Everything below concerns Alpha-MSH. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-04-27. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
Published research on the compound remains limited. Much of the human data comes from small, early-stage studies rather than large controlled trials, and several questions about effects and variability between individuals remain open. Investigators have examined receptor activity, pigment pathways, and related physiological responses in laboratory and animal models. Findings from those models do not automatically translate to human outcomes. Reviews frequently note the scarcity of rigorous clinical evidence and call for better-characterized study material.
Because the substance circulates mainly through informal markets, verification is a recurring theme in technical discussion. Independent analyses have found that labeled content and actual content can diverge, and that purity varies between samples. Analytical laboratories use reversed-phase chromatography to separate components and mass spectrometry to confirm identity. Isotope-labeled internal standards improve quantification in complex matrices. Such methods describe what a sample contains but say nothing about its sterility, lawful status, or suitability for any use. Open questions remain about how consistently testing is applied across the supply chain.
Regulatory treatment of this peptide varies by country. It holds no marketing authorization as a medicine in the United States, the European Union, or most other jurisdictions. Some countries classify products containing it as prescription-only or unlicensed medicines, which restricts lawful supply. Authorities have issued public notices warning that unregulated products may contain undeclared or incorrect ingredients. The molecule also appears on prohibited lists for competitive sport. These measures address supply oversight rather than any approved therapeutic role.
| Property | Value | Notes |
|---|---|---|
| Compound class | Synthetic cyclic heptapeptide | Alpha-MSH analogue containing a D-phenylalanine residue |
| Molecular formula | C50H69N15O9 | Average molecular mass approximately 1024.2 g/mol |
| Appearance | White to off-white lyophilised powder | Normally supplied as a freeze-dried solid in a sealed vial |
| Solubility | Freely soluble in water and polar solvents | Dissolves readily in aqueous buffers and in alcohol-water mixtures |
| Receptor targets | MC1R, MC3R, MC4R, MC5R | Acts as a non-selective melanocortin receptor agonist |
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 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.
Analytical confirmation of identity relies on mass spectrometry, most often coupled to liquid chromatography. Reversed-phase high-performance liquid chromatography separates the peptide from related impurities and provides a purity estimate based on peak area. Electrospray ionization mass spectrometry then confirms the expected molecular mass, while tandem mass spectrometry can map the fragment sequence. For research-grade material, these two techniques together form the standard minimum. Purity figures reported by vendors are frequently not traceable to an independent laboratory.
Independent verification is central to quality control because the compound is not produced under pharmaceutical manufacturing standards. Third-party laboratories can measure purity, identity, residual solvents, and microbial contamination, though the scope of testing varies between services. Reported analyses of vendor samples have shown batch-to-batch variation in peptide content and the presence of truncated or oxidized species. How much of this variation reflects synthesis conditions versus storage and shipping is not well characterized. No harmonized reference standard exists for the material as sold.
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.
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.
Lyophilized peptide powder is generally stored frozen, protected from light and moisture. Tryptophan residues are susceptible to oxidation, and the lactam bridge can hydrolyze under strongly acidic or basic conditions. Solutions prepared for laboratory work degrade faster than dry powder, and repeated freeze-thaw cycles accelerate loss. Common practice is to aliquot solutions before freezing and to avoid alkaline buffers. Reported stability windows vary with concentration, buffer, and temperature, so exact shelf lives are method-specific rather than universal.
Regulatory status differs by country, and in many places supplying the compound for human consumption is unlawful. Vendors frequently label material as intended for research use only, a designation that shifts stated purpose but does not create a legal pathway for personal use. Certificates of analysis accompanying such products vary widely in detail and provenance. Third-party testing exists but is voluntary, and results are rarely linked to a specific lot in a publicly verifiable way.
Identity testing for a synthetic peptide relies on several complementary methods. Reversed-phase high-performance liquid chromatography separates the target from related impurities and reports purity as a percentage of total peak area. Mass spectrometry confirms molecular mass and can reveal deletions or truncations. Amino acid analysis and peptide mapping provide sequence-level confirmation, while counter-ion content and residual solvents are measured separately. A purity figure alone does not establish identity, so a complete dataset combines chromatographic and spectrometric evidence.
==== Relations of being, becoming, existence and ultimate reality ==== According to Bhikkhu Bodhi, Peter Harvey and Paul Williams, dependent arising can be understood as an ontological principle; that is, a theory to explain the nature and relations of being, becoming, existence and ultimate reality. (Theravada) Buddhism asserts that there is nothing independent, except nirvana. This ontology holds that all physical and mental states depend on and arise from other pre-existing states, and in turn from them arise other dependent states while they cease. These 'dependent arisings' are causally conditioned, and thus pratityasamutpada is the Buddhist belief that causality is the basis of ontology. As Williams explains, "all elements of samsara exist in some sense or another relative to their causes and conditions. That is why they are impermanent, for if the cause is impermanent then so too will be the effect." Gombrich describes dependent origination as the idea that "nothing accessible to our reason or our normal experience exists without a cause". Furthermore, this can be seen as a metaphysical middle way which does not see phenomena as existing essentially nor as not-existing at all. Instead it sees the world as "a world of flux and process", a world of "verbs, not nouns." According to Rupert Gethin, the ontological principle of dependent origination is applied not only to explain the nature and existence of matter and empirically observed phenomenon, but also to the causally conditioned nature and existence of life.
=== Immunity === Function of heat-shock proteins in immunity is based on their ability to bind not only whole proteins, but also peptides. The affinity and specificity of this interaction is typically low. It was shown, that at least some of the HSPs possess this ability, mainly hsp70, hsp90, gp96 and calreticulin, and their peptide-binding sites were identified. In the case of gp96 it is not clear whether it can bind peptides in vivo, although its peptide-binding site has been found. But gp96 immune function could be peptide-independent, because it is involved in proper folding of many immune receptors, like TLR or integrins. Apart from that, HSPs can stimulate immune receptors and are important in proper folding of proteins involved in pro-inflammatory signaling pathways.
=== Bacterial or viral === As bacterial and viral infections can both cause the same kinds of symptoms, it can be difficult to distinguish which is the cause of a specific infection. Distinguishing the two is important, since viral infections cannot be cured by antibiotics whereas bacterial infections can.
In 1959 Ernst Freese coined the terms "transitions" or "transversions" to categorize different types of point mutations. Transitions are replacement of a purine base with another purine or replacement of a pyrimidine with another pyrimidine. Transversions are replacement of a purine with a pyrimidine or vice versa. There is a systematic difference in mutation rates for transitions (Alpha) and transversions (Beta). Transition mutations are about ten times more common than transversions.
Sources: en.wikipedia.org
The layers of the body can be approximated as a thin layer of epidermis, dermis, adipose tissue (subcutaneous fat), and muscle tissue. At dozens of gigahertz, the radiation is absorbed in the top fraction to top few millimeters of skin. Muscle tissue is a much more efficient absorber than fat, so at lower frequencies that can penetrate sufficiently deep, most energy gets deposited there. In a homogeneous medium, the energy-depth dependence is an exponential curve with the exponent depending on the frequency and tissue. For 2.5 GHz, the first millimeter of muscle tissue absorbs 11% of the heat energy, the first two millimeters together absorb 20%. For lower frequencies, the attenuation factors are much lower, the achievable heating depths are higher, and the temperature gradient within the tissue is lower.
where N is 100, nx is the percentage of sequences with residue x (e.g. methionine) at position i, and px corresponds to the approximate distribution of amino acid x in all positions among all sequenced proteins. The summation runs over all 20 amino acids. After ΔGistat is computed, the conservation for position i in a subalignment produced after a perturbation of amino acid distribution at j (ΔGi | δjstat) is taken. Statistical coupling energy, denoted ΔΔGi, jstat, is simply the difference between these two values. That is:
=== For La Niña === 2000 Mozambique flood 2010 Pakistan floods 2010–2011 Queensland floods 2010–2012 La Niña event 2010–2011 Southern Africa floods 2010–2013 Southern United States and Mexico drought 2011 East Africa drought 2020 Atlantic hurricane season 2021 eastern Australia floods 2022 Suriname floods 2023 Auckland Anniversary Weekend floods 2020–2023 La Niña event
AAV is of particular interest to gene therapists due to its apparent limited capacity to induce immune responses in humans, a factor which should positively influence vector transduction efficiency while reducing the risk of any immune-associated pathology. AAV is not considered to have any known role in disease. However, host immune system response and immune tolerance reduce the efficacy of AAV-mediated gene therapy. Host immune response has been shown to respond to the AAV vectors, the transduced cells, and the transduced proteins. The immune response can be subdivided into two categories: innate and adaptive, the latter of which is divided into humoral and cell-mediated.
DNA binding site prediction on protein DNA the Double Helix Game From the official Nobel Prize web site DNA under electron microscope Dolan DNA Learning Center Double Helix: 50 years of DNA, Nature Proteopedia DNA Proteopedia Forms_of_DNA ENCODE threads explorer ENCODE home page at Nature Double Helix 1953–2003 National Centre for Biotechnology Education Genetic Education Modules for Teachers – DNA from the Beginning Study Guide PDB Molecule of the Month DNA "Clue to chemistry of heredity found". The New York Times, June 1953. First American newspaper coverage of the discovery of the DNA structure DNA from the Beginning Another DNA Learning Center site on DNA, genes, and heredity from Mendel to the human genome project. The Register of Francis Crick Personal Papers 1938 – 2007 at Mandeville Special Collections Library, University of California, San Diego Seven-page, handwritten letter that Crick sent to his 12-year-old son Michael in 1953 describing the structure of DNA. See Crick's medal goes under the hammer, Nature, 5 April 2013.
Sources: en.wikipedia.org
Thorium-232 (232Th) is the main naturally occurring isotope of thorium, with a relative abundance of approximately 99.98%. It has a half-life of 14.0 billion years, which makes it the longest-lived isotope of thorium. It decays by alpha decay to radium-228; its decay chain terminates at stable lead-208. Thorium-232 is a fertile material; it can capture a neutron to form thorium-233, which subsequently undergoes two successive beta decays to uranium-233, which is fissile. As such, it has been used in the thorium fuel cycle in nuclear reactors; various prototype thorium-fueled reactors have been designed. However, as of 2024, thorium fuel has not been widely adopted for commercial-scale nuclear power. In 2025, China reported thorium-to-uranium conversion in an experimental molten-salt reactor.
reuteri-and-tryptophan-diet for checkpoint inhibitor potentiation (6 Apr), doxycycline post-exposure prophylaxis against STIs (6 Apr), an engineered probiotic against alcohol-induced damage (11 Apr), phase 2 trialed AXA1125 against long COVID fatigue (14 Apr), review finds cranberry products useful against UTIs in women (17 Apr) (but is not suggested for older people, those have trouble emptying their bladder, or people who are pregnant), and macaques-tested low-intensity focus ultrasound delivery of AAV into brain regions against brain diseases (19 Apr). Progress in screening: an α-synuclein SAA (assay) against Parkinson's disease (12 Apr), and exogenously administered bioengineered sensors that amplify urinary cancer biomarkers for detection (24 Apr). Promising innovations relating to global challenges are reported: a laser-using drone-based methane plume localization method, approval of the first yeast-based cow-free dairy (Remilk), a Tor browser-equivalent Web browser for privacy-protected browsing when using a VPN (Mullvad browser), a concentrated solar-to-hydrogen device approaching viability, a method for fat tissue cultured meat, flexible organic solar cells on balloons in the 35 km stratosphere.
At branch points, two or more separate reactions compete for the same reactant. This affects the isotopic composition of all products downstream of the branch point. To illustrate this, consider the network below: Here, the flux of material into pool B (φAB) is balanced by two fluxes, one into pool C and the other into pool D (φBC and φBD respectively). The mass balance for the heavier isotope in this system is represented by
As part of decolonization, France established the French Union in 1946 and reorganized Indochina in 1949 as a confederation of associated states within it. In June 1949, they united French Cochinchina with the protectorates of Annam and Tonkin to form the State of Vietnam within the French Union, and installed former Emperor Bảo Đại as head of state. The Chinese Communist victory of 1949 changed the nature of the Indochina War. In 1950, the newly established People's Republic of China and the Soviet Union recognized the DRV while the United States recognized the State of Vietnam. The conflict largely resembled a conventional war between two armies equipped with modern weapons, although guerrilla warfare continued to occur in many areas. The United States provided assistance to France, while China assisted the Viet Minh. French Union forces included colonial troops from the empire – North Africans, Sub-Saharan Africans, Laotian, Cambodian and Vietnamese ethnic minorities – and professional French troops, European volunteers, and units of the Foreign Legion. The use of French metropolitan recruits was forbidden by the government to prevent the war from becoming more unpopular at home. It was called the "dirty war" (la sale guerre) by French leftists. In December 1950, France officially established an army for the State of Vietnam. In September 1951, the US began providing direct economic aid to the State of Vietnam. Segments of the population supported neither the communist Viet Minh nor the French colonialists, and were labeled attentistes.
Sources: en.wikipedia.org
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.
No approved regulatory indication exists in major markets. An approval exists for a different peptide, afamelanotide, which is used for a rare photosensitivity disorder called erythropoietic protoporphyria. Melanotan-2 itself remains a research compound with no cleared clinical role.
Melanocortin-1 receptors on melanocytes are the receptor most closely linked to pigment production. The peptide is not selective, however, and also activates melanocortin-3, melanocortin-4, and melanocortin-5 receptors. That lack of selectivity is the usual explanation offered for both its range of observed effects and its off-target effects.
Only a small number of early-stage human studies have been reported, and most were limited in size and duration. No large late-stage program has established a general efficacy or safety profile. The evidence base is therefore thin compared with approved medicines.