Everything below concerns LC-MS. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-02-27. Numbers and descriptions here follow the published literature rather than marketing material.
Activity is attributed to agonism at melanocortin receptors, particularly MC1R and MC4R. Activation of MC1R on melanocytes increases melanin synthesis, which underlies the reported tanning effect. MC4R engagement in the central nervous system is linked to appetite suppression and to effects on sexual arousal reported in early clinical studies. Those studies were small and were not designed to establish efficacy or long-term safety. Receptor selectivity among the melanocortin subtypes is not absolute, which complicates attribution of any effect to a single pathway.
Regulatory treatment varies between countries. Several national medicines agencies have classified the peptide as unapproved, and customs authorities in some jurisdictions seize shipments on that basis. A few jurisdictions channel supply through prescription-only frameworks that do not list the substance by name. Because the material circulates mainly through online vendors, composition and purity are rarely verified before sale. Surveys of unapproved peptide products have reported labels that did not match measured content in a substantial fraction of samples.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Analogue of alpha-melanocyte-stimulating hormone |
| Common synonyms | MT-II; melanotan 2 | No internationally accepted non-proprietary name |
| Typical presentation | Lyophilised powder in a sealed vial | Often supplied alongside a separate diluent |
| Regulatory status | Unapproved therapeutic substance | Customs seizure reported in several jurisdictions |
| Reported route in use | Subcutaneous injection | Self-administered outside clinical settings |
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.
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 compound was developed in the late 1980s and early 1990s by academic researchers investigating melanocortin signaling and pigmentation. Early work explored whether synthetic analogs could reproduce effects of the natural hormone under controlled conditions. The molecule never advanced through the full regulatory pathway required for approval as a medicine. From the mid-2000s onward it appeared in unregulated consumer markets, often distributed through informal channels. That gap between research origins and commercial availability shapes how the compound is discussed today.
Melanotan-2 is a synthetic peptide designed as an analog of alpha-melanocyte-stimulating hormone, a signaling molecule produced in the pituitary and skin. Its structure is a linear chain of seven amino acids that folds into a ring through an internal lactam bridge joining two side chains. The compound is sometimes written as MT-II or MEL-2 in informal and commercial contexts. It belongs to the melanocortin peptide family, a group of short signaling molecules that share a conserved core sequence recognized by melanocortin receptors.
Two structural changes distinguish the synthetic peptide from the natural hormone. A norleucine residue replaces methionine at one position, and a D-configured phenylalanine replaces the natural L-form at another. Both substitutions slow enzymatic breakdown, which extends the molecule's persistence relative to the parent hormone. The lactam bridge further constrains the backbone into a stable conformation. These features are standard design strategies in peptide chemistry and are not unique to this compound; they appear across many research peptides built for improved stability.
The Randle cycle is a biochemical mechanism involving the mutual inhibition of glucose and fatty acids in their oxidation and uptake in muscle and adipose tissue. The cycle controls fuel selection and adapts the substrate supply and demand in normal tissues. This cycle adds a nutrient-mediated fine tuning on top of the more coarse hormonal control on fuel metabolism. This adaptation to nutrient availability applies to the interaction between adipose tissue and muscle. Hormones that control adipose tissue lipolysis affect circulating concentrations of fatty acids; these in turn control the fuel selection in muscle. Mechanisms involved in the Randle Cycle include allosteric control, reversible phosphorylation and the expression of key enzymes. The energy balance from meals composed of differing macronutrient composition is identical, but the glucose and fat balances that contribute to the overall energy balance change reciprocally with meal composition.
== Clinical significance == Parenteral (intravenous) administration of glucagon is a common human medical intervention in diabetic emergencies when sugar cannot be given orally. It can also be administered intramuscularly.
Indigenous allies were crucial to conquest, as well as to creating and maintaining empire. Indigenous peoples in Colombia experienced a decline in population due to conquest as well as Eurasian diseases, such as smallpox, to which they had no immunity. Regarding the land as deserted, the Spanish Crown sold properties to all persons interested in colonized territories, creating large farms and possession of mines. In the 16th century, the nautical science in Spain reached a great development thanks to numerous scientific figures of the Casa de Contratación and nautical science was an essential pillar of the Iberian expansion. In 1542, the region of New Granada, along with all other Spanish possessions in South America, became part of the Viceroyalty of Peru, with its capital in Lima. In 1547, New Granada became a separate captaincy-general within the viceroyalty, with its capital at Santa Fe de Bogota. In 1549, the Royal Audiencia was created by a royal decree, and New Granada was ruled by the Royal Audience of Santa Fe de Bogotá, which at that time comprised the provinces of Santa Marta, Rio de San Juan, Popayán, Guayana and Cartagena. But important decisions were taken from the colony to Spain by the Council of the Indies.
Sources: en.wikipedia.org
The fledgling is employed by Sebastian LaCroix (voiced by Andy Milder), prince of Los Angeles's vampires. The fledgling's travels through the vampire world bring them into contact with other undead creatures such as the deformed information broker Bertram Tung, the anarch Smiling Jack (John DiMaggio), and the dissociative Voerman sisters, Jeanette and Therese. Chinatown is controlled by the Kuei-Jin, Asian vampires led by Ming-Xiao, who do not require blood and consider themselves superior to other vampires.
== Function == This protein is expressed largely in cells possessing a regulated secretory pathway, such as endocrine/neuroendocrine cells and neurons. The intact proSAAS protein, as well as the carboxyy-terminal peptide containing the inhibitory hexapeptide LLRVKR, functions as an inhibitor of prohormone convertase 1/3, which accomplishes the initial proteolytic cleavage of peptide precursors. ProSAAS is further processed at the N- and C-termini into multiple short peptides, leaving the central segment intact. This central, unprocessed portion of the protein may function as a neural- and endocrine-specific chaperone due to its potent ability to block the aggregation of beta amyloid and alpha synuclein in vitro, and to block oligomer cytotoxicity in cells. Recent data show that nigral proSAAS expression blocks the deterioration of the striatonigral pathway in a synuclein rat model of Parkinson's disease. ProSAAS also oligomerizes and undergoes liquid-liquid phase separation. Differential expression of this gene may be associated with obesity.
Heinz Kähler: Die Augustusstatue von Primaporta. Köln 1959. Erika Simon: Der Augustus von Prima Porta. Bremen, Dorn 1959. (Opus nobile 13) Hans Jucker: Dokumentationen zur Augustusstatue von Primaporta, in: Hefte des Archäologischen Seminars Bern 3 (1977) S. 16–37. Paul Zanker: Augustus und die Macht der Bilder. München, C. H. Beck 1987, ISBN 3-406-32067-8 Kaiser Augustus und die verlorene Republik, Ausstellung Berlin 1988. Mainz, Zabern 1988. S. 386 f. Nr. 215. Erika Simon: Altes und Neues zur Statue des Augustus von Primaporta, in: G. Binder (Hrsg.), Saeculum Augustum, Bd. 3, Darmstadt, WBG 1991, S. 204–233. Dietrich Boschung: Die Bildnisse des Augustus, Gebr. Mann Verlag, Berlin 1993 (Das römische Herrscherbild, Abt. 1, Bd. 2) ISBN 3-7861-1695-4 Thomas Schäfer: Der Augustus von Primaporta im Wechsel der Medien, in: H. J. Wendel u.a. (Hrsg.), Wechsel des Mediums. Zur Interdependenz von Form und Inhalt, Rostock 2001, S. 37–58. Vinzenz Brinkmann und Raimund Wünsche (eds.): Bunte Götter. Die Farbigkeit antiker Skulptur. Eine Ausstellung der Staatlichen Antikensammlungen und Glyptothek München in Zusammenarbeit mit der Ny Carlsberg Glyptotek Kopenhagen und den Vatikanischen Museen, Rom, Staatliche Antikensammlungen und Glyptothek, München 2004 ISBN 3-933200-08-3. In Italian
Sources: en.wikipedia.org
No. No major regulatory agency has granted a marketing authorisation for melanotan II as a medicine. Products sold under this name are generally presented as laboratory reagents and are not subject to the batch-release testing applied to approved drugs.
It was developed in the 1980s by researchers investigating analogues of alpha-melanocyte-stimulating hormone for pigmentation and related endpoints. Early work included small human studies during the 1990s. Development did not progress to licensing, and the compound remained a research and grey-market item.
Peptides are prone to truncation, oxidation and aggregation during synthesis and handling. Without independent testing, a buyer cannot confirm the identity or the content of a vial. Analytical surveys of unapproved peptide products have repeatedly found discrepancies between label claims and measured composition.
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.