The short version of eumelanin fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-06-05 and is reviewed periodically as new material appears.
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.
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 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.
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.
| 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 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.
Pharmacologically, melanotan-2 behaves as a non-selective agonist across the melanocortin receptor family. Binding at MC1R on dermal melanocytes promotes eumelanin synthesis, which underlies the tanning response described in early human work. Activity at the centrally expressed MC4R receptor is associated with reported effects on appetite and erectile function. Because the peptide does not discriminate strongly among receptor subtypes, attributing any single observed effect to one receptor pathway is generally not possible without selective antagonists or receptor knockout models.
== Education == Frank completed her M.D. and Ph.D. in biochemistry at the University of Pennsylvania. She completed a clinical pathology residency at the Brigham and Women's Hospital. During her postdoctoral research fellowship in immunology, she focused on V(D)J recombination in developing lymphocytes in the Howard Hughes Medical Institute laboratory of Frederick Alt at the Boston Children's Hospital. As a faculty member, her studies included DNA repair mechanisms relevant to both cancer and immunology, followed by microbiological investigations of Staphylococcus aureus and enterobacteriaceae.
=== Design for specificity === The design of protein–protein interactions must be highly specific because proteins can interact with a large number of proteins; successful design requires selective binders. Thus, protein design algorithms must be able to distinguish between on-target (or positive design) and off-target binding (or negative design). One of the most prominent examples of design for specificity is the design of specific bZIP-binding peptides by Amy Keating and coworkers for 19 out of the 20 bZIP families; 8 of these peptides were specific for their intended partner over competing peptides. Further, positive and negative design was also used by Anderson and coworkers to predict mutations in the active site of a drug target that conferred resistance to a new drug; positive design was used to maintain wild-type activity, while negative design was used to disrupt binding of the drug. Recent computational redesign by Costas Maranas and coworkers was also capable of experimentally switching the cofactor specificity of Candida boidinii xylose reductase from NADPH to NADH.
SR-15099, also known as SR 2.0, is an atypical opioid and close analogue of SR-17018 and brorphine. It is the analogue of SR-17018 in which the chlorine atom on the benzyl ring has been replaced with a bromine atom. The drug is a non-competitive partial biased agonist of the μ-opioid receptor (MOR) similarly to SR-17018. It has similar effects in animals as SR-17018, such as having robust analgesic effects but producing minimal respiratory depression or hyperlocomotion. SR-15099 was first described in the scientific literature by Laura M. Bohn and colleagues by 2017.
Sources: en.wikipedia.org
Although these are both aspects of earthworm activities the net effect is important to ascertain, in particular in the frame of organic matter disappearance linked to global warming. It seems that there is now a consensus about the prominent role of earthworms in carbon sequestration due to the fact that part of organic matter is mineralized at or near the soil surface while the major part is incorporated in the deep soil where it is stabilized by links with clay minerals.
=== Sanger sequencing === Sanger sequencing recently was used to evaluate the enrichment of mutant DNA from a mixture of 1:20 mutant:wildtype DNA. The variant DNA containing a mutation was obtained from a breast cancer cell line known to contain p53 mutations. Comparison of Sanger sequencing chromatograms indicated that the mutant allele was enriched 13 fold when COLD-PCR was used compared to traditional PCR alone. This was determined by the size of the peaks on the chromatogram at the variant allele location. As well, COLD-PCR was used to detect p53 mutations from lung-adenocarcinoma samples. The study was able to detect 8 low level (under 20% abundance) mutations that would likely have been missed using conventional methods that don't enrich for variant sequence DNA.
== Religious customs == Jewish and Muslim dietary laws require the removal of blood from freshly slaughtered meat. Salt and brine are used for the purpose in both traditions, but salting is more common in Kosher Shechita (where it is all but required) than in Halal Dhabiha (as in most cases, draining alone will suffice).
Sources: en.wikipedia.org
=== NNPC, NEITI Set Up Joint Committee to Strengthen Transparency === In keeping with the Transparency, Accountability, and Performance Excellence (TAPE) agenda of the Mele Kyari-led management of the Nigerian National Petroleum Corporation (NNPC), the corporation and the Nigeria Extractive Industries Transparency Initiative (NEITI) have set up a joint committee to deepen collaboration in order to promote transparency in the Oil and Gas Industry. Speaking at the inauguration of the NNPC-NEITI Joint Committee on Mainstreaming and Remedial Issues, group managing director of NNPC, Kyari, said the joint committee was part of efforts to further deepen the robust history of collaboration that both organisations had enjoyed over the years. He said NNPC was in complete sync with the activities of NEITI because it was the right of the over 200 million Nigerians who are the shareholders of the corporation to know everything about the operations of their company.
On April 12, 2001, the CPL Winter Championship commenced at the Hyatt Regency in Dallas, Texas. The event featured 48 competing teams, marking the first large-scale Counter-Strike tournament. The competition attracted over 800 attendees, including participants and Bring Your Own Computer (BYOC) players. Many professional Quake players were notably absent, while the Counter-Strike community saw an influx of new competitors. This tournament was the largest Counter-Strike event at the time and contributed to the game's rise in professional esports. In 2003, the Esports World Convention hosted a Counter-Strike tournament which featured 37 teams competing for a $100,000 prize pool. In 2012, the Electronic Sports League removed the game from the main titles for the 2012–2013 Intel Extreme Masters due to its decreasing popularity outside of Europe.
For coal samples originating near the Equator, δD is around −50‰, while for those originating from polar regions, δD is around −150‰. This δD trend along latitude is consistent meteoric water trend and thus is an evidence that coals can preserve much of the original signals. There are two types of approach to study the alteration of DHRs of kerogen during catagenesis: (1) laboratory incubation of organic matter that enables mechanistic study with controlled experiments; (2) natural sample measurement that provides information of combined effects over geologic timescales. The complex composition and chemistry of kerogen complicates the results. Nevertheless, most research on HIC of kerogen show D enrichment with increasing maturity. Type II kerogen (marine derived) from New Albany Shale is reported to have δD rise from −120‰ to −70‰ as vitrinite reflectance increase from 0.3% to 1.5%. Two main mechanisms have been proposed for enrichment. One of them is kinetic fractionation during hydrocarbon generation while the other is isotopic exchange with surrounding water. Anhydrous incubation experiments have shown that the products are generally more D-depleted than their precursors, causing enrichment in residual kerogen. Schimmelmann et al. studied the relationship between terrestrially derived oil and their source rock kerogens from four Australian Basins. They found that on average the oil is depleted to corresponding kerogen by 23‰. Hydrous incubation experiments suggest that 36–79% of bulk organic hydrogen may come from water at moderate maturity.
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. 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.