Everything below concerns melanocortin receptor. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-08-01. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Melanotan II is a synthetic cyclic heptapeptide analog derived from the core sequence of alpha-melanocyte-stimulating hormone. Researchers at the University of Arizona synthesized it during the 1980s while studying pigmentation and appetite signaling. The compound is not an approved medicine in any major jurisdiction and appears mainly in laboratory and research-chemical settings. Its structure incorporates a lactam bridge between side chains, which constrains the ring and slows enzymatic breakdown relative to the natural hormone.
Melanotan II binds several melanocortin receptor subtypes rather than a single target. MC1R on melanocytes drives melanin synthesis, while MC3R and MC4R participate in energy balance, appetite, and sexual response pathways. This lack of selectivity explains why reported effects extend beyond skin darkening. Substitutions at positions four and seven, including norleucine and D-phenylalanine, increase potency and resistance to peptidases. Understanding which receptor mediates which effect remains an active area of investigation.
| 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 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.
Melanotan II is a synthetic cyclic heptapeptide that acts as an agonist at melanocortin receptors. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous peptide involved in pigment production. The analogue carries a lactam bridge that constrains the ring and slows enzymatic breakdown relative to the native hormone. In research literature it appears under several abbreviations, and naming conventions are not fully standardized. Published descriptions usually place it within the broader melanocortin agonist family.
Receptor binding at MC1R on melanocytes raises intracellular cyclic AMP and increases expression of tyrosinase and related enzymes. The downstream result is greater synthesis of eumelanin, the dark pigment, without ultraviolet exposure acting as the trigger. The compound is not selective, however, and also engages MC3R, MC4R and MC5R, which are expressed in the central nervous system and elsewhere. That lack of selectivity is the explanation usually offered for effects reported outside pigmentation, including appetite suppression and nausea. Selectivity remains a central theme in comparative studies of related peptides.
This proved that in aqueous solution, nobelium is most stable in the divalent state when strong oxidizers are absent. Later experimentation in 1974 showed that nobelium eluted with the alkaline earth metals, between Ca2+ and Sr2+. Nobelium is the only known f-block element for which the +2 state is the most common and stable one in aqueous solution. This occurs because of the large energy gap between the 5f and 6d orbitals at the end of the actinide series. It is expected that the relativistic stabilization of the 7s subshell greatly destabilizes nobelium dihydride, NoH2, and relativistic stabilisation of the 7p1/2 spinor over the 6d3/2 spinor mean that excited states in nobelium atoms have 7s and 7p contribution instead of the expected 6d contribution. The long No–H distances in the NoH2 molecule and the significant charge transfer lead to extreme ionicity with a dipole moment of 5.94 D for this molecule. In this molecule, nobelium is expected to exhibit main-group-like behavior, specifically acting like an alkaline earth metal with its ns2 valence shell configuration and core-like 5f orbitals. Nobelium's complexing ability with chloride ions is most similar to that of barium, which complexes rather weakly. Its complexing ability with citrate, oxalate, and acetate in an aqueous solution of 0.5 M ammonium nitrate is between that of calcium and strontium, although it is somewhat closer to that of strontium. The standard reduction potential of the E°(No3+→No2+) couple was estimated in 1969 to be between +1.4 and +1.5 V; it was later found in 2009 to be only about +0.75 V.
On the same day, a study reports the assembly of 43 diverse Y chromosomes, revealing large variability such as a range in size from 45.2 to 84.9 million base-pairs. A study indicates factors contributing to the longevity of long-living organisms can be transferred between species, particularly from naked mole-rats to mice. 28 August A study estimates that global warming of 2 °C could result in the mass deaths of 1 billion people by 2100. Astronomers film an impact event, likely by an asteroid, on the planet Jupiter. Researchers demonstrate in two separate studies that quantum simulators, e.g. using trapped ions, can be used to directly observe quantum effects at time-scales far beyond prior approaches, slowing down femtosecond-scale photo-chemical reactions or dynamics around conical intersections 100 billion times. A preprint models Earth as seen from TRAPPIST-1e and indicates that from this 41 light-years distant vantage point, human civilization would be detectable with the James Webb Space Telescope due to atmospheric signatures including air pollution. 30 August – Autonomous drones win first races against human champions of FPV drone racing. 31 August – Researchers report, based on genetic studies, that a human ancestor population bottleneck (from a possible 100,000 to 1,000 individuals) occurred "around 930,000 and 813,000 years ago ... lasted for about 117,000 years and brought human ancestors close to extinction."
=== Bone mineral density === Bone mineral density (BMD) is a measure commonly used to quantify bone health. A lower BMD value indicates an increased risk of an osteoporosis or a fracture. There is a large range of factors influencing BMD. Protein consumption has shown to be beneficial for bone density by providing amino acid substrates necessary for bone matrix formation. It is also thought that blood concentration of the bone formation stimulant, Insulin-like Growth Factor-I (IGF-I), is increased from high protein consumption and parathyroid hormone (PTH), a bone resorption stimulant, is decreased. Although protein has shown to be beneficial for increasing bone mass, or bone mineral density, there is no significant association between protein intake and fracture incidence. In other words, a low BMD can be predictive of osteoporosis and increased fracture risk, but a higher BMD does not necessarily mean better bone health. High BMD is also correlated with other health issues. For example, a higher BMD has also been associated with increased risk of breast cancer.
Sources: en.wikipedia.org
=== Phytochemicals === Polyphenol phytochemicals present in the fruit, seeds, and leaves are being investigated for their potential biological activities. Major anthocyanins in blackcurrant pomace – delphinidin-3-O-glucoside, delphinidin-3-O-rutinoside, cyanidin-3-O-glucoside, and cyanidin-3-O-rutinoside, which are retained in the juice concentrate – are among other polyphenols.
== Epidemiology == In the United States, approximately 550,000 people die each year from heart-related arterial embolism and thrombosis. Approximately 250,000 of these individuals are female, and approximately 100,000 of all these deaths are considered premature, that is, prior to the age of average life expectancy.
Looking Glass (or Operation Looking Glass) is the historic code name for an airborne command and control center operated by the United States. Since 2016 it has been referred to as the ABNCP (Airborne National Command Post). It provides command and control of U.S. nuclear forces in the event that ground-based command centers have been destroyed or otherwise rendered inoperable. In such an event, the general officer aboard the Looking Glass serves as the Airborne Emergency Action Officer (AEAO), and by law assumes the authority of the National Command Authority and could command execution of nuclear attacks. The AEAO is supported by a battle staff of approximately 20 people, with another dozen responsible for the operation of the aircraft systems. The name Looking Glass, which is another name for a mirror, was chosen for the Airborne Command Post because the mission operates in parallel with the underground command post at Offutt Air Force Base.
Sources: en.wikipedia.org
The history of visual art in Portugal dates back into the Paleolithic. An early evidence showing an attempt at depicting motion was found at the Prehistoric Rock Art Sites in the Côa Valley and Siega Verde. Over time, foreign and native influences, together with advancements in manufacturing, developed distinctive art styles, such as the Manueline and Pombaline, and also a number of crafts that are typical of Portugal, namely the azulejo, talha dourada, and Portuguese pavement. Historically, Christianity played an influential role in Portuguese art and was a recurrent theme in many art forms, including painting. Throughout the country's history, artwork in Portugal was typically done by local artists who, depending on location, followed different variations in style, giving Portugal a diverse array of artistic styles throughout the country, an example of this being the thatch houses of Santana, in Madeira.
== Side effects == Common adverse reactions include nausea, headache, fatigue, vomiting, diarrhea, Anorexia (symptom) (loss of appetite), and insomnia (trouble sleeping). Rare but serious side effects include hypersensitivity reaction such as rash, elevated AST and ALT, depression, anxiety, fever/chills, URI, lactic acidosis, hypertriglyceridemia, and lipodystrophy.
== Adverse effects == Torsades de pointes is the most serious side effect of dofetilide therapy. The incidence of torsades de pointes is 0.3-10.5% and is dose-related, with increased incidence associated with higher doses. The majority of episodes of torsades de pointes have occurred within the first three days of initial dosing. Patients should be hospitalized and monitored for the first three days after starting dofetilide. The risk of inducing torsades de pointes can be decreased by taking precautions when initiating therapy, such as hospitalizing individuals for a minimum of three days for serial creatinine measurement, continuous telemetry monitoring and availability of cardiac resuscitation.
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.
No regulator in a major market has approved it for human use. It appears in research settings and in products marketed outside pharmacy channels. Legal status for personal possession varies by country.