cyclic peptide comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2025-12-12. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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-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controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports.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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Analog of alpha-melanocyte-stimulating hormone |
| Primary receptor family | Melanocortin receptors MC1R through MC5R | Binding is not subtype-selective |
| Development period | 1980s | Synthesized during pigmentation and appetite research |
| Regulatory status | Not an approved medicine | No major regulator has authorized human use |
| Related compound | Afamelanotide | Linear analog studied for photoprotection |
Activity is attributed to agonism at melanocortin receptors, particularly MC1R and MC4R. Activation of MC1R on melanocytes increases melanin synthesis, which underlies the reported tanning effect. MC4R engagement in the central nervous system is linked to appetite suppression and to effects on sexual arousal reported in early clinical studies. Those studies were small and were not designed to establish efficacy or long-term safety. Receptor selectivity among the melanocortin subtypes is not absolute, which complicates attribution of any effect to a single pathway.
Regulatory treatment varies between countries. Several national medicines agencies have classified the peptide as unapproved, and customs authorities in some jurisdictions seize shipments on that basis. A few jurisdictions channel supply through prescription-only frameworks that do not list the substance by name. Because the material circulates mainly through online vendors, composition and purity are rarely verified before sale. Surveys of unapproved peptide products have reported labels that did not match measured content in a substantial fraction of samples.
== Genetics == In humans and many other tetrapods, the RLN/INSL-encoding genes exist in four distinct clusters. The largest cluster contains four loci: RLN1, RLN2, INSL4 and INSL6, situated in tandem on human chromosome 9. This cluster arose from multiple local gene duplications that took place in the ancestor of placental mammals. The other three RLN/INSL genes exist as single loci in two linkage groups: RLN3 (chromosome 19), INSL3 (chromosome 19, 3.8 Mb apart from RLN3) and INSL5 (chromosome 1).
=== Early delivery === Magnesium sulfate was once used as a tocolytic, but meta-analyses have failed to support it as an anti-contraction medication. Usage for prolonged periods (more than five to seven days) may result in health problems for the baby. In those at risk of an early delivery (preterm birth), treatment with magnesium sulfate has a neuroprotective role and decreases the risk of cerebral palsy. The World Health Organization strongly recommends use of magnesium sulfate for women with risk of imminent birth before 32 weeks of gestation. It is unclear if it helps those who are born at term. Guidelines for the use of magnesium sulfate in mothers at risk of preterm labour are not strongly adhered to and the effects of this treatment later in early childhood are unknown.
=== 1967 === March 11: The Cambodian Civil War begins with the Samlaut Uprising. March 12: General Suharto officially overthrows Sukarno and appointed as president of Indonesia. Indonesia switches sides from being friendly with Eastern Bloc countries such as the Soviet Union, the People's Republic of China, North Korea, and Cuba during the Sukarno administration to becoming friends with western countries such as the United States during the Suharto administration or New Order era. Foreign capital and investors began to enter Indonesia. April 21: The Hellenic Armed Forces successfully stage a coup d'état against the Greek government, leading to the Greek Junta to rule Greece until 1974. April 25: 33 Latin American and Caribbean countries sign the Treaty of Tlatelolco in Mexico City, which seek the prohibition of nuclear weapons in Latin America and the Caribbean. May 18: Yuri Andropov becomes chairman of the KGB. May 23: The United Arab Republic blocks the Straits of Tiran, then expels UN peacekeepers and moves its army into the Sinai Peninsula in preparation for possible attack on Israel. May 25: Uprising in Naxalbari, India marking the expansion of Maoism as a violent, anti-US and anti-Soviet, revolutionary movement across a number of developing countries. May 30: The Nigerian state of Biafra secedes from the rest of Nigeria, declaring itself as the Republic of Biafra. June 5: In response to Egypt's aggression, Israel invades the Sinai Peninsula, beginning the Six-Day War. June 17: China detonates its first hydrogen bomb. June 23: U.S. President Lyndon B.
If the temperature is decreased, the metabolic activity in the fish from microbial or autolytic processes can be reduced or stopped. This is achieved by refrigeration where the temperature is dropped to about 0 °C, or freezing where the temperature is dropped below -18 °C. On fishing vessels, the fish are refrigerated mechanically by circulating cold air or by packing the fish in boxes with ice. Forage fish, which are often caught in large numbers, are usually chilled with refrigerated or chilled seawater. Once chilled or frozen, the fish need further cooling to maintain the low temperature. There are key issues with fish cold store design and management, such as how large and energy efficient they are, and the way they are insulated and palletized. An effective method of preserving the freshness of fish is to chill with ice by distributing ice uniformly around the fish. It is a safe cooling method that keeps the fish moist and in an easily stored form suitable for transport. It has become widely used since the development of mechanical refrigeration, which makes ice easy and cheap to produce. Ice is produced in various shapes; crushed ice and ice flakes, plates, tubes and blocks are commonly used to cool fish. Particularly effective is slurry ice, made from microcrystals of ice formed and suspended within a solution of water and a freezing point depressant, such as common salt. A more recent development is pumpable ice technology.
=== Other biosynthetic pathways === Carbamoyl phosphate is a carbamate mixed anhydride that is an intermediate in the urea cycle and the biosynthesis of pyrimidines. 5-carboxyamino-1-(5-phospho-D-ribosyl)imidazole (N5-CAIR), a carbamate derivative of aminoimidazole, is an intermediate in the biosynthesis of inosine. Both carbamates are produced via reaction of −NH2 groups with carboxyphosphate (HO−C(O)−OPO2−3).
Sources: en.wikipedia.org
In addition to structures, nuclear magnetic resonance can yield information on the dynamics of various parts of the protein. This usually involves measuring relaxation times such as T1 and T2 to determine order parameters, correlation times, and chemical exchange rates. NMR relaxation is a consequence of local fluctuating magnetic fields within a molecule. Local fluctuating magnetic fields are generated by molecular motions. In this way, measurements of relaxation times can provide information of motions within a molecule on the atomic level. In NMR studies of protein dynamics, the nitrogen-15 isotope is the preferred nucleus to study because its relaxation times are relatively simple to relate to molecular motions. This, however, requires isotope labeling of the protein. The T1 and T2 relaxation times can be measured using various types of HSQC-based experiments. The types of motions that can be detected are motions that occur on a time-scale ranging from about 10 picoseconds to about 10 nanoseconds. In addition, slower motions, which take place on a time-scale ranging from about 10 microseconds to 100 milliseconds, can also be studied. However, since nitrogen atoms are found mainly in the backbone of a protein, the results mainly reflect the motions of the backbone, which is the most rigid part of a protein molecule. Thus, the results obtained from nitrogen-15 relaxation measurements may not be representative of the whole protein.
=== Potential technology === A new family of LEDs are based on the semiconductors called perovskites. In 2018, less than four years after their discovery, the ability of perovskite LEDs (PLEDs) to produce light from electrons already rivaled those of the best performing OLEDs. They have a potential for cost-effectiveness as they can be processed from solution, a low-cost and low-tech method, which might allow perovskite-based devices that have large areas to be made with extremely low cost. Their efficiency is superior by eliminating non-radiative losses, in other words, elimination of recombination pathways that do not produce photons; or by solving outcoupling problem (prevalent for thin-film LEDs) or balancing charge carrier injection to increase the EQE (external quantum efficiency). The most up-to-date PLED devices have broken the performance barrier by shooting the EQE above 20%. In 2018, Cao et al. and Lin et al. independently published two papers on developing perovskite LEDs with EQE greater than 20%, which made these two papers a mile-stone in PLED development. Their device have similar planar structure, i.e. the active layer (perovskite) is sandwiched between two electrodes. To achieve a high EQE, they not only reduced non-radiative recombination, but also utilized their own, subtly different methods to improve the EQE. In the work of Cao et al., researchers targeted the outcoupling problem, which is that the optical physics of thin-film LEDs causes the majority of light generated by the semiconductor to be trapped in the device.
For Charitable Service. Colonel (Rtd) Brian Mark Gorski, MBE. For services to Museums and to the community in Bury, Greater Manchester. Solange Anna-Natasha Urdang. Chief Executive Officer and Founder, The Dang Studios, London, Co-Founder and Director, Black British Theatre Awards and lately Chief Executive Officer, Urdang Academy. For services to Dance and Musical Theatre. Andrew Graham. Deputy Director, Strategic Finance Directorate, Department for Education. For Public Service and to the community in County Durham. Natasha Jane Grant. Deputy Director, Cabinet Office. For Public Service. Edward James Gray. Lately Chair, Antivirals Taskforce. For services to Public Health during Covid-19. Betsy Gregory. For services to Dance. Yvette Mona Griffith. Co-Chief Executive, Jazz re:freshed, Founder Member, GiveBLACK and Founding Trustee, Black Funding Network. For services to Cultural Philanthropy and to Music. Neil Francis Guckian. Chief Executive, The Western Health and Social Care Trust. For services to Health and Social Care and to the community in Northern Ireland. Professor Gavin Halbert. Director, Cancer Research UK Formulation Unit, University of Strathclyde. For services to Cancer Treatment and Research. Professor David Rodney Heath-Brown. Emeritus Fellow, University of Oxford. For services to Mathematics and Mathematical Research. Paul Michael Heygate. Joint Managing Director, Heygate Group. For services to the Food Industry and to Charity. Gordon Arthur Woolnough Hickman. Head of Exotic Disease Policy, Department for Environment, Food and Rural Affairs.
Petersburg, Florida, was subject to an FCA claim that resulted in a total judgment of US$1.179 million on 214 fraudulent claims to Medicare that totaled US$755.54 stemming from the lack of a CLIA certificate. The oncology practice had its own CLIA certificate and acquired another oncology clinic with an in-house lab, but did not obtain the clinic's CLIA license, so the existing CLIA certificate did not cover the new practice. Because the lab at the newly acquired oncology practice lacked a proper CLIA certificate, reimbursement was denied. The practice opted to resubmit the bills to fraudulently claim the tests were performed at an office with a valid CLIA certificate. In doing so 214 times, the federal government suffered $755.54 in damages. The court trebled the damages to $2,266.62 and imposed the minimum statutory penalty of $5,500 per violation for each of the 214 violations. The Eleventh circuit noted that "[s]eeing a judgment of $1.179 million based on $755.54 in actual damages may raise an eyebrow," noting that "[f]raud harms the United States in ways untethered to the value of any ultimate payment" and that "[i]n the context of the FCA, we also consider the deterrent effect of a monetary award."
Sources: en.wikipedia.org
== Presentation == Blastic plasmacytoid dendritic cell neoplasm occurs in children, including neonates, but is more common in adults, particularly those between the ages 60–80. BPDCN usually (i.e. 61% to 90% of cases) presents with skin lesions, i.e. nodules, tumors, red or purple papules, bruise-like patches, and/or ulcers that most often occur on the head, face, and upper torso. The lesions are due to diffuse infiltrations of the skin by malignant pDC. In one large study, this presentation was accompanied by swollen lymph nodes, usually in the neck, due to malignant pDC infiltrations (~50% of cases); enlarged liver (~16% of cases) and/or spleen (26% of cases), also due to malignant pDC infiltrations; increased levels of malignant pDC in blood (i.e. >2% of nucleated cells) (~40% of cases), bone marrow (~65% of cases) and cerebrospinal fluid (47% of childhood cases but less often detected in adult cases). More advanced or severe cases may present with extreme organ and/or lymph node enlargements, skin lesions in virtually any site, and clinical evidence of malignant pDC infiltrations in the breasts, eyes, kidneys, lungs, gastrointestinal tract, bone, sinuses, ears, or testes. About 10% of individuals with BPDCN present with a leukemia-like disease, i.e. they exhibit circulating malignant pDC, anemia, thrombocytopenia, and/or leukopenia due to extensive malignant pDC infiltrations in the bone marrow. A leukemic phase of the disease is a common feature of end stage and post-therapy relapsing BPDCN.
== Gender-affirming care == Various options are available for transgender people to pursue physical transition. There have been options for transitioning for transgender individuals since 1917. Gender-affirming care helps people to change their physical appearance and/or sex characteristics to accord with their gender identity; it includes gender-affirming hormone therapy and gender-affirming surgery. While many transgender people do elect to transition physically, every transgender person has different needs and, as such, there is no required transition plan. Preventive health care is a crucial part of transitioning and a primary care physician is recommended for transgender people who are transitioning.
== Career == In 2001, Nigam founded the Swansea University Maggot Research Group, of which she is a director. The group focuses on therapeutic applications of the medicinal maggot Lucilia sericata. She then became an associate professor at Swansea University. In 2018, Nigam was promoted to professor which included a move from the research to the innovation and engagement strand. Nigam fulfills many roles outside of her permanent academic position. In 2007, she became a member of the Welsh Wound Network group, an enterprise which aims to support the clinical development of wound healing science. In April 2014, she was an elected participant of the Welsh Crucible Programme. Nigam is an elected Fellow of the Royal Entomological Society (FRES).
Sources: en.wikipedia.org
No regulator in a major market has approved it for human use. It appears in research settings and in products marketed outside pharmacy channels. Legal status for personal possession varies by country.
Afamelanotide is a linear analog that has received approval in some jurisdictions for a specific photoprotection indication. Melanotan II is cyclic and less selective across melanocortin receptors. The two are related but are not interchangeable in regulatory or clinical terms.
A compound that activates several receptor subtypes may produce effects beyond pigmentation. Selectivity influences which tissues respond and shapes the side-effect profile described in reports. Designing subtype-selective analogs is a stated goal of melanocortin research.
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.