The short version of cyclic heptapeptide fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-06-17 and is reviewed periodically as new material appears.
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.
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 | Analogue of alpha-melanocyte-stimulating hormone |
| Common synonyms | MT-II; melanotan 2 | No internationally accepted non-proprietary name |
| Typical presentation | Lyophilised powder in a sealed vial | Often supplied alongside a separate diluent |
| Regulatory status | Unapproved therapeutic substance | Customs seizure reported in several jurisdictions |
| Reported route in use | Subcutaneous injection | Self-administered outside clinical settings |
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.
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.
== Life and work == Bergmann was born in Fürth, Bavaria, Germany on February 12, 1886, the seventh child of coal wholesalers Salomon and Rosalie Bergmann. Bergmann started studying biology at the Ludwig-Maximilians-Universität München, but lectures by Adolf von Baeyer captured his interest and eventually persuaded him to switch to Organic Chemistry. He continued his chemical studies at the Friedrich Wilhelm University of Berlin, where he was taught by Emil Fischer. After receiving his PhD under the supervision of Ignaz Bloch [de] in 1911 for his thesis on acyl(polysulfides), he became the assistant to Fischer at the University of Berlin, where he stayed until Fischer's death in 1919. He received his habilitation in 1921. In 1922 Bergmann was made the first director of the Kaiser Wilhelm Institute for Leather Research in Dresden, which was created in 1921 and from which the Max Planck Institute of Biochemistry descends. It was there that he worked with his former doctoral student, Leonidas Zervas, who eventually rose to vice-director of the institute and briefly succeeded Bergmann as director. In the early 1930s, the two scientists developed the Bergmann-Zervas carbobenzoxy method for the synthesis of polypeptides, which started the field of controlled peptide chemical synthesis and remained the dominant method in it for the next 20 years. Bergmann and Zervas gained international academic fame as a result. Bergmann was nonetheless forced to abandon his institute due to his Jewish origin after the passage of the Civil Service Law and emigrated from Nazi Germany in 1933.
Contraction is achieved by the muscle's structural unit, the muscle fiber, and by its functional unit, the motor unit. Muscle fibers are excitable cells stimulated by motor neurons. The motor unit consists of a motor neuron and the many fibers that it makes contact with. A single muscle is stimulated by many motor units. Muscle fibers are subject to depolarization by the neurotransmitter acetylcholine, released by the motor neurons at the neuromuscular junctions. In addition to the actin and myosin myofilaments in the myofibrils that make up the contractile sarcomeres, there are two other important regulatory proteins – troponin and tropomyosin, that make muscle contraction possible. These proteins are associated with actin and cooperate to prevent its interaction with myosin. Once a cell is sufficiently stimulated, the cell's sarcoplasmic reticulum releases ionic calcium (Ca2+), which then interacts with the regulatory protein troponin. Calcium-bound troponin undergoes a conformational change that leads to the movement of tropomyosin, subsequently exposing the myosin-binding sites on actin. This allows for myosin and actin ATP-dependent cross-bridge cycling and shortening of the muscle.
== Investigation == Between March and June 2022, unusually high infant mortality rates occurred at a neonatal nursing unit in the Ramón Castillo Neonatal Hospital in Córdoba, Argentina. A series of investigations initially pointed to a hospital-acquired infection or malpractice. The provincial government then intervened at the Ramón Castillo Neonatal Hospital after these reports of healthy babies dying without cause. Prosecutor Raúl Garzón labelled the case as "enormously grave" but initially insisted that they could have been either cases of malpractice or hospital-acquired infections, and no accusations were made. Nonetheless, Garzón ordered a search warrant on the hospital and relieved twenty employees from their duties. Police and prosecutors began to suspect that there had been foul play when no more deaths occurred after the suspension of those twenty employees. On the same day that the hospital was searched, authorities suspended the head of the hospital. The investigation was prompted by a doctor who refused to sign the death certificates of two healthy babies who died on the same day in June 2022; allegedly the two last babies to die from an external cause (murder). As the search warrant was served, the prosecution asked for the exhumation of the remains of the deceased babies, whose autopsies showed abnormal levels of potassium, which medical investigators attributed to being deliberately injected into the babies, as said levels of potassium are not normally produced by the body.
Sources: en.wikipedia.org
The Russell 1000 is a stock market index tracking the stock performance of 1,000 companies listed on stock exchanges in the United States that are considered to have large or medium market capitalizations. The Russell 1000 is a subset of the Russell 3000. It is maintained by FTSE Russell and its components are determined via strict rules-based methodology, with an annual rebalancing in late June, the only time new entrants are added to the index. The index is a public-float-weighted/capitalization-weighted index. The index includes approximately 93% of the total market capitalization of U.S. public companies, with an aggregate market capitalization of more than $70.70 trillion as of September 25, 2026. As of June 16, 2026, the median market capitalization of the components of the index is $17.5 billion and components range in market capitalization from $5.7 billion to $4.8 trillion. Products linked to the Russell 1000 include index funds (exchange-traded funds/ETFs and mutual funds) as well as derivatives (options and futures contracts), which are available for trading in many countries with the goal of replicating the performance of the index. Also available are modified index funds; they replicate the performance of the index with modifications such as the use of covered call strategies, equal weighting, performance buffers, leverage, inclusion of only growth or value stocks, or exclusion of certain sectors, all with the goal of changing the risk/return and yield.
Thy-1 levels in the neonatal rat brain, as well as the developing human brain, are low compared to adult brain. During the first few weeks of postnatal development, Thy-1 levels increase exponentially as the brain matures. Lymphoid tissue Thy-1 expression is highly variable between species. In humans, Thy-1 expression is restricted to only a small population of cortical thymocytes and not expressed in mature human T cells. It is probably the most abundant glycoprotein of murine thymocytes, with about One million copies per cell covering up to 10–20% of the cell surface. Mouse cortical thymocytes express higher levels of Thy-1 than medullary thymocytes which in turn express more than lymph node cells (~200,000 copies/cell). A similar inverse developmental temporal expression profile is seen in rats T cells, although rat Thy-1 is lost at an earlier stage of T cell maturation. Thy-1 is only expressed on thymocytes in rats (contrast to thymocytes and splenocytes in mice). The third intron of the mouse Thy-1 gene has a 36 base pair region that recruits nuclear transcription factors, such as Ets-1-like NF, expressed in thymocytes and splenocytes. The homologous region of the rat gene lacks the Ets-1-like NF binding site, but instead binds another NF expressed in rat thymocytes but not splenocytes.
==== Czech Republic ==== In the Czech Republic, possession of "amount larger than small" of LSD is criminalized, while possession of smaller amounts is a misdemeanor. The definition of "amount larger than small" is determined by judicial practice and specific regulations.
Sources: en.wikipedia.org
No. No major regulatory agency has granted a marketing authorisation for melanotan II as a medicine. Products sold under this name are generally presented as laboratory reagents and are not subject to the batch-release testing applied to approved drugs.
It was developed in the 1980s by researchers investigating analogues of alpha-melanocyte-stimulating hormone for pigmentation and related endpoints. Early work included small human studies during the 1990s. Development did not progress to licensing, and the compound remained a research and grey-market item.
Peptides are prone to truncation, oxidation and aggregation during synthesis and handling. Without independent testing, a buyer cannot confirm the identity or the content of a vial. Analytical surveys of unapproved peptide products have repeatedly found discrepancies between label claims and measured composition.
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.