This is a working overview of post-marketing surveillance, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-01-27 and is reviewed periodically as new material appears.
Melanotan II is a synthetic peptide analog modeled on alpha-melanocyte-stimulating hormone, a naturally occurring signaling peptide involved in pigmentation. Its structure is a cyclic heptapeptide containing two non-natural substitutions, norleucine at position four and D-phenylalanine at position seven. These modifications resist enzymatic breakdown and extend the molecule's activity relative to the native hormone. The compound binds melanocortin receptors and is studied mainly as a pharmacological tool rather than a therapeutic product. It has never received approval as a medicine in any major jurisdiction.
The compound was developed in the late 1980s and 1990s by academic researchers investigating photoprotection. The rationale held that stimulating melanin production might reduce ultraviolet damage to skin and lower skin cancer risk. Early work examined receptor binding, pigment response, and short-term tolerability in small studies. That program did not produce an approved drug, and formal development stalled after early-phase trials. Whether induced pigmentation confers meaningful photoprotection remains an open question.
Outside regulated medicine, melanotan II circulates through online vendors as a research chemical, often marketed for tanning. Products sold this way vary widely in purity, concentration, and labeling accuracy, and independent testing has documented discrepancies. Published reports describe both pigment effects and adverse reactions, including nausea, flushing, and darkening of existing moles. Long-term safety data are sparse, and no large controlled trial has established a risk profile. Questions about cumulative effects on melanocytes remain unresolved in the literature.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Belongs to the melanocortin agonist family |
| Key substitutions | Nle4 and D-Phe7 | Improve resistance to enzymatic degradation |
| Molecular formula | C50H69N15O9 | Approximately 1024 g/mol |
| Regulatory status | Not approved as a medicine | Distributed as a research chemical |
| Common synonyms | Melanotan II, MT-II, MT-2 | Spelling varies across sources |
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.
Melanotan-2 has not received marketing authorisation from major regulatory agencies for any therapeutic indication. Several jurisdictions classify it as a prescription-only medicine or a controlled substance when supplied for human use. Because approved products do not exist, material sold online usually sits outside pharmaceutical supply chains and formal quality oversight. Regulators have issued public notices describing the compound as unapproved. Enforcement varies, and the legal position differs between countries, which complicates any single general statement about its status.
Scientific discussion of Melanotan-2 spans pharmacology, dermatology, and public-health literature. Laboratory studies examine its receptor binding and cellular effects, while clinical reports describe outcomes observed after unregulated use. These two bodies of work differ in rigour and intent. Peer-reviewed trials of the compound as a medicine are limited, so much of the available information comes from case reports and surveillance data. Authors frequently note the gap between experimental findings and real-world use.
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.
Research interest has centred on photoprotection and pigmentation, with a smaller body of work on appetite and sexual function. Published human data remain limited to small, frequently uncontrolled studies, and the compound has never received marketing approval from a national medicines regulator. Most laboratory work treats it as a pharmacological tool for probing melanocortin signalling in cell culture or animal models. Whether pigmentation changes observed in people translate into measurable protection against ultraviolet-induced DNA damage remains an open question.
Calcitonin gene-related peptide (CGRP) receptor antagonists, commonly known as gepants, are a class of drugs that act as antagonists of the calcitonin gene-related peptide receptor (CGRPR). The CGRP family of small proteins are present in the sensory nerves of the head and neck and are involved in transmission of pain. Nerve activation can trigger the release of CGRP and other neuropeptides, leading to inflammation, pain, and swelling in the case of migraine. Several monoclonal antibodies that bind to the CGRP receptor or peptide have been approved for prevention of migraine. As of March 11, 2024, the American Headache Society issued a statement that "CGRP targeting therapies are a first-line option for migraine prevention" in the United States. The prior use of non-specific migraine preventive medication approaches is therefore no longer required before CGRP treatments can be prescribed. Small molecule CGRPR antagonists have also been approved in the U.S. as antimigraine agents.
The aqueous humour is a transparent water-like fluid similar to blood plasma, but containing low protein concentrations. It is secreted from the ciliary body, a structure supporting the lens of the eyeball. It fills both the anterior and the posterior chambers of the eye, and is not to be confused with the vitreous humour, which is located in the space between the lens and the retina, also known as the posterior cavity or vitreous chamber. Blood cannot normally enter the eyeball.
== Endolithic fungi found in the eggs of Cretaceous dinosaurs == Evidence of endolithic fungi were discovered within dinosaur eggshell found in central China. They were characterized as being “needle-like, ribbon-like, and silk-like.". Fungus is seldom fossilized and even when it is preserved it can be difficult to distinguish endolithic hyphae from endolithic cyanobacteria and algae. Endolithic microbes can, however, be distinguished based on their distribution, ecology, and morphology. According to a 2008 study, the endolithic fungi that formed on the eggshells would have resulted in the abnormal incubation of the eggs and may have killed the embryos in infected eggs of these dinosaurs. It may also have led to the preservation of dinosaur eggs, including some that contained embryos.
Sources: en.wikipedia.org
The supernatant contains a mitogenic factor, a mitosis promoting factor, that is characterized heat and trypsin sensitivity, both of which characterize it as a peptide. Treatment of Schwann cells with the collected supernatant shows that it is a mitogenic factor and thus plays an important role in the proliferation of Schwann cells. Macrophages are also involved in the secretion factors that promote nerve regeneration. Macrophages secrete not only interleukin-1, a cytokine that induces expression of nerve growth factor (NGF) in Schwann cells but also an interleukin-1 receptor antagonist (IL-1ra). Expression of IL-1ra in mice with transected sciatic nerves via implantation of a tube releasing IL-1ra showed the regrowth of fewer myelinated and unmyelinated axons. Macrophage secretion of interleukin-1 is involved in stimulation of nerve regeneration.
== History == In February 2003, Nabil Seidah and Jae Byun, a scientist at the Clinical Research Institute of Montreal in Canada, discovered a novel human proprotein convertase, the gene for which was located on the short arm of chromosome 1. Meanwhile, a lab led by Catherine Boileau at the Necker–Enfants Malades Hospital in Paris had been following families with familial hypercholesterolaemia, a genetic condition that, in 90% of cases causes coronary artery disease (FRAMINGHAM study) and in 60% of cases may lead to an early death; they had identified a mutation on chromosome 1 carried by some of these families, but had been unable to identify the relevant gene. The labs got together and by the end of the year published their work, linking mutations in the gene, now identified as PCSK9, to the condition. In their paper, they speculated that the mutations might make the gene overactive. In that same year, investigators at Rockefeller University and University of Texas Southwestern had discovered the same protein in mice, and had worked out the novel pathway that regulates LDL cholesterol in which PCSK9 is involved, and it soon became clear that the mutations identified in France led to excessive PCSK9 activity, and thus excessive removal of the LDL receptor, leaving people carrying the mutations with too much LDL cholesterol. Meanwhile, Helen H. Hobbs and Jonathan Cohen at UT-Southwestern had been studying people with very high and very low cholesterol, and had been collecting DNA samples.
=== Expression in bacterial hosts === There currently are very few effective methods for expressing functional plant Rubisco in bacterial hosts for genetic manipulation studies. This is largely due to Rubisco's requirement of complex cellular machinery for its biogenesis and metabolic maintenance including the nuclear-encoded RbcS subunits, which are typically imported into chloroplasts as unfolded proteins. Furthermore, sufficient expression and interaction with Rubisco activase are major challenges as well. One successful method for expression of Rubisco in E. coli involves the co-expression of multiple chloroplast chaperones, though this has only been shown for Arabidopsis thaliana Rubisco.
Sources: en.wikipedia.org
== Discovery == Asprosin was first identified by Dr. Atul Chopra and colleagues at Baylor College of Medicine during their study of Marfanoid–progeroid–lipodystrophy syndrome (MPL), also known as neonatal progeroid syndrome (NPS), a rare genetic disorder caused by mutations in the FBN1 gene. These mutations produce truncated profibrillin-1 protein, resulting in two key effects: the production of a mutant fibrillin-1 protein and significantly reduced plasma asprosin levels due to a dominant-negative mechanism. The discovery of asprosin's role as a fasting-induced glucogenic hormone, stimulating hepatic glucose release, stemmed from the observation of low plasma insulin levels in the two patients. A subsequent study by Chopra and colleagues investigated the patients' extreme thinness and abnormally low appetite, uncovering asprosin's additional role as an orexigenic hormone that regulates appetite through hypothalamic neurons. To further investigate the condition, Chopra and colleagues developed a mouse model carrying the MPL mutation, which faithfully phenocopied the human disorder. These mice exhibited the same features as the patients, including low plasma asprosin levels, extreme thinness, reduced appetite, and resistance to diet-induced obesity and diabetes. This model confirmed the role of asprosin in regulating appetite and body weight through its orexigenic effects on hypothalamic neurons and demonstrated its broader implications in metabolic health.
=== Sources === For the most part, vitamins are obtained from the diet, but some are acquired by other means: for example, microorganisms in the gut flora produce vitamin K and biotin; and one form of vitamin D is synthesized in skin cells when they are exposed to a certain wavelength of ultraviolet light present in sunlight. Humans can produce some vitamins from precursors they consume: for example, vitamin A is synthesized from beta carotene; and niacin is synthesized from the amino acid tryptophan. Vitamin C can be synthesized by some species but not by others. Vitamin B12 is the only vitamin or nutrient not available from plant sources. The Food Fortification Initiative lists countries which have mandatory fortification programs for vitamins folic acid, niacin, vitamin A and vitamins B1, B2 and B12.
== Memberships == She was a member of the American Chemical Society and the Society of Biological Chemists. She became a Fellow of the American Association for the Advancement of Science in 1947, and was also a Fellow of the American Society of Refrigerating Engineers. She was also a member of the Philadelphia Pathological Society, Sigma Xi, and the Kappa Kappa Gamma sorority.
Sources: en.wikipedia.org
It is a synthetic cyclic peptide designed as an analog of alpha-melanocyte-stimulating hormone. It acts on melanocortin receptors and is best known from research into pigmentation. It is not an approved pharmaceutical product.
No regulatory agency has approved it for any indication. It is encountered as a research chemical sold outside pharmaceutical supply chains. Products marketed this way are not subject to the manufacturing and labeling requirements that apply to approved drugs.
Reports describe increased skin pigmentation as well as side effects such as nausea, flushing, and changes to existing moles. Much of the evidence comes from small studies and case reports rather than large trials. The long-term safety profile is therefore uncertain.
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.