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 2025-09-30. Numbers and descriptions here follow the published literature rather than marketing material.
Regulatory treatment varies by country. In the United States the peptide is not approved as a medicine, and products offered for human use may be treated as unapproved new drugs; some states also restrict sale. Australia, the United Kingdom, and European Union member states apply comparable restrictions to unapproved peptide products. Border agencies have seized shipments labelled as research chemicals. Classification may change over time, and the legal position for personal importation is not clearly settled in most published guidance.
Lyophilised melanotan-2 is supplied as a solid, which is more stable than a solution. The material is hygroscopic, so weighing is done quickly, in low humidity, with the container kept sealed. Reconstitution usually uses water for injection or bacteriostatic water, added down the wall of the vial to limit foaming. A reconstituted solution is held at 2 to 8 °C and kept away from light. Repeated freezing and thawing of the same vial is avoided because ice crystal formation and concentration effects degrade the peptide.
Reversed-phase high-performance liquid chromatography is the routine method for purity assessment. Peptides absorb near 214 nm because of the peptide bond, and a gradient of acetonitrile in water separates the intact peptide from deletion sequences, oxidised products, and earlier-eluting fragments at neutral pH. Electrospray ionisation mass spectrometry provides an orthogonal check: the measured mass must agree with the theoretical value. Amino acid analysis and peptide mapping confirm structure but are used less often. Reference standards remain scarce because the peptide is not described in any pharmacopoeia.
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.
| Property | Value | Notes |
|---|---|---|
| Lyophilised storage | −20 °C, dry, protected from light | Vials are sealed and allowed to reach room temperature before opening |
| Reconstituted storage | 2 to 8 °C, protected from light | Short-term holding; avoid repeated freeze-thaw cycles |
| Reconstitution solvent | Water for injection or bacteriostatic water | Added slowly along the vial wall to reduce foaming and shear |
| Purity measurement | RP-HPLC with area normalisation | Acetonitrile-water gradient monitored at roughly 214 nm |
| Identity confirmation | Electrospray ionisation mass spectrometry | Observed mass compared against the calculated peptide mass |
Verification of a purchased sample requires documentation linking a batch to a certificate of analysis, and that document should be read for the methods used rather than the headline purity figure. A single chromatographic percentage does not establish identity. Independent laboratories can perform identity and content assays, but no such test establishes that a product is suitable for human use. Claims about efficacy rest largely on small, early studies rather than on replicated controlled trials, and that gap remains open.
Identity testing for a cyclic peptide of this size usually relies on reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The mass spectrum confirms molecular weight, while the chromatographic trace indicates the proportion of related impurities. Tandem mass spectrometry can provide sequence-level information when fragmentation data are compared against a reference standard. Nuclear magnetic resonance is sometimes used to confirm the lactam bridge, although it requires more material and greater operator expertise than routine chromatographic methods.
Lyophilised peptide powder is comparatively stable when kept dry, cold and protected from light. Once dissolved, the molecule is exposed to hydrolysis, oxidation and microbial growth, and degradation accelerates at higher temperatures and in alkaline solution. Repeated freeze-thaw cycles concentrate solutes and promote aggregation. Handling guidance for research peptides commonly clusters around freezer temperatures for powder and short refrigerated use for reconstituted solutions, with pH control and sterile technique applied throughout.
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.
=== Ber–Bla === Paul Berg (1926–2023), American biochemist known for research on nucleic acids, especially recombinant DNA, 1980 Nobel Prize in Chemistry Friedrich Bergius (1884–1949), German chemist known for known for production of synthetic fuel from coal, 1931 Nobel Prize in Chemistry Helen M. Berman (born 1943), American chemist who worked on structural analysis of protein-nucleic acid complexes Marcellin Berthelot (1827–1907), French chemist, a prominent anti-vitalist who synthesized many organic compounds from inorganic substances, and developed thermochemistry Claude Louis Berthollet (1748–1822), French chemist who developed the theory of chemical equilibria Carolyn R. Bertozzi (born 1966) American chemist who studies chemical reactions compatible with living systems ("bioorthogonal chemistry"), 2022 Nobel Prize in Chemistry Guy Bertrand (born 1952) French chemist working on carbenes, nitrenes, phosphinidenes, radicals and biradicals Jöns Jakob Berzelius (1779–1848), Swedish chemist who discovered several elements Johannes Martin Bijvoet (1892–1980), Dutch chemist and crystallographer who determined the absolute configuration of sodium rubidium tartrate Leonora Bilger (1893–1975), American chemist who studied nitrogenous compounds Katherine Bitting (1869–1937), Canadian and American food chemist for the United States Department of Agriculture and the National Canners Association Joseph Black (1728–1799), British chemist known for discoveries of magnesium, latent heat, specific heat, and carbon dioxide
Adipose tissue (also known as body fat or simply fat) is a loose connective tissue composed mostly of adipocytes. It also contains the stromal vascular fraction of cells including preadipocytes, fibroblasts, vascular endothelial cells and a variety of immune cells such as adipose tissue macrophages. Its main role is to store energy in the form of lipids, although it also cushions and insulates the body. Previously treated as being hormonally inert, in recent years adipose tissue has been recognized as a major endocrine organ, as it produces hormones such as leptin, estrogen, resistin, and cytokines (especially TNFα). In obesity, adipose tissue is implicated in the chronic release of pro-inflammatory markers known as adipokines, which are responsible for the development of metabolic syndrome—a constellation of diseases including type 2 diabetes, cardiovascular disease and atherosclerosis. Adipose tissue is derived from preadipocytes and its formation appears to be controlled in part by the adipose gene. The two types of adipose tissue are white adipose tissue (WAT), which stores energy, and brown adipose tissue (BAT), which generates body heat. Adipose tissue—more specifically brown adipose tissue—was first identified by the Swiss naturalist Conrad Gessner in 1551.
=== Underlying disorders === If an underlying muscle disease is suspected, for instance, if there is no obvious explanation or there have been multiple episodes, it may be necessary to perform further investigations. During an attack, low levels of carnitine in the blood and high levels of acylcarnitine in blood and urine may indicate a lipid metabolism defect, but these abnormalities revert to normal during convalescence. Other tests may be used at that stage to demonstrate these disorders. Disorders of glycolysis can be detected by various means, including the measurement of lactate after exercise; a failure of the lactate to rise may be indicative of a disorder in glycolysis, while an exaggerated response is typical of mitochondrial diseases. Electromyography (EMG) may show particular patterns in specific muscle diseases; for instance, McArdle's disease and phosphofructokinase deficiency show a phenomenon called cramp-like contracture. There are genetic tests available for many of the hereditary muscle conditions that predispose to myoglobinuria and rhabdomyolysis. Muscle biopsy can be useful if an episode of rhabdomyolysis is thought to be the result of an underlying muscle disorder. A biopsy sample taken during an episode is often uninformative, as it will show only evidence of cell death or may appear normal. Taking the sample is therefore delayed for several weeks or months. The histopathological appearance on the biopsy indicates the nature of the underlying disorder. For instance, mitochondrial diseases are characterized by ragged red fibers.
== Key issues == The agreed version of the declaration, a single sentence of just 67 words, was sent on 2 November 1917 in a short letter from Balfour to Walter Rothschild, for transmission to the Zionist Federation of Great Britain and Ireland. The declaration contained four clauses, of which the first two promised to support "the establishment in Palestine of a national home for the Jewish people", followed by two "safeguard clauses" with respect to "the civil and religious rights of existing non-Jewish communities in Palestine", and "the rights and political status enjoyed by Jews in any other country".
=== Control of oxidative stress === Cysteine residues from MTs can capture harmful oxidant radicals like the superoxide and hydroxyl radicals. In this reaction, cysteine is oxidized to cystine, and the metal ions which were bound to cysteine are liberated to the media. As explained in the Expression and regulation section, this Zn can activate the synthesis of more MTs. This mechanism has been proposed to be an important mechanism in the control of the oxidative stress by MTs. The role of MTs in reducing oxidative stress has been confirmed by MT Knockout mutants, but some experiments propose also a prooxidant role for MTs. In mammalian cells, spontaneous mutagenesis is caused to a large extent by oxidative DNA damage, and the occurrence of such damage can be blocked by metallothionein. Metallothionein also plays a role in hematopoietic cell differentiation and proliferation, as well as prevention of apoptosis of early differentiated cells. Induced MT levels were adversely associated with sensitivity to etoposide-induced apoptosis, signifying that MT is a potential negative controller of apoptosis.
Sources: en.wikipedia.org
== Cultivation == Parsley grows best in moist, well-drained soil, with full sun. It grows best between 22–30 °C (72–86 °F), and usually is grown from seed. Germination is slow, taking four to six weeks, and it often is difficult because of furanocoumarins in its seed coat. Typically, plants grown for the leaf crop are spaced 10 cm (3.9 in) apart, while those grown as a root crop are spaced 20 cm (7.9 in) apart to allow for the root development. Parsley attracts several species of wildlife. Some swallowtail butterflies use parsley as a host plant for their larvae; their caterpillars are black and green striped with yellow dots, and will feed on parsley for two weeks before turning into butterflies. Bees and other nectar-feeding insects also visit the flowers.
This stratified squamous epithelium is maintained by cell division within the stratum basale, in which differentiating cells slowly displace outwards through the stratum spinosum to the stratum corneum, where cells are continually shed from the surface. In normal skin, the rate of production equals the rate of loss; about two weeks are needed for a cell to migrate from the basal cell layer to the top of the granular cell layer, and an additional two weeks to cross the stratum corneum. The dermis is the layer of skin between the epidermis and subcutaneous tissue, and comprises two sections, the papillary dermis and the reticular dermis. The superficial papillary dermis interdigitates with the overlying rete ridges of the epidermis, between which the two layers interact through the basement membrane zone. Structural components of the dermis are collagen, elastic fibers, and ground substance. Within these components are the pilosebaceous units, arrector pili muscles, and the eccrine and apocrine glands. The dermis contains two vascular networks that run parallel to the skin surface—one superficial and one deep plexus—which are connected by vertical communicating vessels. The function of blood vessels within the dermis is fourfold: to supply nutrition, to regulate temperature, to modulate inflammation, and to participate in wound healing. The subcutaneous tissue is a layer of fat between the dermis and underlying fascia.
=== Other workup methods === Penile nerves function Tests such as the bulbocavernosus reflex test are used to ascertain whether there is enough nerve sensation in the penis. The physician squeezes the glans (head) of the penis, which immediately causes the anus to contract if nerve function is normal. A physician measures the latency between squeeze and contraction by observing the anal sphincter or by feeling it with a gloved finger in the anus. Nocturnal penile tumescence (NPT) It is normal for a man to have five to six erections during sleep, especially during rapid eye movement (REM). Their absence may indicate a problem with nerve function or blood supply in the penis. There are two methods for measuring changes in penile rigidity and circumference during nocturnal erection: snap gauge and strain gauge. A significant proportion of males who have no sexual dysfunction nonetheless do not have regular nocturnal erections. Penile biothesiometry This test uses electromagnetic vibration to evaluate sensitivity and nerve function in the glans and shaft of the penis. Dynamic infusion cavernosometry (DICC) Technique in which fluid is pumped into the penis at a known rate and pressure. It gives a measurement of the vascular pressure in the corpus cavernosum during an erection. Corpus cavernosometry Cavernosography measurement of the vascular pressure in the corpus cavernosum. Saline is infused under pressure into the corpus cavernosum with a butterfly needle, and the flow rate needed to maintain an erection indicates the degree of venous leakage.
== External links == Woon, David E. (October 1, 2010). "Interstellar and Circumstellar Molecules". Retrieved 2010-10-04. "Molecules in Space". Universität zu Köln. April 2022. Retrieved 2022-05-25. Dworkin, Jason P. (February 1, 2007). "Interstellar Molecules". NASA's Cosmic Ice Lab. Retrieved 2010-12-23. Wootten, Al (November 2005). "The 129 reported interstellar and circumstellar molecules". National Radio Astronomy Observatory. Retrieved 2007-02-13. Lovas, F. J.; Dragoset, R. A. (February 2004). "NIST Recommended Rest Frequencies for Observed Interstellar Molecular Microwave Transitions, 2002 Revision". Journal of Physical and Chemical Reference Data. 33 (1): 177. Bibcode:2004JPCRD..33..177L. doi:10.1063/1.1633275. Archived from the original on 2013-02-01. Retrieved 2007-02-13. Williams, David A.; Cecchi-Pestellini, Cesare (8 February 2023). Astrochemistry: Chemistry in Interstellar and Circumstellar Space. Royal Society of Chemistry. ISBN 978-1-83916-939-7.
== Hybrid techniques == Combinations of the above techniques produce "hybrid" or "hyphenated" techniques. Several examples are in popular use today and new hybrid techniques are under development. Hyphenated separation techniques refer to a combination of two or more techniques to separate chemicals from solutions and detect them. Most often, the other technique is some form of chromatography. Hyphenated techniques are widely used in chemistry and biochemistry. A slash is sometimes used instead of hyphen, especially if the name of one of the methods contains a hyphen itself. Examples of hyphenated techniques:
Sources: en.wikipedia.org
Low temperature slows hydrolysis and oxidation, the two main routes by which the peptide backbone and side chains are modified. A lyophilised powder stored at −20 °C is more stable than one kept at room temperature, and once the material is dissolved the degradation rate rises, making refrigeration more important.
Liquid chromatography coupled to mass spectrometry is the most common approach because it combines a retention time with a mass measurement. A chromatographic peak alone cannot establish which peptide is present, so mass determination or amino acid analysis is used as an orthogonal confirmation alongside the separation.
This depends on buffer, pH, and concentration, and published stability data for this peptide are limited. In practice laboratories work through a refrigerated solution within a few weeks and discard samples that show cloudiness or visible particles. Freezing and thawing repeatedly is generally discouraged.
No regulatory agency has authorised melanotan-2 as a medicine for any indication. It circulates mainly as a research chemical or through unregulated channels. As a result, identity, purity and content are not independently guaranteed.