This is a working overview of Heptapeptide, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-11-05. Anything still debated is marked as such rather than presented as settled.
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.
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.
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.
| 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 |
Regulatory treatment varies between countries. Several national medicines agencies have classified the peptide as unapproved, and customs authorities in some jurisdictions seize shipments on that basis. A few jurisdictions channel supply through prescription-only frameworks that do not list the substance by name. Because the material circulates mainly through online vendors, composition and purity are rarely verified before sale. Surveys of unapproved peptide products have reported labels that did not match measured content in a substantial fraction of samples.
Melanotan II is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its structure substitutes a lactam bridge between side chains to increase stability relative to the native hormone. The compound is also known by the shorthand MT-II and by several non-proprietary synonyms used in research catalogues. It is not an approved therapeutic product in any major jurisdiction; material sold under this name is typically offered as a laboratory reagent rather than as a medicine.
Solid peptide kept dry at minus twenty degrees Celsius, shielded from light and moisture, is generally considered stable for extended periods. Solutions are divided into single-use aliquots and held at minus twenty or minus eighty degrees Celsius, because repeated freeze-thaw cycles promote aggregation and loss of material to container surfaces. Hydrolysis of the backbone and oxidation of tryptophan are the principal degradation routes in aqueous solution, and both accelerate at ambient temperature. Hygroscopic uptake after a vial is opened can also shift the actual mass weighed, which affects any concentration calculated from it.
Routine characterisation relies on reversed-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres, using a C18 column and a water-acetonitrile gradient containing trifluoroacetic acid. Electrospray ionisation mass spectrometry confirms the expected molecular mass and can reveal truncated or oxidised by-products that co-elute poorly. Sequence and stereochemistry require additional work, such as peptide mapping or amino acid analysis, because a chromatographic purity figure alone does not distinguish a diastereomer from the target peptide. Independent testing of research-grade material frequently shows measured content below the stated label, so a certificate of analysis is best read together with the method that produced it.
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.
Amphetamine is a methyl homolog of the mammalian neurotransmitter phenethylamine with the chemical formula C9H13N. The carbon atom adjacent to the primary amine is a stereogenic center, and amphetamine is composed of a racemic 1:1 mixture of two enantiomers. This racemic mixture can be separated into its optical isomers: levoamphetamine and dextroamphetamine. At room temperature, the pure free base of amphetamine is a mobile, colorless, and volatile liquid with a characteristically strong amine odor, and acrid, burning taste. Frequently prepared solid salts of amphetamine include amphetamine adipate, aspartate, hydrochloride, phosphate, saccharate, sulfate, and tannate. Dextroamphetamine sulfate is the most common enantiopure salt. Amphetamine is also the parent compound of its own structural class, which includes a number of psychoactive derivatives. In organic chemistry, amphetamine is an excellent chiral ligand for the stereoselective synthesis of 1,1'-bi-2-naphthol.
non-small cell lung cancers (30–46%) head and neck squamous cell carcinomas (30–50%) pancreatic carcinomas (25%) bladder cancer (15%) pituitary adenomas (49–54%) breast carcinoma (13%) Cyclin D1 overexpression is strongly correlated to ER+ breast cancer and deregulation of cyclin D1 is associated with hormone therapy resistance in breast cancer. Overexpression of Cyclin D1b, an isoform, is also present in breast and prostate cancers. Chromosomal translocation around the cyclin D1 gene locus is often seen in B mantle cell lymphoma. In mantle cell lymphoma, cyclin D1 is translocated to the IgH promoter leading to cyclin D1 overexpression. Chromosomal translocation of the cyclin D1 gene locus is also observed in 15–20% of multiple myelomas.
=== Mechanism of action === Levomethadone (the R-(–)-methadone enantiomer) is a μ-opioid receptor agonist with higher intrinsic activity than morphine, but lower affinity. Dextromethadone (the S-(+)-methadone enantiomer) has a much lower affinity to the μ-opioid receptor than levomethadone. Both enantiomers bind to the glutamatergic NMDA (N-methyl-D-aspartate) receptor, acting as noncompetitive antagonists. Methadone has been shown to reduce neuropathic pain in rat models, primarily through NMDA receptor antagonism. NMDA antagonists such as dextromethorphan, ketamine, tiletamine and ibogaine are being studied for their role in decreasing the development of tolerance to opioids and as possible for eliminating addiction/tolerance/withdrawal, possibly by disrupting memory circuitry. Acting as an NMDA antagonist may be one mechanism by which methadone decreases craving for opioids and tolerance, and has been proposed as a possible mechanism for its distinguished efficacy regarding the treatment of neuropathic pain. Methadone also acted as a potent, noncompetitive α3β4 neuronal nicotinic acetylcholine receptor antagonist in rat receptors, expressed in human embryonic kidney cell lines.
Early space food was primarily composed of bite-sized cubes, freeze-dried powders, and thick liquids stuffed in aluminum tubes. First used on the 3rd Mercury mission in 1962, US astronaut John Glenn was the first to eat directly from an aluminum tube, specifically applesauce. However the tubes were eventually discontinued as their design did not allow the food to be smelled or seen, and the texture also posed limitations on the variety of food that could be made available. Freeze-dried powders that could be re-hydrated were also available, as well as high-calorie bite sized cubes of food. These solutions had their own challenges, however over time, the powders were made easier to re-freeze, and the cubes were coated in gelatin to prevent crumbling on the equipment. With the introduction of the "spoon bowl," on the Apollo 8 mission, astronauts were able to open the contents of the package and eat the simple meal with a spoon. For lunch on Vostok 1 (1961), Yuri Gagarin ate from three 160 g (5.6 oz) toothpaste-type tubes, two of which contained servings of puréed meat and one which contained chocolate sauce. In August 1961, Soviet Cosmonaut Gherman Titov became the first human to experience space sickness on Vostok 2; he holds the record for being the first person to vomit in space. This event "heralded the need for space flight nutrition." John Glenn, as the first American to orbit Earth in 1962, was to experiment with eating in weightless conditions. Some experts had been concerned that weightlessness would impair swallowing.
Sources: en.wikipedia.org
This engagement is widely regarded in South Africa as the start of the Border War, and according to SWAPO, officially marked the beginning of its revolutionary armed struggle. Operation Blouwildebees triggered accusations of treachery within SWALA's senior ranks. According to SADF accounts, an unidentified informant had accompanied the security forces during the attack. Sam Nujoma asserted that one of the eight guerrillas from the second group who were captured in Kavangoland was a South African mole. Suspicion immediately fell on Leonard "Castro" Shuuya. SWALA suffered a second major reversal on 18 May 1967, when Tobias Hainyeko, its commander, was killed by the South African police. Heinyeko and his men had been attempting to cross the Zambezi River, as part of a general survey aimed at opening new lines of communication between the front lines in South West Africa and SWAPO's political leadership in Tanzania. They were intercepted by a South African patrol, and the ensuing firefight left Heinyeko dead and two policemen seriously wounded. Rumours again abounded that Shuuya was responsible, resulting in his dismissal and subsequent imprisonment. In the weeks following the raid on Omugulugwombashe, South Africa detained thirty-seven SWAPO politicians, namely Andimba Toivo ya Toivo, Johnny Otto, Nathaniel Maxuilili, and Jason Mutumbulua. Together with the captured SWALA guerrillas, they were jailed in Pretoria and held there until July 1967. All were charged retroactively under the Terrorism Act.
Mary Wortley Montagu, who had witnessed variolation in Turkey, had her four-year-old daughter variolated in the presence of physicians of the Royal Court in 1721 upon her return to England. Later on that year, Charles Maitland conducted an experimental variolation of six prisoners in Newgate Prison in London. The experiment was a success, and soon variolation was drawing attention from the royal family, who helped promote the procedure. However, in 1783, several days after Prince Octavius of Great Britain was inoculated, he died. In 1796, the physician Edward Jenner took pus from the hand of a milkmaid with cowpox, scratched it into the arm of an 8-year-old boy, James Phipps, and six weeks later variolated the boy with smallpox, afterwards observing that he did not catch smallpox. Jenner extended his studies and, in 1798, reported that his vaccine was safe in children and adults, and could be transferred from arm-to-arm, which reduced reliance on uncertain supplies from infected cows. In 1804, the Spanish Balmis smallpox vaccination expedition to Spain's colonies Mexico and Philippines used the arm-to-arm transport method to get around the fact the vaccine survived for only 12 days in vitro. They used cowpox. Since vaccination with cowpox was much safer than smallpox inoculation, the latter, though still widely practiced in England, was banned in 1840.
=== Outside mainland China === PRC Customs said exports of dairy products and eggs in 2007 were valued at US$359 million, a year-on-year increase of 90 per cent. Since the news of the melamine contamination began to circulate, at least 25 countries stopped importing Chinese dairy products. A number of countries had imposed blanket bans on Chinese milk products or its derivatives—among which were Bangladesh, Bhutan, Brunei, Burundi, Cameroon, Chile, Colombia, Dominican Republic, Gabon, India, Côte d'Ivoire, Maldives, Mali, Mexico, Nepal, Papua New Guinea, Paraguay, South Korea, Suriname, Tanzania, Togo, and the United Arab Emirates —joining Indonesia, Taiwan, Japan, Singapore and Malaysia which had also imposed specific bans on Chinese dairy products which tested positive for melamine.
At the time, only Mike Piazza (35), David Justice (28), and Darryl Strawberry (26) had hit more home runs as an NL rookie since 1972, and only Piazza had more RBI (112). Helton finished second to Kerry Wood of the Chicago Cubs in the voting for NL Rookie of the Year. The Tennessee Sports Hall of Fame named Helton its 1998 Professional Athlete of the Year. In 1999, Helton put up a slash line of .320/.395/.587. He slugged 35 home runs and drove in 113 RBI, while also drawing 68 walks. On June 19, in a 10–2 home win over the Florida Marlins, Helton hit for the cycle. He fell one hit shy of hitting for a second cycle on four occasions during the 1999 season. Had he managed to repeat the performance that season, he would have become only the second player since 1900 to pull it off, the other being Babe Herman in 1931.
An insurgent was killed and eight captured in a military operation in the Greda Shah Jahan village of Bannu District, while three more alleged militants were captured from Saidu Sharif by police. Two children were injured in an insurgent mortar attack Dabar Malano Jalwaana area of Wara Mamund tehsil. On 20 July, four militants were killed in a military operation in Lakrai area of Mohmand District while six were killed in raids throughout Bannu District, six IEDs were also neutralized in Bannu District. Three Excise Department personnel were abducted from a checkpoint on the Dalbandin–Taftan Highway in Chagai District. On 21 July, a peace committee member was assassinated by an IED attack in Karrapa area of Hangu District while TTP claimed to have killed two in the Muhammad Khel area of Boya Tehsil. The Wadigram area in Salarzai Tehsil was hit by two mortar shells while insurgents blew up a Government school in Mamund Tehsil. On 22 July, a TTP insurgent was captured from the Syed Ali Mela Khor area of Kurram District while three were captured from Khyber District, three more were killed in a military operation in Chapri Naryab Chowk area of Hangu District. On 23 July, insurgents ambushed and killed a Police Constable near Moula Khan Sarai in the Sarwekai area of South Waziristan District. Four TTP militants were killed and five captured in a military operation in Talgai mountains of Wazir Tehsil, while two militant hideouts were destroyed in the Sipah Tandi Kalay area of Bara.
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.
The lyophilised solid is best kept cold, dry and dark, typically at minus twenty degrees Celsius. Moisture and repeated warming cycles are the main causes of degradation. Solutions prepared from the powder are less stable and are normally used quickly.