A practical reference on afamelanotide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-07-22. Anything still debated is marked as such rather than presented as settled.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Typical storage temperature | -20 °C or below | For the lyophilised powder, desiccated |
| Storage form | Sealed vial, protected from light | Amber glass or foil-wrapped containers |
| Reconstituted stability | Short, refrigerate | Degradation accelerates in solution |
| Typical analytical method | Reversed-phase HPLC with mass spectrometry | Purity assessment plus identity confirmation |
| Common synonyms | Melanotan II, MT-II | Also written melanotan-2 |
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.
Reversed-phase high-performance liquid chromatography is the routine method for purity assessment. Peptides absorb near 214 nm because of the peptide bond, and a gradient of acetonitrile in water separates the intact peptide from deletion sequences, oxidised products, and earlier-eluting fragments at neutral pH. Electrospray ionisation mass spectrometry provides an orthogonal check: the measured mass must agree with the theoretical value. Amino acid analysis and peptide mapping confirm structure but are used less often. Reference standards remain scarce because the peptide is not described in any pharmacopoeia.
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.
Published research on the compound remains limited. Much of the human data comes from small, early-stage studies rather than large controlled trials, and several questions about effects and variability between individuals remain open. Investigators have examined receptor activity, pigment pathways, and related physiological responses in laboratory and animal models. Findings from those models do not automatically translate to human outcomes. Reviews frequently note the scarcity of rigorous clinical evidence and call for better-characterized study material.
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.
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.
== F == FCS – Fluorescence correlation spectroscopy FCCS – Fluorescence cross-correlation spectroscopy FEM – Field emission microscopy FIB – Focused ion beam microscopy FIM-AP – Field ion microscopy–atom probe Flow birefringence Fluorescence anisotropy FLIM – Fluorescence lifetime imaging Fluorescence microscopy FOSPM – Feature-oriented scanning probe microscopy FRET – Fluorescence resonance energy transfer FRS – Forward Recoil Spectrometry, a synonym of ERD FTICR or FT-MS – Fourier-transform ion cyclotron resonance or Fourier-transform mass spectrometry FTIR – Fourier-transform infrared spectroscopy
Antifungals, e.g. ketoconazole. Antibiotics, e.g. erythromycin, rifampicin. Ergot derivatives used to treat migraine or Parkinson's disease may cause an increase in blood pressure. Any potassium-depleting diuretics (medicines for eliminating water), e.g. thiazides. Carbamazepine and phenobarbital, medicines used to control fits or seizures. Herbal medicines that contain St. John's Wort.
=== Age === Historically, obesity primarily affected adults, but childhood obesity has grown significantly in recent decades. From the mid-1980s to the mid-2010s, obesity roughly doubled among U.S. children ages 2 to 5 and roughly tripled among young people over the age of 6. Overall, obesity in the United States peaks during the middle aged years. During the period 2015–16, the prevalence of obesity among adults aged 20–39 was 35.7%, among those aged 40–59, 42.8%, and among those 60 and over, 41.0%.
biotin) or clickable handles (azides or alkynes) enable enrichment of labeled enzymes prior to identification by liquid chromatography-tandem mass spectrometry (LC-MS/MS). After covalent labeling in cells or lysates, enzyme-probe adducts are captured using streptavidin or other affinity matrices, washed to remove unlabeled proteins, and digested for MS-based peptide identification. This strategy provides high sensitivity and depth of coverage, which facilitates the discovery of novel enzyme targets, detection of low-abundance enzymes and analysis of complex enzyme families. To compare enzyme activity across biological conditions, ABPP can be integrated with quantitative proteomic technologies to measure relative enzyme activity across samples. Techniques such as SILAC (Stable Isotope Labeling by Amino acids in Cell culture) incorporate heavy or light isotope-encoded amino acids into cellular proteins, facilitating direct MS-based comparison of probe-labeled peptides from different samples. TMT (Tandem mass tagging) which uses isobaric mass tags allows labeled peptides from multiple samples to be multiplexed and quantified simultaneously. These strategies have been widely applied to assess selectivity of covalent inhibitors and genome-wide changes in enzymatic activity. isoTOP-ABPP (Isotope Tagging of Optimized Probes for Activity-Based Protein Profiling) is a specialized workflow that was developed to address some of the limitations of conventional ABPP, including poor specificity, limited sensitivity, and the absence of selective chemical ligands for many human enzymes.
Charles III returns to his public duties for the first time since his cancer diagnosis with a visit to University College Hospital's Macmillan Cancer Centre. He also becomes patron of Cancer Research UK. A bid by an Abu Dhabi based consortium to buy The Telegraph collapses, meaning the newspaper is for sale again.
Sources: en.wikipedia.org
In particular, how much a person is able to exhale in one second (called forced expiratory volume (FEV1)) as a proportion of how much they are able to exhale in total (FEV). This ratio, the FEV1/FEV ratio, is important to distinguish whether a lung disease is restrictive or obstructive. Another test is that of the lung's diffusing capacity – this is a measure of the transfer of gas from air to the blood in the lung capillaries.
Many reaction intermediates with variable stability can thus be envisaged during the course of a reaction. Reaction mechanisms are proposed to explain the kinetics and the relative product mix of a reaction. Many physical chemists specialize in exploring and proposing the mechanisms of various chemical reactions. Several empirical rules, like the Woodward–Hoffmann rules often come in handy while proposing a mechanism for a chemical reaction. According to the IUPAC gold book, a chemical reaction is "a process that results in the interconversion of chemical species." Accordingly, a chemical reaction may be an elementary reaction or a stepwise reaction. An additional caveat is made, in that this definition includes cases where the interconversion of conformers is experimentally observable. Such detectable chemical reactions normally involve sets of molecular entities as indicated by this definition, but it is often conceptually convenient to use the term also for changes involving single molecular entities (i.e. 'microscopic chemical events').
Xi called for a crackdown on corruption immediately after he ascended to power, starting an anti-corruption campaign. In his inaugural speech as general secretary, Xi mentioned that fighting corruption was one of the toughest challenges for the party. A few months into his term, Xi outlined the Eight-point Regulation, listing rules intended to curb corruption and waste during official party business; it aimed at stricter discipline on the conduct of officials. Xi vowed to root out "tigers and flies", that is, high-ranking officials and ordinary party functionaries. He also launched the Party's Mass Line Education and Practice Activities, aiming CCP cadres to use mass line and instill Party discipline. The campaign lasted from 2013 to 2014. Xi's anti-corruption campaign has led to the downfall of prominent incumbent and retired CCP officials, including members of the PSC. Xi initiated cases against former CMC vice chairmen Xu Caihou and Guo Boxiong, former PSC member and security chief Zhou Yongkang and former CCP General Office director Ling Jihua. Xi has overseen significant reforms of the Central Commission for Discipline Inspection (CCDI), CCP's highest internal control institution. He and CCDI Secretary Wang Qishan further institutionalized CCDI's independence from the day-to-day operations of the CCP, improving its ability to function as a bona fide control body. Along with Wang Qishan, Xi's administration spearheaded the formation of "centrally-dispatched inspection teams".
==== Individual droplet addressability ==== DMF allows for droplet level addressability, meaning individual droplets can be treated as spatially distinct microreactors. This level of droplet control is important for workflows where reactions are sensitive to the order of reagent mixing and incubation times, but where the optimal values of these parameters may still need to be determined. These types of workflows are common in cell-free biology, and Liu et al. were able to demonstrate a proof-of-concept DMF-based strategy for carrying out remote-controlled cell-free protein expression on an OpenDrop chip.
=== Variable contact rates === It is well known that the probability of getting a disease is not constant in time. As a pandemic progresses, reactions to the pandemic may change the contact rates which are assumed constant in the simpler models. Counter-measures such as masks, social distancing, and lockdown will alter the contact rate in a way to reduce the speed of the pandemic. In addition, Some diseases are seasonal, such as the common cold viruses, which are more prevalent during winter. With childhood diseases, such as measles, mumps, and rubella, there is a strong correlation with the school calendar, so that during the school holidays the probability of getting such a disease dramatically decreases. As a consequence, for many classes of diseases, one should consider a force of infection with periodically ('seasonal') varying contact rate
Sources: en.wikipedia.org
21 July: Health Minister Simeon Brown announces that the New Zealand Government will contribute NZ$82.5 million to the establishment of the University of Waikato's medical school; with the university and private philanthropists contributing the remaining NZ$150 million. The Commerce Commission files criminal charges against electronics retailer Noel Leeming for alleged breaches of the Fair Trading Act 1986. The Gore District Council lifts its "do not drink tap water" directive for Gore. 22 July: Sky TV buys TV3 for a symbolic $1; marking the exit of Warner Bros. Discovery from New Zealand's free-to-air television space. The sale comes into effect on 1 August. New Zealand joins 24 other countries including Australia, the United Kingdom, Canada, Japan and the European Union in issuing a joint statement calling for the Gaza war to end. Representatives of several Jewish and Muslim community groups including the New Zealand Jewish Council and the Federation of Islamic Associations of New Zealand (FIANZ) sign a "harmony and peace accord" to improve interfaith relations amidst the Gaza war. 24 July — The primary school teachers' union, the New Zealand Educational Institute, files for a judicial review at the Wellington High Court of the New Zealand Government's decision to reduce funding for literacy and Māori resource teachers during the 2025 New Zealand budget, which was released in May 2025. 30 July: 36,000 nurses, midwives, and other health workers affiliated with the New Zealand Nurses Organisation strike to protest unsafe staffing levels at Te Whatu Ora facilities.
Diffuse axonal injury A form of traumatic brain injury where widespread lesions in white matter tracts occur due to rapid acceleration or deceleration, commonly associated with concussions and coma. Dissociation (neuropsychology) A situation where one cognitive function is impaired while another is preserved, often used to infer the independence of brain processes or structures. Dizygotic twins Also known as fraternal twins; twins that result from two separate eggs fertilized by two different sperm. Used in genetic studies to explore heritability in neurological traits. Dopamine A neurotransmitter involved in reward, motivation, motor control, and mood regulation. Imbalances are associated with disorders such as Parkinson’s disease, schizophrenia, and addiction. Dorsal column–medial lemniscus pathway A sensory pathway of the spinal cord that conveys fine touch, vibration, and proprioceptive information to the brain. Dorsal horn A region in the gray matter of the spinal cord that receives and processes incoming sensory information from peripheral nerves. Dorsal root ganglion A cluster of sensory neuron cell bodies located just outside the spinal cord, which transmit sensory signals to the central nervous system. Dorsal stream One of the two major visual processing pathways in the brain. Often referred to as the “where” pathway, it processes motion and spatial information. Downregulation A decrease in the number or sensitivity of receptors in response to prolonged stimulation by a neurotransmitter or drug, reducing cellular response.
=== Offices (Ämter) === Ämter ("offices" or "bureaus"): in some states, there is an administrative unit between the districts and the municipalities, called Ämter (singular Amt), Amtsgemeinden, Gemeindeverwaltungsverbände, Landgemeinden, Verbandsgemeinden, Verwaltungsgemeinschaften, or Kirchspiellandgemeinden.
== Development and patents == D-Ribose-L-cysteine was developed by Herbert T. Nagasawa, a medicinal chemist formerly affiliated with the United States Department of Veterans Affairs and the University of Minnesota, whose research focused on sulfur amino acid metabolism and hepatic toxicology. The compound and its use as a glutathione-enhancing agent are protected by multiple patents, including United States Patent US 9,173,917 B2, assigned to Max International and the U.S. Department of Veterans Affairs. D-Ribose-L-cysteine has since been incorporated into dietary supplement formulations marketed by Max International, Inc. and LiveMax, LLC.
==== Antipsychotics ==== Certain typical antipsychotics (first-generation) like chlorpromazine and atypical antipsychotics (second-generation) including clozapine, olanzapine, quetiapine, risperidone, ziprasidone, and zotepine may have sedative and/or hypnotic effects and have been used in the treatment of insomnia. However, the most commonly used agents for insomnia are quetiapine and olanzapine. They are thought to produce these effects via multiple mechanisms of action, including histamine H1 receptor antagonism, serotonin 5-HT2A receptor antagonism, α1-adrenergic receptor antagonism, and/or dopamine D2 receptor antagonism. While some of these drugs are frequently prescribed for insomnia, such use is not recommended unless the insomnia is due to an underlying mental health condition treatable by antipsychotics as the risks frequently outweigh the benefits. Some of the more serious adverse effects have been observed to occur at the low doses used for this off-label prescribing, such as dyslipidemia and neutropenia, and a recent network meta-analysis of 154 double-blind, randomized controlled trials of drug therapies vs. placebo for insomnia in adults found that quetiapine had not demonstrated any short-term benefits in sleep quality.
Sources: en.wikipedia.org
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.
Reversed-phase liquid chromatography assesses purity, while mass spectrometry confirms molecular mass and detects sequence errors. Amino acid analysis and peptide mapping add structural detail. These techniques are complementary rather than interchangeable.
It is listed as a prohibited peptide hormone by the World Anti-Doping Agency. No medicines regulator has approved it for human use. Import and sale rules vary by country.
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.