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 2025-07-23. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Free base; salt forms add to total mass |
| Molecular mass | About 1024 daltons | Calculated for the free base |
| Structural class | Cyclic heptapeptide | Contains D-phenylalanine and norleucine |
| Parent hormone | Alpha-melanocyte-stimulating hormone | Endogenous tridecapeptide of 13 residues |
| Receptor profile | Non-selective melanocortin agonist | Interacts with MC1R, MC3R, MC4R and MC5R |
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.
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.
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.
In October 2020, GSK told some staff that while at work they should disable the contact tracing function of the NHS test-and-trace app which monitors the spread of COVID-19. GSK explained the reason for this was due to social distancing measures in place at their sites rendering the technology unnecessary. In November 2023, GSK filed a lawsuit against Moderna Inc. in U.S. federal court in Delaware, accusing the company of violating GSK's patents related to messenger RNA (mRNA) technology. The lawsuit claims that Moderna's COVID-19 vaccine Spikevax and RSV vaccine mResvia infringe on several of GSK's patents, particularly those related to lipid nanoparticles used for delivering mRNA into the human body. This legal action follows a similar lawsuit GSK filed against Pfizer and BioNTech earlier in 2024, also over patent infringement concerning their mRNA-based COVID-19 vaccine. The current litigation seeks unspecified monetary damages from Moderna.
==== Aerosol mass spectrometer ==== The Aerodyne AMS provides real-time aerosol mass spectrometry analysis of size-resolved mass concentration of non-refractory components (Ex. organics, sulfate, nitrate, and ammonium). The term non-refractory is assigned to species that evaporate rapidly at 600 °C under vacuum conditions (e.g. organic matter, NH4NO3 and (NH4)2SO4. The schematic of a typical AMS is shown in the figure to the right. The Aerodyne AMS is made up of three sections; The aerosol inlet, the particle sizing chamber, and the particle detection chamber. The aerosol inlet has a flow limiting orifice entrance that is around 100 um in diameter. Once in the chamber the sample goes through aerodynamic focusing lens system, which consist of several orifice lenses that are mount in sequence of decreasing inner diameter. The lens focuses the particles into a narrow particle beam. The beam now travels through the particle sizing chamber, where the particle aerodynamic diameter is measured. The particle sizing chamber is made up of a flight tube maintained at (~ 10−5 torr). The entrance of the flight tube is a mechanical chopper that's used to modulate the particle beam; then using both the fixed length of the tube and the time-resolved detection of the arrival at the end, the particles' velocities can be determined. Using the velocity, the particle's diameter is obtained. As the particle beam exits the flight tube, it enters the particle composition detection chamber. In this section, the particles collide with a heated tungsten element (~600 °C).
== History == Metribolone was first described in the literature in 1965. It was studied clinically in the late 1960s and early 1970s, most notably in the treatment of advanced breast cancer. The drug was found to be effective and showed weak androgenicity, but also produced severe signs of hepatotoxicity, and was ultimately never marketed. By the mid-1970s, metribolone was becoming an accepted standard as a ligand and agonist of the AR in scientific research. It remains in wide use for this purpose today. Aside from scientific research, metribolone has also been encountered as an AAS in non-medical contexts, for instance in doping in sports and bodybuilding.
Sources: en.wikipedia.org
After drug withdrawal, the effects fade away slowly, but may persist for more than 6–12 weeks after cessation of AAS use. Strength improvements in the range of 5 to 20% of baseline strength, depending largely on the drugs and dose used as well as the administration period. Overall, the exercise where the most significant improvements were observed is the bench press. For almost two decades, it was assumed that AAS exerted significant effects only in experienced strength athletes. A randomized controlled trial demonstrated, however, that even in novice athletes a 10-week strength training program accompanied by testosterone enanthate at 600 mg/week may improve strength more than training alone does. This dose is sufficient to significantly improve lean muscle mass relative to placebo even in subjects that did not exercise at all. The anabolic effects of testosterone enanthate were highly dose dependent.
== Society == Mass Party, a political party in Thailand (2006–2009?) Mass society, a society based on relations between huge numbers of people, whose prototypical denizen is the "mass man" Mass politics, politics in the mass society, featuring especially the modern political party
=== Legal status === United States In the United States, bromazolam was placed under emergency Schedule I status on March 18, 2026, effective until March 18, 2028, with a possible temporary extension or permanent placement. A number of states, such as Virginia, have also placed bromazolam into Schedule 1 at the state level, but this does not include the 6-(2-chlorophenyl) analog phenazolam. Prior to its emergency scheduling, there have been several arrests in the United States for mismarketing bromazolam as alprazolam, typically in the shape of brand name Xanax tablets which constitutes a counterfeit drug charge among others. In August 2021, at least 1 person in Illinois was arrested for "unlawful possession of a controlled substance, a Class 4 felony." for the possession of less than 15 grams (½ oz.) of bromazolam, similar to being charged for unlawful possession of alprazolam in Illinois. It is unknown if this arrest involved counterfeit Xanax shaped tablets or powder. However, bromazolam was not scheduled in Illinois at the time of the arrest. In June 2022, the U.S. Department of Justice reported that bromazolam seizures were "surging" across the United States, driven in part by increasing detections alongside fentanyl. Canada In Canada, illicit opioids such as heroin or fentanyl analogues are mixed with bromazolam and sold at the street level; the product is sometimes referred to as "benzo-dope." United Kingdom In the United Kingdom, bromazolam is a Class C controlled substance.
Sources: en.wikipedia.org
In 1896, the engineer Wolfram Fuchs, based on his experience with numerous X-ray examinations, recommended keeping the exposure time as short as possible, staying away from the tube, and covering the skin with Vaseline. In 1897, Chicago doctors William Fuchs and Otto Schmidt became the first users to have to pay compensation to a patient for radiation damage. In 1901, dentist William Herbert Rollins (1852-1929) called for using lead-glass goggles when working with X-rays, for the X-ray tube to be encased in lead, and for all areas of the body to be covered with lead aprons. He published over 200 articles on the potential dangers of X-rays, but his suggestions were long ignored. A year later, Rollins wrote in despair that his warnings about the dangers of X-rays were not being heeded by either the industry or his colleagues. By this time, Rollins had demonstrated that X-rays could kill laboratory animals and induce miscarriages in guinea pigs. Rollins' achievements were not recognized until later. Since then, he has gone down in the history of radiology as the "father of radiation protection". He became a member of the Radiological Society of North America and its first treasurer.
==== Oxygen ==== Oxygen isotopic ratios are commonly compared to both the VSMOW and the VPDB references. Traditionally oxygen in water is reported relative to VSMOW while oxygen liberated from carbonate rocks or other geologic archives is reported relative to VPDB. As in the case of hydrogen, the oxygen isotopic scale is defined by two materials, VSMOW2 and SLAP2. Measurements of sample δ18O vs. VSMOW can be converted to the VPDB reference frame through the following equation: δ18OVPDB = 0.97001*δ18OVSMOW - 29.99‰ (Brand et al., 2014).
Typically, a broker will market a property on behalf of the seller. Brokers representing buyers or buyers' representatives identify property meeting a set of criteria set out by the buyer. Types of buyers may include an owner-user, private investor, acquisitions, capital investment, or private equity firms. The buyer or its agents will perform an initial assessment of the physical property, location and potential profitability (if for investment) or adequacy of property for its intended use (if for owner-user). If it is determined the prospective investment meets the buyer's criteria, they may signal their intent to move forward with a letter of intent (LOI). Letters of Intent are used to outline the major terms of an offer in order to avoid unnecessary costs of drafting legal documents in the event the parties do not agree to the terms as drafted. Once a Letter of Intent is signed by both parties, a purchase and sale agreement (PSA) is drafted. Not all commercial property transactions utilize a Letter of Intent although it is common. A PSA is a legal agreement between the seller and a single interested buyer which establishes the terms, conditions and timeline of the sale between the buyer and seller. A PSA may be a highly negotiated document with customized terms or may be a standardized contract similar to those used in residential transactions. Once a PSA is executed, the buyer is commonly required to submit an escrow deposit, which may be refundable under certain conditions, to a title company office or held by a brokerage in escrow.
Sources: en.wikipedia.org
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.
Melanotan-1, also called afamelanotide, is a linear analogue with greater selectivity for MC1R and has received approval in some jurisdictions for a specific photosensitivity disorder. Melanotan-2 is cyclic, less selective, and reaches central receptors more readily. The two are often confused in online discussion despite different pharmacology and regulatory status.
Alpha-MSH is an endogenous tridecapeptide derived from pro-opiomelanocortin. Melanotan-2 reproduces its core receptor-binding sequence inside a shortened, stabilised ring. The result is a molecule with a longer effective half-life and higher potency than the parent hormone.
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.