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 2025-09-12 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 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.
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.
| 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 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.
Receptor studies place melanotan-2 among non-selective melanocortin agonists, binding MC1R, MC3R, MC4R and MC5R rather than a single subtype. Activation of MC1R on cutaneous melanocytes raises tyrosinase activity and shifts pigment synthesis toward eumelanin, which is darker and more photostable than pheomelanin. Central receptors, particularly MC4R, are associated with appetite suppression and with reported effects on sexual function. Because subtype selectivity is low, the same molecule engages pigment, metabolic and vascular pathways at once, and this breadth is a common explanation offered for the range of adverse events described in user reports.
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.
== Discovery == R7 was synthesized by the same researchers who were involved in the discovery of tropoflavin. A patent was filed for R7 in 2013 and was published in 2015. In 2016, it was reported to be in the preclinical stage of development. R7 was superseded by R13 because while R7 had a good drug profile in animals, it showed almost no conversion into tropoflavin in human liver microsomes. Tropoflavin, a naturally occurring flavonoid, was found to act as an agonist of the TrkB with nanomolar affinity (Kd ≈ 320 nM). Due to the presence of a vulnerable catechol group on its 2-phenyl-4H-chromene ring, tropoflavin is extensively conjugated via glucuronidation, sulfation, and methylation during first-pass metabolism in the liver and has a poor oral bioavailability of only 5% in mice upon oral administration. As such, tropoflavin itself is a poor candidate for clinical development as an oral medication. R7 is a derivative of tropoflavin with carbamate moieties on its hydroxyl groups, thereby protecting it from metabolism.
==== Corneal Allogenic Intrastromal Ring Segments (CAIRS) ==== Corneal Allogenic Intrastromal Ring Segment Keratoplasty (CAIRS Keratoplasty) is a modern surgical technique used in the treatment of keratoconus. It involves implanting finely shaped pieces of donor corneal tissue into the corneal stroma to reinforce and reshape the weakened, ectatic cornea, thereby improving both corneal structure and visual clarity. Because CAIRS uses biological graft material and has demonstrated strong outcomes with a favourable safety profile, it is formally recognised as a corneal transplantation procedure by health funding authorities in Australia, the United Kingdom, Japan, Germany, Brazil, the Netherlands, and a number of other countries. In contrast to traditional synthetic intrastromal corneal ring segments (ICRS) made from materials such as PMMA, CAIRS keratoplasty uses preserved allogeneic corneal tissue. This biological compatibility reduces the likelihood of complications sometimes seen with non-organic implants, including extrusion, infection, or chronic foreign body reaction. The CAIRS technique was pioneered by Dr Soosan Jacob, who first introduced it in 2018 through a large case series published in the Journal of Refractive Surgery. One of its key strengths is its suitability for corneas with irregular or decentered cones. The donor segments can be individually designed to achieve targeted corneal flattening and astigmatism improvement.
== Track listing == "Strange Meridian" (Russ Gershon) – 8:28 "Premonitions" (Curtis Hasselbring) – 5:29 "The Half-Life of Desire" (Gershon) – 5:30 "He Who Hesitates" (Hasselbring) – 7:54 "Temptation" (Nacio Herb Brown, Arthur Freed) – 5:17 "Circle in the Round/I Got It Bad" (Miles Davis/Duke Ellington) – 11:18 "Red" (Robert Fripp) – 11:21
Sources: en.wikipedia.org
=== Indigenous Uses === Legend has it that the indigenous people of the Niger Delta attempted to use crude oil for lighting because of its flammable trait in earlier times. However, it was not appropriate in lamps because of its stink and intense fumes while it burned. It holds a certain importance in the metaphysical beliefs of the Niger Delta people as they believed it cured illnesses related to ingestion, such as gastrointestinal disorders and fertility. As such, remedial uses for it came up in detoxification and the treatment of poison, anti-convulsion and dermal inflammation, etc. People ingested Bonny Light Crude directly, usually, along with olive oil. They applied it on burnt skin, fungating feet and leg ulcers. Also, as a way of complementing protein, most of the people in the Delta ate marine animals from coastal areas, which is a form of consuming crude oil indirectly.
By the possession of an intra-main-chain hydrogen bond between the CO of residue i and the NH of residue i+3; By having a distance of less than 7Å between the Cα atoms of residues i and i+3. The hydrogen bond criterion is the one most appropriate for everyday use, partly because it gives rise to four distinct categories; the distance criterion gives rise to the same four categories but yields additional turn types.
The two DNA strands then become templates for DNA polymerase to enzymatically assemble a new DNA strand from free nucleotides, the building blocks of DNA. As PCR progresses, the DNA generated is itself used as a template for replication, setting in motion a chain reaction in which the original DNA template is exponentially amplified. Almost all PCR applications employ a heat-stable DNA polymerase, such as Taq polymerase, an enzyme originally isolated from the thermophilic bacterium Thermus aquaticus. If the polymerase used was heat-susceptible, it would denature under the high temperatures of the denaturation step. Before the use of Taq polymerase, DNA polymerase had to be manually added every cycle, which was a tedious and costly process. Applications of the technique include DNA cloning for sequencing, gene cloning and manipulation, gene mutagenesis; construction of DNA-based phylogenies, or functional analysis of genes; diagnosis and monitoring of genetic disorders; amplification of ancient DNA; analysis of genetic fingerprints for DNA profiling (for example, in forensic science and parentage testing); and detection of pathogens in nucleic acid tests for the diagnosis of infectious diseases.
Sources: en.wikipedia.org
=== Conversion of UDP-GlcNAc to UDP-GalNAc === Human and some bacterial GALE isoforms reversibly catalyze the conversion of UDP-GlcNAc to UDP-GalNAc through an identical mechanism, inverting the stereochemical configuration at the sugar's 4' hydroxyl group.
Likewise, the Cohesin protein which binds sister chromatids in metaphase is able to be targeted by SUMOylation to allow the Cdc48 segregase to separate Cohesin and allow sister chromatid separation in early anaphase. In research as is often the case, scientists test drugs known to have significant effects on living systems; one such example is Rapamycin (known in pharmaceuticals as Sirolimus), the well-known inhibitor of mechanistic Target of Rapamycin, or mTOR. With respect to SUMOylation, Rapamycin may be thought of as having a "Sledge Hammer" effect, in which the drug promotes cellular autophagy, part of which includes broad-spectrum promotion of nonspecific SUMOylation for many proteins. This may be beneficial in some circumstances as it supports the breakdown of accumulated waste products. The importance of these studies in models such as yeast lies in their potential to inform scientists in the research and development of precise biomedical interventions that can translate to the improvement of human health in an array of clinical aspects.
== Analysis == The groups of bioactive compounds present in E. planum are phenolic acids, triterpenoid saponins, flavonoids, coumarins, and essential oils. The wide range of compounds is reflected in the wide range of uses. Qualitative and quantitative determinations of the phenolic acids by reverse phase high-performance liquid chromatography (RP HPLC) show relatively small amounts of rosmarinic, chlorogenic, and caffeic acids in the basal leaves and the roots of intact plants, and greater concentrations in E. planum from in vitro cultures. Qualitative and quantitative analyses of the essential oil compounds performed by gas chromatography with a flame ionization detector linked to a mass spectrometer (GC-FID-MS) show the main components of stalk leaf oil, and rosette leaf oil, as monoterpenes (limonene, and α- and β-pinene), sesquiterpenes, and hydrocarbons. (Z)-Falcarinol was found as the major component of root essential oil.
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.
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.