alpha-MSH analog comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2025-07-18. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Free base; salt forms add to total mass |
| Molecular mass | About 1024 daltons | Calculated for the free base |
| Structural class | Cyclic heptapeptide | Contains D-phenylalanine and norleucine |
| Parent hormone | Alpha-melanocyte-stimulating hormone | Endogenous tridecapeptide of 13 residues |
| Receptor profile | Non-selective melanocortin agonist | Interacts with MC1R, MC3R, MC4R and MC5R |
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.
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 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.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, the naturally occurring peptide involved in pigmentation signalling. Its sequence is conventionally written as Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, with a lactam bridge joining the aspartate side chain to the lysine side chain. The empirical formula is C50H69N15O9 and the monoisotopic mass lies near 1023.5 daltons. N-terminal acetylation and the D-configured phenylalanine both increase resistance to enzymatic breakdown compared with the parent hormone.
Pharmacologically, melanotan-2 behaves as a non-selective agonist across the melanocortin receptor family. Binding at MC1R on dermal melanocytes promotes eumelanin synthesis, which underlies the tanning response described in early human work. Activity at the centrally expressed MC4R receptor is associated with reported effects on appetite and erectile function. Because the peptide does not discriminate strongly among receptor subtypes, attributing any single observed effect to one receptor pathway is generally not possible without selective antagonists or receptor knockout models.
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.
=== Clinical applications === Recombinant resilins have been studied for potential application in the fields of biomedical engineering and medicine. In particular, hydrogels composed of recombinant resilins have been used as tissue engineering scaffolds for mechanically-active tissues including cardiovascular, cartilage and vocal cord tissues. Early work has focused on optimizing the mechanical properties, chemistry and cytocompability of these materials, but some in vivo testing of resilin hydrogels has also been performed. Researchers at the University of Delaware and Purdue University have developed methods for creating elastic hydrogels composed of resilin that were compatible with stem cells and displayed similar rubber elasticity to that of natural resilin. Semi-synthetic resilin-based hydrogels, which incorporate poly(ethylene glycols), have also been reported.
Addiction is a neuropsychological disorder characterized by a persistent and intense urge to use a drug or engage in a behavior that produces an immediate psychological reward, despite substantial harm and other negative consequences. Repeated substance use produces long-lasting changes in brain networks involved in reward, executive function, stress reactivity and mood. These changes underlie both the intense drive to use a substance and the reduced capacity to control that urge. It is therefore understood as a brain disorder arising from a complex mix of psychosocial and neurobiological factors. A number of researchers argue that this framing is incomplete, and that addiction is better understood as learned behavior shaped by choice and social context. Addiction takes both substance and non-substance forms. Substance addictions include alcoholism, cannabis addiction, amphetamine addiction, cocaine addiction, nicotine addiction, and opioid addiction. The DSM-5-TR recognizes only gambling disorder as a behavioral (non-substance) addiction and lists internet gaming disorder as a condition for further study, while the ICD-11 additionally classifies gaming disorder as a disorder due to addictive behaviors. Other candidate behavioral addictions, and the question of whether food can be addictive, are debated in the research literature but are not recognized in either manual.
== Management == There is currently no cure for PFBC nor a standard course of treatment. The available treatment is directed symptomatic control. If parkinsonian features develop, there is generally poor response to levodopa therapy. Case reports have suggested that haloperidol or lithium carbonate may help with psychotic symptoms. One case report described an improvement with the use of a bisphosphonate.
Sources: en.wikipedia.org
Larazotide (INN; also known as AT-1001; formulated as the salt with acetic acid, larazotide acetate) is a synthetic eight amino acid peptide that functions as a tight junction regulator and reverses leaky junctions to their normally closed state. It has been studied in people with coeliac disease.
==== Kidney functions ==== The pendrin protein promotes the electroneutral exchange of tissue chloride (Cl−) for urinary bicarbonate (HCO3−) in the apical surfaces (i.e., surfaces facing the urine) of the kidney's renal β-intercalated cells (also termed type B intercalated cells) and non-α non-β intercalated cells (also termed non-A non-B intercalated cells) in the kidney's collecting duct system (i.e., CDS). A study in mice found that OXGR1 colocalizes with pendrin in the β-intercalated cells and non-α non-β intercalated cells lining the tubules of their kidney's CDS. The intercalated cells in the CDS tubules isolated from mice used pendrin in cooperation with the electroneutral sodium bicarbonate exchanger 1 protein to mediate the Cl− for HCO3− exchange. α-Ketoglutarate stimulated the rate of this exchange in CDS tubules isolated from control mice (i.e., mice that had the Oxgr1 gene and protein) but not in CDS tubules isolated from Oxgr1 gene knockout mice (i.e., mice that lacked the Oxgr1 gene and protein). This study also showed that the α-ketoglutarate in the blood of mice filtered through their kidney's glomeruli into the proximal tubules and loops of Henle where it was reabsorbed. Mice drinking water with a basic pH (i.e., >7) due to the addition of sodium bicarbonate and mice lacking the Oxgr1 gene and protein who drink water without sodium bicarbonate had urines that were more basic (i.e., pH about 7.8) and contained higher levels of urinary α-ketoglutarate than control mice drinking water without this additive.
The etymology of the various words for tea reflects the history of transmission of tea drinking and trade from China. Nearly all of the words for tea worldwide fall into three broad groups: te, cha and chai, present in English as tea, cha or char, and chai. The earliest of the three to enter English is cha, which came in the 1590s via the Portuguese, who traded in Macao and picked up the Cantonese pronunciation of the word. The more common tea form arrived in the 17th century via the Dutch, who acquired it via trades from their colonial empire either indirectly from the Malay teh, or directly from the tê pronunciation in Min Chinese. The third form chai (meaning "spiced tea") originated from a northern Chinese pronunciation of cha, which travelled via the overland Silk Road to Central Asia and Persia, where it picked up a Persian ending yi. The Chinese word for tea itself was perhaps derived from the non-Sinitic languages of the botanical homeland of the tea plant in southwest China and northeastern Burma (modern-day Kachin and Shan), possibly from an archaic Austro-Asiatic root word *la, meaning "leaf".
Sources: en.wikipedia.org
Sequence homology is the biological homology between DNA, RNA, or protein sequences, defined in terms of shared ancestry in the evolutionary history of life. Two segments of DNA can have shared ancestry because of three phenomena: either a speciation event (orthologs), or a duplication event (paralogs), or else a horizontal (or lateral) gene transfer event (xenologs). Homology among DNA, RNA, or proteins is typically inferred from their nucleotide or amino acid sequence similarity. Significant similarity is strong evidence that two sequences are related by evolutionary changes from a common ancestral sequence. Alignments of multiple sequences are used to indicate which regions of each sequence are homologous.
For instance, oxycodone and diamorphine may be tested, both sedative analgesics. If such a test is not requested specifically, the more general test (in the preceding case, the test for opioids) will detect most of the drugs of a class, but the employer or physician will not have the benefit of the identity of the drug. Employment-related test results are relayed to a medical review office (MRO) where a medical physician reviews the results. If the result of the screen is negative, the MRO informs the employer that the employee has no detectable drug in the urine, typically within 24 hours. However, if the test result of the immunoassay and GC-MS are non-negative and show a concentration level of parent drug or metabolite above the established limit, the MRO contacts the employee to determine if there is any legitimate reason—such as a medical treatment or prescription. On-site instant drug testing is a more cost-efficient method of effectively detecting substance use amongst employees, as well as in rehabilitation programs to monitor patient progress. These instant tests can be used for both urine and saliva testing. Although the accuracy of such tests varies with the manufacturer, some kits have rates of accuracy correlating closely with laboratory test results.
=== Global security program === The Lab's work in global security aims to reduce and mitigate the dangers posed by the spread or use of weapons of mass destruction and by threats to energy and environmental security. Livermore has been working on global security and homeland security for decades, predating both the collapse of the Soviet Union in 1991 and the September 11, 2001, terrorist attacks. LLNL staff have been heavily involved in the cooperative nonproliferation programs with Russia to secure at-risk weapons materials and assist former weapons workers in developing peaceful applications and self-sustaining job opportunities for their expertise and technologies. In the mid-1990s, Lab scientists began devising improved biodetection capabilities, leading to miniaturized and autonomous instruments that can detect biothreat agents in a few minutes instead of the days to weeks previously required for DNA analysis. Livermore researchers address a spectrum of threats – radiological/nuclear, chemical, biological, explosives, and cyber. They combine physical and life sciences, engineering, computations, and analysis to develop technologies that solve real-world problems. Activities are grouped into five programs:
Sources: en.wikipedia.org
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.
Melanotan-1, also called afamelanotide, is a linear analogue with greater selectivity for MC1R and has received approval in some jurisdictions for a specific photosensitivity disorder. Melanotan-2 is cyclic, less selective, and reaches central receptors more readily. The two are often confused in online discussion despite different pharmacology and regulatory status.
Alpha-MSH is an endogenous tridecapeptide derived from pro-opiomelanocortin. Melanotan-2 reproduces its core receptor-binding sequence inside a shortened, stabilised ring. The result is a molecule with a longer effective half-life and higher potency than the parent hormone.
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.