If you have been reading about afamelanotide 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.
Updated 2025-11-27. Numbers and descriptions here follow the published literature rather than marketing material.
Melanotan-2 is a synthetic linear peptide built from seven amino acids arranged in a short chain. Its sequence is commonly written as Ac-Nle-Asp-His-D-Phe-Arg-Trp-Lys-NH2, which includes a modified N-terminus and an amidated C-terminus. The molecule belongs to the melanocortin family and acts as a receptor agonist. Structural features such as the D-phenylalanine residue and the Nle substitution are associated with increased stability against enzymatic degradation relative to the natural parent peptide.
The compound emerged from research programs in the 1980s that examined analogues of alpha-melanocyte-stimulating hormone for pigmentation and photoprotection. Investigators modified the native sequence to extend activity duration and potency. A related analogue, afamelanotide, was developed within the same broad line of inquiry and eventually gained approval in certain jurisdictions for a rare light-sensitivity condition. Melanotan-2 itself did not progress through the same regulatory route and has no approved therapeutic indication.
Melanocytes are the pigment-producing cells of the skin, and they carry melanocortin-1 receptors on their surface. When the receptor is activated, cyclic adenosine monophosphate rises inside the cell and raises the activity of enzymes such as tyrosinase, which increases melanin output. Melanotan-2 binds melanocortin-1 receptors in vitro and in animal models, and this binding is generally described as the basis for the tanning effect. Other receptors account for different effects: melanocortin-4 receptors contribute to appetite and erectile signalling, while melanocortin-3 and melanocortin-5 receptors contribute to energy balance and exocrine function.
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 |
|---|---|---|
| Molecular formula | C50H69N15O9 | Free base; salt forms differ |
| Molecular weight | Approximately 1024 g/mol | Calculated for the free base |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water and polar solvents | Poorly soluble in non-polar solvents |
| Typical storage | -20 degrees Celsius, dry, protected from light | Refers to the solid form |
There are more than 50 types of treatments for CTS with varied levels of evidence and recommendations across healthcare guidelines, with evidence most strongly supporting surgery, steroids, splinting for wrist positioning, and physical or occupational therapy interventions. When selecting treatment, it is important to consider the severity and chronicity of the CTS pathophysiology and to distinguish treatments that can alter the natural history of the pathophysiology (disease-modifying treatments) and treatments that only alleviate symptoms (palliative treatments). The strongest evidence for disease-modifying treatment in chronic or severe CTS cases is carpal tunnel surgery to change the shape of the carpal tunnel. The American Academy of Orthopedic Surgeons recommends proceeding conservatively with a course of nonsurgical therapies tried before release surgery is considered. A different treatment should be tried if the current treatment fails to resolve the symptoms within 2 to 7 weeks. Early surgery with carpal tunnel release is indicated where there is evidence of median nerve denervation or a person elects to proceed directly to surgical treatment. Recommendations may differ when carpal tunnel syndrome is found in association with the following conditions: diabetes mellitus, coexistent cervical radiculopathy, hypothyroidism, polyneuropathy, pregnancy, rheumatoid arthritis, and carpal tunnel syndrome in the workplace. CTS related to another pathophysiology is addressed by treating that pathology.
====== LAESI ====== In Laser ablation electrospray ionization (LAESI), a laser is used to ablate the surface of the sample and the emitted molecules are ionized in the gas phase by charged droplets from electrospray. Similar to DESI the ionization happens in ambient conditions. Anderton et al. used this ionization technique coupled to a Fourier transform mass spectrometer to analyze 200 single cells of Allium cepa (red onion) with high spatial resolution.
== Use and effects == 4-HO-EPT was not included nor mentioned in Alexander Shulgin's book TiHKAL (Tryptamines I Have Known and Loved). Subsequently, however, an assumed prodrug of 4-HO-EPT, 4-AcO-EPT, has emerged as a novel designer drug, and has been said based on online anecdotal reports to have a dose of 20 to 30 mg orally.
NhX3 → NhX + X2 Nihonium thus continues the trend down group 13 of reduced stability of the +3 oxidation state, as all five of these compounds have lower reaction energies than the unknown thallium(III) iodide. The +3 state is stabilised for thallium in anionic complexes such as TlI−4, and the presence of a possible vacant coordination site on the lighter T-shaped nihonium trihalides is expected to allow a similar stabilisation of NhF−4 and perhaps NhCl−4. The +5 oxidation state is unknown for all lighter group 13 elements: calculations predict that nihonium pentahydride (NhH5) and pentafluoride (NhF5) should have a square pyramidal molecular geometry, but also that both would be highly thermodynamically unstable to loss of an X2 molecule and reduction to nihonium(III). Again, some stabilisation is expected for anionic complexes, such as NhF−6. The structures of the nihonium trifluoride and pentafluoride molecules are the same as those for chlorine trifluoride and pentafluoride.
Sources: en.wikipedia.org
== Clinical trials == As of September 2024, traneurocin is in phase 3 clinical trials for COVID-19, phase 2 clinical trials for Alzheimer's disease, fragile X syndrome, and Rett syndrome, and phase 1 clinical trials for major depressive disorder. No development has been reported for treatment of other neurological disorders. Traneurocin was first developed, under the name cycloprolylglycine (CPG), in Russia in 1991 as a drug related structurally and pharmacologically to piracetam. Cycloprolylglycine is also related to and known to be the major metabolite of omberacetam (Noopept). Another drug, vineurocin (NA-704), is also being developed for treatment of Alzheimer's disease. This drug is described as a recombinant growth hormone with neuroprotective and neurogenic effects.
=== Prohormone supplements === The most everyday use of prohormones is as supplements for muscle growth via ergogenic and anabolic agents. Prohormone supplements became popular from 1960 to 2001 and became used unregulated in Major League Baseball before select prohormones such as androstenedione and androstenediol became banned in the United States' Anabolic Steroid Control Act of 2004. Many prohormone supplements that were claimed to impart anabolic or ergogenic effects in men were banned for their poor side effects, commonly in supplements such as in 3β-hydroxy-5α-androst-1-en-17-one, commonly known as 1-testosterone, which are as follows:
A broader survey of Drosophila de novo proteins likewise found that most differ from conserved proteins in predicted properties, but that a subset are predicted to adopt known folds and participate in specific cellular processes. Inference from prediction tools requires caution because many predictors were trained and benchmarked primarily on conserved, globular proteins, and their performance can be biased for short or low-homology sequences. In particular, disorder predictions can be sensitive to parameter choices, and different structure predictors (including alignment-based and protein language model approaches) may disagree on de novo proteins and yield low-confidence models. Comparisons of "newly born" orphan proteins to "never born" random polypeptides using multiple deep-learning structure predictors similarly reported that predicted models are often of low quality while still allowing limited qualitative comparisons across sequence sets.
=== Technical limitations === When the patient's body has insufficient adipocyte tissue to harvest as injectable breast filler, a combination of fat grafting and breast implants might provide the desired outcome. Although non-surgical breast augmentation with fat graft injections is not associated with implant-related medical complications (filler leakage, deflation, visibility, palpability, capsular contracture), the achievable breast volumes are physically limited; the large-volume, global bust augmentations realised with breast implants are not possible with the method of structural fat grafting. Global breast augmentation contrasts with the controlled breast augmentation of fat-graft injection, in the degree of control that the plastic surgeon has in achieving the desired breast contour and volume. The controlled augmentation is realised by infiltrating and diffusing the fat grafts throughout the breast; and it is feather-layered into the adjacent pectoral areas until achieving the desired outcome of breast volume and contour. Nonetheless, the physical fullness-of-breast achieved with injected fat-grafts does not visually translate into the type of buxom fullness achieved with breast implants; hence, patients who had plentiful fat-tissue to harvest attained a maximum breast augmentation of one bra cup size in one session of fat grafting to the breast.
==== Matrix assisted laser desorption electrospray ionization ==== Another method good for biomolecules is matrix assisted laser desorption electrospray ionization (MALDESI). In this technique, it utilizes Infrared laser ionization to excite the sample molecules to allow for the desorbed ions to be ready for MS analysis. The geometry of the source and the distance between the ESI and matrix will have and effect on the efficiency of the sample compound. This technique can also be used with aqueous samples as well. The water droplet can be placed at the focal point of the laser, or the droplet can be dried to form the solid. Planar samples do not need sample preparation to perform this experiment.
Sources: en.wikipedia.org
A branched-chain amino acid (BCAA) is an amino acid having an aliphatic side-chain with a branch (a central carbon atom bound to three or more carbon atoms). Among the proteinogenic amino acids, there are three BCAAs: leucine, isoleucine, and valine. Non-proteinogenic BCAAs include 2-aminoisobutyric acid and alloisoleucine. The three proteinogenic BCAAs are among the nine essential amino acids for humans, accounting for 35% of the essential amino acids in muscle proteins and 40% of the preformed amino acids required by mammals. Synthesis for BCAAs occurs in all locations of plants, within the plastids of the cell, as determined by presence of mRNAs which encode for enzymes in the metabolic pathway. Oxidation of BCAAs may increase fatty acid oxidation and play a role in obesity. Physiologically, BCAAs take on roles in the immune system and in brain function. BCAAs are broken down effectively by dehydrogenase and decarboxylase enzymes expressed by immune cells, and are required for lymphocyte growth and proliferation and cytotoxic T lymphocyte activity. Lastly, BCAAs share the same transport protein into the brain with aromatic amino acids (Trp, Tyr, and Phe). Once in the brain BCAAs may have a role in protein synthesis, synthesis of neurotransmitters, and production of energy.
== Example of preparing a series of standard solutions == Suppose the concentration of glutamine in an unknown sample needs to be measured. To do so, a series of standard solutions containing glutamine is prepared to create a calibration curve. A table summarizing a method for creating these solutions is shown below:
The country's ten largest self-reported ethnic or cultural origins in 2021 were Canadian (accounting for 15.6 percent of the population), followed by English (14.7%), Irish (12.1%), Scottish (12.1%), French (11.0%), German (8.1%), Chinese (4.7%), Italian (4.3%), Indian (3.7%), and Ukrainian (3.5%). Of the 36.3 million people enumerated in 2021, approximately 25.4 million reported being "White", representing 69.8 percent of the population. The Indigenous population representing 5 percent or 1.8 million people, grew by 9.4 percent compared to the non-Indigenous population, which grew by 5.3 percent from 2016 to 2021. One out of every four Canadians or 26.5 percent of the population belonged to a non-White and non-Indigenous visible minority, the largest of which in 2021 were South Asian (2.6 million people; 7.1%), Chinese (1.7 million; 4.7%), Black (1.5 million; 4.3%), Filipinos (960,000 2.6%), Arabs (690,000; 1.9%), Latin Americans (580,000; 1.6%), Southeast Asians (390,000; 1.1%), West Asians (360,000; 1.0%), Koreans (220,000; 0.6%) and Japanese (99,000; 0.3%). Between 2011 and 2016, the visible minority population rose by 18.4 percent. In 1961, about 300,000 people, less than two percent of Canada's population, were members of visible minority groups. The 2021 census indicated that 8.3 million people, or almost one-quarter (23.0%) of the population, reported themselves as being or having been a landed immigrant or permanent resident in Canada—above the 1921 census previous record of 22.3 percent.
== Further reading == Martin, Christopher S.; Chung, Tammy; Langenbucher, James W. (2017). "Part 1: Defining and Characterizing the Nature and Extent of Substance Use Disorders – Historical and Cultural Perspectives on Substance Use and Substance Use Disorders". In Sher, Kenneth J. (ed.). The Oxford Handbook of Substance Use and Substance Use Disorders: Volume 1. Oxford Library of Psychology. Oxford and New York: Oxford University Press. pp. 27–59. doi:10.1093/oxfordhb/9780199381678.013.001. ISBN 978-0-19-938167-8. LCCN 2016020729. Anthony, James; Barondess, David A.; Radovanovic, Mirjana; Lopez-Quintero, Catalina (2017). "Part 1: Psychiatric Comorbidity – Polydrug Use: Research Topics and Issues". In Sher, Kenneth J. (ed.). The Oxford Handbook of Substance Use and Substance Use Disorders: Volume 2. Oxford Library of Psychology. Oxford and New York: Oxford University Press. pp. 27–59. doi:10.1093/oxfordhb/9780199381708.013.006. ISBN 978-0-19-938170-8. LCCN 2016020729. Hernández-Serrano, Olga; Gras, Maria E.; Font-Mayolas, Sílvia; Sullman, Mark J. M. (2016). "Part VI: Dual and Polydrug Abuse – Chapter 83: Types of Polydrug Usage". In Preedy, Victor R. (ed.). Neuropathology of Drug Addictions and Substance Misuse, Volume 3: General Processes and Mechanisms, Prescription Medications, Caffeine and Areca, Polydrug Misuse, Emerging Addictions and Non-Drug Addictions. Cambridge, Massachusetts: Academic Press, imprint of Elsevier. pp. 839–849. doi:10.1016/B978-0-12-800634-4.00083-4. ISBN 978-0-12-800634-4.
Sources: en.wikipedia.org
No. Melanotan-2 is manufactured synthetically. The naturally occurring peptide in the same family is alpha-melanocyte-stimulating hormone, which the body produces as part of normal endocrine and neural signalling.
Both are synthetic analogues derived from the same parent hormone. Reference descriptions usually characterise afamelanotide as more selective for the MC1R subtype, whereas melanotan-2 is reported to interact with a wider range of melanocortin receptors.
Early studies explored melanocortin signalling and pigmentation, which later led to informal use of the label tanning peptide. That label is not a regulatory category and does not imply approved status for any purpose.
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.