eumelanin comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-04-28. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Receptor studies place melanotan-2 among non-selective melanocortin agonists, binding MC1R, MC3R, MC4R and MC5R rather than a single subtype. Activation of MC1R on cutaneous melanocytes raises tyrosinase activity and shifts pigment synthesis toward eumelanin, which is darker and more photostable than pheomelanin. Central receptors, particularly MC4R, are associated with appetite suppression and with reported effects on sexual function. Because subtype selectivity is low, the same molecule engages pigment, metabolic and vascular pathways at once, and this breadth is a common explanation offered for the range of adverse events described in user reports.
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.
| 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 |
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.
== Nomenclature == This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is shikimate:NADP+ 3-oxidoreductase. Other names in common use include:
== History and preparation == Graphite oxide was first prepared by Oxford chemist Benjamin C. Brodie in 1859 by treating graphite with a mixture of potassium chlorate (KClO3) and fuming nitric acid (HNO3). He reported synthesis of "paper-like foils" with 0.05 mm thickness. In 1957, Hummers and Offeman developed a safer, quicker, and more efficient process called Hummers' method, using a mixture of sulfuric acid (H2SO4), sodium nitrate (NaNO3), and potassium permanganate (KMnO4), which is still widely used, often with some modifications. Largest monolayer GO with highly intact carbon framework and minimal residual impurity concentrations can be synthesized in inert containers using highly pure reactants and solvents. Graphite oxides exhibit considerable variation in properties with oxidation degree and synthesis method. For example, the temperature point of explosive exfoliation is generally higher for graphite oxide prepared by the Brodie method compared to Hummers graphite oxide, the difference is up to 100 degrees with the same heating rates. The hydration and solvation properties of Brodie and Hummers graphite oxides are also remarkably different. Recently a mixture of H2SO4 and KMnO4 has been used to cut open carbon nanotubes lengthwise, resulting in microscopic flat ribbons of graphene, a few atoms wide, with the edges "capped" by oxygen atoms (=O) or hydroxyl groups (–OH).
In particular, mimic miRNAs are used to introduce miRNAs that act as tumor suppressors into cancerous tissues, while miRNA antagonists are used to target oncogenic miRNAs to prevent their cancer-promoting activity. Therapeutic miRNA is also used in addition to common therapies (such as cancer therapies) that are known to overexpress or destabilize the patient miRNA levels. An example of one mimic miRNA therapy that demonstrated efficacy in impeding lung cancer tumor growth in mouse studies is miR-34a. One concerning aspect of miRNA-based therapies is the potential for the exogeneous miRNA to affect miRNA silencing mechanisms within normal body cells, thereby affecting normal cellular biochemical pathways. However, in vivo studies have indicated that miRNAs display little to no effect in non-target tissues/organs.
=== Mammography === Molybdenum targets are used in mammography because they produce X-rays in the energy range of 17–20 keV, which is optimal for imaging soft tissues like the breast. The characteristic X-rays emitted from molybdenum provide high contrast between different types of tissues, allowing for the effective visualization of microcalcifications and other subtle abnormalities in breast tissue. This energy range also minimizes radiation dose while maximizing image quality, making molybdenum targets particularly suitable for breast cancer screening.
Sources: en.wikipedia.org
To measure the hemoglobin concentration, a reagent chemical is added to the sample to destroy (lyse) the red cells in a channel separate from that used for red blood cell counts. On analyzers that perform white blood cell counts in the same channel as hemoglobin measurement, this permits white blood cells to be counted more easily. Hematology analyzers measure hemoglobin using spectrophotometry and are based on the linear relationship between the absorbance of light and the amount of hemoglobin present. Chemicals are used to convert different forms of hemoglobin, such as oxyhemoglobin and carboxyhemoglobin, to one stable form, usually cyanmethemoglobin, and to create a permanent colour change. The absorbance of the resulting colour, when measured at a specific wavelength—usually 540 nanometres—corresponds with the concentration of hemoglobin. Sensors count and identify the cells in the sample using two main principles: electrical impedance and light scattering. Impedance-based cell counting operates on the Coulter principle: cells are suspended in a fluid carrying an electric current, and as they pass through a small opening (an aperture), they cause decreases in current because of their poor electrical conductivity. The amplitude of the voltage pulse generated as a cell crosses the aperture correlates with the amount of fluid displaced by the cell, and thus the cell's volume, while the total number of pulses correlates with the number of cells in the sample.
== Honours and awards == In 1970 Iphigenia Vourvidou-Photaki was awarded the one-off Georgios Panopoulos Prize of the Academy of Athens, presented to her for "...her research on the chemical synthesis of polypeptide hormones and investigation of enzyme active sites, which constitute an internationally notable contribution of Greek science to the modern discipline of Chemistry". During her lifetime, she was invited many times as a distinguished researcher in academic conferences related to her subject; some examples were the personal invitations she received to the 3rd European Peptide Symposium (EPS) (Basel, 1960), the 5th EPS (Oxford, 1962), 6th EPS (Athens, 1963 as organiser), 6th International Biochemistry Conference (New York, 1964), 7th EPS (Budapest, 1964), Symposium on Natural Sulfur Compounds (Copenhagen, 1966), NATO Seminar of Molecular Biology (Spetses, 1966), 8th EPS (Noordwijk, 1966), 9th EPS (Paris, 1968), 10th EPS (Abano, 1970), 11th EPS (Vienna, 1971), 3rd American Peptide Symposium (APS) (Boston, 1972), 13th EPS (Kiryat, 1974), 4th APS (New York, 1975), and the 14th EPS (Wépion, 1976) over which she presided.
Research shows that breastfeeding is not the factor that many thought it was. Rinker concluded that "breastfeeding does not appear to have an adverse effect upon breast appearance." Also discounted as causes affecting ptosis are weight gain during pregnancy and lack of participation in regular upper body exercise.
== Disease == In people with lung diseases, heart disease, cancer, kidney disease, immune disorders, and periodontal disease, the interstitial fluid and lymph system are sites where disease mechanisms may develop. Interstitial fluid flow is associated with the migration of cancer cells to metastatic sites. The enhanced permeability and retention effects refers to increased interstitial flow causing a neutral or reversed pressure differential between blood vessels and healthy tissue, limiting the distribution of intravenous drugs to tumors, which under other circumstances display a high-pressure gradient at their periphery. Changes in interstitial volume and pressure play critical roles in the onset of conditions like shock and inflammation. During hypovolemic shock, digestive enzymes and inflammatory agents diffuse to the interstitial space, then drain into the mesenteric lymphatic system and enter into circulation, contributing to systemic inflammation. Accumulating fluid in the interstitial space (interstitial edema) is caused by increased microvascular pressure and permeability, a positive feedback loop mechanism resulting in an associated in increasing the rate of microvascular filtration into the interstitial space. Decreased lymphatic drainage due to blockage can compound these effects. Interstitial edema can prevent oxygen diffusion across tissue and in the brain, kidney and intestines lead to the onset of compartment syndrome.
== Structure == Collagen XVII is a homotrimer of three alpha1(XVII)-chains and a transmembrane protein in type II orientation. Each 180 kD a-chain contains a globular intracellular domain of approximately 70 kDa, which interacts with beta4-integrin, plectin, and BP230 and is necessary for the stable attachment of hemidesmosomes to keratin intermediate filaments. The large C-terminal ectodomain with a molecular mass of approximately 120 kDa consists of 15 collagenous subdomains, characterized by typical collagenous G-X-Y repeat sequences, flanked by 16 short non-collagenous stretches. The overall structure of the ectodomain is that of a flexible, rod-like triple helix with a significant thermal stability. The membrane proximal part of the ectodomain, within amino acids 506-519, is responsible for binding to alpha 6 integrin, this binding seems to be important for the collagen XVII integration into hemidesmosomes . The largest collagenous domain, Col15, which contains 232 amino acids (amino acids 567-808), contributes significantly to stability of collagen XVII homotrimer. The C-terminus of collagen XVII binds to laminin 5, and correct integration of laminin 5 into the matrix requires collagen XVII.
Sources: en.wikipedia.org
=== Chemical === Flerovium is the heaviest known member of group 14, below lead, and is projected to be the second member of the 7p series of elements. Nihonium and flerovium are expected to form a very short subperiod corresponding to the filling of the 7p1/2 orbital, coming between the filling of the 6d5/2 and 7p3/2 subshells. Their chemical behaviour is expected to be very distinctive: nihonium's homology to thallium has been called "doubtful" by computational chemists, while flerovium's to lead has been called only "formal". The first five group 14 members show a +4 oxidation state and the latter members have increasingly prominent +2 chemistry due to onset of the inert pair effect. For tin, the +2 and +4 states are similar in stability, and lead(II) is the most stable of all the chemically well-understood +2 oxidation states in group 14. The 7s orbitals are very highly stabilized in flerovium, so a very large sp3 orbital hybridization is needed to achieve a +4 oxidation state, so flerovium is expected to be even more stable than lead in its strongly predominant +2 oxidation state and its +4 oxidation state should be highly unstable.
Sitagliptin/simvastatin, sold under the brand name Juvisync, is a fixed-dose combination anti-diabetic medication used to treat type 2 diabetes and hypercholesterolemia. It contains sitagliptin and simvastatin. Sitagliptin is a dipeptidyl peptidase-4 inhibitor and simvastatin is an HMG-CoA reductase inhibitor. These two disorders commonly occur in people at the same time, and have been typically treated with administration of these medications separately. The combination was approved in 2011, and sold under the brand name Juvisync by Merck. Juvisync was later removed from the market in 2013, due to business reasons.
Iranian support for the Houthis List of military units named after people Red Sea crisis – Houthi involvement in the Gaza war Timeline of the Yemeni crisis (2011–present) Outline of the Yemeni crisis, revolution, and civil war (2011–present) Muhammad Abd al-Karim al-Ghamari
=== PFA-100 === The PFA-100 (Platelet Function Assay — 100) is a system for analysing platelet function in which citrated whole blood is aspirated through a disposable cartridge containing an aperture within a membrane coated with either collagen and epinephrine or collagen and ADP. These agonists induce platelet adhesion, activation and aggregation, leading to rapid occlusion of the aperture and cessation of blood flow termed the closure time (CT). An elevated CT with EPI and collagen can indicate intrinsic defects such as von Willebrand disease, uremia, or circulating platelet inhibitors. A follow-up test involving collagen and ADP is used to indicate if the abnormal CT with collagen and EPI was caused by the effects of acetyl sulfosalicylic acid (aspirin) or medications containing inhibitors. The PFA-100 is highly sensitive to von Willebrand disease, but is only moderately sensitive to defects in platelet function.
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 regulatory agency has authorised melanotan-2 as a medicine for any indication. It circulates mainly as a research chemical or through unregulated channels. As a result, identity, purity and content are not independently guaranteed.