reference standard 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.
Updated 2025-10-04. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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 material is commonly handled as a lyophilized powder in sealed vials. The solid dissolves readily in water and in polar organic solvents, producing a clear solution after reconstitution. Light, heat and repeated freeze-thaw cycles are the concerns most often raised in handling guidance, because peptide bonds and the constrained ring can degrade. Working solutions are generally prepared fresh, and material left in solution is treated as less stable than the dry form. These properties shape how laboratories store and aliquot reference material.
Identity and purity are assessed mainly by reversed-phase high-performance liquid chromatography with ultraviolet detection, often paired with mass spectrometry. Retention time supports identity, while the mass spectrum confirms the molecular weight of the intact peptide. Purity is frequently reported as a percentage of total peak area, a figure that depends on the wavelength, column and gradient used. Impurity profiling may also look for truncated sequences, oxidised forms and residual counterions. Amino acid analysis and peptide mapping provide orthogonal confirmation when required.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Belongs to the melanocortin agonist family |
| Key substitutions | Nle4 and D-Phe7 | Improve resistance to enzymatic degradation |
| Molecular formula | C50H69N15O9 | Approximately 1024 g/mol |
| Regulatory status | Not approved as a medicine | Distributed as a research chemical |
| Common synonyms | Melanotan II, MT-II, MT-2 | Spelling varies across sources |
Melanotan II is a synthetic cyclic heptapeptide analog derived from the core sequence of alpha-melanocyte-stimulating hormone. Researchers at the University of Arizona synthesized it during the 1980s while studying pigmentation and appetite signaling. The compound is not an approved medicine in any major jurisdiction and appears mainly in laboratory and research-chemical settings. Its structure incorporates a lactam bridge between side chains, which constrains the ring and slows enzymatic breakdown relative to the natural hormone.
Melanotan II binds several melanocortin receptor subtypes rather than a single target. MC1R on melanocytes drives melanin synthesis, while MC3R and MC4R participate in energy balance, appetite, and sexual response pathways. This lack of selectivity explains why reported effects extend beyond skin darkening. Substitutions at positions four and seven, including norleucine and D-phenylalanine, increase potency and resistance to peptidases. Understanding which receptor mediates which effect remains an active area of investigation.
Published human data come mostly from small, short studies rather than large controlled trials. Reported outcomes include increased skin pigmentation and, in some reports, effects on appetite and libido, but sample sizes are small and follow-up is limited. Whether long-term use produces durable pigment changes or adverse effects is not established. Because products sold outside pharmacies are not standardized, the actual content of any given vial is often unknown. Independent testing of such material is uncommon.
Melanotan II holds no marketing authorisation from the Food and Drug Administration, the European Medicines Agency, the UK Medicines and Healthcare products Regulatory Agency or Australia's Therapeutic Goods Administration. Products sold under that name are treated as unapproved new drugs, and their sale or import is prohibited in several jurisdictions. Other countries classify the peptide as a prescription-only medicine or place it among controlled substances, so the legal position changes with the destination market. No pharmacopoeial monograph supplies an official specification, because the material is not a licensed pharmaceutical. Consequently, products offered online are not manufactured to a shared public standard.
The peer-reviewed record is dominated by small early-phase studies, case reports and pharmacovigilance summaries rather than large randomised trials. Papers typically examine tanning response, receptor selectivity or patterns of reported adverse events. Many note that participants obtained the peptide outside a clinical setting, which limits verification of composition and administered amount. Reported events vary widely, and causality is frequently unclear because the identity and purity of self-sourced material are unknown. Open questions include whether repeated melanocortin receptor stimulation produces cumulative effects, and how often label claims match actual content.
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.
Freeze-dried melanotan-2 is normally kept as a desiccated powder at minus twenty degrees Celsius or lower, shielded from light and moisture. Peptides of this size degrade through hydrolysis, oxidation and deamidation, and each pathway accelerates as temperature and water activity rise. Repeated freeze-thaw cycles promote aggregation and loss of material, so aliquoting a stock solution before freezing is standard laboratory practice. Once dissolved, the solution is markedly less stable than the powder. In laboratory work, solutions are generally refrigerated and used within days rather than kept for months.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, which separates the target peptide from truncated or oxidised impurities. Mass spectrometry, most often coupled to liquid chromatography, confirms molecular mass and detects substitutions that chromatography alone may miss. Amino acid analysis and peptide mapping supply additional structural evidence, while nuclear magnetic resonance is reserved for full structural confirmation. Laboratories that examine samples sold online report wide variation in actual content, with some vials containing little or none of the labelled material.
Melanotan-2 appears on the World Anti-Doping Agency prohibited list within the peptide hormone class, and several national regulators treat it as an unapproved prescription substance. Some countries restrict importation or sale for personal use. Because the compound is widely traded as a research chemical, the practical legal picture differs between jurisdictions and shifts over time. Human safety data covering long periods are limited, and whether repeated pigmentation changes carry any lasting risk to melanocytes remains an open question.
== Commercial production == Large-scale commercial cherry juice production is typically produced using a hot extraction or a cold extraction method. Hot extraction involves heating the cherries, pressing them, and then straining and filtering to remove solids. Hot pressed cherry juice typically has a deeper coloration compared to that produced using cold extraction. The heating of the fruit also serves to prevent the juice from browning, because the heating stops natural enzymic actions that occur when the fruit is macerated. Cold extraction involves first removing the pits from fresh cherries and then pressing them and collecting the juice. The juice is then heated to kill microorganisms, stop enzyme activity and to solidify particulate matter prior to filtering. As with hot-extracted juice, the cold-extracted juice is also typically strained and filtered. Cold-extracted cherry juice has a greater likeness to the flavor of fresh cherries, and its coloration is lighter compared to that of hot-extracted juice. Frozen cherries are sometimes used, which enables the creation of a juice that has the cherry-like flavor of cold-extracted juice and a deeper coloration such as that produced by hot extraction. Ascorbic acid is sometimes added as a color stabilizer prior to the cherries being pressed. The juice is typically filtered and clarified prior to being packaged, and pasteurization or flash pasteurization is typically utilized. It is sometimes processed as a frozen concentrate.
==== Byzantine writers ==== Physician Oribasius (c. 320–403), personal physician of the emperor and philosopher Julian, compiled all known ancient medical texts of his time by theme into medical encyclopedia. He quotes Galen and Rufus on diabetes, considering it to be a polyuric disease of the kidneys. Various descriptive names are given for the condition, including: chamber-pot dropsy, diarrhea of the urine (diarrhea urinosa), and the thirsty disease. These descriptions, along with a number of other names for the condition ("liuria", "extreme thirst or dipsacus"), were echoed by later Byzantine writers in key encyclopedic texts.
Family 15 contains the plant MTs, which in 2002 have been further classified by Cobbet and Goldsbrough into 4 Types (1, 2, 3 and 4) depending on the distribution of their Cys residues and a Cys-devoid regions (called spacers) characteristic of plant MTs. A table including the principal aspects of the two latter classifications is included.
Sources: en.wikipedia.org
=== Cancer === HSP expression plays a pivotal role in cancer identification. Recent discoveries have shown that high concentrations of eHSP can indicate the presence of contentious tumors. Additionally, HSPs have been shown to benefit oncologists in oral cancer diagnosis. Using techniques such as dot immunoassay and ELISA test researchers have been able to determine that HSP-specific phage antibodies could be beneficial in-vitro cancer diagnosis markers. HSPs have also been shown to interact with cancer adaptations such as drug resistance, tumor cell production and lifespan, and the up-regulation and down-regulation of oncomirs.
Food and beverage products containing cannabidiol were widely marketed in the United States as early as 2017. Hemp seed ingredients which do not naturally contain THC or CBD (but which may be contaminated with trace amounts on the outside during harvesting) were declared by the US Food and Drug Administration as generally recognized as safe (GRAS) in December 2018. CBD itself has not been declared GRAS, and under US federal law is illegal to sell as a food, dietary supplement, or animal feed. State laws vary considerably as non-medical cannabis and derived products have been legalized in various jurisdictions. Despite once having a promising market, the industry for CBD stalled out during the COVID-19 pandemic beginning in 2020, and, by 2024, it collapsed due to withdrawal of investors, the absence of a FDA ruling on efficacy and safety, inconsistent state-by-state legislation, and consumer ambivalence. Similar to energy drinks and protein bars which may contain vitamin or herbal additives, food and beverage items can be infused with CBD as an alternative means of ingesting the substance. In the United States, numerous products are marketed as containing CBD, but in reality contain little or none. Some companies marketing CBD-infused food products with claims that are similar to the effects of prescription drugs have received warning letters from the FDA for making unsubstantiated health claims. In February 2019, the New York City Department of Health announced plans to fine restaurants that sell food or drinks containing CBD, beginning in October 2019.
In 1947, Howard Hughes redirected the Hughes Aircraft Company's efforts from airplanes to helicopters. The effort began in earnest in 1948, when helicopter manufacturer Kellett Autogiro Corporation sold their latest design to Hughes for production. The XH-17 "Sky Crane" first flew in October 1952, but was commercially unsuccessful. In 1955 the company began building light helicopters when Howard Hughes split the helicopter production unit from the Hughes Aircraft Co., and reconstituted it with the Hughes Tool Co. as the Hughes Tool Co. Aircraft Division, with a focus on the production of light helicopters. The Hughes Model 269 was the company's first successful helicopter design. Built in 1956, and entering production in 1957, it served to capture a large portion of the commercial market for Hughes. It would eventually become part of the Army inventory as a primary trainer (TH-55 Osage). In May 1965, the company won the contract for a new observation helicopter for the U.S. Army, and produced the OH-6 Cayuse (Hughes Model 369). The OH-6 was later developed into the civilian Model 500, variants of which remain in production to this day.
Sources: en.wikipedia.org
It is a synthetic cyclic peptide designed as an analog of alpha-melanocyte-stimulating hormone. It acts on melanocortin receptors and is best known from research into pigmentation. It is not an approved pharmaceutical product.
No regulatory agency has approved it for any indication. It is encountered as a research chemical sold outside pharmaceutical supply chains. Products marketed this way are not subject to the manufacturing and labeling requirements that apply to approved drugs.
Reports describe increased skin pigmentation as well as side effects such as nausea, flushing, and changes to existing moles. Much of the evidence comes from small studies and case reports rather than large trials. The long-term safety profile is therefore uncertain.
The dry powder is more stable during transport and storage than a solution. It also allows a known amount of material to be reconstituted at a chosen concentration.