alpha-MSH comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-03-26. Where a claim depends on a specific study, the study is described rather than over-claimed.
Published pharmacokinetic information is limited and comes mainly from small studies rather than registrational trials. Plasma half-life is usually described as short, on the order of tens of minutes, followed by rapid tissue distribution and clearance of the intact peptide. Metabolites and low concentrations of parent compound have been reported in urine, a detail relevant to anti-doping and forensic testing. Whether repeated exposure changes receptor sensitivity or clearance over time remains an open question. Values differ noticeably between analytical assays, so published numbers should be read as approximate rather than definitive.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Cyclic heptapeptide, C-terminally amidated |
| Approximate molecular mass | 1024 Da | Monoisotopic mass of the free peptide |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility class | Soluble in water and polar solvents | Also dissolves in neutral aqueous buffer |
| Common synonyms | Melanotan II, MT-II, MT-2 | Described as a melanocortin agonist in early literature |
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.
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.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, the naturally occurring peptide involved in pigmentation signalling. Its sequence is conventionally written as Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, with a lactam bridge joining the aspartate side chain to the lysine side chain. The empirical formula is C50H69N15O9 and the monoisotopic mass lies near 1023.5 daltons. N-terminal acetylation and the D-configured phenylalanine both increase resistance to enzymatic breakdown compared with the parent hormone.
==== Luspatercept ==== Luspatercept is a drug used to treat anemia in adults with β-thalassemia, it can improve the maturation of red blood cells and reduce the need for frequent blood transfusions. It is administered by injection every three weeks. Luspatercept was authorised for use in the US in 2019 and by the European Medicines Agency in 2020.
The side effect profile of bicalutamide in men and women differs from that of other antiandrogens and is considered favorable in comparison. Relative to GnRH analogues and the steroidal antiandrogen (SAA) cyproterone acetate (CPA), bicalutamide monotherapy has a much lower incidence and severity of hot flashes and sexual dysfunction. In addition, unlike GnRH analogues and CPA, bicalutamide monotherapy is not associated with decreased bone mineral density or osteoporosis. Conversely, bicalutamide monotherapy is associated with much higher rates of breast tenderness, gynecomastia, and feminization in men than GnRH analogues and CPA. However, gynecomastia with bicalutamide is rarely severe and discontinuation rates due to this side effect are fairly low. These differences in side effects between bicalutamide monotherapy, GnRH analogues, and CPA are attributed to the fact that whereas GnRH analogues and CPA suppress estrogen production, bicalutamide monotherapy does not lower estrogen levels and in fact actually increases them. Bicalutamide does not share the risk of neuropsychiatric side effects like fatigue as well as cardiovascular side effects like coagulation changes, blood clots, fluid retention, ischemic cardiomyopathy, and adverse serum lipid changes that CPA has been associated with. It has a much lower risk of hepatotoxicity than flutamide and CPA and of interstitial pneumonitis than nilutamide. The drug also does not share the unique risks of diarrhea with flutamide and nausea, vomiting, visual disturbances, and alcohol intolerance with nilutamide.
=== 2 December === The commander of the SAF's 22nd Infantry Division, Major-General Abdelmajid al-Haj, and an unidentified brigadier general who commanded the SAF's 170th Artillery Brigade were killed in an RSF ambush while retreating from Babanusa towards Heglig. The SAF retook the town of Mabsouta in South Kordofan from the SPLM-N (al-Hilu), which had occupied the area since 2011.
== History of profession == The idea of physician extenders was conceived in 1966 by physician-educator Eugene A. Stead at Duke University, where the first physician assistant program was established. Three years later, also at Duke, Chairman of Pathology, Dr. Thomas Kinney established the first pathologists’ assistant program. As of June 2025, seventeen accredited programs have been established across the United States and Canada and six others are in various stages of accreditation.
In contrast to LAPs, where cyclodehydration occurs via the action of two distinct proteins responsible for leader peptide binding and cyclodehydrative catalysis, these are fused into a single protein (G protein) in cyanobactin and thiopeptide biosynthesis. However, in thiopeptides, an additional protein, designated the Ocin-ThiF-like protein (F protein) is necessary for leader peptide recognition and potentially recruiting other biosynthetic enzymes.
Sources: en.wikipedia.org
In CYP2D6 extensive metabolizers, the half-lives of 4-hydroxyatomoxetine and N-desmethylatomoxetine are similar at around 6 to 8 hours, whereas in CYP2D6 poor metabolizers, the half-life of N-desmethylatomoxetine is much longer at around 33 to 40 hours. Atomoxetine levels in cerebrospinal fluid (CSF) with atomoxetine at a dosage of 80 mg/day were 6.6 ng/mL at 8 hours post-dose and 1.4 ng/mL at 24 hours post-dose following 2 weeks of administration.
=== Spinal puncture === Following spinal anesthesia or puncture, people who are being treated with anti-thrombotic agents are at higher risk for developing a hematoma, which causes long-term or permanent paralysis. The risk of this may be increased by using epidural or intrathecal catheters after a surgical operation or from the concurrent use of medicinal agents that affect hemostasis.
Therefore I should infer from analogy that probably all the organic beings which have ever lived on this earth have descended from some one primordial form, into which life was first breathed. But he precedes that remark by, "Analogy would lead me one step further, namely, to the belief that all animals and plants have descended from some one prototype. But analogy may be a deceitful guide." And in the subsequent edition, he asserts rather, "We do not know all the possible transitional gradations between the simplest and the most perfect organs; it cannot be pretended that we know all the varied means of Distribution during the long lapse of years, or that we know how imperfect the Geological Record is. Grave as these several difficulties are, in my judgment they do not overthrow the theory of descent from a few created forms with subsequent modification". Common descent was widely accepted amongst the scientific community after Darwin's publication. In 1907, Vernon Kellogg commented that "practically no naturalists of position and recognized attainment doubt the theory of descent." In 2008, biologist T. Ryan Gregory noted that:
the flow must be steady, that is, the flow parameters (velocity, density, etc.) at any point cannot change with time, the flow must be incompressible—even though pressure varies, the density must remain constant along a streamline; friction by viscous forces must be negligible. For conservative force fields (not limited to the gravitational field), Bernoulli's equation can be generalized as:
Sources: en.wikipedia.org
=== T cells === Some T cells (e.g. regulatory T cells) release TGF-β1 to inhibit the actions of other T cells. Specifically, TGF-β1 prevents the interleukin(IL)-1- & interleukin-2-dependent proliferation in activated T cells, as well as the activation of quiescent helper T cells and cytotoxic T cells. Similarly, TGF-β1 can inhibit the secretion and activity of many other cytokines including interferon-γ, tumor necrosis factor-alpha (TNF-α), and various interleukins. It can also decrease the expression levels of cytokine receptors, such as the IL-2 receptor to down-regulate the activity of immune cells. However, TGF-β1 can also increase the expression of certain cytokines in T cells and promote their proliferation, particularly if the cells are immature.
In Japan, iced coffee (アイスコーヒー, aisu kōhī) has been drunk since the Taishō period (around the 1920s) in coffeehouses. It is served with gum syrup and milk. Cold tea was already popular, so it was natural to drink cold coffee. Cold brew coffee is also common in Japan, where it is known as Dutch coffee (ダッチ・コーヒー, dacchi kōhī), due to the historical Dutch coffee trade from Indonesia. In 1969, UCC Ueshima Coffee released canned coffee, which made coffee available everywhere. Today, canned liquid coffee is consumed both cold and hot. Some Japanese iced coffee is prepared by brewing the coffee with hot water and allowing the coffee to drip over ice cubes. The volume of hot water is reduced to account for the dilution of the coffee by the melting ice. This method produces results similar to other iced coffees but is comparable to brewing hot coffee in time and effort.
=== Graphene quantum dots === A graphene quantum dot (GQD) is a graphene fragment with a size less than 100 nm. The properties of GQDs are different from bulk graphene due to the quantum confinement effects which only become apparent when the size is smaller than 100 nm.
=== Sperm morphology === Regarding sperm morphology, the WHO criteria as described in 2021 state that a sample is normal (samples from men whose partners had a pregnancy in the last 12 months) if 4% (or 5th centile) or more of the observed sperm have normal morphology. If the sample has less than 4% of morphologically normal spermatozoa, it's classified as teratozoospermia. Normal sperm morphology is hard to classify because of lack of objectivity and variations in interpretation, for instance. In order to classify spermatozoa as normal or abnormal, the different parts should be considered. Sperm has a head, a midpiece and a tail. Firstly, the head should be oval-shaped, smooth and with a regular outline. What is more, the acrosomal region should comprise the 40–70% area of the head, be defined and not contain large vacuoles. The amount of vacuoles should not excess the 20% of the head's area. It should be 4–5 μm long and a width of 2.5–3.5 μm. Secondly, the midpiece and the neck should be regular, with a maximal width of 1 μm and a length of 7–8 μm. The axis of the midpiece should be aligned with the major axis of the head. Finally, the tail should be thinner than the midpiece and have a length of 45 μm approximately and a constant diameter along its length. It is important that it is not rolled up. Since abnormalities are frequently mixed, the teratozoospermia index (TZI) is really helpful. This index is the mean number of abnormalities per abnormal sperm. To calculate it, 200 spermatozoa are counted (this is a good number).
Two different types of experiments were conducted: one-stepwise pyrolysis and two-stepwise pyrolysis. One-stepwise pyrolysis consisted of a constant heating rate (10 °C min−1) from 30 to 720 °C. In the second step of the two-stepwise pyrolysis test the pyrolysates from the one-stepwise pyrolysis were pyrolyzed in the second heating zone which was controlled isothermally at 650 °C. The two-stepwise pyrolysis was used to focus primarily on how well CO2 affects carbon redistribution when adding heat through the second heating zone. First noted was the thermolytic behaviors of TLW and TSW in both the CO2 and N2 environments. For both TLW and TSW the thermolytic behaviors were identical at less than or equal to 660 °C in the CO2 and N2 environments. The differences between the environments start to occur when temperatures increase above 660 °C and the residual mass percentages significantly decrease in the CO2 environment compared to that in the N2 environment. This observation is likely due to the Boudouard reaction, where we see spontaneous gasification happening when temperatures exceed 710 °C. Although these observations were seen at temperatures lower than 710 °C it is most likely due to the catalytic capabilities of inorganics in TLW. It was further investigated by doing ICP-OES measurements and found that a fifth of the residual mass percentage was Ca species. CaCO3 is used in cigarette papers and filter material, leading to the explanation that degradation of CaCO3 causes pure CO2 reacting with CaO in a dynamic equilibrium state.
Sources: en.wikipedia.org
No. It is a synthetic analogue carrying four amino acid changes, a lactam ring and an amidated C-terminus. The natural hormone is a linear thirteen-amino-acid peptide processed from proopiomelanocortin.
Afamelanotide is the linear analogue [Nle4-D-Phe7]-alpha-MSH, sometimes called melanotan I, while melanotan II is cyclic and carries three further substitutions. The two are distinct molecules and are not interchangeable in analytical testing.
Binding to the four melanocortin receptor subtypes is well documented in vitro. The relative contribution of each subtype to whole-body effects in humans is far less certain.
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.