Everything below concerns cyclic heptapeptide. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-03-16. Where a claim depends on a specific study, the study is described rather than over-claimed.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence incorporates a lactam bridge that constrains the peptide into a ring, which increases resistance to enzymatic breakdown relative to the natural hormone. Researchers at the University of Arizona synthesised the compound in the late 1980s and early 1990s while studying pigmentation pathways. It has never received marketing approval from any national medicines regulator. In the scientific literature it is usually described as a laboratory research reagent rather than a therapeutic product.
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controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports.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.
Reversed-phase high-performance liquid chromatography is the routine method for purity assessment. Peptides absorb near 214 nm because of the peptide bond, and a gradient of acetonitrile in water separates the intact peptide from deletion sequences, oxidised products, and earlier-eluting fragments at neutral pH. Electrospray ionisation mass spectrometry provides an orthogonal check: the measured mass must agree with the theoretical value. Amino acid analysis and peptide mapping confirm structure but are used less often. Reference standards remain scarce because the peptide is not described in any pharmacopoeia.
Regulatory treatment varies by country. In the United States the peptide is not approved as a medicine, and products offered for human use may be treated as unapproved new drugs; some states also restrict sale. Australia, the United Kingdom, and European Union member states apply comparable restrictions to unapproved peptide products. Border agencies have seized shipments labelled as research chemicals. Classification may change over time, and the legal position for personal importation is not clearly settled in most published guidance.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Alpha-MSH analogue with a lactam ring |
| Molecular formula | C50H69N15O9 | Commonly cited value for the neutral peptide |
| Molecular weight | 1024.18 g/mol | Calculated for the free molecule |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water, DMSO and ethanol | Dissolution in pure water is often slow |
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.
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.
Verification of a purchased sample requires documentation linking a batch to a certificate of analysis, and that document should be read for the methods used rather than the headline purity figure. A single chromatographic percentage does not establish identity. Independent laboratories can perform identity and content assays, but no such test establishes that a product is suitable for human use. Claims about efficacy rest largely on small, early studies rather than on replicated controlled trials, and that gap remains open.
Identity testing for a cyclic peptide of this size usually relies on reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The mass spectrum confirms molecular weight, while the chromatographic trace indicates the proportion of related impurities. Tandem mass spectrometry can provide sequence-level information when fragmentation data are compared against a reference standard. Nuclear magnetic resonance is sometimes used to confirm the lactam bridge, although it requires more material and greater operator expertise than routine chromatographic methods.
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.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its sequence incorporates modified residues that increase potency and extend biological activity relative to the native hormone. The compound binds receptors of the melanocortin family and is examined mainly in laboratory research. It does not occur naturally and exists only as a manufactured chemical entity produced by solid-phase synthesis.
In dental anatomy, the apical foramen, literally translated "small opening of the apex," is the tooth's natural opening, found at the root's very tip—that is, the root apex — whereby an artery, vein, and nerve enter the tooth and commingle with the tooth's internal soft tissue, called pulp. Additionally, the apical foramen is the point where the pulp meets the periodontal tissues, the connective tissues that surround and support the tooth. The foramen is located 0.5mm to 1.5mm from the apex of the tooth. Each tooth has an apical foramen.
=== Stimulation and rising phase === A typical action potential begins at the axon hillock with a sufficiently strong depolarization, e.g., a stimulus that increases Vm. This depolarization is often caused by the injection of extra sodium cations into the cell; these cations can come from a wide variety of sources, such as chemical synapses, sensory neurons or pacemaker potentials. For a neuron at rest, there is a high concentration of sodium and chloride ions in the extracellular fluid compared to the intracellular fluid, while there is a high concentration of potassium ions in the intracellular fluid compared to the extracellular fluid. The difference in concentrations, which causes ions to move from a high to a low concentration, and electrostatic effects (attraction of opposite charges) are responsible for the movement of ions in and out of the neuron. The inside of a neuron has a negative charge, relative to the cell exterior, from the movement of K+ out of the cell. The neuron membrane is more permeable to K+ than to other ions, allowing this ion to selectively move out of the cell, down its concentration gradient. This concentration gradient along with potassium leak channels present on the membrane of the neuron causes an efflux of potassium ions making the resting potential close to EK ≈ −75 mV. Since Na+ ions are in higher concentrations outside of the cell, the concentration and voltage differences both drive them into the cell when Na+ channels open.
In 2014, the Party General Office and State Council issued guidance on strengthening ideological education in colleges and universities. During Xi Jinping's tenure, numerous colleges and universities have established schools of Marxism. Xi has implemented a number of education reforms. Schools are required to adjust their opening hours to be consistent with work hours in their area so that parents can pick-up their children directly after work (in order to reduce reliance on private classes for adult supervision after school hours). Schools must also promote health by requiring outdoor physical education classes daily and providing eye examinations twice per term. Educational reforms have also limited the amount of homework students can be assigned. In 2021, Xi enacted the Double Reduction Policy (reducing excessive off-campus tutoring and reducing homework burdens), mandating schools may not assign homework to children to grades one and two, homework is limited to no more than 60 minutes for children in grades three to six, and no more than 90 minutes for middle school children. In July 2021, China enacted a series of rules designed to shutdown the private tutoring sector as part of its common prosperity program. Rules issued in July 2021 prohibits new registration of private tuition tutoring centers and required existing centers to re-organize as non-profits. Tuition centers are prohibited from being listed on the stock market or receiving "excessive capital." They are no longer permitted to offer tutoring on the weekends or during public holidays.
==== STS-118 ==== Caldwell Dyson was assigned to STS-118 on May 17, 2006. It was announced that she would serve as mission specialist 1 on the first flight of Space Shuttle Endeavour after the Columbia disaster. On August 8, 2007, Caldwell Dyson lifted off for the first time on the 119th Space Shuttle flight, the 22nd flight to the station, and the 20th flight for Endeavour. During the mission, she successfully added another truss segment, a new gyroscope and external spare parts platform to the International Space Station. A new system that enables docked shuttles to draw electrical power from the station to extend visits to the outpost was activated successfully. A total of four spacewalks (EVAs) were performed by three crew members. Endeavour carried some 5,000 pounds of equipment and supplies to the station and returned to Earth with some 4,000 pounds of hardware and no-longer-needed equipment. Traveling 5.3 million miles in space, the STS-118 mission was completed in 12 days, 17 hours, 55 minutes and 34 seconds. On day 7 of the flight of STS-118, Caldwell-Dyson celebrated her 38th birthday.
Sources: en.wikipedia.org
BMR (Males) in Kcals/day = 88.36 + 13.40 (weight in kg) + 4.8 (height in cm) – 5.68 (age in years) BMR (Females) in Kcals/day = 447.59 + 9.25 (weight in kg) + 3.10 (height in cm) – 4.33 (age in years) The Mifflin St. Jeor Equation is as follows:
High-performance liquid chromatography or high-pressure liquid chromatography is a form of chromatography applying high pressure to drive the solutes through the column faster. This means that the diffusion is limited and the resolution is improved. The most common form is "reversed phase" HPLC, where the column material is hydrophobic. The proteins are eluted by a gradient of increasing amounts of an organic solvent, such as acetonitrile. The proteins elute according to their hydrophobicity. After purification by HPLC the protein is in a solution that only contains volatile compounds, and can easily be lyophilized. HPLC purification frequently results in denaturation of the purified proteins and is thus not applicable to proteins that do not spontaneously refold.
During World War II and the Cold War, the Hanford Site produced plutonium for U.S. nuclear weapons for more than 50 years. The plutonium for the first plutonium bomb, Fat Man, also came from there. Hanford is considered the most radioactively contaminated site in the Western Hemisphere. A total of 110,000 tons of nuclear fuel was produced there. In 1948, a radioactive cloud leaked from the plant. The amount of 131I alone was 5500 curies. Most of the reactors at Hanford were shut down in the 1960s, but no disposal or decontamination was done. After preliminary work, the world's largest decontamination operation began at Hanford in 2001 to safely dispose of the radioactive and toxic waste. In 2006, some 11,000 workers were still cleaning up contaminated buildings and soil to reduce radiation levels at the site to acceptable levels. This work is expected to continue until 2052. It is estimated that more than four million liters of radioactive liquid have leaked from storage tanks. It was only after the two superpowers agreed on a Partial Test Ban Treaty in 1963, which allowed only underground nuclear weapons testing, that the level of radioactivity in food began to decline. Shields Warren (1896-1980), one of the authors of a report on the effects of the atomic bombs dropped on Japan, was criticized for downplaying the effects of residual radiation in Hiroshima and Nagasaki, but later warned of the dangers of fallout. Fallout refers to the spread of radioactivity in the context of a given meteorological situation. A model experiment was conducted in 2008.
=== Inhibition of ACTH production === Corticotropes contain glucocorticoid receptors (GRs) and corticosteroid-binding globulin (CBG, or transcortin). GR is a nuclear receptor that inhibits transcription of ACTH via a negative glucocorticoid recognition element (GRE) that binds cortisol on POMC DNA, but generally transcortin binds glucocorticoids (including cortisol, cortisone, deoxycortisone, and aldosterone) with high affinity and prevents this inhibition. Tonic inhibition of corticotropes requires high concentrations of glucocorticoids, exceeding CBG capacity. This causes ACTH secretion to be vulnerable to inhibition in patients taking glucocorticoids for medical purposes such as treatment of autoimmune disease or as an anti-transplant-rejection medication.
== Overview == Dating analyses in 2016 determined that Denny (Denisova 11) died about 90,000 years ago, and the bone's cortical thickness indicates an age at death of at least 13 years. An analysis of the whole genome sequence (total mitochondrial and nuclear DNA) indicates she was female, with a Neanderthal mother and a Denisovan father. While previous analyses of other ancient genomes concluded that Denisovans, Neanderthals, and modern humans interbred during the ice age in Europe and Asia, this find is the most direct evidence yet that various ancient hominins mated with each other and had offspring. Previous analyses from other fossils found in this Siberian cave have shown that modern humans, Neanderthals, and Denisovans inhabited this site at various times, and that all three human species interbred with each other. The genes of both archaic human species are present in many people today, which suggests that when these groups met, gene flow occurred. It is not evident if the mating was consensual or if Denny was fertile. The discovery of Denisova 11 may support the notion that Neanderthals and Denisovans may not have undergone direct extinction but were partly assimilated into modern human populations.
Sources: en.wikipedia.org
=== Senior team === Townsend's first call-up to the senior England squad came in September 2013, for the World Cup qualifiers against Moldova and Ukraine. He made his senior debut against Montenegro in a World Cup qualifier on 11 October, during which he scored the third goal of a 4–1 win with a "low swerving finish" from outside the penalty area after 78 minutes, two minutes before being substituted, and was named man of the match. He earned a second cap four days later against Poland, playing almost all of the 2–0 home win. A second England goal came in the Euro 2016 qualification campaign in a 5–0 win over San Marino on 9 October 2014, as he came on for the final third of the match. His next appearance marked his third England goal; on 31 March 2015 he scored the equaliser in the 79th minute against Italy, having come on seven minutes earlier in a friendly match which ended 1–1. The 20-yard strike was described as a "sweet right-foot drive into the bottom corner"; Townsend took to Twitter immediately after the match to respond to Paul Merson after he had said Townsend's club form did not justify him being in the England team.
These traits include being born and living within the territorial borders of Israel or Judah, speaking Hebrew, living in specific house types, using locally produced pottery, and following particular burial practices. Israelites were also part of a rural kin-based society, and adhered to Yahwism, though not necessarily in a monotheistic way. Their material culture was simple but distinct, and their societal organization was centered around family and inheritance. These traits, while shared with some neighbouring peoples, were uniquely Israelite in their specific combination.
Tris(hydroxymethyl)aminomethane (buffer) Sodium chloride (salt) Sucrose (sugar) Magnesium chloride hexahydrate Disodium EDTA dihydrate (a chelation ligand; sequestrant) Polysorbate 80 Ethanol 95% Water No adjuvants and no other components or ingredients should be included in the vaccine.
The first death row prisoner to be hanged in Singapore during the COVID-19 pandemic was 68-year-old Singaporean drug offender Abdul Kahar Othman on 30 March 2022, who had not appealed against his sentence and later executed as scheduled, therefore resuming executions in Singapore. By the time Abdul Kahar was executed, there were 62 prisoners on death row, awaiting execution (reduced to 61 with Nagaenthran's execution). Nagaenthran K. Dharmalingam was the second to be hanged on 27 April 2022 after Abdul Kahar. Datchinamurthy Kataiah was originally the third in line to be executed on 29 April 2022 after Nagaenthran before his execution was postponed due to an appeal. On 7 July 2022, Kalwant Singh Jogindar Singh and Norasharee Gous became the third and fourth convicts to be hanged in Singapore in 2022. In the same month, Nazeri Lajim was executed 15 days after Kalwant and Norasharee. Three more hangings - one on 26 July and two (Malaysian Rahmat Karimon and his accomplice Zainal Hamad) on 2 August - were conducted after Nazeri's execution. On 5 August 2022, 45-year-old Singaporean Abdul Rahim Shapiee and his 49-year-old accomplice Ong Seow Ping were the ninth and tenth to be executed. A 55-year-old Singaporean, whose name is unknown, was the eleventh to be executed for a drug charge on 7 October 2022. In total, eleven executions, all for drug trafficking, took place in the year 2022. In 2023, the first execution was carried out on 26 April 2023, when a 46-year-old Singaporean Tangaraju Suppiah, who was convicted in 2018 of marijuana trafficking, was hanged at dawn.
== Risks == Easy access to sophisticated labs can be a potential biosecurity or bioterrorism threat. Filippa Lentzos, an expert in biological risk and biosecurity, said "there are some pretty crazy people out there ... Barriers are coming down if you want to deliberately do something harmful". Cloud labs say that they review all scheduled experiments and can flag or reject any that appear illegal or dangerous, and that detailed record-keeping makes monitoring what is done easier than in a traditional laboratory.
Sources: en.wikipedia.org
It is a synthetic cyclic heptapeptide modelled on alpha-melanocyte-stimulating hormone. A lactam bridge links two side chains, forming a ring that stabilises the molecule against proteolysis. It belongs to the broader melanocortin peptide family.
No national medicines agency has approved melanotan-2 for clinical use. Afamelanotide, a related but distinct peptide, holds a marketing authorisation in the European Union for a rare photosensitivity disorder. Melanotan-2 itself is handled as a laboratory chemical.
Its broad activity across melanocortin receptors makes it a tool for probing pigmentation, appetite and vascular signalling. Early trials recorded skin darkening and other effects that were not the original focus of the work. Those observations generated hypotheses that later studies have examined.
Low temperature slows hydrolysis and oxidation, the two main routes by which the peptide backbone and side chains are modified. A lyophilised powder stored at −20 °C is more stable than one kept at room temperature, and once the material is dissolved the degradation rate rises, making refrigeration more important.