If you have been reading about melanotan-2 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 2026-01-15. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Melanotan-2, also written Melanotan II, is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, and the lactam bridge between the aspartate and lysine side chains constrains the peptide into a ring. This structural change increases receptor affinity and metabolic stability relative to the native hormone. The compound was created in the 1980s as a research tool for studying pigmentation biology.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Compound class | Synthetic cyclic heptapeptide | Alpha-MSH analogue containing a D-phenylalanine residue |
| Molecular formula | C50H69N15O9 | Average molecular mass approximately 1024.2 g/mol |
| Appearance | White to off-white lyophilised powder | Normally supplied as a freeze-dried solid in a sealed vial |
| Solubility | Freely soluble in water and polar solvents | Dissolves readily in aqueous buffers and in alcohol-water mixtures |
| Receptor targets | MC1R, MC3R, MC4R, MC5R | Acts as a non-selective melanocortin receptor agonist |
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.
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.
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.
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 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.
In May 1968, Bush joined the United States Air Force and was commissioned into the Texas Air National Guard. After two years of training in active-duty service, he was assigned to Houston, flying Convair F-102s with the 147th Reconnaissance Wing out of Ellington Field Joint Reserve Base. Critics, including former Democratic National Committee Chairman Terry McAuliffe, have alleged that Bush was favorably treated due to his father's political standing as a member of the House of Representatives, citing his selection as a pilot despite his low pilot aptitude test scores and his irregular attendance. In June 2005, the Department of Defense released all the records of Bush's Texas Air National Guard service, which remain in its official archives. In late 1972 and early 1973, he drilled with the 187th Fighter Wing of the Alabama Air National Guard. He had moved to Montgomery, Alabama, to work on the unsuccessful U.S. Senate campaign of Republican Winton M. Blount. In 1972, Bush was suspended from flying for failure to take a scheduled physical exam. He was honorably discharged from the Air Force Reserve on November 21, 1974. Bush remains the most recent president to have served in the military.
More color variants are possible via chromophore binding. The critical mutation in cyan derivatives is the Y66W substitution, which causes the chromophore to form with an indole rather than phenol component. Several additional compensatory mutations in the surrounding barrel are required to restore brightness to this modified chromophore due to the increased bulk of the indole group. In ECFP and Cerulean, the N-terminal half of the seventh strand exhibits two conformations. These conformations both have a complex set of van der Waals interactions with the chromophore. The Y145A and H148D mutations in Cerulean stabilize these interactions and allow the chromophore to be more planar, better packed, and less prone to collisional quenching. Additional site-directed random mutagenesis in combination with fluorescence lifetime based screening has further stabilized the seventh β-strand resulting in a bright variant, mTurquoise2, with a quantum yield (QY) of 0.93. The red-shifted wavelength of the YFP derivatives is accomplished by the T203Y mutation and is due to π-electron stacking interactions between the substituted tyrosine residue and the chromophore. These two classes of spectral variants are often employed for Förster resonance energy transfer (FRET) experiments. Genetically encoded FRET reporters sensitive to cell signaling molecules, such as calcium or glutamate, protein phosphorylation state, protein complementation, receptor dimerization, and other processes provide highly specific optical readouts of cell activity in real time.
Superheated water is liquid water under pressure at temperatures between the usual boiling point, 100 °C (212 °F) and the critical temperature, 374 °C (705 °F). It is also known as "subcritical water" or "pressurized hot water". Superheated water is stable because of overpressure that raises the boiling point, or by heating it in a sealed vessel with a headspace, where the liquid water is in equilibrium with vapour at the saturated vapor pressure. This is distinct from the use of the term superheating to refer to water at atmospheric pressure above its normal boiling point, which has not boiled due to a lack of nucleation sites (sometimes experienced by heating liquids in a microwave). Many of water's anomalous properties are due to very strong hydrogen bonding. Over the superheated temperature range the hydrogen bonds break, changing the properties more than usually expected by increasing temperature alone. Water becomes less polar and behaves more like an organic solvent such as methanol or ethanol. Solubility of organic materials and gases increases by several orders of magnitude and the water itself can act as a solvent, reagent, and catalyst in industrial and analytical applications, including extraction, chemical reactions and cleaning.
=== Research tool === Due to its high proteolytic specificity, thrombin is a valuable biochemical tool. The thrombin cleavage site (Leu-Val-Pro-Arg-Gly-Ser) is commonly included in linker regions of recombinant fusion protein constructs. Following purification of the fusion protein, thrombin can be used to selectively cleave between the arginine and glycine residues of the cleavage site, effectively removing the purification tag from the protein of interest with a high degree of specificity.
Sources: en.wikipedia.org
=== Reproduction === Komagataella can undergo both asexual reproduction and sexual reproduction, by budding and ascospore. In this case, two types of cells of Komagataella exist: haploid and diploid cells. In the asexual life cycle, haploid cells undergo mitosis for reproduction. In the sexual life cycle, diploid cells undergo sporulation and meiosis. The growth rate of its colonies can vary by a large range, from near to 0 to a doubling time of one hour, which is suitable for industrial processes.
The relationship between SHBG and insulin resistance has been known for some time; decades prior, ratios of SHBG and adiponectin were used before glucose to predict insulin resistance. Patients with Laron syndrome, with resultant deficient IGF, demonstrate varying degrees of alopecia and structural defects in hair follicles when examined microscopically. Because of its association with metabolic syndrome and altered glucose metabolism, anyone with early androgenic hair loss should be screened for impaired glucose tolerance and diabetes mellitus II. Measurement of subcutaneous and visceral adipose stores by MRI, demonstrated inverse association between visceral adipose tissue and testosterone/DHT, while subcutaneous adipose correlated negatively with SHBG and positively with estrogen. SHBG association with fasting blood glucose is most dependent on intrahepatic fat, which can be measured by MRI in and out of phase imaging sequences. Serum indices of hepatic function and surrogate markers for diabetes, previously used, show less correlation with SHBG by comparison. Female patients with mineralocorticoid resistance present with androgenic alopecia. IGF levels are lower in those with metabolic syndrome. Circulating serum levels of IGF-1 are increased with vertex balding, although this study did not look at mRNA expression at the follicle itself. Locally, IGF is mitogenic at the dermal papillae and promotes elongation of hair follicles. The major site of production of IGF is the liver, although local mRNA expression at hair follicles correlates with an increase in hair growth.
Anagani Satya Prasad is cabinet Minister ( Revenue, Registration & Stamps ) & MLA of Andhra Pradesh from Repalle Constituency in Guntur district, Andhra Pradesh. He was elected to assembly elections in 2014 & 2019 defeating Mopidevi Venkata Ramana of YSRCP and in 2024 defeating Evuri Ganesh of YSRCP.
Magnesium is the eighth-most-abundant element in the Earth's crust by mass and tied in seventh place with iron in molarity. It is found in large deposits of magnesite, dolomite, and other minerals, and in mineral waters, where magnesium ion is soluble. Although magnesium is found in more than 60 minerals, only dolomite, magnesite, brucite, carnallite, talc, and olivine are of commercial importance. The Mg2+ cation is the second-most-abundant cation in seawater (about 1⁄8 the mass of sodium ions in a given sample), which makes seawater and sea salt attractive commercial sources for Mg.
Ozata DM, Gainetdinov I, Zoch A, Phillip D, Zamore PD (2019). "PIWI-Interacting RNAs: Small RNAs With Big Functions" (PDF). Nature Reviews Genetics. 20 (2): 89–108. doi:10.1038/s41576-018-0073-3. hdl:20.500.11820/9f12a0e2-1d56-4a44-968d-6f6300efa2b6. PMID 30446728. S2CID 53565676. Secondary source, 2019 Marc S, Weinberg; Kevin V, Morris (August 2016). "Transcriptional Gene Silencing in Humans". Nucleic Acids Research. 44 (14): 6505–6517. doi:10.1093/nar/gkw139. PMC 5001580. PMID 27060137. Secondary source, 2016 Carthew RW, Sontheimer EJ (February 2009). "Origins and Mechanisms of miRNAs and siRNAs". Cell. 136 (4): 642–55. doi:10.1016/j.cell.2009.01.035. PMC 2675692. PMID 19239886. Secondary source, 2009 Hannon GJ, Rossi JJ (September 2004). "Unlocking the Potential of the Human Genome With RNA Interference". Nature. 431 (7006): 371–8. Bibcode:2004Natur.431..371H. doi:10.1038/nature02870. PMID 15372045. S2CID 4410723. Secondary source, 2004
Sources: en.wikipedia.org
Sarcomas are typically divided into two major groups: bone sarcomas and soft-tissue sarcomas, each of which has multiple subtypes. In the United States, the American Joint Committee on Cancer (AJCC) publishes guidelines that classify the subtypes of sarcoma. These subtypes are as follows:
An acid dye is a dye that is typically applied to a textile at low pH. They are mainly used to dye wool, not cotton fabrics. Some acid dyes are used as food colorants, and some can be used to stain organelles for medical microscopy. Acid dyes are anionic, soluble in water and are essentially applied from acidic bath. They possess acidic groups, such as SO3H and COOH and are applied on wool, silk and nylon when an ionic bond is established between a protonated –NH2 group of the fibre and acid group of the dye. Overall wash fastness is poor, although lightfastness is quite good. As dye and fibre contain opposite electrical natures, strike rate and uptake of acid dye on these fibres is faster; electrolyte at higher concentration is added to retard dye uptake and to form levelled shades. Acid generates cations on fibre and temperature helps to substitute the negative part of the acid with anionic dye molecules.
Desmosine is an amino acid found uniquely in elastin, a protein found in connective tissue such as skin, lungs, and elastic arteries. Desmosine is a component of elastin and cross links with its isomer, isodesmosine, giving elasticity to the tissue. Detection of desmosine in urine, plasma or sputum samples can be a marker for elastin breakdown due to high elastase activity related to certain diseases.
==== Auxiliary channel ==== The DisplayPort AUX channel is a half-duplex data channel used for miscellaneous additional data beyond video and audio, such as EDID (I2C) or CEC commands. This bidirectional data channel is required, since the video lane signals are unidirectional (simplex) from source to display. AUX signals are transmitted across a dedicated set of twisted-pair wires. DisplayPort 1.0 specified Manchester encoding with a 2 MBd signal rate (1 Mbit/s data rate). Version 1.2 of the DisplayPort standard introduced a second transmission mode called FAUX (Fast AUX), which operated at 720 Mbit/s with 8b/10b encoding (576 Mbit/s data rate), but it was deprecated in version 1.3.
Sources: en.wikipedia.org
No. It is a laboratory-made peptide, while the natural hormone is alpha-melanocyte-stimulating hormone, a longer peptide produced by the pituitary gland and by skin cells. Melanotan-2 mimics only a short active region of that hormone and contains non-natural residues such as D-phenylalanine.
No approved regulatory indication exists in major markets. An approval exists for a different peptide, afamelanotide, which is used for a rare photosensitivity disorder called erythropoietic protoporphyria. Melanotan-2 itself remains a research compound with no cleared clinical role.
Melanocortin-1 receptors on melanocytes are the receptor most closely linked to pigment production. The peptide is not selective, however, and also activates melanocortin-3, melanocortin-4, and melanocortin-5 receptors. That lack of selectivity is the usual explanation offered for both its range of observed effects and its off-target effects.
It is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, containing seven amino acids with a lactam ring and a D-configured phenylalanine residue. It is supplied as a lyophilised powder for laboratory research.