reversed-phase HPLC is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2025-11-03. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Free base; salt forms add to total mass |
| Molecular mass | About 1024 daltons | Calculated for the free base |
| Structural class | Cyclic heptapeptide | Contains D-phenylalanine and norleucine |
| Parent hormone | Alpha-melanocyte-stimulating hormone | Endogenous tridecapeptide of 13 residues |
| Receptor profile | Non-selective melanocortin agonist | Interacts with MC1R, MC3R, MC4R and MC5R |
Melanotan-2 is a synthetic peptide designed as an analog of alpha-melanocyte-stimulating hormone, a signaling molecule produced in the pituitary and skin. Its structure is a linear chain of seven amino acids that folds into a ring through an internal lactam bridge joining two side chains. The compound is sometimes written as MT-II or MEL-2 in informal and commercial contexts. It belongs to the melanocortin peptide family, a group of short signaling molecules that share a conserved core sequence recognized by melanocortin receptors.
Two structural changes distinguish the synthetic peptide from the natural hormone. A norleucine residue replaces methionine at one position, and a D-configured phenylalanine replaces the natural L-form at another. Both substitutions slow enzymatic breakdown, which extends the molecule's persistence relative to the parent hormone. The lactam bridge further constrains the backbone into a stable conformation. These features are standard design strategies in peptide chemistry and are not unique to this compound; they appear across many research peptides built for improved stability.
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.
== Awards and honours == 2007: Foreign associate of the National Academy of Sciences of the United States 2007: Robert Koch Gold Medal 1998: Fellow of the Academy of Medical Sciences (FMedSci). 1973: Elected Fellow of the Royal Society
=== Stabilization === Material treated with plastic or water glass is termed "bonded" or "stabilized" turquoise. This process consists of pressure impregnation of otherwise unsaleable chalky American material by epoxy and plastics (such as polystyrene) and water glass (sodium silicate) to produce a wetting effect and improve durability. Plastic and water glass treatments are far more permanent and stable than waxing and oiling, and can be applied to material too chemically or physically unstable for oil or wax to provide sufficient improvement. Conversely, stabilization and bonding are rejected by some as too radical an alteration. The epoxy binding technique was first developed in the 1950s and has been attributed to Colbaugh Processing of Arizona, a company that still operates today.
In ibritumomab tiuxetan, the chelator tiuxetan is a modified version of DTPA whose carbon backbone contains an isothiocyanatobenzyl and a methyl group. In capromab pendetide and satumomab pendetide, the chelator pendetide (GYK-DTPA) is a modified DTPA containing a peptide linker used to connect the chelate to an antibody. Pentetreotide is a modified DTPA attached to a peptide segment. DTPA and derivatives are used to chelate gadolinium to form an MRI contrast agent, such as Magnevist. Technetium-99m is chelated with DTPA for ventilation perfusion (V/Q) scans and radioisotope renography nuclear medicine scans.
Sources: en.wikipedia.org
Hormones predominate at the left part of the scale, shown with a red at ng/L or pmol/L, being in very low concentration. There appears to be the greatest cluster of substances in the yellow part (μg/L or nmol/L), becoming sparser in the green part (mg/L or μmol/L). However, there is another cluster containing many metabolic substances like cholesterol and glucose at the limit with the blue part (g/L or mmol/L). The unit conversions of substance concentrations from the molar to the mass concentration scale above are made as follows:
== Post-translational modifications == The POMC gene encodes a 285-amino acid polypeptide precursor that undergoes extensive, tissue-specific post-translational processing. This processing is primarily mediated by subtilisin-like prohormone convertases, which cleave the precursor at specific basic amino acid sequences—typically Arg-Lys, Lys-Arg, or Lys-Lys. In many tissues, four primary cleavage sites are utilized, resulting in the production of two major bioactive peptides: adrenocorticotrophin (ACTH), which is essential for normal steroidogenesis and adrenal gland maintenance, and β-lipotropin. However, the POMC precursor contains at least eight potential cleavage sites, and depending on the tissue type and the specific convertases expressed, it can be processed into up to ten biologically active peptides with diverse functions. Key processing enzymes include prohormone convertase 1 (PC1), prohormone convertase 2 (PC2), carboxypeptidase E (CPE), peptidyl α-amidating monooxygenase (PAM), N-acetyltransferase (N-AT), and prolylcarboxypeptidase (PRCP). In addition to proteolytic cleavage, POMC processing involves other post-translational modifications such as glycosylation and acetylation. The specific pattern of cleavage and modification is tissue-dependent. For example, in the hypothalamus, placenta, and epithelium, all cleavage sites may be active, generating peptides involved in pain modulation, energy homeostasis, immune responses, and melanocyte stimulation.
== Personal life, illness and death == On 7 July 1967, Olofsson became engaged to Madiorie Britmer in prison. He married Marijke Demuynck from Belgium in 1976; they occasionally lived in a large house in the Belgian countryside. The marriage with Marijke ended in 1999. He was the father of six children: the youngest son with his fiancée, three older sons with Marijke and two daughters from before his marriage. Olofsson died in Arvika, Sweden, on 24 June 2025, aged 78, following a long period of ill health.
Sources: en.wikipedia.org
The current supply is based on a semisynthetic process developed by PharmaMar starting from safracin B, a chemical obtained by fermentation of the bacterium Pseudomonas fluorescens. PharmaMar entered into an agreement with Johnson & Johnson to market the compound outside Europe.
==== Universities, libraries, and academic research ==== Conversely, academia and libraries are concerned that narrow copyright and TDM exceptions restrict access to research for AI training. Major academic publishers restrict universities from using subscribed databases for AI training without permission, while simultaneously selling access to commercial AI developers. This creates a "triple payment" problem where publicly funded research is paid for multiple times by universities. Advocacy groups argue publishers use contract law to override statutory rights, hindering the UK's sovereign AI research capacity. In response, Jisc advised universities to resist restrictive AI clauses in publisher licences. The UK's TDM exception is limited to non-commercial research, which groups like Knowledge Rights 21 argue will hobble the UK's "AI for Science" strategy.
To date, medical psychologists (prescribing psychologists) may prescribe psychotropic medications in Guam, Iowa, Idaho, Illinois, New Mexico, Louisiana, Colorado, Utah, Vermont, the Public Health Service, the Indian Health Service, and the United States Military. In contrast, psychiatrists are legally authorized to prescribe psychotropic medications in all states of the U.S. and in all provinces of Canada. However, psychiatrists are not usually involved in psychometric assessment. In education, clinical psychologists attend a graduate institution and have a Doctor of Philosophy (Ph.D.) or a Doctor of Psychology (Psy.D.) degree, usually following both an undergraduate and master's degree in Psychology or a related discipline. Conversely, psychiatrists complete their studies at a medical school and hold a medical degree (M.D.), Bachelor of Medicine, Bachelor of Surgery (with additional post-graduate training), or an osteopathic degree and the (D.O.) which is only available in the United States. Due to their scientist-practitioner model of training, clinical psychologists have more advanced research knowledge and skills, including advanced training in statistics, compared with standard psychiatric training.
Sources: en.wikipedia.org
No regulatory agency has authorised melanotan-2 as a medicine for any indication. It circulates mainly as a research chemical or through unregulated channels. As a result, identity, purity and content are not independently guaranteed.
Melanotan-1, also called afamelanotide, is a linear analogue with greater selectivity for MC1R and has received approval in some jurisdictions for a specific photosensitivity disorder. Melanotan-2 is cyclic, less selective, and reaches central receptors more readily. The two are often confused in online discussion despite different pharmacology and regulatory status.
Alpha-MSH is an endogenous tridecapeptide derived from pro-opiomelanocortin. Melanotan-2 reproduces its core receptor-binding sequence inside a shortened, stabilised ring. The result is a molecule with a longer effective half-life and higher potency than the parent hormone.
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.