This is a working overview of cyclic heptapeptide, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-06-15 and is reviewed periodically as new material appears.
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.
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.
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.
| 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-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.
Melanotan II is a synthetic cyclic heptapeptide that acts as an agonist at melanocortin receptors. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous peptide involved in pigment production. The analogue carries a lactam bridge that constrains the ring and slows enzymatic breakdown relative to the native hormone. In research literature it appears under several abbreviations, and naming conventions are not fully standardized. Published descriptions usually place it within the broader melanocortin agonist family.
Receptor binding at MC1R on melanocytes raises intracellular cyclic AMP and increases expression of tyrosinase and related enzymes. The downstream result is greater synthesis of eumelanin, the dark pigment, without ultraviolet exposure acting as the trigger. The compound is not selective, however, and also engages MC3R, MC4R and MC5R, which are expressed in the central nervous system and elsewhere. That lack of selectivity is the explanation usually offered for effects reported outside pigmentation, including appetite suppression and nausea. Selectivity remains a central theme in comparative studies of related peptides.
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.
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.
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.
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.
=== By mouth === An oral preparation exists but is not widely available. The amphipathic nature of amphotericin along with its low solubility and permeability has posed major hurdles for oral administration given its low bioavailability. In the past it had been used for fungal infections of the surface of the GI tract such as thrush, but has been replaced by other antifungals such as nystatin and fluconazole. However, recently novel nanoparticulate drug delivery systems such as AmbiOnp, nanosuspensions, lipid-based drug delivery systems including cochleates, self-emulsifying drug delivery systems, solid lipid nanoparticles and polymeric nanoparticles—such as amphotericin B in pegylated polylactide coglycolide copolymer nanoparticles—have demonstrated potential for oral formulation of amphotericin B. The oral lipid nanocrystal amphotericin by Matinas Biopharma is furthest along, having completed a successful phase 2 clinical trial in cryptococcal meningitis.
===== Mood ===== We can describe mood not as specific to an emotional status, but as associated with a relatively long-lasting emotional state. Serotonin's association with mood is most known for various forms of depression and bipolar disorders in humans. Disorders caused by serotonergic activity potentially contribute to the many symptoms of major depression, such as overall mood, activity, suicidal thoughts and sexual and cognitive dysfunction. Selective serotonin reuptake inhibitors (SSRI's) are a class of drugs demonstrated to be an effective treatment in major depressive disorder and are the most prescribed class of antidepressants. SSRI's function is to block the reuptake of serotonin, making more serotonin available to absorb by the receiving neuron. Animals have been studied for decades in order to understand depressive behavior among species. One of the most familiar studies, the forced swimming test (FST), was performed to measure potential antidepressant activity. Rats were placed in an inescapable container of water, at which point time spent immobile and number of active behaviors (such as splashing or climbing) were compared before and after a panel of anti-depressant drugs were administered. Antidepressants that selectively inhibit NE reuptake were shown to reduce immobility and selectively increase climbing without affecting swimming. However, results of the SSRI's also show reduced immobility but increased swimming without affecting climbing.
Pneumatic post or pneumatic mail is a system to deliver letters through pressurized air tubes. It was invented by the Scottish engineer William Murdoch in the 19th century and was later developed by the London Pneumatic Despatch Company. Pneumatic post systems were used in several large cities starting in the second half of the 19th century (including an 1866 London system powerful and large enough to transport humans during trial runs – though not intended for that purpose), but later were largely abandoned. A major network of tubes in Paris (the Paris pneumatic post) was in use until 1984, when it was abandoned in favor of computers and fax machines. The Prague pneumatic post commenced for the public in 1889 in Prague, now in the Czech Republic, and the network extended approximately 60 kilometres (37 mi). Pneumatic post stations usually connect post offices, stock exchanges, banks and ministries. Italy was the only country to issue postage stamps (between 1913 and 1966) specifically for pneumatic post. Austria, France, and Germany issued postal stationery for pneumatic use. Typical applications are in banks, hospitals, and supermarkets. Many large retailers used pneumatic tubes to transport cheques or other documents from cashiers to the accounting office.
Sources: en.wikipedia.org
=== 18th century === In 2009, a handwritten household book authored by a Cornishwoman in 1707 was discovered in a house in Hasfield, Gloucestershire, containing a "Recipe for the Scurvy" amongst other largely medicinal and herbal recipes. The recipe consisted of extracts from various plants mixed with a plentiful supply of orange juice, white wine, or beer. In 1734, Leiden-based physician Johann Bachstrom published a book on scurvy in which he stated, "scurvy is solely owing to a total abstinence from fresh vegetable food, and greens; which is alone the primary cause of the disease", and urged the use of fresh fruit and vegetables as a cure.
=== Classical-like === Classical-like EDS (clEDS) is characterized by skin hyperextensibility with velvety skin texture and no presence of atrophic scarring, generalized joint hypermobility with or without recurrent dislocations (most often shoulder and ankle), and easily bruised skin or spontaneous ecchymoses (discolorations of the skin resulting from bleeding underneath). It can be caused by autosomal recessive variations in the TNXB gene.
Ravenholm is a fictional ghost town in the 2004 first-person shooter game Half-Life 2 created by Valve. It is the setting for the game's sixth chapter, "We Don't Go To Ravenholm...", which follows protagonist Gordon Freeman as he journeys through the area after escaping a Combine attack in order to reach a nearby Resistance outpost. An Eastern European mining town, Ravenholm's residents have turned into hostile zombies due to Combine attacks. The town's sole survivor, Father Grigori, offers his assistance to Freeman throughout the level, culminating in a last stand at the town cemetery. The level received critical praise due to its level design and unexpected usage of horror aspects involving headcrabs and zombies, with some critics calling it one of the most well-designed levels in a Valve game and one of the best first-person shooter levels ever made. Due to its popularity, Valve initially contracted Junction Point Studios to make a prequel featuring the town, a project that later became a spinoff game developed by Arkane Studios that further followed the story of Grigori and his fight against the Combine. However, both projects were ultimately cancelled partway through development.
Sources: en.wikipedia.org
Clinical trials involving new drugs are commonly classified into five phases. Each phase of the drug approval process is treated as a separate clinical trial. The drug development process will normally proceed through phases I–IV over many years, frequently involving a decade or longer. If the drug successfully passes through phases I, II, and III, it will usually be approved by the national regulatory authority for use in the general population. Phase IV trials are performed after the newly approved drug, diagnostic or device is marketed, providing assessment about risks, benefits, or best uses.
== References == British National Formulary 2004 Merck Index 13th Edition Oxford textbook of clinical pharmacology Second Edition (09. October 1992) Martindale: The complete drug reference 35th Edition (2007) Goodman & Gilman's The Pharmacological Basis of Therapeutics, 11th Edition Information on the packaging leaflet in Co-dydramol from Hammed
== History == The company was founded in April 2012 by former Morgan Stanley investment banker Adam Forste, who formed Bay Grove Capital, LLC, through the consolidation of acquired warehousing and logistics companies beginning, in December 2008, with the purchase of Seafreeze from Toyo Susian Kaisha. The company then acquired CityIce, in 2009, and Flint River Services, in 2010, followed, in 2011, by Terminal Freezers of Santa Maria, California, and Richmond Cold Storage, purchased from Atlanta Equity. Lineage was formed with the fifth-largest network of temperature-controlled warehouse facilities in North America in 2012, according to International Association of Refrigerated Warehouses (IARW) rankings, with 40 facilities in eight states, including near international ports at Savannah, Georgia, Seattle, Washington and Norfolk, Virginia; as well as providing warehouse management, consulting, and food processing support. In a March 2021 interview with Bloomberg, Lineage CEO Greg Lehmkuhl said the company is actively preparing its initial public offering (IPO). The company completed its IPO in July 2024 with a listing on the Nasdaq, raising around $4.5 billion, valuing the company at over $18 billion. On April 21, 2024, a fire broke out at the Lineage cold storage facility in Benton County, Washington. The fire burned for 60 days. On June 17, 2026 a large fire broke out at the Lineage cold storage facility in Boyle Heights, Los Angeles, accelerated by the large facility's solar panels encompassing its entire roof, refrigerants, and decaying food within the building.
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.
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.