cyclic heptapeptide raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2025-12-19. Anything still debated is marked as such rather than presented as settled.
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controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports.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.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence incorporates a lactam bridge that constrains the peptide into a ring, which increases resistance to enzymatic breakdown relative to the natural hormone. Researchers at the University of Arizona synthesised the compound in the late 1980s and early 1990s while studying pigmentation pathways. It has never received marketing approval from any national medicines regulator. In the scientific literature it is usually described as a laboratory research reagent rather than a therapeutic product.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Alpha-MSH analogue with a lactam ring |
| Molecular formula | C50H69N15O9 | Commonly cited value for the neutral peptide |
| Molecular weight | 1024.18 g/mol | Calculated for the free molecule |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water, DMSO and ethanol | Dissolution in pure water is often slow |
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.
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.
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.
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.
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.
According to a study by Colombia's National Centre for Historical Memory, 220,000 people died in the conflict between 1958 and 2013, most of them civilians (177,307 civilians and 40,787 fighters), and more than five million civilians were forced from their homes between 1985 and 2012, generating the world's second-largest population of internally displaced persons (IDPs). 16.9% of the population in Colombia has been a direct victim of the war. 2.3 million children have been displaced from their homes and 45,000 children have been killed, according to national figures cited by UNICEF. In total, one in three of the 7.6 million registered victims of the conflict are children and 8,000 minors have disappeared since 1985. A Special Unit was created to search for persons deemed as missing within the context of and due to the armed conflict. As of April 2022, the Single Registry of Victims reported 9,263,826 victims of the Colombian conflict, with 2,048,563 of them being children. Approximately 80% of those killed in the conflict have been civilians. In 2022, the Truth Commission of Colombia estimated that paramilitaries were responsible for 45% of civilian deaths, the guerrillas for 27%, and state forces for 12%, with the remaining 16% attributable to other groups or mixed responsibility. On June 23, 2016, the Colombian government and the FARC rebels signed a historic ceasefire deal, bringing them closer to ending more than five decades of conflict.
== Honors and awards == Independent Scientist Research (K02) Award, National Institute of Mental Health, 2002–2007. Fellow, Association for Psychological Science, 2003. Fellow, Society for Personality and Social Psychology, 2005. Fellow, American Psychological Association, 2005. Career Trajectory Award, Society of Experimental Social Psychology, 2006. Cattell Fund Fellowship, 2007–2008. NIH Director's Pioneer Award, 2007–2012, to study how the brain creates emotion. Kavli Fellow, National Academy of Sciences, 2008. Elected Fellow, American Association for the Advancement of Science, 2008. Arts in Academics award, University of Waterloo, 2010. Excellence in Research and Creative Activity Award, Northeastern University, 2012. Elected Fellow, Royal Society of Canada, 2012. Award for Distinguished Service in Psychological Science, American Psychological Association, 2013. Elected Fellow, Society of Experimental Psychologists, 2013. Diener Award in Social Psychology, Society for Personality and Social Psychology, 2014. Heritage Wall of Fame, Foundation for Personality and Social Psychology, 2016. Mentor Award for Lifetime Achievement, Association for Psychological Science, 2018. Elected Fellow, American Academy of Arts and Sciences, 2018. President, Association for Psychological Science, 2019–2020. Guggenheim Fellowship in neuroscience, 2019. John P. McGovern Award in the Behavioral Sciences, American Association for the Advancement of Science, 2020. APA Award for Distinguished Scientific Contributions, American Psychological Association, 2021.
In practice, the solid support is used in excess (often tenfold) to be sure that all expected components are formed. The above limitation is completely removed if the solid support is omitted and the synthesis is carried out in solution. In this case, there is no upper limit concerning the number of components of the library. Both the number of components and the quantity of the library can be freely decided based only on practical considerations. An important modification was introduced in the synthesis of DNA encoded combinatorial libraries by Harbury and Halpin. The solid support in their case is replaced by the encoding DNA oligomers. This makes it possible to synthesize libraries containing even trillions of components and screen them using affinity binding methods. A different way of carrying out solution-phase S&P synthesis is applying scavenger resins to remove the byproducts. Scavenger resins are polymers having functional groups that make it possible to react with and bind components of the excess of reagents then filtered them out from the reaction mixture Two examples: a resin containing primary amino groups can remove the excess of acyl chlorides from reaction mixtures while an acyl chloride resin removes amines. A fluorous technology was described by Curran The fluorous synthesis employs functionalized perfluoroalkyl (Rf) groups like 4,4,5,5,6,6,7,7,8,8,9,9,9-Tridecafluorononyl {CF3(CF2)4CF2CH2CH2-} group attached to substrates or reagents. The Rf groups make it possible to remove either the product or the reagents from the reaction mixture.
As well as being an optical feature, the Schreger pattern could point towards a micropattern well-designed to prevent crack propagation by dispersing stresses. Additionally, this intricate microstructure lends a strong anisotropy to ivory's mechanical characteristics. Separate hardness measurements on three orthogonal tusk directions indicated that circumferential planes of tusk had up to 25% greater hardness than radial planes of the same specimen. During hardness testing, inelastic and elastic recovery was observed on circumferential planes while the radial planes displayed plastic deformation. This implies that ivory has directional viscoelasticity. These anisotropic properties can be explained by the reinforcement of collagen fibers in the composite oriented along the circumference.
Sources: en.wikipedia.org
=== Skin === The weak connective tissue causes abnormal skin. This may present as stretchy or, in other types, simply be velvet soft. In all types, some increased fragility occurs, but the degree varies depending on the underlying subtype. The skin may tear and bruise easily, and may heal with abnormal atrophic scars; atrophic scars that resemble cigarette paper are a sign seen in those whose skin might appear otherwise normal. In some subtypes, though not the hypermobile subtype, redundant skin folds occur, especially on the eyelids. Redundant skin folds are areas of excess skin lying in folds. Other skin symptoms include molluscoid pseudotumors, especially on pressure points, petechiae, subcutaneous spheroids, livedo reticularis; piezogenic papules are less common. In vascular EDS, skin can also be thin and translucent. In dermatosparaxis EDS, the skin is extremely fragile and saggy.
The Medical Companion, Or Family Physician, a book from 1827, gave the following recipe: Paregoric Elixir – Take of purified opium, flowers of Benzoin, camphor, and essential oil of annis-seed, each, two drachms; brandy, two pints. Digest for eight or ten days, frequently shaking the bottle, and then strain the elixir.
Dimethocaine, also known as DMC or larocaine, is a compound with local anesthetic and stimulatory effects. The stimulatory effect resembles that of cocaine, although less potent. Similarly to cocaine, dimethocaine is addictive due to its stimulation of the reward pathway in the brain. However, dimethocaine is a legal cocaine replacement in some countries and is listed by the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) under the "synthetic cocaine derivatives" category. The structure of dimethocaine, being a 4-aminobenzoic acid ester, resembles that of procaine. It is found as a white powder at room temperature. When a product sold online in the UK in June 2010, advertised as dimethocaine was tested, it was found to be a mixture of caffeine and lidocaine, and the lack of any dopaminergic stimulant ingredient in such mixes may explain the limited recreational effects reported by many users. Other samples tested have however been shown to contain genuine dimethocaine, and one branded "bath salt" product containing primarily dimethocaine as the active ingredient, was noted to have been particularly subject to abuse by intravenous drug users in Ireland.
13 June – Science and the 2022 Russian invasion of Ukraine:Groups of academics report how global science community could help Ukraine via an action plan, including for helping organizing (re)vitalization of Ukrainian science and reconstruction in the future. On the same day, a researcher outlined a number of possible major policy-based actions that could mitigate the energy and resource crises caused or exacerbated by the war. Russian space agency Roscosmos announces the intent to, unilaterally and hazardously, take over paused telescope eROSITA, launched in collaboration with Germany (4 June). A science journalist outlines some of the food system-related environmental impacts of the war (21 June). A study reports a number of humanitarian, economic, and financial impacts of the war (23 June). 15 June Astronomers identify J1144 as the fastest-growing black hole of the last nine billion years, consuming matter equivalent to one Earth every second, as well as being the most luminous quasi-stellar object of that period. Researchers report Lac-Phe as the most significantly induced circulating metabolite in two animal models of exercise which – including via chronic administration – reduces food intake and suppresses obesity. 20 June A study suggests global food miles CO2 emissions are 3.5–7.5 times higher than previously estimated, with transport accounting for about 19% of total food-system emissions, albeit shifting towards plant-based diets remains substantially more important.
=== Mode === HPTLC comprises three modes: linear mode, circular mode, and anticircular mode. Among these modes, the anticircular mode stands out as the fastest in theory and practice within the realm of HPTLC. This mode achieves separation by allowing the mobile phase to enter the plate layer precisely along an outer circular path, after which it flows toward the center at a nearly constant speed. This approach maximizes sample capacity while minimizing time, layer, and mobile phase consumption, making it the most cost-effective HPTLC technique. The narrow spot-path unique to anticircular HPTLC facilitates automated quantification. When compared to the linear and circular modes, the anticircular mode demonstrates superior separation and significantly heightened sensitivity, especially at higher Rf-values.
Sources: en.wikipedia.org
It is a synthetic cyclic heptapeptide modelled on alpha-melanocyte-stimulating hormone. A lactam bridge links two side chains, forming a ring that stabilises the molecule against proteolysis. It belongs to the broader melanocortin peptide family.
No national medicines agency has approved melanotan-2 for clinical use. Afamelanotide, a related but distinct peptide, holds a marketing authorisation in the European Union for a rare photosensitivity disorder. Melanotan-2 itself is handled as a laboratory chemical.
Its broad activity across melanocortin receptors makes it a tool for probing pigmentation, appetite and vascular signalling. Early trials recorded skin darkening and other effects that were not the original focus of the work. Those observations generated hypotheses that later studies have examined.
Low temperature slows hydrolysis and oxidation, the two main routes by which the peptide backbone and side chains are modified. A lyophilised powder stored at −20 °C is more stable than one kept at room temperature, and once the material is dissolved the degradation rate rises, making refrigeration more important.