Everything below concerns melanocortin receptor. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-07-12. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Identity testing for a cyclic peptide of this size usually relies on reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The mass spectrum confirms molecular weight, while the chromatographic trace indicates the proportion of related impurities. Tandem mass spectrometry can provide sequence-level information when fragmentation data are compared against a reference standard. Nuclear magnetic resonance is sometimes used to confirm the lactam bridge, although it requires more material and greater operator expertise than routine chromatographic methods.
Lyophilised peptide powder is comparatively stable when kept dry, cold and protected from light. Once dissolved, the molecule is exposed to hydrolysis, oxidation and microbial growth, and degradation accelerates at higher temperatures and in alkaline solution. Repeated freeze-thaw cycles concentrate solutes and promote aggregation. Handling guidance for research peptides commonly clusters around freezer temperatures for powder and short refrigerated use for reconstituted solutions, with pH control and sterile technique applied throughout.
Verification of a purchased sample requires documentation linking a batch to a certificate of analysis, and that document should be read for the methods used rather than the headline purity figure. A single chromatographic percentage does not establish identity. Independent laboratories can perform identity and content assays, but no such test establishes that a product is suitable for human use. Claims about efficacy rest largely on small, early studies rather than on replicated controlled trials, and that gap remains open.
| 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 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.
Lyophilised melanotan-2 is comparatively robust when kept dry, cold and dark, and a desiccated powder stored at minus twenty degrees Celsius or below is generally expected to retain its chemical integrity for extended periods. In solution the peptide is far less stable, with degradation proceeding through oxidation of tryptophan and histidine residues, hydrolysis adjacent to the lactam bridge, and aggregation at higher concentrations. Repeated freeze-thaw cycling accelerates loss of the parent peak. Working aliquots are therefore prepared once, held cold, and used without letting the stock return to ambient temperature.
Quality assessment of research-grade peptide rests mainly on reversed-phase high-performance liquid chromatography for purity and on mass spectrometry for identity confirmation. A single main peak above a stated threshold, commonly ninety-eight percent by peak area, is the usual release criterion applied by suppliers. Independent analyses commissioned by laboratories and consumer organisations have repeatedly reported discrepancies between label claims and measured content, including truncated sequences, residual trifluoroacetate, and lower-than-declared peptide mass. Those findings do not establish that every supplier is unreliable, but they indicate that purity figures printed on a vial are claims requiring verification rather than settled facts.
Three vessels traveling in a convoy were struck on 30 December, killing three people. After the first vessel was hit, an unknown number of survivors jumped overboard from the other two vessels before they were sunk. Unnamed sources reported at least six, and possibly eight survivors. On 2 January 2026, US Coast Guard suspended a search for survivors southwest of the Mexican–Guatemalan border, in the fourth strike where crew members survived the initial strike. A 23 January strike killed two people and left one survivor, for whom the US Coast Guard activated a search-and-rescue mission. A 5 February strike on an alleged Designated Terrorist Organization killed two people. A US military strike on 9 February killed two people and left one survivor for whom the Maritime Rescue Coordination Center Ecuador launched a search-and-rescue mission with technical assistance from the US Coast Guard. On 16 February, the US struck two boats in the Pacific, killing four people per boat. A 20 February strike killed three people. An 8 March strike killed six. A 19 March strike killed two and left one survivor who was captured. A 18 June strike killed three.
== Principle == This technique is applicable to gases or any materials that can be vaporized. It uses a non-fragmenting non-conventional ionisation mode, by attachment of a lithium (or alkaline) ion to the gas to be analysed with a more traditional mass filter. This instrument is more dedicated to analysis of moderately-sized molecules such as organic or aromatic compounds.
In 1968, a period of political liberalization took place in Czechoslovakia called the Prague Spring. An "Action Program" of reforms included increasing freedom of the press, freedom of speech and freedom of movement, along with an economic emphasis on consumer goods, the possibility of a multiparty government, limitations on the power of the secret police, and potential withdrawal from the Warsaw Pact. In answer to the Prague Spring, on 20 August 1968, the Soviet Army, together with most of their Warsaw Pact allies, invaded Czechoslovakia. The invasion was followed by a wave of emigration, including an estimated 70,000 Czechs and Slovaks initially fleeing, with the total eventually reaching 300,000. The invasion sparked intense protests from Yugoslavia, Romania, China, and from Western European countries.
Sources: en.wikipedia.org
The most common set of catabolic reactions in animals can be separated into three main stages. In the first stage, large organic molecules, such as proteins, polysaccharides or lipids, are digested into their smaller components outside cells. Next, these smaller molecules are taken up by cells and converted to smaller molecules, usually acetyl coenzyme A (acetyl-CoA), which releases some energy. Finally, the acetyl group on acetyl-CoA is oxidized to water and carbon dioxide during the citric acid cycle and electron transport chain, releasing more energy while reducing the coenzyme nicotinamide adenine dinucleotide (NAD+) into NADH.
=== Cutaneous angiofibroma === These papule, nodule, and/or tumor lesions occur on the: 1) face and are typically termed fibrous papules; 2) penis and are typically termed pearly penile papules; and 3) underneath a fingernail or toenail and are typically termed periungual angiofibromas. Some of these cutaneous AGF lesions occur in individuals with one or more of 3 different genetic diseases: tuberous sclerosis, multiple endocrine neoplasia type 1, and Birt-Hogg-Dube syndrome. The following are examples of these cutaneous angiofibromas and their alternate names.
== Epidemiology == According to a Japanese study from 2007, Bethlem myopathy 1 affects about 1 in 200,000 people. A 2009 study, concerning the prevalence of genetic muscle disease in Northern England, estimated the prevalence of Bethlem myopathy 1 to be at 0.77:100,000. Together with Ullrich congenital muscular dystrophy 1, Bethlem myopathy 1 is believed to be underdiagnosed. Both conditions have been described in individuals from a variety of ethnic backgrounds. Bethlem myopathy 2 affects less than 1 in 1,000,000 people.
Sources: en.wikipedia.org
Light or fresh (生抽; pinyin: shēng chōu; Jyutping: saang1 cau1; Cantonese Yale: sāangchāu or 醬清; pinyin: jiàng qīng; Jyutping: zoeng3 cing1; Cantonese Yale: jeungchīng): is a thin (low viscosity), opaque, lighter brown soy sauce, brewed by first culturing steamed wheat and soybeans with Aspergillus, and then letting the mixture ferment in brine. It is the main soy sauce used for seasoning, since it is saltier, has less noticeable color, and also adds a distinct flavor. Tóu chōu (頭抽): A light soy sauce made from the first pressing of the soybeans, this can be loosely translated as "first soy sauce" or referred to as premium light soy sauce. Tóu chōu is sold at a premium because, like extra virgin olive oil, the flavor of the first pressing is considered superior. Due to its delicate flavor it is used primarily for seasoning light dishes and for dipping. Shuāng huáng (雙璜): A light soy sauce that is double-fermented by using the light soy sauce from another batch to take the place of brine for a second brewing. This adds further complexity to the flavor of the light soy sauce. Due to its complex flavor this soy sauce is used primarily for dipping. Yìn yóu (蔭油): A darker soy sauce brewed primarily in Taiwan by culturing only steamed soybeans with Aspergillus and mixing the cultured soybeans with coarse rock salt before undergoing prolonged dry fermentation. The flavor of this soy sauce is complex and rich and is used for dipping or in red cooking. For the former use, yìn yóu can be thickened with starch to make a thick soy sauce.
=== Board game === Main articles: Le Havre (board game) Le Havre is a board game about the development of the town of Le Havre. It was inspired by the games Caylus and Agricola and was developed in December 2007.
There is overwhelming scientific consensus that vaccines are a very safe and effective way to fight and eradicate infectious diseases. The immune system recognizes vaccine agents as foreign, destroys them, and "remembers" them. When the virulent version of an agent is encountered, the body recognizes the protein coat on the agent, and thus is prepared to respond, by first neutralizing the target agent before it can enter cells, and secondly by recognizing and destroying infected cells before that agent can multiply to vast numbers. In 1958, there were 763,094 cases of measles in the United States; 552 deaths resulted. After the introduction of new vaccines, the number of cases dropped to fewer than 150 per year (median of 56). In early 2008, there were 64 suspected cases of measles. Fifty-four of those infections were associated with importation from another country, although only thirteen percent were actually acquired outside the United States; 63 of the 64 individuals either had never been vaccinated against measles or were uncertain whether they had been vaccinated. The measles vaccine is estimated to prevent a million deaths every year. Vaccines led to the eradication of smallpox, one of the most contagious and deadly diseases in humans. Other diseases such as rubella, polio, measles, mumps, chickenpox, and typhoid are nowhere near as common as they were a hundred years ago thanks to widespread vaccination programs. As long as the vast majority of people are vaccinated, it is much more difficult for an outbreak of disease to occur, let alone spread.
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.
Mass spectrometry combined with liquid chromatography provides both molecular weight confirmation and a measure of related impurities. Tandem mass spectrometry adds sequence information. A purity percentage reported without a mass measurement does not confirm what the material is.