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 2025-12-18. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Identity and purity are assessed with chromatographic and mass spectrometric techniques. Reversed-phase high-performance liquid chromatography separates the target peptide from related impurities and degradation products, and the resulting retention time is compared against a reference standard. Mass spectrometry, often coupled to liquid chromatography, confirms molecular mass. Amino acid analysis or peptide mapping can provide additional sequence-level confirmation when required. Results are only as reliable as the reference materials used alongside them.
Regulatory treatment varies by country. In the United States, melanotan-2 is not approved for any indication, and products marketed for human use fall outside the approved drug framework. Some other jurisdictions have placed it under prescription controls or listed it as a prohibited or restricted substance. Online listings frequently describe the material as a research chemical, a category that does not carry the same manufacturing and labelling requirements as approved medicines.
Solid peptide material is generally stable when kept cold and dry. Common practice is storage at -20 degrees Celsius or lower, with desiccant and protection from light. Repeated freeze-thaw cycles and exposure to moisture are associated with degradation, aggregation, or loss of material. Once dissolved, stability depends on solvent, concentration, and temperature, and solutions are usually treated as short-lived unless stability data support longer periods. Handling notes typically emphasise minimising time at ambient temperature.
| Property | Value | Notes |
|---|---|---|
| Compound class | Synthetic cyclic heptapeptide | Alpha-MSH analogue containing a D-phenylalanine residue |
| Molecular formula | C50H69N15O9 | Average molecular mass approximately 1024.2 g/mol |
| Appearance | White to off-white lyophilised powder | Normally supplied as a freeze-dried solid in a sealed vial |
| Solubility | Freely soluble in water and polar solvents | Dissolves readily in aqueous buffers and in alcohol-water mixtures |
| Receptor targets | MC1R, MC3R, MC4R, MC5R | Acts as a non-selective melanocortin receptor agonist |
Human data remain limited and mostly short-term. Reports describe small trials and observational accounts rather than large controlled studies, so questions about dose-response relationships and long-term effects on melanocytes stay open. Whether repeated exposure alters naevus behaviour is not settled in the published record. Researchers also note that self-administered use outside clinical settings makes actual exposure difficult to quantify. Statements about efficacy and safety should therefore be read as preliminary rather than established.
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.
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.
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.
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.
He visited the tomb of Frederick the Great and instructed his marshals to remove their hats there, saying, "If he were alive we wouldn't be here today". Napoleon had taken only 19 days from beginning his attack on Prussia to knock it out of the war with the capture of Berlin and the destruction of its principal armies at Jena and Auerstädt. Saxony abandoned Prussia, and together with small states from north Germany, allied with France.
==== MeSH D06.472.734 – pituitary hormones ==== MeSH D06.472.734.525 – pituitary hormones, anterior MeSH D06.472.734.525.343 – gonadotropins, pituitary MeSH D06.472.734.525.343.288 – follicle stimulating hormone MeSH D06.472.734.525.343.288.500 – follicle stimulating hormone, beta subunit MeSH D06.472.734.525.343.288.625 – follicle stimulating hormone, human MeSH D06.472.734.525.343.288.750 – glycoprotein hormones, alpha subunit MeSH D06.472.734.525.343.463 – luteinizing hormone MeSH D06.472.734.525.343.463.249 – glycoprotein hormones, alpha subunit MeSH D06.472.734.525.343.463.500 – luteinizing hormone, beta subunit MeSH D06.472.734.525.343.583 – menotropins MeSH D06.472.734.525.343.583.500 – urofollitropin MeSH D06.472.734.525.343.773 – prolactin MeSH D06.472.734.525.425 – growth hormone MeSH D06.472.734.525.425.875 – human growth hormone MeSH D06.472.734.525.690 – pro-opiomelanocortin MeSH D06.472.734.525.690.130 – corticotropin MeSH D06.472.734.525.690.130.050 – alpha-msh MeSH D06.472.734.525.690.130.200 – cosyntropin MeSH D06.472.734.525.690.480 – lipotropin MeSH D06.472.734.525.690.583 – melanocyte-stimulating hormones MeSH D06.472.734.525.690.583.050 – alpha-msh MeSH D06.472.734.525.690.583.075 – beta-msh MeSH D06.472.734.525.690.583.115 – gamma-msh MeSH D06.472.734.525.883 – thyrotropin MeSH D06.472.734.525.883.249 – glycoprotein hormones, alpha subunit MeSH D06.472.734.525.883.500 – thyrotropin, beta subunit MeSH D06.472.734.692 – pituitary hormones, posterior MeSH D06.472.734.692.433 – oxytocin MeSH D06.472.734.692.781 – vasopressins MeSH D06.472.734.692.781.100 – argipressin MeSH D06.472.734.692.781.100.250 – deamino arginine vasopressin MeSH D06.472.734.692.781.400 – lypressin MeSH D06.472.734.692.781.400.350 – felypressin MeSH D06.472.734.692.781.700 – ornipressin MeSH D06.472.734.692.881 – vasotocin
=== G04CA Alpha-adrenoreceptor antagonists === G04CA01 Alfuzosin G04CA02 Tamsulosin G04CA03 Terazosin G04CA04 Silodosin G04CA51 Alfuzosin and finasteride G04CA52 Tamsulosin and dutasteride G04CA53 Tamsulosin and solifenacin G04CA54 Tamsulosin and tadalafil G04CA55 Doxazosin and finasteride
When a silicone breast implant ruptures it usually does not deflate, yet the filler gel does leak from it, which can migrate to the implant pocket; therefore, an intracapsular rupture (in-capsule leak) can become an extracapsular rupture (out-of-capsule leak), and each occurrence is resolved by explantation. Although the leaked silicone filler-gel can migrate from the chest tissues to elsewhere in the woman's body, most clinical complications are limited to the breast and armpit areas, usually manifested as granulomas (inflammatory nodules) and axillary lymphadenopathy (enlarged lymph glands in the armpit area). The suspected mechanisms of breast implant rupture are:
Sources: en.wikipedia.org
==== Effect of local refractive index ==== Changes in the apparent color of a gold nanoparticle solution can also be caused by the environment in which the colloidal gold is suspended. The optical properties of gold nanoparticles depend on the refractive index near the nanoparticle surface, so the molecules directly attached to the nanoparticle surface (i.e. nanoparticle ligands) and the nanoparticle solvent may both influence the observed optical features. As the refractive index near the gold surface increases, the LSPR shifts to longer wavelengths. In addition to solvent environment, the extinction peak can be tuned by coating the nanoparticles with non-conducting shells such as silica, biomolecules, or aluminium oxide.
The peculiarity of this invention compared to former treatment approaches for treating sleep disorders is the so far unknown therapeutic efficacy of (R)-phenylpiracetam, which is presumably based at least in part on the newly identified activity of (R)-phenylpiracetam as the dopamine re-uptake inhibitor Both enantiomers of phenylpiracetam, (R)-phenylpiracetam and (S)-phenylpiracetam, have been described in peer-reviewed research as dopamine transporter (DAT) inhibitors in rodents, confirming the patent claim. Their actions at the norepinephrine transporter (NET) vary: (R)-phenylpiracetam acts as a dual norepinephrine–dopamine reuptake inhibitor (NDRI), with 11-fold lower affinity for the NET than for the DAT, whereas the (S)-enantiomer is selective for the DAT. However, whereas (R)-phenylpiracetam stimulates locomotor activity, (S)-phenylpiracetam does not do so. This kind of variation in effects has also been seen with other dopamine reuptake inhibitors. Other atypical dopamine reuptake inhibitors include modafinil, mesocarb (Sydnocarb), and solriamfetol.
== 2018 suicide attempt and introduction to DMT == On January 15, 2018, Cantelmo contacted his children and told them he intended to kill himself. Police placed him on a 5150 hold, an involuntary psychiatric detention. While in the facility he decided to try DMT after his release. After leaving the hospital he ordered mimosa hostilis root bark online, extracted DMT using methods based on his chemistry background, and began experimenting with the substance. He later described a breakthrough experience that ended his lifelong atheism and convinced him of the existence of a higher power and of entities he encountered during the trips. He resolved to promote DMT publicly.
=== Position of Tantulocarida === According to Petrunina A.S. and Kolbasov G.A., the sixth subclass of Maxillopoda Tantulocarida may lie within Thecostraca, forming a clade with thecostracan infraclass Cirripedia (if so, Thecostraca excluding Tantulocarida is paraphyletic):
The LLNL chemistry, materials, and life science research focuses on chemical engineering, nuclear chemistry, materials science, and biology and bio-nanotechnology. Physics thrust areas include condensed matter and high-pressure physics, optical science and high energy density physics, medical physics and biophysics, and nuclear, particle and accelerator physics. In the area of energy and environmental science, Livermore's emphasis is on carbon and climate, energy, water and the environment, and the national nuclear waste repository. The LLNL engineering activities include micro- and nanotechnology, lasers and optics, biotechnology, precision engineering, nondestructive characterization, modeling and simulation, systems and decision science, and sensors, imaging and communications. LLNL is a computing organization with capabilities in computer science, software engineering, data science, modeling and simulation, information technology, and cyber security. Lawrence Livermore National Laboratory has worked out several energy technologies in the field of coal gasification, shale oil extraction, geothermal energy, advanced battery research, solar energy, and fusion energy. Main oil shale processing technologies worked out by the Lawrence Livermore National Laboratory are LLNL HRS (hot-recycled-solid), LLNL RISE (in situ extraction technology) and LLNL radiofrequency technologies.
Sources: en.wikipedia.org
The game's production was turbulent, as the design's scope exceeded the available resources, and the team was left without a producer for nearly a year until Activision appointed David Mullich to the role, where he found designs and levels unfinished or abandoned. After three years in development with no end in sight and running over budget, Activision set a strict deadline for completion, and Bloodlines was released incomplete in November 2004. Released in competition with Half-Life 2 and several other titles, Bloodlines sold fewer than 80,000 copies during its initial release, which was considered a poor performance. It received generally positive reviews from contemporary critics, who praised the game's writing and the scale of choice, although they criticized its technical flaws. It was Troika Games's last production before its failure in early 2005, when it could not secure additional projects. The game has a cult following as a rarely replicated example of gameplay and narrative, and modern reception recognizes it as a flawed masterpiece. Since its original release, Bloodlines received post-release support from fans, supplying unofficial fixes and re-adding unused content. A sequel, Vampire: The Masquerade – Bloodlines 2, was released in 2025.
A 2014 Cochrane review found tentative evidence that people treated with sulfonylureas have fewer non-fatal cardiovascular events than those treated with metformin (RR 0.7) but a higher risk of severe hypoglycemia (RR 5.6). There was not enough data available to determine the risk of mortality or of cardiovascular mortality. The FDA requires sulfonylureas to carry a label warning regarding increased risk of cardiovascular death. A 2020 Cochrane systematic review comparing metformin monotherapy to sulfonylureas did not find enough evidence of reduction of all-cause mortality, serious adverse events, cardiovascular mortality, non-fatal myocardial infarction, non-fatal stroke or end-stage renal disease. Second-generation sulfonylureas have increased potency by weight, compared to first-generation sulfonylureas. Similarly, ACCORD (Action to Control Cardiovascular Risk in Diabetes) and the VADT (Veterans Affairs Diabetes Trial) studies showed no reduction in heart attack or death in patients assigned to tight glucose control with various drugs.
== History == Pineapples have a long tradition as a medicinal plant among the natives of South and Central America. The first isolation of bromelain was recorded by the Venezuelan chemist Vicente Marcano in 1891 by fermenting the fruit of the pineapple. In 1892, Russell Henry Chittenden, assisted by Elliott P. Joslin and Frank Sherman Meara, investigated the matter more completely, and called it 'bromelin'. Later, the term 'bromelain' was introduced and originally applied to any protease from any member of the plant family Bromeliaceae.
=== Ligament and tendon repair === Autologous stem cell-based treatments for ligament injury, tendon injury, osteoarthritis, osteochondrosis, and sub-chondral bone cysts have been commercially available to practicing veterinarians to treat horses since 2003 in the United States and since 2006 in the United Kingdom. Autologous stem cell based treatments for tendon injury, ligament injury, and osteoarthritis in dogs have been available to veterinarians in the United States since 2005. Over 3000 privately owned horses and dogs have been treated with autologous adipose-derived stem cells. The efficacy of these treatments has been shown in double-blind clinical trials for dogs with osteoarthritis of the hip and elbow and horses with tendon damage. Race horses are especially prone to injuries of the tendon and ligaments. Conventional therapies are very unsuccessful in returning the horse to full functioning potential. Natural healing, guided by the conventional treatments, leads to the formation of fibrous scar tissue that reduces flexibility and full joint movement. Traditional treatments prevented a large number of horses from returning to full activity and also have a high incidence of re-injury due to the stiff nature of the scarred tendon. Introduction of both bone marrow and adipose derived stem cells, along with natural mechanical stimulus promoted the regeneration of tendon tissue. The natural movement promoted the alignment of the new fibers and tendocytes with the natural alignment found in uninjured tendons.
Sources: en.wikipedia.org
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.
No approved regulatory indication exists in major markets. An approval exists for a different peptide, afamelanotide, which is used for a rare photosensitivity disorder called erythropoietic protoporphyria. Melanotan-2 itself remains a research compound with no cleared clinical role.
Melanocortin-1 receptors on melanocytes are the receptor most closely linked to pigment production. The peptide is not selective, however, and also activates melanocortin-3, melanocortin-4, and melanocortin-5 receptors. That lack of selectivity is the usual explanation offered for both its range of observed effects and its off-target effects.
Laboratory confirmation typically combines retention time matching on a chromatographic system with mass measurement. A reference standard of known identity is needed for a meaningful comparison. Sequence-level techniques can add further confirmation.