testing can confirm whether the expected molecule is present and at what concentration. It cannot establish how a product was manufactured or whether it meets any purity standard.
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.