If you have been reading about MC1R 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.
Last reviewed on 2025-12-01. 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.
The peptide was developed during the 1980s by researchers investigating melanocortin signalling and skin pigmentation pathways. Early work focused on analogues of alpha-melanocyte-stimulating hormone that would resist enzymatic breakdown more effectively than the parent molecule. Melanotan-2 emerged from that programme as a shortened, cyclised variant. Reports describing its synthesis and receptor activity later appeared in the scientific literature. Commercial availability grew through unregulated channels rather than through pharmaceutical approval.
Structurally, Melanotan-2 retains the core recognition motif of alpha-melanocyte-stimulating hormone while adding a lactam bridge that links two side chains and constrains the molecule into a ring. This modification lowers susceptibility to enzymatic degradation. The compound acts as an agonist at melanocortin receptors, particularly subtypes associated with melanin production. Because the same receptor family influences several physiological processes, researchers note that its activity is not confined to pigmentation alone. Receptor selectivity continues to be examined in published studies.
| 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 |
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 peptide acts as a non-selective agonist at melanocortin receptors, showing affinity for MC1R, MC3R, MC4R and MC5R. Activation of MC1R on melanocytes drives the conversion of tyrosine into melanin and shifts production toward the darker eumelanin form. MC4R signalling in the central nervous system is linked to appetite and energy balance, which helps explain why reduced food intake appeared in early human studies. Effects on MC4R and on vascular tone also account for the erectile responses recorded as unexpected findings in those same trials.
Melanotan-2 is frequently confused with afamelanotide, a linear analogue authorised in the European Union for erythropoietic protoporphyria. The two compounds differ in chain length, ring structure and receptor selectivity, so findings for one cannot be transferred directly to the other. Published controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports. Questions about effect size, dose-response behaviour and long-term safety therefore remain unresolved.
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.
Receptor binding at MC1R on melanocytes raises intracellular cyclic AMP and increases expression of tyrosinase and related enzymes. The downstream result is greater synthesis of eumelanin, the dark pigment, without ultraviolet exposure acting as the trigger. The compound is not selective, however, and also engages MC3R, MC4R and MC5R, which are expressed in the central nervous system and elsewhere. That lack of selectivity is the explanation usually offered for effects reported outside pigmentation, including appetite suppression and nausea. Selectivity remains a central theme in comparative studies of related peptides.
Human data remain limited and mostly short-term. Reports describe small trials and observational accounts rather than large controlled studies, so questions about dose-response relationships and long-term effects on melanocytes stay open. Whether repeated exposure alters naevus behaviour is not settled in the published record. Researchers also note that self-administered use outside clinical settings makes actual exposure difficult to quantify. Statements about efficacy and safety should therefore be read as preliminary rather than established.
Accepted methods to detect and quantify the fluorescence wavelength shift include measuring the intensity at a single wavelength, computing a ratio of the intensity at two wavelengths (typically 330 nm and 350 nm), or calculating the barycentric mean (BCM) by measuring the center of mass of the fluorescence waveform. The latter BCM method takes advantage of the entire UV-fluorescence spectrum, thus allowing for flexibility when auto-fluorescent small molecules are present. Applications of nanoDSF include protein or antibody engineering, membrane protein research, quality control and formulation development, and ligand binding. NanoDSF has also been utilized to rapidly evaluate the melting points of enzyme libraries for biotechnological applications. Currently there are at least four instruments on the market that can measure fluorescence wavelength shifts in a high-throughput manner while heating the samples through a defined temperature ramp. These instruments employ either proprietary quartz capillaries, cartridges, or plates or generic high-throughput 384-well plastic plates for sample analysis.
== External links == FML – Functional Materials Laboratory of the ETH Zürich Properties and use of magnetic nanoparticle clusters (magnetic nanobeads) Magnetic nanoparticles target human cancer cells Magnetic Nanoparticles Remove Ovarian Cancer Cells from the Abdominal Cavity Wiedwald, U. and Ziemann, P. (Ed.): Properties and applications of magnetic nanoparticles, Thematic Series in the Open Access Beilstein Journal of Nanotechnology. Effects of surfactant on the structural and magnetic properties of hydrothermally synthesized NiFe2O4 nanoparticles
=== Names === It is often sold as a salt in the form of either codeine sulfate or codeine phosphate in the United States, United Kingdom, and Australia. Codeine hydrochloride is more common worldwide and the citrate, hydroiodide, hydrobromide, tartrate, and other salts are also seen. The chemical name for codeine is morphinan-6-ol, 7,8-didehydro-4,5-epoxy-3-methoxy-17-methyl-, (5α,6α)-
Endomorphins are natural, endogenous opioid neuropeptides that are considered to be central to pain relief. They were first described in 1997 by James Zadina, Abba Kastin and colleagues. The two known endomorphins, endomorphin-1 and endomorphin-2, are tetrapeptides, consisting of Tyr-Pro-Trp-Phe and Tyr-Pro-Phe-Phe amino acid sequences respectively. These sequences fold into tertiary structures with high specificity and affinity for the μ-opioid receptor, binding it exclusively and strongly. Bound μ-opioid receptors typically induce inhibitory effects on neuronal activity. Endomorphin-like immunoreactivity exists within the central and peripheral nervous systems, where endomorphin-1 appears to be concentrated in the brain and upper brainstem, and endomorphin-2 is located mainly in the spinal cord and lower brainstem. Because endomorphins activate the μ-opioid receptor, which is the target receptor of morphine and its derivatives, endomorphins possess significant potential as analgesics with reduced side effects and risk of addiction.
Sources: en.wikipedia.org
== Structure == At the center of every tooth is a hollow area that houses soft tissues, such as the nerve, blood vessels, and connective tissue. This hollow area contains a relatively wide space in the coronal portion of the tooth called the pulp chamber. These canals run through the center of the roots, similar to the way graphite runs through a pencil. The pulp receives nutrition through the blood vessels, and sensory nerves carry signals back to the brain. In the case of irreversible damage to the pulp, root canal treatment can relieve associated dental pain. Root canal anatomy consists of the pulp chamber and root canals. Both contain the dental pulp. The smaller branches, referred to as accessory canals, are most frequently found near the root end (apex), but may be encountered anywhere along the root length. The total number of root canals per tooth depends on the number of the tooth roots ranging from one to four, five or more in some cases. Sometimes there are more than one root canal per root. Some teeth have a more variable internal anatomy than others. An unusual root canal shape, complex branching (especially the existence of horizontal branches), and multiple root canals are considered as the main causes of root canal treatment failures. (For example, if a secondary root canal goes unnoticed by the dentist and is not cleaned and sealed, it will remain infected, causing the root canal therapy to fail.)
Acetyl-CoA (acetyl coenzyme A) is a molecule that participates in many biochemical reactions in protein, carbohydrate and lipid metabolism. Its main function is to deliver the acetyl group to the citric acid cycle (Krebs cycle) to be oxidized for energy production. Coenzyme A (CoASH or CoA) consists of a β-mercaptoethylamine group linked to pantothenic acid (vitamin B5) through an amide linkage and 3', 5'-phosphorylated ADP. The acetyl group (indicated in blue in the structural diagram on the right) of acetyl-CoA is linked to the sulfhydryl substituent of the β-mercaptoethylamine group. This thioester linkage is a "high energy" bond, which is particularly reactive. Hydrolysis of the thioester bond is exergonic (−31.5 kJ/mol). CoA is acetylated to acetyl-CoA by the breakdown of carbohydrates through glycolysis and by the breakdown of fatty acids through β-oxidation. Acetyl-CoA then enters the citric acid cycle, where the acetyl group is oxidized to carbon dioxide and water, and the energy released is captured in the form of 11 ATP and one GTP per acetyl group. Konrad Bloch and Feodor Lynen were awarded the 1964 Nobel Prize in Physiology or Medicine for their discoveries linking acetyl-CoA and fatty acid metabolism. Fritz Lipmann won the Nobel Prize in 1953 for his discovery of the cofactor coenzyme A.
He died in Adyar, Madras on the 17th of February, 1907. Margaret Woodrow Wilson, the daughter of the 28th U.S. President Woodrow Wilson, became a devotee and member of the ashram of Sri Aurobindo in Pondicherry for the remainder of her later life. Wilson changed her name to Nistha, meaning "dedication" in Sanskrit. In 1942, she collaborated with Joseph Campbell, as they undertook the editing of the English translation of The Gospel of Sri Ramakrishna, originally authored by Swami Nikhilananda, a classical work on the Hindu mystic Sri Ramakrishna. This edited version was subsequently published by the Ramakrishna-Vivekananda Center in New York. She died in Pondicherry on the 12th of February, 1944.
Blood accounts for 7% of the human body weight, with an average density around 1060 kg/m3, very close to pure water's density of 1000 kg/m3. The average adult has a blood volume of roughly 5 litres (11 US pt) or 1.3 gallons, which is composed of plasma and formed elements. The formed elements are the two types of blood cell or corpuscle – the red blood cells, (erythrocytes) and white blood cells (leukocytes) – and the cell fragments called platelets that are involved in clotting. By volume, the red blood cells constitute about 45% of whole blood, the plasma about 54.3%, and white cells about 0.7%.
Concanavalin A (ConA) is a lectin (carbohydrate-binding protein) originally extracted from the jack-bean (Canavalia ensiformis). It is a member of the legume lectin family. It binds specifically to certain structures found in various sugars, glycoproteins, and glycolipids, mainly internal and nonreducing terminal α-D-mannosyl and α-D-glucosyl groups. Its physiological function in plants, however, is still unknown. ConA is a plant mitogen, and is known for its ability to stimulate mouse T-cell subsets giving rise to four functionally distinct T cell populations, including precursors to regulatory T cells; a subset of human suppressor T-cells is also sensitive to ConA. ConA was the first lectin to be available on a commercial basis, and is widely used in biology and biochemistry to characterize glycoproteins and other sugar-containing entities on the surface of various cells. It is also used to purify glycosylated macromolecules in lectin affinity chromatography, as well as to study immune regulation by various immune cells.
Sources: en.wikipedia.org
=== Protein per calorie === Protein content in foods is often measured in protein per serving rather than protein per calorie. For instance, the USDA lists 6 grams of protein per large whole egg (a 50-gram serving) rather than 84 mg of protein per calorie (71 calories total). For comparison, there are 2.8 grams of protein in a serving of raw broccoli (100 grams) or 82 mg of protein per calorie (34 calories total), or the Daily Value of 47.67g of protein after eating 1,690g of raw broccoli a day at 574 cal. An egg contains 12.5g of protein per 100g, but 4 mg more protein per calorie, or the protein DV after 381g of egg, which is 545 cal. The ratio of essential amino acids (the quality of protein) is not taken into account, one would actually need to eat more than 3 kg of broccoli a day to have a healthy protein profile, and almost 6 kg to get enough calories. It is recommended that adult humans obtain between 10–35% of their 2000 calories a day as protein.
== Further reading == De Nevers (1970). Fluid Mechanics. Addison–Wesley. ISBN 0-201-01497-1. Shah, R. K.; London, A. L. (1978). "Laminar Flow Forced Convection in Ducts". Supplement 1 to Advances in Heat Transfer. New York: Academic. Rohsenhow, W. M.; Hartnett, J. P.; Ganić, E. N. (1985). Handbook of Heat Transfer Fundamentals (2nd ed.). McGraw–Hill Book Company. ISBN 0-07-053554-X. Glenn O. Brown (2002). "The History of the Darcy-Weisbach Equation for Pipe Flow Resistance". researchgate.net.
Traditional additive solutions are hypotonic, although experiments with next-generation additive solutions suggest that an alkali pH in combination with low chloride concentrations may be able to prolong the red blood cell viability. Leucocyte depletion of blood components, including red blood cell concentrates, is increasingly becoming standard practise; in many of the high-income countries of the world, 100% of the red blood cell supply is already being leucocyte depleted. Leucocyte depletion, usually by a leucocyte filter included in the blood bag system, is an efficient yet relatively cheap way of reducing the risk of transfusion reactions. Leucocyte depletion is most commonly performed as an integrated processing step, as bedside filtration is considered a less efficient method.
A clinical trial in which the participants are not assigned by chance to different treatment groups. Participants may choose which group they want to be in, or they may be assigned to the groups by the researchers. (NCI)
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.
It is a synthetic cyclic heptapeptide and an analogue of alpha-melanocyte-stimulating hormone. The molecule is produced by chemical synthesis rather than extracted from a biological source.