cyclic heptapeptide raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-05-20 and is reviewed periodically as new material appears.
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.
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.
Research interest has centred on photoprotection and pigmentation, with a smaller body of work on appetite and sexual function. Published human data remain limited to small, frequently uncontrolled studies, and the compound has never received marketing approval from a national medicines regulator. Most laboratory work treats it as a pharmacological tool for probing melanocortin signalling in cell culture or animal models. Whether pigmentation changes observed in people translate into measurable protection against ultraviolet-induced DNA damage remains an open question.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white solid | Lyophilised cake or flake |
| Solubility class | Soluble in water and aqueous buffer | Also soluble in some polar organic solvents |
| Typical storage temperature | Minus 20 degrees Celsius or below | Desiccated and protected from light |
| Typical analytical method | LC-MS/MS | Reversed-phase separation with mass detection |
| Molecular formula | C50H69N15O9 | Free base; salt forms differ |
Melanotan II holds no marketing authorisation from the Food and Drug Administration, the European Medicines Agency, the UK Medicines and Healthcare products Regulatory Agency or Australia's Therapeutic Goods Administration. Products sold under that name are treated as unapproved new drugs, and their sale or import is prohibited in several jurisdictions. Other countries classify the peptide as a prescription-only medicine or place it among controlled substances, so the legal position changes with the destination market. No pharmacopoeial monograph supplies an official specification, because the material is not a licensed pharmaceutical. Consequently, products offered online are not manufactured to a shared public standard.
The peer-reviewed record is dominated by small early-phase studies, case reports and pharmacovigilance summaries rather than large randomised trials. Papers typically examine tanning response, receptor selectivity or patterns of reported adverse events. Many note that participants obtained the peptide outside a clinical setting, which limits verification of composition and administered amount. Reported events vary widely, and causality is frequently unclear because the identity and purity of self-sourced material are unknown. Open questions include whether repeated melanocortin receptor stimulation produces cumulative effects, and how often label claims match actual content.
Identification in laboratories relies on reversed-phase liquid chromatography coupled with tandem mass spectrometry, with product-ion spectra compared against a certified reference standard. High-resolution mass spectrometry supplies accurate mass confirmation, and peptide mapping after enzymatic digestion separates melanotan II from closely related analogues. Quantitation of seized material is complicated by unknown counter-ions and residual trifluoroacetate left from purification. Immunoassays raised against alpha-melanocyte-stimulating hormone can cross-react, so chromatographic confirmation is normally required. Urinary detection windows are short, and reported limits of detection differ substantially between laboratories.
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.
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.
Because the substance circulates mainly through informal markets, verification is a recurring theme in technical discussion. Independent analyses have found that labeled content and actual content can diverge, and that purity varies between samples. Analytical laboratories use reversed-phase chromatography to separate components and mass spectrometry to confirm identity. Isotope-labeled internal standards improve quantification in complex matrices. Such methods describe what a sample contains but say nothing about its sterility, lawful status, or suitability for any use. Open questions remain about how consistently testing is applied across the supply chain.
Regulatory treatment of this peptide varies by country. It holds no marketing authorization as a medicine in the United States, the European Union, or most other jurisdictions. Some countries classify products containing it as prescription-only or unlicensed medicines, which restricts lawful supply. Authorities have issued public notices warning that unregulated products may contain undeclared or incorrect ingredients. The molecule also appears on prohibited lists for competitive sport. These measures address supply oversight rather than any approved therapeutic role.
Published research on the compound remains limited. Much of the human data comes from small, early-stage studies rather than large controlled trials, and several questions about effects and variability between individuals remain open. Investigators have examined receptor activity, pigment pathways, and related physiological responses in laboratory and animal models. Findings from those models do not automatically translate to human outcomes. Reviews frequently note the scarcity of rigorous clinical evidence and call for better-characterized study material.
Outside regulated medicine, melanotan II circulates through online vendors as a research chemical, often marketed for tanning. Products sold this way vary widely in purity, concentration, and labeling accuracy, and independent testing has documented discrepancies. Published reports describe both pigment effects and adverse reactions, including nausea, flushing, and darkening of existing moles. Long-term safety data are sparse, and no large controlled trial has established a risk profile. Questions about cumulative effects on melanocytes remain unresolved in the literature.
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.
Apadoline (INNTooltip International Nonproprietary Name; developmental code name RP-60180) is a κ-opioid receptor agonist and experimental analgesic which was under development for the treatment of cancer pain but was never marketed. It produces effects and adverse effects in humans including analgesia, drowsiness, and headache, among others. Its affinities (Ki) for the opioid receptors are 0.55 nM for the κ-opioid receptor, 11.4 nM for the δ-opioid receptor, and 57 nM for the μ-opioid receptor. Apadoline was first described in the scientific literature by 1990. It was under development by Rhône-Poulenc in the 1990s and reached phase 2 clinical trials prior to the discontinuation of its development. An analogue with greater potency, RP-61127, has also been described.
Because many risk factors for addiction are social and modifiable, prevention strategies that target them can improve outcomes; when delivered during childhood and adolescence, such strategies reduce the risk of later substance use disorder. Prevention is usually organized in three tiers: universal programs aimed at a whole population, selective programs aimed at groups at raised risk, and indicated programs aimed at individuals already showing early signs of problem use. Interventions with the strongest evidence include family skills programs, personal and social skills education delivered in schools, and policies that limit availability and raise the price of alcohol and tobacco. Programs based on information provision alone, or on fear-based messaging, have not been found effective and may be counterproductive.
RCH=CH2 + H2 + CO2 → RCH2−CH2CO2H Other methods, e.g. the Koch reaction, effect "net" carboxylation involve the use of carbon monoxide, either directly or generated in situ. These methods are variants of carbonylation reactions. Carboxylation of epoxides gives cyclic carbonates. Such reactions are catalyzed by N-Heterocyclic carbenes and catalysts based on silver.
==== FAST ==== Fusion-associated small transmembrane proteins (FAST) are the smallest type of fusion protein. They are found in reoviruses, which are non-enveloped viruses and are specialized for cell-cell rather than virus-cell fusion, forming syncytia. They are the only known membrane fusion proteins found in non-enveloped viruses. They exploit the cell-cell adhesion machinery to achieve initial attachment. They might encourage fusion by inducing membrane curvature using a variety of hydrophobic motifs and modified residues.
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== SEM-EDX results == A positive result using SEM-EDX spectroscopy will generate x-ray spectra characteristic of GSR, likely containing combinations of metals such as Pb-Sb-Ba or Sb-Ba. Spectra may also indicate the presence of Ca, S and Si but is not always indicative of GSR. GSR may be present when an individual discharged a firearm or was close by when a discharge occurred. GSR has been observed to undergo both secondary and tertiary transfers, meaning the presence of GSR may be attributed to the persistence of the residue and the unpredictability of human interaction. A negative result on someone could mean they were near it but not close enough for gunshot residue to land on them, or it can mean that the gunshot residue deposited on them wore off. Gunshot residue can also be removed from surfaces by washing, wiping, or brushing it off, so a negative result cannot fully rule out a gun was not fired by the tested object or area. Expelled gunshot residue does not travel very far from the muzzle because the particles lack momentum. Depending on the type of fire arm and ammunition used, it will typically travel no farther than 3–5 feet (0.9–1.5 meters) from the muzzle of the gun.
Equine polysaccharide storage myopathy (EPSM, PSSM, EPSSM) is a hereditary glycogen storage disease of horses that causes exertional rhabdomyolysis. It is currently known to affect the following breeds: American Quarter Horses, American Paint Horses, Warmbloods, Cobs, Dales Ponies, Thoroughbreds, Arabians, New Forest ponies, and a large number of heavy horse breeds. While incurable, PSSM can be managed with appropriate diet and exercise. There are currently 2 subtypes, known as Type 1 PSSM and Type 2 PSSM.
1993/1483) A11 Trunk Road (Stump Cross to A505 Junction Improvement) Slip Roads Order 1993 (S.I. 1993/1484) M11 Motorway (Stump Cross Junction Improvement) and Connecting Roads Scheme 1993 (S.I. 1993/1485) A11 Trunk Road (Stump Cross to A505 Junction Improvement) (Detrunking) Order 1993 (S.I. 1993/1486) Firearms (Dangerous Air Weapons) (Amendment) Rules 1993 (S.I. 1993/1490) Education (Schools) Act 1992 (Commencement No. 3) Order 1993 (S.I. 1993/1491) Education (School Inspection) Regulations 1993 (S.I. 1993/1492) Non-Domestic Rating (Collection and Enforcement) (Local Lists) (Amendment) Regulations 1993 (S.I. 1993/1493) Non-Domestic Rating (Collection and Enforcement) (Central Lists) (Amendment) Regulations 1993 (S.I. 1993/1494) Non-Domestic Rating (Payment of Interest) (Amendment) Regulations 1993 (S.I. 1993/1495) Non-Domestic Rating Contributions (England) (Amendment) Regulations 1993 (S.I. 1993/1496)
Sources: en.wikipedia.org
=== CRF1 === Agonists: Cortagine Corticorelin Corticotropin-releasing hormone Sauvagine Stressin I Urocortin Antagonists: Antalarmin Astressin-B CP-154,526 Emicerfont Hypericin LWH-234 NBI-27914 NBI-74788 Pexacerfont R-121919 TS-041 Verucerfont
=== Amphetamines === Substituted amphetamines are a chemical class of stimulants, entactogens, hallucinogens, and other drugs. They feature a phenethylamine core with a methyl group attached to the alpha carbon resulting in amphetamine, along with additional substitutions.
== Function == As an isocitrate dehydrogenase, IDH1 catalyzes the reversible oxidative decarboxylation of isocitrate to yield α-ketoglutarate (α-KG) as part of the TCA cycle in glucose metabolism. IDH1 interacts with isocitrate and a divalent metal ion cofactor, typically Mg2+ or Mn2+, which plays a crucial role in stabilizing the negatively charged intermediates formed during the enzymatic reaction. It undergoes oxidation at the hydroxyl group on the C2 carbon, a reaction that removes electrons and produces oxalosuccinate. During this step, NAD(P)+ acts as an electron acceptor, transforming into NAD(P)H by gaining these electrons. Subsequently, oxalosuccinate undergoes decarboxylation, meaning it loses a carbon dioxide molecule, resulting in the formation of α-ketoglutarate. This step also allows for the concomitant reduction of nicotinamide adenine dinucleotide phosphate (NADP+) to reduced nicotinamide adenine dinucleotide phosphate (NADPH). Since NADPH and α-KG function in cellular detoxification processes in response to oxidative stress, IDH1 also indirectly participates in mitigating oxidative damage. In addition, IDH1 is key to β-oxidation of unsaturated fatty acids in the peroxisomes of liver cells. IDH1 also participates in the regulation of glucose-induced insulin secretion. Notably, IDH1 is the primary producer of NADPH in most tissues, especially in brain. Within cells, IDH1 has been observed to localize to the cytoplasm, peroxisome, and endoplasmic reticulum.
Sophia Hober (born 1965) is a Swedish researcher in biotechnology and professor at The Royal Institute of Technology (KTH) in Stockholm. Sophia Hober got her Master of Science in chemical engineering at KTH in 1989 and defended her doctorate in biochemistry in 1996. Since 2007, Hober is a professor of molecular biotechnology at KTH. During 2011–2015, Professor Hober served as dean at KTH and was part of the management team. Sophia Hober was elected member of the Royal Swedish Academy of Engineering Sciences in 2012. Hober's research is centered around the development of affinity proteins for use in biotechnology and medicine. Her main scientific achievements in the field of protein purification include improvements of the alkaline tolerance of protein A for the industrial purification of monoclonal antibodies. This work led to the product MabSelect SuRe, currently sold by Cytiva. Professor Hober has also developed a new protein domain with calcium-dependent affinity that can be used for gentle purification of monoclonal antibodies. Further in her work she has developed protein domains with the ability to strongly and selectively bind cancer markers. One of these has, in clinical trials, been shown to work very well for the precision diagnosis of cancer in situ. Hober is, among others, a co-founder of the biotechnology companies Affibody AB and Atlas Antibodies AB.
Sources: en.wikipedia.org
Mass spectrometry combined with liquid chromatography provides both molecular weight confirmation and a measure of related impurities. Tandem mass spectrometry adds sequence information. A purity percentage reported without a mass measurement does not confirm what the material is.
No. Lyophilisation slows degradation rather than stopping it, and the rate depends on residual moisture, temperature and light exposure. Freezer storage extends useful life but does not make the material permanent.
A certificate is only as good as its traceability to a specific batch and a named laboratory. Documents lacking batch numbers, method descriptions or laboratory identifiers carry little weight. Confirming what was actually received generally requires a separate test of the material in hand.
It is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, containing seven amino acids with a lactam ring and a D-configured phenylalanine residue. It is supplied as a lyophilised powder for laboratory research.