Everything below concerns Melanotan II. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-04-19. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
Melanotan II is a synthetic cyclic heptapeptide with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, corresponding to a molecular formula of C50H69N15O9 and a monoisotopic mass near 1024 daltons. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, a peptide hormone produced by cleavage of proopiomelanocortin. A lactam bridge between the aspartate and lysine side chains closes the ring, and the C-terminal amide removes a free carboxyl group. Both modifications increase resistance to enzymatic degradation compared with the linear parent hormone. Four substitutions distinguish it from afamelanotide, the linear analogue studied under the name melanotan I.
Receptor-binding studies classify melanotan II as a non-selective melanocortin agonist. It interacts with MC1R, MC3R, MC4R and MC5R, with reported affinities in the low nanomolar range and no strong subtype preference. Activation of MC1R on dermal melanocytes shifts pigment synthesis toward eumelanin, the dark polymer deposited in melanosomes and transferred to keratinocytes. Because the same peptide engages MC4R in the hypothalamus, it also appears in animal work on food intake and erectile response, which is why it is discussed in both pigment and metabolic research. Which receptor populations dominate after systemic exposure in humans is not fully established.
Published pharmacokinetic information is limited and comes mainly from small studies rather than registrational trials. Plasma half-life is usually described as short, on the order of tens of minutes, followed by rapid tissue distribution and clearance of the intact peptide. Metabolites and low concentrations of parent compound have been reported in urine, a detail relevant to anti-doping and forensic testing. Whether repeated exposure changes receptor sensitivity or clearance over time remains an open question. Values differ noticeably between analytical assays, so published numbers should be read as approximate rather than definitive.
| 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, 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.
Evidence from the study of strontium, carbon and oxygen isotopic composition of remains of Notiomastodon platensis from Pleistocene sites in the states of Pernambuco, Paraíba and Sergipe (Brazil), indicative of a predominantly C4-based diet of the studied individuals and indicating that the studied sample included both sedentary and mobile individuals, is presented by Cruz et al. (2026). The first complete skull of a member of the genus Cuvieronius (C. cf. tropicus) from North America reported to date is described from the Pleistocene (Irvingtonian) strata of the Camp Rice Formation (New Mexico, United States) by Houde et al. (2026), who argue that North/Central American and South American members of the genus Cuvieronius likely represent two distinct cryptic species. González-Guarda et al. (2026) reconstruct the environment of late Pleistocene Notiomastodon platensis and Cuvieronius hyodon from Ecuador on the basis of their tooth wear and carbon isotopic composition of their tooth enamel, interpreted as indicative of predominantly open and dry habitats. Kumar (2026) reports the first discovery of fossil material of Anancus sivalensis from Indian Siwaliks, recovered from the Pliocene Tatrot Formation in Himachal Pradesh.
Moreover, other undetermined proteins may be a part of Ppk1/Ppk26 channel complex, as co-expression of exclusively Ppk and Bba together does not produce mechanosensitive currents. Even very diluted concentrations of velvet ant venom (1:8,192) activate cIV da nociceptors through Ppk1/Ppk26, meaning that the key venom peptide is highly potent and affinitive.
The majority of synthetic platelet studies rely on animal models to assess their safety, efficacy, and hemostatic performance. In various experimental models, platelet-mimicking particles have demonstrated the ability to reduce bleeding and improve survival rates, which mirrors the fundamental functions of natural platelets. While these findings suggest promising therapeutic applications, further research is required to refine synthetic platelet designs that ensure long-term safety and facilitate clinical translation for human use.
Sources: en.wikipedia.org
is the partial derivative in the direction x of the flow velocity component v that is oriented along the direction y. We can now generalize to the case of an incompressible flow with a general direction in the 3‑D space, the above constitutive equation becomes
=== Transforming growth factor beta === Transforming growth factor beta (TGF-β) is a physiological regulator of osteoblast differentiation, and acts as a central component in the coupling of bone formation and its resorption during bone remodeling.
The targeting of journalists has prompted national and international condemnation. International watchdogs have urged Mexican authorities to end impunity for attacks on journalists. About 74 percent of the journalists killed since 1992 in Mexico have been reporters for print newspapers, followed in number by Internet media and radio at about 11 percent each. Television journalism accounts for 4 percent of the deaths.
Sources: en.wikipedia.org
Майкл Вайс, Хасан Хасан. Исламское государство: Армия террора. — Альпина Паблишер, 2015-11-03. — 346 с. — ISBN 978-5-9614-4068-3. Даша Никольсон. Иностранные боевики-террористы с Северного Кавказа: понимание влияния Исламского государства в этом регионе // Connections: The Quarterly Journal. — 2017. — Т. 16, вып. 4 Манойло А.В. «Русская весна» в Сирии // Мировая политика. — 2015–04. — Т. 4, вып. 4. — С. 1–26. — ISSN 2409-8671 | doi:10.7256/2409-8671.2015.4.17318
Roseiflexus castenholzii is a heterotrophic, thermophilic, filamentous anoxygenetic phototroph (FAP) bacterium. This species is in one of two genera of FAPs that lack chlorosomes. R. castenholzii was first isolated from red-colored bacterial mats located Nakabusa hot springs in Japan. Because this organism is a phototroph, it utilizes photosynthesis to fix carbon dioxide and build biomolecules. R. castenholzii has three photosynthetic complexes: light-harvesting only, reaction center only, and light-harvesting with reaction center.
In 2017, Forever 21 produced a clothing line in partnership with Taco Bell, featuring branded T-shirts and sweatshirts, as well as bodysuits made to look like Border Sauce packets. In November 2019, Taco Bell announced Taco Bell's Taco Shop, an online store with Taco Bell branded merchandise including hoodies and tees, holiday ornaments, inflatable sauce packets, and wedding-related items.
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. It is a synthetic analogue carrying four amino acid changes, a lactam ring and an amidated C-terminus. The natural hormone is a linear thirteen-amino-acid peptide processed from proopiomelanocortin.