cyclic heptapeptide 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 2025-11-20. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Identity and purity are assessed with chromatographic and mass spectrometric techniques. Reversed-phase high-performance liquid chromatography separates the target peptide from related impurities and degradation products, and the resulting retention time is compared against a reference standard. Mass spectrometry, often coupled to liquid chromatography, confirms molecular mass. Amino acid analysis or peptide mapping can provide additional sequence-level confirmation when required. Results are only as reliable as the reference materials used alongside them.
Regulatory treatment varies by country. In the United States, melanotan-2 is not approved for any indication, and products marketed for human use fall outside the approved drug framework. Some other jurisdictions have placed it under prescription controls or listed it as a prohibited or restricted substance. Online listings frequently describe the material as a research chemical, a category that does not carry the same manufacturing and labelling requirements as approved medicines.
Solid peptide material is generally stable when kept cold and dry. Common practice is storage at -20 degrees Celsius or lower, with desiccant and protection from light. Repeated freeze-thaw cycles and exposure to moisture are associated with degradation, aggregation, or loss of material. Once dissolved, stability depends on solvent, concentration, and temperature, and solutions are usually treated as short-lived unless stability data support longer periods. Handling notes typically emphasise minimising time at ambient temperature.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Alpha-MSH analogue with a lactam ring |
| Molecular formula | C50H69N15O9 | Commonly cited value for the neutral peptide |
| Molecular weight | 1024.18 g/mol | Calculated for the free molecule |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water, DMSO and ethanol | Dissolution in pure water is often slow |
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.
Receptor studies place melanotan-2 among non-selective melanocortin agonists, binding MC1R, MC3R, MC4R and MC5R rather than a single subtype. Activation of MC1R on cutaneous melanocytes raises tyrosinase activity and shifts pigment synthesis toward eumelanin, which is darker and more photostable than pheomelanin. Central receptors, particularly MC4R, are associated with appetite suppression and with reported effects on sexual function. Because subtype selectivity is low, the same molecule engages pigment, metabolic and vascular pathways at once, and this breadth is a common explanation offered for the range of adverse events described in user reports.
Regulatory status varies by jurisdiction, and the substance is frequently described as unapproved for therapeutic use. Some authorities classify it alongside prescription-only medicines or controlled categories, while others address it through general consumer protection rules. Analytical surveys have reported mismatches between label claims and measured content in products sold online, although the scope of such testing is limited. Whether these discrepancies are widespread remains an open question. Discussion in the literature therefore tends to combine chemistry, supply-chain observation and policy analysis.
The material is commonly handled as a lyophilized powder in sealed vials. The solid dissolves readily in water and in polar organic solvents, producing a clear solution after reconstitution. Light, heat and repeated freeze-thaw cycles are the concerns most often raised in handling guidance, because peptide bonds and the constrained ring can degrade. Working solutions are generally prepared fresh, and material left in solution is treated as less stable than the dry form. These properties shape how laboratories store and aliquot reference material.
The peptide was developed during the 1980s by researchers investigating melanocortin signalling and skin pigmentation pathways. Early work focused on analogues of alpha-melanocyte-stimulating hormone that would resist enzymatic breakdown more effectively than the parent molecule. Melanotan-2 emerged from that programme as a shortened, cyclised variant. Reports describing its synthesis and receptor activity later appeared in the scientific literature. Commercial availability grew through unregulated channels rather than through pharmaceutical approval.
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.
Melanotan II holds no marketing authorisation from the Food and Drug Administration, the European Medicines Agency, the UK Medicines and Healthcare products Regulatory Agency or Australia's Therapeutic Goods Administration. Products sold under that name are treated as unapproved new drugs, and their sale or import is prohibited in several jurisdictions. Other countries classify the peptide as a prescription-only medicine or place it among controlled substances, so the legal position changes with the destination market. No pharmacopoeial monograph supplies an official specification, because the material is not a licensed pharmaceutical. Consequently, products offered online are not manufactured to a shared public standard.
The peer-reviewed record is dominated by small early-phase studies, case reports and pharmacovigilance summaries rather than large randomised trials. Papers typically examine tanning response, receptor selectivity or patterns of reported adverse events. Many note that participants obtained the peptide outside a clinical setting, which limits verification of composition and administered amount. Reported events vary widely, and causality is frequently unclear because the identity and purity of self-sourced material are unknown. Open questions include whether repeated melanocortin receptor stimulation produces cumulative effects, and how often label claims match actual content.
is completely uniform, and by convention we direct it "into the page" along the negative z-axis so that the resulting motion for our positively-charged particle is counter-clockwise. The axial and planar equations of motion can then be obtained directly from the Lorentz Force law
=== Generic names === Nicergoline is the generic name of the drug and its INNTooltip International Nonproprietary Name, USANTooltip United States Adopted Name, BANTooltip British Approved Name, and DCFTooltip Dénomination Commune Française.
There have been a few instances of general population poisoning as the result of long-term exposure to cadmium in contaminated food and water. Research into an estrogen mimicry that may induce breast cancer is ongoing, as of 2012. In the decades leading up to World War II, mining operations contaminated the Jinzū River in Japan with cadmium and traces of other toxic metals. As a consequence, cadmium accumulated in the rice crops along the riverbanks downstream of the mines. Some members of the local agricultural communities consumed the contaminated rice and developed itai-itai disease and renal abnormalities, including proteinuria and glucosuria. The victims of this poisoning were almost exclusively post-menopausal women with low iron and low body stores of other minerals. Similar general population cadmium exposures in other parts of the world have not resulted in the same health problems because the populations maintained sufficient iron and other mineral levels. Thus, although cadmium is a major factor in the itai-itai disease in Japan, most researchers have concluded that it was one of several factors. Cadmium is one of ten substances banned by the European Union's Restriction of Hazardous Substances (RoHS) directive, which regulates hazardous substances in electrical and electronic equipment, but allows for certain exemptions and exclusions from the scope of the law. The International Agency for Research on Cancer has classified cadmium and cadmium compounds as carcinogenic to humans.
=== Processing === Water is removed from the sample in successive stages by the use of increasing concentrations of alcohol. Xylene is used in the last dehydration phase instead of alcohol - this is because the wax used in the next stage is soluble in xylene where it is not in alcohol allowing wax to permeate (infiltrate) the specimen. This process is generally automated and done overnight. The wax infiltrated specimen is then transferred to an individual specimen embedding (usually metal) container. Finally, molten wax is introduced around the specimen in the container and cooled to solidification so as to embed it in the wax block. This process is needed to provide a properly oriented sample sturdy enough for obtaining a thin microtome section(s) for the slide. Once the wax embedded block is finished, sections will be cut from it and usually placed to float on a water bath surface which spreads the section out. This is usually done by hand and is a skilled job (histotechnologist) with the lab personnel making choices about which parts of the specimen microtome wax ribbon to place on slides. A number of slides will usually be prepared from different levels throughout the block. After this the thin section mounted slide is stained and a protective cover slip is mounted on it. For common stains, an automatic process is normally used; but rarely used stains are often done by hand.
Sources: en.wikipedia.org
The Grand Lodge, being only responsible for the first three degrees, does not represent all of Cuban Freemasonry without the Supreme Council, which is responsible for all the higher degrees, from the 4th to the 33rd degrees. Cuban Freemasons considered this as an insult to the Supreme Council, and an attempt to reject the Grand Commander's authority. Cuban Freemasons sent a flood of calls, emails, and letters to the office of Grand Master Zamora Fernández to refuse to meet with the President. On August 23, Zamora Fernández wrote a letter distributed to Cuban Freemasons indicating that the office of the Grand Master had decided not to attend the meeting "...in order to preserve Masonic unity". The Freemason and Cuban activist writer Ángel Santiesteban Prats stated that President Díaz-Canel's full intention was to completely fracture Freemasonry in Cuba. Santiesteban said: "I doth my hat to the Grand Master's wise decision. Masonic unity above all. History is being made... it is a milestone in our country's history, especially over the last 62 years. I remind you that Freemasonry is the only institution in Cuba that didn't dance like puppets on the stage with Fidel Castro and demand the return of that boy Elián. Everybody else gave in. The Abakuás, the spiritists, and the Yoruba Association, they all caved to Castro." On March 28, 2022, Grand Treasurer Francisco Javier Alfonso Vidal was elected as Grand Master of the Grand Lodge of Cuba.
=== In newborns === Newborns have a uniform single layered lamina propria, which appears loose with no vocal ligament. The monolayered lamina propria is composed of ground substances such as hyaluronic acid and fibronectin, fibroblasts, elastic fibers, and collagenous fibers. While the fibrous components are sparse, making the lamina propria structure loose, the hyaluronic acid (HA) content is high. HA is a bulky, negatively charged glycosaminoglycan, whose strong affinity with water procures hyaluronic acid its viscoelastic and shock absorbing properties essential to vocal biomechanics. Viscosity and elasticity are critical to voice production. Chan, Gray and Titze, quantified the effect of hyaluronic acid on both the viscosity and the elasticity of vocal folds by comparing the properties of tissues with and without HA. The results showed that removal of hyaluronic acid decreased the stiffness of the vocal cords by an average of 35%, but increased their dynamic viscosity by an average of 70% at frequencies higher than 1 Hz. Newborns have been shown to cry an average of 6.7 hours per day during the first 3 months, with a sustained pitch of 400–600 Hz, and a mean duration per day of 2 hours. Similar treatment on adult vocal cords would quickly result in edema, and subsequently aphonia. Schweinfurth and al. presented the hypothesis that high hyaluronic acid content and distribution in newborn vocal cords is directly associated with newborn crying endurance.
== Fleet replacement and lifecycle management == The timely replacement of vehicles and equipment is a process that requires the ability to predict asset lifecycles based on costing information, utilization, and asset age. Organizations prefer to use new fleet as a strategy for cost reduction where the used fleet is sold so that a new fleet is maintained. Funding requirements are also an issue, because many organizations, especially government, purchase vehicles with cash. The ad hoc nature and traditional low funding levels with cash has put many operations in an aged fleet. This lack of adequate funding for replacement can also result in higher maintenance costs due to aged vehicles.
=== Preservation of bog bodies === The preservation of bog bodies is dependent on a set of specific physical conditions, which can occur in peat bogs. A sphagnum moss bog must have a temperature lower than 4 °C (39 °F) at the time of deposition of the body. The subsequent average annual temperature must be lower than 10 °C (50 °F). Moisture must be stable in the bog year-round: it cannot dry out. Sphagnum moss affects the chemistry of nearby water, which becomes highly acidic (a pH of roughly 3.3 to 4.5) relative to a more ordinary environment. The concentration of dissolved minerals also tends to be low. Dying moss forms layers of sediment and releases sugars and humic acids which consume oxygen. Since the surface of the water is covered by living moss, water becomes anaerobic. As a result, human tissues buried in the bog tend to tan rather than decay.
== Electronic Associates, Inc. == In 1963, Finnigan and Uthe joined Electronic Associates, Inc. (EAI). The main research department of the company was based in Princeton, New Jersey, but Finnigan founded a new Scientific Instruments Division in Palo Alto, California. Finnigan's vision involved creation of a broad-based line of process-control instruments, beginning with the quadrupole mass spectrometer. Based on previous research at SRI, Finnigan was convinced that a market existed, but EAI and other companies such as IBM and Beckman Instruments were not interested in developing the quadrupole as a product at that time. Finnigan's group proposed to contract parts of the quadrupole production to SRI, but management at SRI were not interested in its commercial development either. Eventually Finnigan collaborated with staff from SRI, who supplied knowledge and expertise to help Finnigan's group bootstrap development of a prototype quadrupole analyzer at EAI. Because of the strong market demand the EAI division was able to sell more than 500 of these quadrupole residual gas analyzers between 1964 and 1966. Finnigan wanted to pursue development of computer-controlled instrumentation for a combined gas chromatograph (GC) and quadrupole mass spectrometer (MS). However, EAI's main focus was analog computers, and they were not interested in developing a computerized GC/MS. On December 31, 1966, after EAI unsuccessfully attempted to sell the division to Syntex Corporation, Finnigan submitted his resignation to EAI.
Sources: en.wikipedia.org
Glass, soap, sugar, paper and chemical industries also developed along the Avon valley. Edmund Burke was elected as Whig Member of Parliament for Bristol in 1774 and campaigned for free trade, Catholic emancipation and the rights of the American colonists, but he angered his merchant sponsors with his detestation of the slave trade and lost the seat in 1780. Anti-slavery campaigners, inspired by Non-conformist preachers such as John Wesley, started some of the earliest campaigns against the practice. Prominent local opponents of both the trade and the institution of slavery itself included Anne Yearsley, Hannah More, Harry Gandey, Mary Carpenter, Robert Southey, William Wordsworth and Samuel Coleridge. The campaign itself proved to be the beginning of movements for reform and women's emancipation.
Fox Islands (the main islands are Unimak, Akutan, Unalaska and Umnak) Islands of Four Mountains (the main islands are Yunaska and Chuginadak) Andreanof Islands (the main islands are Adak, Atka, Amlia, Seguam, Kanaga and Tanaga) Rat Islands (the main islands are Kiska and Amchitka) Near Islands (the main islands are Attu Island, Agattu Island and the Semichi Islands - Alaid, Nizki and Shemya) Commander Islands (the main islands are Bering and Medny) All six are located between 51° and 55° N latitude and 172° E and 163° W longitude. The largest islands in the Aleutians are Attu, and Unalaska, Umnak, and Unimak in the Fox Islands. The largest of those is Unimak Island, with an area of 1,571.41 mi2 (4,069.9 km2), followed by Unalaska Island, the only other Aleutian Island with an area over 1,000 square miles (2,600 km2). The axis of the archipelago near the mainland of Alaska has a southwest trend, but at Tanaga Island (about 178° W) its direction changes to the northwest. This change of direction corresponds to a curve in the line of volcanic fissures that have contributed their products to the building of the islands. Such curved chains are repeated about the Pacific Ocean in the Kuril Islands, the Japanese chain, and in the Philippines. All these island arcs are at the edge of the Pacific Plate and experience much seismic activity, but are still habitable; the Aleutians lie between the Pacific and North American tectonic plates. The general elevation is greatest in the eastern islands and least in the western.
Cys530 is conserved in all amidase-active vertebrate and invertebrate PGRPs, whereas non-catalytic PGRPs (including mammalian PGLYRP1, PGLYRP3, and PGLYRP4) have serine in this position, and thus the presence of Cys or Ser in this position can be used to predict amidase activity of PGRPs. However, Cys530 and seven other amino acids that are all required for the amidase activity of PGRPs are not sufficient for the amidase activity, which requires additional so far unidentified amino acids.
took over mass production, but without an exclusive license, as the patent was transferred to the Medical Research Council to prevent exploitation. In the summer of 1923 Macleod resumed other research. He took interest in teleost fish, which have separate regions of islet and acinar tissue in their pancreas. Working at the Marine Biological Station in St. Andrews, New Brunswick, he made extracts from each of those parts separately and proved that insulin is derived from the insular and not the acinar tissue of the pancreas. Meanwhile, Banting remained in Toronto and relationships soon deteriorated again because of conflicting press accounts. Banting eventually started to claim that he deserved all the credit and that Macleod had only hindered him the whole time and had made no contribution other than to leave the keys to the laboratory when he went on vacation. MacLeod wrote a report on the discovery in 1922 to explain his side of the story, but otherwise refrained from active involvement in controversy about credit. Banting hated him passionately, and the two never spoke again. When Macleod left the University of Toronto in 1928, Banting harbored such enmity that he refused to attend the farewell dinner for Macleod.
== Diagnosis == Lymphocytosis is usually detected when a complete blood count is obtained. If not provided the lymphocyte count can be calculated by multiplying the total white blood cell (WBC) count by the percentage of lymphocytes found in the differential count. The lymphocyte count can also be directly measured by flow cytometry.
Sources: en.wikipedia.org
It is a synthetic cyclic heptapeptide modelled on alpha-melanocyte-stimulating hormone. A lactam bridge links two side chains, forming a ring that stabilises the molecule against proteolysis. It belongs to the broader melanocortin peptide family.
No national medicines agency has approved melanotan-2 for clinical use. Afamelanotide, a related but distinct peptide, holds a marketing authorisation in the European Union for a rare photosensitivity disorder. Melanotan-2 itself is handled as a laboratory chemical.
Its broad activity across melanocortin receptors makes it a tool for probing pigmentation, appetite and vascular signalling. Early trials recorded skin darkening and other effects that were not the original focus of the work. Those observations generated hypotheses that later studies have examined.
Laboratory confirmation typically combines retention time matching on a chromatographic system with mass measurement. A reference standard of known identity is needed for a meaningful comparison. Sequence-level techniques can add further confirmation.