A practical reference on synthetic peptide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-02-09. Anything still debated is marked as such rather than presented as settled.
The compound was developed in the late 1980s and early 1990s by academic researchers investigating melanocortin signaling and pigmentation. Early work explored whether synthetic analogs could reproduce effects of the natural hormone under controlled conditions. The molecule never advanced through the full regulatory pathway required for approval as a medicine. From the mid-2000s onward it appeared in unregulated consumer markets, often distributed through informal channels. That gap between research origins and commercial availability shapes how the compound is discussed today.
Melanotan-2 is a synthetic peptide designed as an analog of alpha-melanocyte-stimulating hormone, a signaling molecule produced in the pituitary and skin. Its structure is a linear chain of seven amino acids that folds into a ring through an internal lactam bridge joining two side chains. The compound is sometimes written as MT-II or MEL-2 in informal and commercial contexts. It belongs to the melanocortin peptide family, a group of short signaling molecules that share a conserved core sequence recognized by melanocortin receptors.
Melanocytes are the pigment-producing cells of the skin, and they carry melanocortin-1 receptors on their surface. When the receptor is activated, cyclic adenosine monophosphate rises inside the cell and raises the activity of enzymes such as tyrosinase, which increases melanin output. Melanotan-2 binds melanocortin-1 receptors in vitro and in animal models, and this binding is generally described as the basis for the tanning effect. Other receptors account for different effects: melanocortin-4 receptors contribute to appetite and erectile signalling, while melanocortin-3 and melanocortin-5 receptors contribute to energy balance and exocrine function.
Early published reports described melanotan-2 as a tanning agent without sun protection, which means darkening is not the same as protection against ultraviolet radiation. Later studies explored the peptide in erectile dysfunction, hemorrhagic shock, and some skin conditions. No regulator in the United States or Europe has approved it for clinical use. Many products labelled melanotan-2 are sold without approval and their identity and purity are unverified. Its long-term safety in humans remains an open question.
Melanotan-2, also written Melanotan II, is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, and the lactam bridge between the aspartate and lysine side chains constrains the peptide into a ring. This structural change increases receptor affinity and metabolic stability relative to the native hormone. The compound was created in the 1980s as a research tool for studying pigmentation biology.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic cyclic heptapeptide | Analog of alpha-MSH with an internal lactam bridge |
| Molecular weight | Approximately 1024 daltons | Free base value; salt forms differ |
| Appearance | White to off-white powder | Usually supplied as a lyophilized solid |
| Solubility | Freely soluble in water | Poorly soluble in nonpolar solvents |
| Typical storage | −20 °C, dry, protected from light | Repeated freeze-thaw cycles degrade peptides |
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.
Melanocortin receptors comprise five subtypes with distinct tissue distributions and functions. Melanotan-2 is described in the literature as a non-selective agonist that engages several of these subtypes, including MC1R, MC3R, MC4R, and MC5R. MC1R is the subtype most directly linked to melanin production in skin cells. Because the compound is not subtype-selective, its observed effects in experimental settings are generally attributed to activity across multiple receptor pathways rather than to a single target.
Melanotan-2 is a synthetic linear peptide built from seven amino acids arranged in a short chain. Its sequence is commonly written as Ac-Nle-Asp-His-D-Phe-Arg-Trp-Lys-NH2, which includes a modified N-terminus and an amidated C-terminus. The molecule belongs to the melanocortin family and acts as a receptor agonist. Structural features such as the D-phenylalanine residue and the Nle substitution are associated with increased stability against enzymatic degradation relative to the natural parent peptide.
== Management == BACM may be alarming to parents and lead to unnecessary extensive tests. Treatment consists of oral analgesics, rest, and adequate hydration. Hospitalization is usually not necessary. Full recovery can be expected within a week, however, recurrences can occur.
The Central Command adds it struck roughly 140 military targets in Iran after the attack. CENTCOM declares that the strait is "open to all vessels" and "Iran does not control" it. CENTCOM announces that it conducted additional strikes on dozens of Iranian targets over attacks against vessels to further degrade the regime's capability to attack civilian sailors and commercial ships in the strait. The US forces use suicide drone boats in combat for the first time to strike an Iranian submarine and ship maintenance facility at Bandar Abbas Naval Base. Mitch McConnell releases a statement amidst ongoing speculation about his health, stating he was hospitalized for pneumonia. July 13 2026 Iran war: Trump announces that the US will reinstate the "Iranian blockade in the Strait of Hormuz" and impose a 20% toll on cargo shipping through the strait. According to Trump, "The U.S.A. will be, from this point forward, known as 'THE GUARDIAN OF THE HORMUZ STRAIT.'" Trump describes it as a matter of fairness, claiming that the toll would cover "any and all costs necessary to do the job of providing safety and security to this very volatile section of the world." American-led Combined Maritime Forces' Joint Maritime Information Centre (JMIC) announces that the US naval blockade on Iran will start the following day. Trump formally informs the US Congress that the country has renewed hostilities against Iran. Trump declares that the US will hit Iran hard on that day and the next day, saying that the MoU was a test that the regime did not honor.
== External links == Francium at The Periodic Table of Videos (University of Nottingham) WebElements.com – Francium Stony Brook University Physics Dept. Scerri, Eric (2013). A Tale of Seven Elements, Oxford University Press, Oxford, ISBN 9780195391312
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Sources: en.wikipedia.org
=== DAPI === DAPI is a fluorescent nuclear stain, excited by ultraviolet light and showing strong blue fluorescence when bound to DNA. DAPI binds with A=T rich repeats of chromosomes. DAPI is also not visible with regular transmission microscopy. It may be used in living or fixed cells. DAPI-stained cells are especially appropriate for cell counting.
Another glycogen storage disease that affects muscle (muscle GSD); Metabolic myopathy other than glycogen storage disease; Endocrine myopathy that affects carbohydrate metabolism secondary to the primary disease; Inadequate blood flow (ischemia), particularly of the calves Intermittent claudication; Popliteal artery entrapment syndrome; Chronic venous insufficiency. Poor diet or malabsorption disease resulting in malnutrition of micronutrients essential for muscle glycogen metabolism; Other rare myopathies, such as Brody disease, Rippling muscle disease, Erythrocyte lactate transporter defect, a small number of muscular dystrophies, Tubular aggregate myopathy (TAM), etc. Exercise-induced muscle fatigue without cramping:
=== Small animal imaging === A miniature animal PET has been constructed that is small enough for a fully conscious rat to be scanned. This RatCAP (rat conscious animal PET) allows animals to be scanned without the confounding effects of anesthesia. PET scanners designed specifically for imaging rodents, often referred to as microPET, as well as scanners for small primates, are marketed for academic and pharmaceutical research. The scanners are based on microminiature scintillators and amplified avalanche photodiodes (APDs) through a system that uses single-chip silicon photomultipliers. In 2018 the UC Davis School of Veterinary Medicine became the first veterinary center to employ a small clinical PET scanner as a scanner for clinical (rather than research) animal diagnosis. Because of cost as well as the marginal utility of detecting cancer metastases in companion animals (the primary use of this modality), veterinary PET scanning is expected to be rarely available in the immediate future.
=== United States === Radiology is a field in medicine that has expanded rapidly after 2000 due to advances in computer technology, which is closely linked to modern imaging techniques. Applying for residency positions in radiology has become highly competitive. Applicants are often near the top of their medical school classes, with high USMLE (board) examination scores. Diagnostic radiologists must complete prerequisite undergraduate education, four years of medical school to earn a medical degree (D.O. or M.D.), one year of internship, and four years of residency training. After residency, most radiologists pursue one or two years of additional specialty fellowship training. The American Board of Radiology (ABR) administers professional certification in Diagnostic Radiology, Radiation Oncology, and Medical Physics as well as subspecialty certification in neuroradiology, nuclear radiology, pediatric radiology, and vascular and interventional radiology. "Board Certification" in diagnostic radiology requires successful completion of two examinations. The Core Exam is given after 36 months of residency. Although previously taken in Chicago or Tucson, Arizona, beginning in February 2021, the computer test transitioned permanently to a remote format. It encompasses 18 categories. A passing score is 350 or above. A fail on one to five categories was previously a Conditioned exam; beginning in June 2021, the conditioned category will no longer exist, and the test will be graded as a whole. The Certification Exam can be taken 15 months after completion of the Radiology residency.
== Discovery == RGD was identified as the minimal recognition sequence within fibronectin required for cell attachment by Ruoslahti and Pierschbacher in the early 1980s. To do this, the authors synthesized various peptides based on the hypothesized cell attachment site of fibronectin. They then coupled those peptides to protein-coated plastic and tested each for cell attachment-promoting activity. Only those that contained the RGD sequence were found to enhance cell attachment. Further, they showed that peptides containing RGD were able to inhibit cell attachment to fibronectin-coated substrates, whereas peptides not containing RGD did not. These foundational studies also identified the cellular receptors that recognize the sequence. These studies utilized a synthetic RGD-containing peptide to isolate the putative receptors, and then demonstrated that liposomes containing the isolated proteins could bind to fibronectin, in much the same way as cells with surface receptors. The discovered receptors were later named integrins. The RGD motif is presented in slightly different ways in different proteins, making it possible for the many RGD-binding integrins to selectively distinguish individual adhesion proteins.
Sources: en.wikipedia.org
It is a synthetic seven-amino-acid peptide modeled on alpha-melanocyte-stimulating hormone. It carries two non-natural substitutions and a cyclic bridge that increase its stability relative to the natural hormone. It circulates as a research chemical and is not an approved medicine.
Melanotan-1, also called afamelanotide, is a shorter linear analog with a different amino acid sequence and no lactam ring. It has been evaluated in formal clinical programs, while melanotan-2 has not. The two are distinct molecules and are not interchangeable.
No. Bremelanotide is a related but distinct cyclic peptide that reached approved status for one specific clinical indication. Melanotan-2 is a separate molecule with its own sequence and properties. Shared ancestry in the melanocortin family does not make them the same substance.
No. It is a laboratory-made peptide, while the natural hormone is alpha-melanocyte-stimulating hormone, a longer peptide produced by the pituitary gland and by skin cells. Melanotan-2 mimics only a short active region of that hormone and contains non-natural residues such as D-phenylalanine.