If you have been reading about alpha-MSH 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 2025-12-27. Numbers and descriptions here follow the published literature rather than marketing material.
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.
The compound emerged from research programs in the 1980s that examined analogues of alpha-melanocyte-stimulating hormone for pigmentation and photoprotection. Investigators modified the native sequence to extend activity duration and potency. A related analogue, afamelanotide, was developed within the same broad line of inquiry and eventually gained approval in certain jurisdictions for a rare light-sensitivity condition. Melanotan-2 itself did not progress through the same regulatory route and has no approved therapeutic indication.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Free base; salt forms differ |
| Molecular weight | Approximately 1024 g/mol | Calculated for the free base |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water and polar solvents | Poorly soluble in non-polar solvents |
| Typical storage | -20 degrees Celsius, dry, protected from light | Refers to the solid form |
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.
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.
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.
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.
== Design == Brentuximab vedotin consists of the chimeric monoclonal antibody brentuximab (cAC10, which targets the cell-membrane protein CD30) linked with maleimide attachment groups, cathepsin-cleavable linkers (valine-citrulline), and para-aminobenzylcarbamate spacers to three to five units of the antimitotic agent monomethyl auristatin E (MMAE, reflected by the 'vedotin' in the drug's name). The peptide-based linker bonds the antibody to the cytotoxic compound in a stable manner so the drug is not easily released from the antibody under physiologic conditions to help prevent toxicity to healthy cells and ensure dosage efficiency. The peptide antibody-drug bond facilitates rapid and efficient drug cleavage inside target tumor cell. The antibody cAC10 part of the drug binds to CD30 which often occurs on diseased cells but rarely on normal tissues. The antibody portion of the drug attaches to CD30 on the surface of malignant cells, delivering MMAE which is responsible for the anti-tumour activity. Once bound, brentuximab vedotin is internalised by endocytosis and thus selectively taken up by targeted cells. The vesicle containing the drug is fused with lysosomes and lysosomal cysteine proteases, particularly cathepsin B, start to break down valine-citrulline linker and MMAE is no longer bound to the antibody and is released directly into the tumor environment.
They wrote in Experientia (later renamed Cellular and Molecular Life Sciences): "Through catalytic actions the macromolecular desoxyribonucleic acids govern the building of macromolecular ribonucleic acids, and, in turn, these control the production of cytoplasmic enzymes. In truth, the enzymic equipment results simultaneously from the effect of ribonucleic acids (catalytic action) and from the effect of substrates (mass action).
There are also the testimonies of Raymond Queneau (1903–1976), born in Le Havre, the city served as a framework for his novel Un rude hiver (A harsh winter) (1939). The plot of Une maison soufflée aux vents (A house blown to the winds) by Émile Danoën, winner of the Popular Novel Prize in 1951, and its sequel Idylle dans un quartier muré (Idyll in a walled neighbourhood) were located in Le Havre during the Second World War. Under the name Port de Brume Le Havre is the setting for three other novels by this author: Cerfs-volants (Kites), L'Aventure de Noël (The Adventure at Christmas), and La Queue à la pègre (Queue to the underworld). Michel Leiris wrote De la littérature considérée comme une tauromachie (Of literature considered like a bullfight) in December 1945. Diana Gabaldon set the second novel in her Outlander series, Dragonfly in Amber (1992), partly in Le Havre. Two mystery novels take place in Le Havre: Le Bilan Maletras (The Maletras Balance) by Georges Simenon and Le Crime de Rouletabille (Crime at the Roulette table) by Gaston Leroux. In Rouge Brésil (Red Brazil), winner of the Goncourt Prize in 2001, Jean-Christophe Rufin describes Le Havre in the 16th century as the port of departure of French expeditions to the New World: the hero Villegagnon leaves of the port to conquer new lands for the French crown which become Brazil. Martine–Marie Muller tells the saga of a clan of Stevedores from Le Havre in the 1950s to the 1970s in Quai des Amériques (Quay of the Americas).
Binding of activated TGF-β to its receptors expressed on alveolar macrophages induces a downstream signaling cascade, including phosphorylation of receptor-regulated Small Mothers Against Decapentaplegic (R-SMAD)homologs 2 and 3. Phosphorylated SMAD-2 and -3 then form heteromeric complexes with common-mediator SMAD 4 (co-SMAD-4). Once assembled, the complexes translocates into the nucleus via the nuclear pore with the assistance of importins alpha/beta. Once in the nucleus, these complexes accumulate and eventually act as a transcription factors, regulating the expression of TGF-β target genes. Thus TGF-β signaling involves a direct pathway from the receptors on the surface of a cell to the nucleus.
Sources: en.wikipedia.org
The El Niño–Southern Oscillation is a single climate phenomenon that recurs in three phases: Neutral, La Niña or El Niño. La Niña and El Niño are opposite phases in the oscillation which are deemed to occur when specific ocean and atmospheric conditions are reached or exceeded. The warming phase of the sea surface temperature is known as "El Niño", and its cooling phase as "La Niña". The "Southern Oscillation" is the oscillation in surface air pressure between the tropical eastern Pacific Ocean waters and the tropical western Pacific Ocean waters. An early recorded mention of the term "El Niño" ("The Boy" in Spanish) in a climate context occurred in 1892, when Captain Camilo Carrillo reported to the geographical society congress in Lima that Peruvian sailors named the warm, south-flowing current after the Christ Child, as it typically appeared around Christmas. Over time, the term has evolved and now refers to the warm and negative phase of the El Niño–Southern Oscillation (ENSO). The original phrase, El Niño de Navidad 'The Christmas Boy', arose centuries ago, when Peruvian fishermen named the weather phenomenon after the newborn Christ. La Niña ("The Girl" in Spanish) is the colder counterpart of El Niño, as part of the broader ENSO climate pattern. In the past, it was also called an anti-El Niño and El Viejo 'the old man'.
Radiocarbon dating is also simply called carbon-14 dating. Carbon-14 is a radioactive isotope of carbon, with a half-life of 5,730 years (which is very short compared with the above isotopes), and decays into nitrogen. In other radiometric dating methods, the heavy parent isotopes were produced by nucleosynthesis in supernovas, meaning that any parent isotope with a short half-life should be extinct by now. Carbon-14, though, is continuously created through collisions of neutrons generated by cosmic rays with nitrogen in the upper atmosphere and thus remains at a near-constant level on Earth. The carbon-14 ends up as a trace component in atmospheric carbon dioxide (CO2). A carbon-based life form acquires carbon during its lifetime. Plants acquire it through photosynthesis, and animals acquire it from consumption of plants and other animals. When an organism dies, it ceases to take in new carbon-14, and the existing isotope decays with a characteristic half-life (5730 years). The proportion of carbon-14 left when the remains of the organism are examined provides an indication of the time elapsed since its death. This makes carbon-14 an ideal dating method to date the age of bones or the remains of an organism. The carbon-14 dating limit lies around 58,000 to 62,000 years. The rate of creation of carbon-14 appears to be roughly constant, as cross-checks of carbon-14 dating with other dating methods show it gives consistent results.
=== Israel trip === During a July 2026 trip to Israel, Chabad "outreach figure" Yossi Farro presented Peters with a "custom necklace" which shows the Star of David fused with the OpenAI logo. The moment was considered the "latest flashpoint" in a debate over how the Jewish community should engage with controversial online figures. Farro joked online that the "mashup" amounted to the AI company's logo "mogging" the Jewish star. The two switched restaurants mid-meal once Peters realized the one they had chosen was not kosher. Farro posted about the trip, saying Peters "is loving Israel and Israel is loving him." "Peters's manager is Jewish," Farro further explained, "and the rabbi of the Chabad community connected to the manager thought it would be worthwhile to introduce us. Thank God, we connected." The Times of Israel reported that Peters had been seen talking to prime minister Benjamin Netanyahu's adviser Topaz Luk at a Tel Aviv nightclub. Israeli influencers who appeared on Peters's streams, Shira Braun and Shira Klein, were reprimanded and demoted from their positions by the Israel Defense Forces.
By binding to nicotinic acetylcholine receptors in the brain, nicotine elicits its psychoactive effects and increases the levels of several neurotransmitters in various brain structures – acting as a sort of "volume control". Nicotine has a higher affinity for nicotinic receptors in the brain than those in skeletal muscle, though at toxic doses it can induce contractions and respiratory paralysis. Nicotine's selectivity is thought to be due to a particular amino acid difference on these receptor subtypes. Nicotine is unusual in comparison to most drugs, as its profile changes from stimulant to sedative with increasing dosages, a phenomenon known as "Nesbitt's paradox" after the doctor who first described it in 1969. At very high doses it dampens neuronal activity. Nicotine induces both behavioral stimulation and anxiety in animals. Research into nicotine's most predominant metabolite, cotinine, suggests that some of nicotine's psychoactive effects are mediated by cotinine. Nicotine activates nicotinic receptors (particularly α4β2 nicotinic receptors, but also α5 nAChRs) on neurons that innervate the ventral tegmental area and within the mesolimbic pathway where it appears to cause the release of dopamine. This nicotine-induced dopamine release occurs at least partially through activation of the cholinergic–dopaminergic reward link in the ventral tegmental area. Nicotine can modulate the firing rate of the ventral tegmental area neurons.
== Modern Use and Clinical Research == Wound Care Recent studies confirm the biochemical role played by the chemical composition of sangre de grado as a cicatrizant beneficial in the reduction of mean wound healing time. The polyphenolic compounds of the sap further create a protective layer at the wound surface, preventing the entry of pathogenic microbes. These compounds condense and bind to surrounding extracellular proteins, clogging the wound and offering vasoconstriction at the site of injury, which is crucial in wound healing. Taspine was found to be the principal cicatrizant agent in murine models as well as able to increase the chemotaxis of human fibroblast cells which is the most likely mechanism by which the resin and taspine accelerate the wound healing process. The chemotaxis of fibroblasts aids the reformation in the reformation of the matrix following re-epithelialization, allowing for the regeneration of damaged skin. Antimicrobial Activity Some compounds of the resin, as found in a particular study, 2,4,6-trimethoxyphenol, 1,3,5-trimethoxybenzene, crolechinic acid, and korberins A and B showed exhibited antibacterial properties individually. Sangre de grado from the closely related Croton urucurana was reported to exhibit antifungal qualities due to the presence of catechins and epigallocatechin contained in the resin, both of which are also found in Croton lechleri.
Sources: en.wikipedia.org
No. Melanotan-2 is manufactured synthetically. The naturally occurring peptide in the same family is alpha-melanocyte-stimulating hormone, which the body produces as part of normal endocrine and neural signalling.
Both are synthetic analogues derived from the same parent hormone. Reference descriptions usually characterise afamelanotide as more selective for the MC1R subtype, whereas melanotan-2 is reported to interact with a wider range of melanocortin receptors.
Early studies explored melanocortin signalling and pigmentation, which later led to informal use of the label tanning peptide. That label is not a regulatory category and does not imply approved status for any purpose.
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.