Everything below concerns afamelanotide. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-08-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
Published human data come mostly from small, short studies rather than large controlled trials. Reported outcomes include increased skin pigmentation and, in some reports, effects on appetite and libido, but sample sizes are small and follow-up is limited. Whether long-term use produces durable pigment changes or adverse effects is not established. Because products sold outside pharmacies are not standardized, the actual content of any given vial is often unknown. Independent testing of such material is uncommon.
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.
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.
Receptor studies place melanotan-2 among non-selective melanocortin agonists, binding MC1R, MC3R, MC4R and MC5R rather than a single subtype. Activation of MC1R on cutaneous melanocytes raises tyrosinase activity and shifts pigment synthesis toward eumelanin, which is darker and more photostable than pheomelanin. Central receptors, particularly MC4R, are associated with appetite suppression and with reported effects on sexual function. Because subtype selectivity is low, the same molecule engages pigment, metabolic and vascular pathways at once, and this breadth is a common explanation offered for the range of adverse events described in user reports.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Analog of alpha-melanocyte-stimulating hormone |
| Primary receptor family | Melanocortin receptors MC1R through MC5R | Binding is not subtype-selective |
| Development period | 1980s | Synthesized during pigmentation and appetite research |
| Regulatory status | Not an approved medicine | No major regulator has authorized human use |
| Related compound | Afamelanotide | Linear analog studied for photoprotection |
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.
The compound was developed in the late 1980s and early 1990s by academic researchers investigating melanocortin signaling and pigmentation. Early work explored whether synthetic analogs could reproduce effects of the natural hormone under controlled conditions. The molecule never advanced through the full regulatory pathway required for approval as a medicine. From the mid-2000s onward it appeared in unregulated consumer markets, often distributed through informal channels. That gap between research origins and commercial availability shapes how the compound is discussed today.
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.
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.
Melanotan II is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its structure substitutes a lactam bridge between side chains to increase stability relative to the native hormone. The compound is also known by the shorthand MT-II and by several non-proprietary synonyms used in research catalogues. It is not an approved therapeutic product in any major jurisdiction; material sold under this name is typically offered as a laboratory reagent rather than as a medicine.
Activity is attributed to agonism at melanocortin receptors, particularly MC1R and MC4R. Activation of MC1R on melanocytes increases melanin synthesis, which underlies the reported tanning effect. MC4R engagement in the central nervous system is linked to appetite suppression and to effects on sexual arousal reported in early clinical studies. Those studies were small and were not designed to establish efficacy or long-term safety. Receptor selectivity among the melanocortin subtypes is not absolute, which complicates attribution of any effect to a single pathway.
Regulatory treatment varies between countries. Several national medicines agencies have classified the peptide as unapproved, and customs authorities in some jurisdictions seize shipments on that basis. A few jurisdictions channel supply through prescription-only frameworks that do not list the substance by name. Because the material circulates mainly through online vendors, composition and purity are rarely verified before sale. Surveys of unapproved peptide products have reported labels that did not match measured content in a substantial fraction of samples.
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.
Among the most important governance standards are rights vote for who is on the board of directors for investors of labour and capital. A Draft Fifth Company Law Directive proposed in 1972, which would have required EU-wide rights for employees to vote for boards stalled mainly because it attempted to require two-tier board structures, although most EU member states have codetermination today with unified boards. The Shareholder Rights Directive 2007 requires shareholders be able to make proposals, ask questions at meetings, vote by proxy and vote through intermediaries. This has become increasingly important as most company shares are held by institutional investors (primarily asset managers or banks, depending on the member state) who are holding "other people's money". A large proportion of this money comes from employees and other people saving for retirement, but who do not have an effective voice. Unlike Switzerland after a 2013 people's initiative, or the U.S. Dodd-Frank Act 2010 in relation to brokers, the EU has not yet prevented intermediaries casting votes without express instructions of beneficiaries. This concentrates power into a small number of financial institutions, and creates the potential for conflicts of interest where financial institutions sell retirement, banking or products to companies in which they cast votes with other people's money. A series of rights for ultimate investors exist in the Institutions for Occupational Retirement Provision Directive 2003.
Tumors are formed by carcinogenesis, a process in which cellular alterations lead to the formation of cancer. Multistage carcinogenesis involves the sequential genetic or epigenetic changes to a cell's DNA, where each step produces a more advanced tumor. It consists of three stages: initiation, promotion and progression. Multiple mutations may occur per stage. Initiation is where the first genetic mutation occurs in a cell. Promotion is the clonal expansion (repeated division) of this transformed cell into a visible tumor that is usually benign. Following promotion, progression may take place where more genetic mutations are acquired in a sub-population of tumor cells. Progression changes the benign tumor into a malignant tumor. A prominent and well studied example of this phenomenon is the tubular adenoma, a common type of colon polyp which is an important precursor to colon cancer. The cells in tubular adenomas, like most tumors that frequently progress to cancer, show certain abnormalities of cell maturation and appearance collectively known as dysplasia. These cellular abnormalities are not seen in benign tumors that rarely or never turn cancerous, but are seen in other pre-cancerous tissue abnormalities which do not form discrete masses, such as pre-cancerous lesions of the uterine cervix.
==== Thyroid hormones ==== There is some evidence for the addition of a thyroid hormone, triiodothyronine, in patients with normal thyroid function. For TRD patients, T3 has been studied in the STAR-D study with having a remission rate of 24.7%. T4 is also being studied for this purpose and found remission rates of 21.5%–64.7% for TRD patients.
Hydraulic cement render (stucco) for finishing brick buildings in wet climates Hydraulic mortars for masonry construction of harbor works, etc., in contact with sea water Development of strong concretes Modern cements are often Portland cement or Portland cement blends, but other cement blends are used in some industrial settings.
=== Palmar and plantar aponeuroses and extensor hood === The palmar aponeuroses occur on the palms of the hands. The extensor hoods are aponeuroses at the back of the fingers. The plantar aponeuroses occur on the plantar aspect of the foot. They extend from the calcaneal tuberosity then diverge to connect to the bones, ligaments and the dermis of the skin around the distal part of the metatarsal bones.
Sources: en.wikipedia.org
Pseudoephedrine induces monoamine release in vitro with an EC50Tooltip half maximal effective concentration of 224 nM for norepinephrine and 1,988 nM for dopamine, whereas it is inactive for serotonin. As such, it is about 9-fold selective for induction of norepinephrine release over dopamine release. The drug has negligible agonistic activity at the α1- and α2-adrenergic receptors (Kact >10,000 nM). At the β1- and β2-adrenergic receptors, it acts as a partial agonist with relatively low affinity (β1 = Kact = 309 μM, IATooltip intrinsic activity = 53%; β2 = 10 μM; IA = 47%). It was an antagonist or very weak partial agonist of the β3-adrenergic receptor (Kact = ND; IA = 7%). It is about 30,000 to 40,000 times less potent as a β-adrenergic receptor agonist than (–)-isoproterenol. Pseudoephedrine's principal mechanism of action relies on its action on the adrenergic system. The vasoconstriction that pseudoephedrine produces is believed to be principally an α-adrenergic receptor response. Pseudoephedrine acts on α- and β2-adrenergic receptors, to cause vasoconstriction and relaxation of smooth muscle in the bronchi, respectively. α-Adrenergic receptors are located on the muscles lining the walls of blood vessels. When these receptors are activated, the muscles contract, causing the blood vessels to constrict (vasoconstriction). The constricted blood vessels now allow less fluid to leave the blood vessels and enter the nose, throat, and sinus linings, which results in decreased inflammation of nasal membranes, as well as decreased mucus production.
Gloves made of natural rubber (latex) do not properly withstand chemical attacks, a.o. by concentrated nitric acid (e.g., 6 M HNO3) commonly used to keep polonium in solution while minimizing its sorption onto glass. They do not provide sufficient protection against the contamination from polonium (diffusion of 210Po solution through the intact latex membrane, or worse, direct contact through tiny holes and cracks produced when the latex begins to suffer degradation by acids or UV from ambient light); additional surgical gloves are necessary (inside the glovebox to protect the main gloves when handling strong acids and bases, and also from outside to protect the operator hands against 210Po contamination from diffusion, or direct contact through glove defects). Chemically more resistant, and also denser, neoprene and butyl gloves shield alpha particles emitted by polonium better than natural rubber. The use of natural rubber gloves is not recommended for handling 210Po solutions.
Health behavior refers to a person's beliefs and actions regarding their health and well-being. Health behaviors are direct factors in maintaining a healthy lifestyle. Health behaviors are influenced by the social, cultural, and physical environments in which we live. They are shaped by individual choices and external constraints. Positive behaviors help promote health and prevent disease, while the opposite is true for risk behaviors. Health behaviors are early indicators of population health. Because of the time lag that often occurs between certain behaviors and the development of disease, these indicators may foreshadow the future burdens and benefits of health-risk and health-promoting behaviors.
Alexandre Marc Raymond was born on 22 January 1872 in Constantinople, in Turkey, then part of the Ottoman Empire. He was the son of Marc Raymond, architect, born in Constantinople in 1846, and Rose Valsamaki, Greek Orthodox, born in Cephalonia. In 1894, he began studying at Sanayi-i Nefise Mektebi (School of Fine Arts) in Constantinople where he was a student of Alexander Vallaury.
Sources: en.wikipedia.org
=== Vocalizations === The American kestrel has three basic vocalizations – the "klee" or "killy", the "whine", and the "chitter". The "klee" is usually delivered as a rapid series – klee, klee, klee, klee when the kestrel is upset or excited. This call is used in a wide variety of situations and is heard from both sexes, but the larger females typically have lower-pitched voices than the males. The "whine" call is primarily associated with feeding but is also uttered during copulation. The "chitter" is used in activities that involve interaction between male and female birds, including courtship feeding, copulation, and the feeding of nestlings. Nestlings can produce calls similar to those of adults at 16 days old.
In Canada and the United States, half and half almost always refers to a light cream typically used in coffee. (See above.) The name refers to the liquid's content of half milk and half cream. It is widely available in the United States, both in individual-serving containers and in bulk. It is also used to make ice cream. Non-fat versions of the product are also available, containing corn syrup and other ingredients. This half and half can be also used to make a dirty soda. In addition to the light coffee cream, half and half can refer to other drinks in some regions of the U.S. A half and half of iced tea and lemonade is popular in the Northeastern United States. It consists of one part iced tea, sweetened, unsweetened or both, and one part lemonade served over ice. This drink is also called an Arnold Palmer, named for an American golfer, but that drink more correctly is mostly tea with one-quarter to one-third lemonade. In the Southern United States (specifically the cities of Atlanta and Houston), "half and half" may also refer to a mixture of half sweet and half unsweetened iced tea. Some coffee shops in colder climates serve a half and half drink consisting of half coffee and half hot chocolate, similar to caffè mocha. Half and half might also refer to a flavor of soda that combines the flavors of grapefruit and lemon.
=== Thermal decomposition === Ethylene oxide is relatively stable to heating – in the absence of a catalyst, it does not dissociate up to 300 °C (572 °F), and only above 570 °C (1,058 °F) there is a major exothermic decomposition, which proceeds through the radical mechanism. The first stage involves isomerization, however high temperature accelerates the radical processes. They result in a gas mixture containing acetaldehyde, ethane, ethyl, methane, hydrogen, carbon dioxide, ketene, and formaldehyde. High-temperature pyrolysis (830–1,200 K (557–927 °C; 1,034–1,700 °F)) at elevated pressure in an inert atmosphere leads to a more complex composition of the gas mixture, which also contains acetylene and propane. Contrary to the isomerization, initiation of the chain occurs mainly as follows:
Sources: en.wikipedia.org
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.
Afamelanotide is a linear analog that has received approval in some jurisdictions for a specific photoprotection indication. Melanotan II is cyclic and less selective across melanocortin receptors. The two are related but are not interchangeable in regulatory or clinical terms.
A compound that activates several receptor subtypes may produce effects beyond pigmentation. Selectivity influences which tissues respond and shapes the side-effect profile described in reports. Designing subtype-selective analogs is a stated goal of melanocortin research.
No regulatory agency has authorised melanotan-2 as a medicine for any indication. It circulates mainly as a research chemical or through unregulated channels. As a result, identity, purity and content are not independently guaranteed.