Everything below concerns melanogenesis. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-11-17. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Structurally, Melanotan-2 retains the core recognition motif of alpha-melanocyte-stimulating hormone while adding a lactam bridge that links two side chains and constrains the molecule into a ring. This modification lowers susceptibility to enzymatic degradation. The compound acts as an agonist at melanocortin receptors, particularly subtypes associated with melanin production. Because the same receptor family influences several physiological processes, researchers note that its activity is not confined to pigmentation alone. Receptor selectivity continues to be examined in published studies.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its sequence incorporates modified residues that increase potency and extend biological activity relative to the native hormone. The compound binds receptors of the melanocortin family and is examined mainly in laboratory research. It does not occur naturally and exists only as a manufactured chemical entity produced by solid-phase synthesis.
| 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 |
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.
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.
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.
== History == Eflornithine was initially developed for cancer treatment at Merrell Dow Research Institute in the late 1970s, but was found to be ineffective in treating malignancies. However, it was discovered to be highly effective in reducing hair growth, as well as in the treatment of African trypanosomiasis (sleeping sickness), especially the West African form (Trypanosoma brucei gambiense).
=== 1988 === February 20: The First Nagorno-Karabakh War was fought between Armenia and Azerbaijan. February 22: USS Yorktown and USS Caron are rammed off the Crimean Peninsula after entering Soviet territorial waters. May 11: Kim Philby (Harold Adrian Russell Philby), the high-ranking UK intelligence officer who defected to the Soviet Union, dies in Moscow. May 15: The Soviets begin withdrawing from Afghanistan. May 29–June 1: Reagan and Gorbachev meet in Moscow. INF Treaty ratified. When asked if he still believes that the Soviet Union is still an evil empire, Reagan replies he was talking about "another time, another era". October 5: Chile's Augusto Pinochet loses a national plebiscite on his rule. November 3: A coup attempt occurred in the Maldives. November 6: Soviet scientist and well-known human rights activist Andrei Sakharov begins a two-week visit to the United States. November 15: The State of Palestine was formally established through the Palestinian Declaration of Independence. December 7: Gorbachev announces in a speech to the United Nations General Assembly that the Soviet Union will no longer militarily interfere with Eastern Europe.
On 20 January 2001 the Indian Space Research Organisation (ISRO) conducted a balloon flight from Hyderabad, India to collect stratospheric dust from a height of 41 km (135,000 ft) with a view to testing for the presence of living cells. The collaborators on this project included a team of UK scientists led by Wickramasinghe. In a paper presented at a SPIE conference in San Diego in 2002 the detection of evidence for viable microorganisms from 41 km above the Earth's surface was presented. However, the experiment did not present evidence as to whether the findings are incoming microbes from space rather than microbes carried up to 41 km from the surface of the Earth. In 2005 the ISRO group carried out a second stratospheric sampling experiment from 41 km altitude and reported the isolation of three new species of bacteria including one that they named Janibacter hoylei sp.nov. in honour of Fred Hoyle. However, these facts do not prove that bacteria on Earth originated in the cosmic environment. Samplings of the stratosphere have also been carried out by Yang et al. (2005, 2009). During the experiment strains of highly radiation-resistant Deinococcus bacterium were detected at heights up to 35 km. Nevertheless, these authors have abstained from linking these discoveries to panspermia. Wickramasinghe was also involved in coordinating analyses of the red rain in Kerala in collaborations with Godfrey Louis.
A Taylor cone refers to the cone observed in electrospinning, electrospraying and hydrodynamic spray processes from which a jet of charged particles emanates above a threshold voltage. Aside from electrospray ionization in mass spectrometry, the Taylor cone is important in field-emission electric propulsion (FEEP) and colloid thrusters used in fine control and high efficiency (low power) thrust of spacecraft.
failed wars like Mr Galloway, who beats an established party, should be instantly savaged as a self-serving demagogue." In October 2013, the Total Politics magazine published an interview with Galloway in which he admitted: "I like elections more than I like serving", and said that he found being an MP was "2% terrifying, and 98% tedium." By 2013, he was a prolific user of Twitter where he had over 116,000 followers. In late 2013, Galloway became Leader of the Respect Party.
Sources: en.wikipedia.org
== Water source == Lake Afdera is fed by numerous hot springs around the lake and, possibly, by underwater springs. The waters of lake Afdera are saline but do not come from the sea. The continental waters gained their salinity by hydrothermal reactions with evaporites and basalts in the underground. The lake level varied significantly in the last tens of thousands of years. During the African Humid Period, the lake level was 50m higher than today and covered much larger area. Since the 1960s' the lake level constantly fluctuated, but these variations were probably less than one meter in amplitude. This suggest that the lake level is controlled by climate and precipitations on the Ethiopian plateau or in the Danakil Alps.
Moreover, chloral hydrate is used as a reagent for the deprotection of acetals, dithioacetals and tetrahydropyranyl ethers in organic solvents. The compound can be crystallized in a variety of polymorphs.
Apoptosis in HeLa cells is inhibited by proteins produced by the cell; these inhibitory proteins target retinoblastoma tumor-suppressing proteins. These tumor-suppressing proteins regulate the cell cycle, but are rendered inactive when bound to an inhibitory protein. HPV E6 and E7 are inhibitory proteins expressed by the human papillomavirus, HPV being responsible for the formation of the cervical tumor from which HeLa cells are derived. HPV E6 causes p53, which regulates the cell cycle, to become inactive. HPV E7 binds to retinoblastoma tumor suppressing proteins and limits its ability to control cell division. These two inhibitory proteins are partially responsible for HeLa cells' immortality by inhibiting apoptosis to occur.
Double-stranded RNA (dsRNA) is RNA with two complementary strands, similar to the DNA found in all cells, but with the replacement of thymine by uracil and the adding of one oxygen atom. dsRNA forms the genetic material of some viruses (double-stranded RNA viruses). Double-stranded RNA, such as viral RNA or siRNA, can trigger RNA interference in eukaryotes, as well as interferon response in vertebrates. In eukaryotes, double-stranded RNA (dsRNA) plays a role in the activation of the innate immune system against viral infections. In the late 1970s, it was shown that there is a single stranded covalently closed, i.e. circular form of RNA expressed throughout the animal and plant kingdom (see circRNA). circRNAs are thought to arise via a "back-splice" reaction where the spliceosome joins a upstream 3' acceptor to a downstream 5' donor splice site. So far the function of circRNAs is largely unknown, although for few examples a microRNA sponging activity has been demonstrated.
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.
It is a synthetic cyclic heptapeptide and an analogue of alpha-melanocyte-stimulating hormone. The molecule is produced by chemical synthesis rather than extracted from a biological source.