If you have been reading about cyclic heptapeptide and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2025-11-05. Numbers and descriptions here follow the published literature rather than marketing material.
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 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 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.
| 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 |
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 II is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its structure substitutes a lactam bridge between side chains to increase stability relative to the native hormone. The compound is also known by the shorthand MT-II and by several non-proprietary synonyms used in research catalogues. It is not an approved therapeutic product in any major jurisdiction; material sold under this name is typically offered as a laboratory reagent rather than as a medicine.
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.
Because of their ability to quickly grow and the relative ease with which they can be manipulated, bacteria are the workhorses for the fields of molecular biology, genetics, and biochemistry. By making mutations in bacterial DNA and examining the resulting phenotypes, scientists can determine the function of genes, enzymes, and metabolic pathways in bacteria, then apply this knowledge to more complex organisms. The aim of understanding the biochemistry of a cell has led to the synthesis of large amounts of enzyme kinetics and gene expression data into mathematical models of entire organisms. This is achievable in some well-studied bacteria, with models of Escherichia coli metabolism now being produced and tested. This understanding of bacterial metabolism and genetics allows the use of biotechnology to bioengineer bacteria for the production of therapeutic proteins, such as insulin, growth factors, or antibodies. Because of their importance for research in general, samples of bacterial strains are isolated and preserved in Biological Resource Centres. This ensures the availability of the strain to scientists worldwide.
== Analysis == In simple manual columns, the eluent is collected in constant volumes, known as fractions. The more similar the particles are in size the more likely they are in the same fraction and not detected separately. More advanced columns overcome this problem by constantly monitoring the eluent.
Fleming resumed his vacation and returned in September. According to his notes on 30 October, he collected the original mould and grew it in culture plates. After four days he found that the plates developed large colonies of the mould. He repeated the experiment with the same bacteria-killing results. He later recounted his experience:
==== Tandem Diabetes Care t:Slim X2 with Control IQ ==== The Tandem Diabetes Care t:Slim X2 was approved by the U.S. Food and Drug Administration in 2019 and is the first insulin pump to be designated as an alternate controller enabled (ACE) insulin pump. ACE insulin pumps allow users to integrate continuous glucose monitors, automated insulin dosing (AID) systems, and other diabetes management devices with the pump to create a personalized diabetes therapy system. Many users of the t:slim X2 integrate the pump with the Dexcom G6, a continuous glucose monitor approved by the FDA in 2018. It was the first CGM authorized for use in an integrated therapy system. The device does not require fingerstick calibrations.
Sources: en.wikipedia.org
== General and cited references == Gabriele Froböse, Rolf Froböse, Michael Gross (Translator): Lust and Love: Is It More than Chemistry? Royal Society of Chemistry, 2006; ISBN 0-85404-867-7. Michael Scott: Pillow Talk: A Comprehensive Guide to Erotic Hypnosis and Relyfe Programming. Blue Deck Press, 2011; ISBN 0-98341-640-0.
=== Láadan === Láadan is not agglutinating as there is no mechanism to combine arbitrary words into one without intermediating grammatical mechanisms (such as the relativizer § In other languages); however, there are a number of affixes that further elucidate the contextual meaning of a word. These are ignored when determining the longest words in the language. The primary reference for vocabulary is the 3rd edition of the official dictionary and grammar.
A genetically modified organism (GMO) is any organism whose genetic material has been altered using genetic engineering techniques. The exact definition of a genetically modified organism and what constitutes genetic engineering varies, with the most common being an organism altered in a way that "does not occur naturally by mating and/or natural recombination". A wide variety of organisms have been genetically modified (GM), including animals, plants, and microorganisms. Genetic modification can include the introduction of new genes or enhancing, altering, or knocking out endogenous genes. In some genetic modifications, genes are transferred within the same species, across species (creating transgenic organisms), and even across kingdoms. Creating a genetically modified organism is a multi-step process. Genetic engineers must isolate the gene they wish to insert into the host organism and combine it with other genetic elements, including a promoter and terminator region and often a selectable marker. A number of techniques are available for inserting the isolated gene into the host genome. Recent advancements using genome editing techniques, notably CRISPR, have made the production of GMOs much simpler. Herbert Boyer and Stanley Cohen made the first genetically modified organism in 1973, a bacterium resistant to the antibiotic kanamycin. The first genetically modified animal, a mouse, was created in 1974 by Rudolf Jaenisch, and the first plant was produced in 1983. In 1994, the Flavr Savr tomato was released, the first commercialized genetically modified food.
=== Ligand removal === In many cases, as in various high-temperature catalytic applications of Au, the removal of the capping ligands produces more desirable physicochemical properties. The removal of ligands from colloidal gold while maintaining a relatively constant number of Au atoms per Au NP can be difficult due to the tendency for these bare clusters to aggregate. The removal of ligands is partially achievable by simply washing away all excess capping ligands, though this method is ineffective in removing all capping ligand. More often ligand removal achieved under high temperature or light ablation followed by washing. Alternatively, the ligands can be electrochemically etched off.
== Political positions == As a party in Albania, the Socialist Party of Albania is described as social-democratic and centre-left. In its 2013 party platform, the party has pledged to replace the flat tax with a progressive tax, and also supports universal health care. Party leader Edi Rama has indicated that he supports LGBT rights in Albania. The party is also pro-European, supports the accession of Albania to the European Union, NATO membership, and considers Kosovo "Albania's main strategic partner and ally".
Sources: en.wikipedia.org
A comparative genomic study (in 2020) analyzed 494 complete genomes from the Pseudomonas genus, of which 189 were P. aeruginosa strains. The study observed that their protein count and GC content ranged between 5500 and 7352 (average: 6192) and between 65.6 and 66.9% (average: 66.1%), respectively. This comparative analysis further identified 1811 aeruginosa-core proteins, which accounts for more than 30% of the proteome. The higher percentage of aeruginosa-core proteins in this latter analysis could partly be attributed to the use of complete genomes. Although P. aeruginosa is a very well-defined monophyletic species, phylogenomically and in terms of ANIm values, it is surprisingly diverse in terms of protein content, thus revealing a very dynamic accessory proteome, in accordance with several analyses. It appears that, on average, industrial strains have the largest genomes, followed by environmental strains, and then clinical isolates. The same comparative study (494 Pseudomonas strains, of which 189 are P. aeruginosa) identified that 41 of the 1811 P. aeruginosa core proteins were present only in this species and not in any other member of the genus, with 26 (of the 41) being annotated as hypothetical. Furthermore, another 19 orthologous protein groups are present in at least 188/189 P. aeruginosa strains and absent in all the other strains of the genus.
The taste of kopi luwak varies with the type and origin of the excreted beans, processing, roasting, aging, and brewing. The ability of the civet to select its berries, and other aspects of the civet's diet and health, like stress levels, may also influence the processing and, hence taste. Within the coffee industry, kopi luwak is widely regarded as a gimmick or novelty item. The Specialty Coffee Association of America (SCAA) states that there is a "general consensus within the industry...it just tastes bad". A coffee professional compared the same beans with and without the kopi luwak process using a rigorous coffee cupping evaluation. He concluded: "It was apparent that luwak coffee sold for the story, not superior quality...Using the SCAA cupping scale, the luwak scored two points below the lowest of the other three coffees. It would appear that the luwak processing diminishes good acidity and flavor and adds smoothness to the body, which is what many people seem to note as a positive to the coffee." Professional coffee tasters were able to distinguish kopi luwak from other coffee samples, but remarked that it tasted "thin". Some critics claim more generally that kopi luwak is simply bad coffee, purchased for novelty rather than taste. A food writer reviewed kopi luwak available to American consumers and concluded, "It tasted just like...Folgers. Stale. Lifeless. Petrified dinosaur droppings steeped in bathtub water.
== History == Its existence was first suggested in 1905 by the British physiologist John Sydney Edkins, and gastrins were isolated in 1964 by Hilda Tracy and Roderic Alfred Gregory at the University of Liverpool. In 1964 the structure of gastrin was determined.
== Pharmacology == The pharmacology of 5α-reductase inhibition is complex, but involves the binding of NADPH to the enzyme followed by the substrate. Specific substrates include testosterone, progesterone, androstenedione, epitestosterone, cortisol, aldosterone, and deoxycorticosterone. The entire physiologic effect of their reduction is unknown, but likely related to their excretion or is itself physiologic. 5α-Reductase reduces the steroid Δ4,5 double bond in testosterone to its more active form DHT. Thus, inhibition results in decreased amounts of DHT. Because of this, slight elevations in testosterone and estradiol levels occur. The 5α-reductase reaction is a rate-limiting step in the testosterone reduction and involves the binding of NADPH to the enzyme followed by the substrate.
=== Aortic regurgitation === Patients with aortic regurgitation may experience heart failure symptoms, such as dyspnea on exertion, orthopnea and paroxysmal nocturnal dyspnea, palpitations, and angina pectoris. In acute cases patients may experience cyanosis and circulatory shock. Medical signs of aortic regurgitation include increased pulse pressure by increased systolic and decreased diastolic blood pressure, but these findings may not be significant if acute. The patient may have a diastolic decrescendo murmur best heard at left sternal border, water hammer pulse, Austin Flint murmur, and a displaced apex beat down and to the left. A third heart sound may be present
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.
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.