salt form is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-06-25. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Melanocortin receptors comprise five subtypes with distinct tissue distributions and functions. Melanotan-2 is described in the literature as a non-selective agonist that engages several of these subtypes, including MC1R, MC3R, MC4R, and MC5R. MC1R is the subtype most directly linked to melanin production in skin cells. Because the compound is not subtype-selective, its observed effects in experimental settings are generally attributed to activity across multiple receptor pathways rather than to a single target.
Solid peptide kept dry at minus twenty degrees Celsius, shielded from light and moisture, is generally considered stable for extended periods. Solutions are divided into single-use aliquots and held at minus twenty or minus eighty degrees Celsius, because repeated freeze-thaw cycles promote aggregation and loss of material to container surfaces. Hydrolysis of the backbone and oxidation of tryptophan are the principal degradation routes in aqueous solution, and both accelerate at ambient temperature. Hygroscopic uptake after a vial is opened can also shift the actual mass weighed, which affects any concentration calculated from it.
Routine characterisation relies on reversed-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres, using a C18 column and a water-acetonitrile gradient containing trifluoroacetic acid. Electrospray ionisation mass spectrometry confirms the expected molecular mass and can reveal truncated or oxidised by-products that co-elute poorly. Sequence and stereochemistry require additional work, such as peptide mapping or amino acid analysis, because a chromatographic purity figure alone does not distinguish a diastereomer from the target peptide. Independent testing of research-grade material frequently shows measured content below the stated label, so a certificate of analysis is best read together with the method that produced it.
Melanotan-2 is handled in the laboratory as a lyophilised powder that dissolves readily in water, dimethyl sulfoxide and dimethylformamide, with limited solubility in ethanol. Stock solutions prepared in an organic solvent often precipitate when diluted into aqueous buffer, so gradual dilution with mixing is standard practice. The peptide carries a tryptophan residue and a histidine residue, both sensitive to oxidation and to alkaline conditions. Working solutions are therefore kept near neutral to slightly acidic pH, protected from light, and consumed within the same working session whenever that is practical.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Free base; salt forms differ |
| Molecular weight | Approximately 1024 g/mol | Calculated for the free base |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water and polar solvents | Poorly soluble in non-polar solvents |
| Typical storage | -20 degrees Celsius, dry, protected from light | Refers to the solid form |
Melanotan-2 is frequently confused with afamelanotide, a linear analogue authorised in the European Union for erythropoietic protoporphyria. The two compounds differ in chain length, ring structure and receptor selectivity, so findings for one cannot be transferred directly to the other. Published controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports. Questions about effect size, dose-response behaviour and long-term safety therefore remain unresolved.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence incorporates a lactam bridge that constrains the peptide into a ring, which increases resistance to enzymatic breakdown relative to the natural hormone. Researchers at the University of Arizona synthesised the compound in the late 1980s and early 1990s while studying pigmentation pathways. It has never received marketing approval from any national medicines regulator. In the scientific literature it is usually described as a laboratory research reagent rather than a therapeutic product.
The peptide acts as a non-selective agonist at melanocortin receptors, showing affinity for MC1R, MC3R, MC4R and MC5R. Activation of MC1R on melanocytes drives the conversion of tyrosine into melanin and shifts production toward the darker eumelanin form. MC4R signalling in the central nervous system is linked to appetite and energy balance, which helps explain why reduced food intake appeared in early human studies. Effects on MC4R and on vascular tone also account for the erectile responses recorded as unexpected findings in those same trials.
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.
Molecular dynamics (MD) simulations are useful for simulating the motions of atoms and molecules according to physical laws. MD simulations are often applied to lipids to study atom-scale properties that may be difficult to observe otherwise. Force field parameters vary based on atom and molecule types. MD simulations may observe interactions between targeted lipids, proteins, hydrocarbons, water, hydrophilic/hydrophobic regions, ions, solvents, and other components that are present near the exterior and interior of a biomembrane.
Despite the strong military presence, the authorities discovered seven bodies inside a Ford Lobo on 8 October 2011 in Veracruz. On 22 December 2011, three public buses were attacked by drug cartel members on Federal Highway 105 in Veracruz, leaving 16 dead. Three U.S. citizens were among those dead. Soon after the shootouts, which happened in the early morning, the authorities carried out an operation to find those responsible, killing five gunmen. The U.S. Consulate in Matamoros asked Americans to avoid traveling on highways between cities in the late hours of the night. In Tampico Alto, Veracruz, on 23 December 2011 the Mexican authorities found 10 dead bodies after an anonymous call from a citizen. The corpses were dumped on a dirt road, and all of them were handcuffed and presented signs of torture. Nine out of the ten bodies were decapitated. Earlier in February 2011, Saturnino Valdés Llanos, the mayor of the municipality of Tampico Alto, was kidnapped in February 2011; his body was left in a garbage dump with 10 more bodies a week later. On 25 December 2011 near Tampico, Tamaulipas, a city on the border with Veracruz, 13 bodies were found inside an 18-wheeler truck. According to officials, the truck had license plates from Veracruz. Authorities indicated that this massacre was related to the other mass murders that had occurred in Veracruz. On 9 February 2012, the Mexican authorities exhumed 15 bodies from clandestine mass graves in Acayucan, Veracruz.
==== Atmosphere- and pressure-dependent plasma processing ==== Plasma processing provides interfacial energies and injected monomer fragments larger than comparable processes. However, limited fluxes prevent high process rates. In addition, plasmas are thermodynamically unfavorable and therefore plasma-processed surfaces lack uniformity, consistency, and permanence. These obstacles with plasma processing preclude it from being a competitive surface modification method within industry. The process begins with production of plasma via ionization either by deposition on monomer mixtures or gaseous carrier ions. The power required to produce the necessary plasma flux can be derived from the active volume mass/energy balance:
==== Rare side effects ==== Infrequent adverse reactions in patients taking opioids for pain relief include: dose-related respiratory depression (especially with more potent opioids), confusion, hallucinations, delirium, urticaria, hypothermia, bradycardia/tachycardia, orthostatic hypotension, dizziness, headache, urinary retention, ureteric or biliary spasm, muscle rigidity, myoclonus (with high doses), and flushing (due to histamine release, except fentanyl and remifentanil). Both therapeutic and chronic use of opioids can compromise the function of the immune system. Opioids decrease the proliferation of macrophage progenitor cells and lymphocytes, and affect cell differentiation (Roy & Loh, 1996). Opioids may also inhibit leukocyte migration. However the relevance of this in the context of pain relief is not known.
Sources: en.wikipedia.org
Bean chips are chips prepared using beans as a primary ingredient. Bean chips have been described as being higher in fiber and protein compared to corn and potato chips. Bean chips may be prepared from a variety of bean types and rice, such as brown rice, pinto beans, black beans, and white beans. Some bean chips are prepared using green beans. They may be prepared from a bean dough that is steamed, sliced, and fried. They may be consumed as a snack food and may be accompanied by various dips.
=== Background === Walter (Walt) A. Anderson (1880–1963), a cook, had been running food stands in Wichita since 1916, when he opened his first diner in a converted streetcar. After a second and third location, he was looking to open a fourth location when he met Edgar Waldo "Billy" A. Ingram (1880–1966), an insurance and real-estate man, and together they started the White Castle chain.
== Professional career == Following her graduation in 1958, Susan Leeman was offered a one-year position as an instructor in the Physiology Department at Harvard Medical School. Realizing she was only a fill-in, the following year she took a job at Brandeis University where she stayed for the next 12 years. During this time she received a Career Development Award which helped her to balance her career and family life. Leeman's research while at Brandeis University mainly focused on the effect a corticotropin-releasing factor (CRF) had on the secretion of adrenocorticotrophic hormone (ACTH) from the anterior pituitary gland. During her effort to purify the CRF, she discovered a peptide that could stimulate the secretion of saliva. This caused her to switch the direction of the project entirely, as she decided to further investigate this peptide. Eventually Leeman and her lab realized she had unintentionally isolated substance P – a peptide originally discovered by Ulf von Euler in the 1930s, but had yet to be chemically defined. Leeman went on to discover the amino acid sequence of substance P and published her findings in the Journal of Biological Chemistry in 1970. During the purification process of substance P, Leeman and a graduate student of hers discovered a different peptide that was distributed throughout the central nervous system, gastrointestinal tract, and immune system, but had yet to be identified. They decided to name their discovery “neurotensin”.
== Structures == CLE peptides are coded by the CLE genes. These peptides vary in structure, with each peptide structure performing a different job within the plant. The minimal length of functioning CLE peptides has been found to be 12 amino acids with several critical residues. There are two different peptide structures that are found within the plant and they are A-type and B-type. When A-type hormones are secreted the plant slows down the rate of root growth whereas the secretion of B-type peptides effects the vascular growth of the plant. The secretion of A-type peptides speeds up the vascular development of the plant that is mediated by the B-type peptides. This suggests that these two types of peptides work together to regulate the growth of the plant. The specific peptides are: A-type peptides
The largest concentration of Southern Rhodesian troops in the Italian Campaign of 1943–45 was the group of about 1,400, mainly from the Southern Rhodesian Reconnaissance Regiment, spread across the South African 6th Armoured Division. The 11th South African Armoured Brigade, one of the 6th Division's two main components, was made up of Prince Alfred's Guard, the Pretoria Regiment (Princess Alice's Own) and the Special Service Battalion, each of which had a Rhodesian squadron of Sherman tanks. The other, the 12th South African Motorised Brigade, comprised infantry—the Witwatersrand Rifles, the Natal Carbineers and the Cape Town Highlanders, the last of which had a large Rhodesian contingent. There were also two Rhodesian artillery batteries—the original Rhodesian Anti-Tank Battery and a newer unit of Rhodesian field gunners. After a year's training in Egypt, the division sailed to Italy in April 1944, landing towards the end of the month at Taranto. No. 237 Squadron, now flying Spitfires, rebased to Corsica the same month to operate over Italy and southern France. The 6th Division moved north-west from Taranto to take its place as part of the Eighth Army alongside the US Fifth Army. It took part in the fourth and final Allied assault of the Battle of Monte Cassino in the second and third weeks of May 1944, helping to force the Germans out, and thereafter advanced north-west up the Liri valley to join the Allied forces at Anzio and advance onwards to Rome.
Sources: en.wikipedia.org
=== Stem-wind, pin-set movements === Much like the lever-set movements, these pocket watches had a small pin or knob next to the watch-stem that had to be depressed before turning the crown to set the time and releasing the pin when the correct time had been set. This style of watch is occasionally referred to as "nail set", as the set button must be pressed using a fingernail.
Important branches today are the tourism industry with TUI AG in Hanover, one of Europe's largest travel companies, as well as trade and telecommunications. Hanover is one of Germany's main hubs for insurance and financial-services companies, for example Talanx and Hannover Re. In October 2018, the Lower Saxony unemployment rate stood at 5.0% and was marginally higher than the national average.
== Occurrence == All isotopes of radium have half-lives much shorter than the age of the Earth, so that any primordial radium would have decayed long ago. Radium nevertheless still occurs in the environment, as the isotopes 223Ra, 224Ra, 226Ra, and 228Ra are part of the decay chains of natural thorium and uranium isotopes; since thorium and uranium have very long half-lives, these daughters are continually being regenerated by their decay. Of these four isotopes, the longest-lived is 226Ra (half-life 1600 years), a decay product of natural uranium. Because of its relative longevity, 226Ra is the most common isotope of the element, making up about one part per trillion of the Earth's crust; essentially all natural radium is 226Ra. Thus, radium is found in tiny quantities in the uranium ore uraninite and various other uranium minerals, and in even tinier quantities in thorium minerals. One ton of pitchblende typically yields about one seventh of a gram of radium. One kilogram of the Earth's crust contains about 900 picograms of radium, and one liter of sea water contains about 89 femtograms of radium.
These are shown in the figure on the right. A change from one main degradation mechanism to another appears as a knee (slope change) in the capacity vs. cycle number plot. Most studies of lithium-ion battery aging have been done at elevated (50–60 °C) temperatures for accelerated aging. Under these storage conditions, fully charged nickel-cobalt-aluminum and lithium-iron phosphate cells lose ca. 20% of their cyclable charge in 1–2 years. It is believed that the aforementioned anode aging is the most important degradation pathway in these cases. On the other hand, manganese-based cathodes show a (ca. 20–50%) faster degradation under these conditions, probably due to the additional mechanism of Mn ion dissolution. At 25 °C the degradation of lithium-ion batteries seems to follow the same pathway(s) as the degradation at 50 °C, but with half the speed. In other words, based on the limited extrapolated experimental data, lithium-ion batteries are expected to lose irreversibly around 20% of their cyclable charge in 3–5 years or 1000–2000 cycles at 25 °C. Lithium-ion batteries with titanate anodes do not suffer from SEI growth, and last longer (>5000 cycles) than graphite anodes. However, in complete cells other degradation mechanisms (i.e. the dissolution of Mn3+ and the Ni2+/Li+ place exchange, decomposition of PVDF binder and particle detachment) show up after 1000–2000 days, and the use titanate anode does not improve full cell durability in practice.
Sources: en.wikipedia.org
No. Melanotan-2 is manufactured synthetically. The naturally occurring peptide in the same family is alpha-melanocyte-stimulating hormone, which the body produces as part of normal endocrine and neural signalling.
Both are synthetic analogues derived from the same parent hormone. Reference descriptions usually characterise afamelanotide as more selective for the MC1R subtype, whereas melanotan-2 is reported to interact with a wider range of melanocortin receptors.
Early studies explored melanocortin signalling and pigmentation, which later led to informal use of the label tanning peptide. That label is not a regulatory category and does not imply approved status for any purpose.
Purity is normally stated as an area percentage from high-performance liquid chromatography, for example ninety-five or ninety-eight percent. That figure describes the proportion of ultraviolet-absorbing material eluting as the main peak. It says nothing about water content, counterions, residual solvents or mass fraction of the peptide itself.