The short version of afamelanotide fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
Handling guidance for melanotan II follows general practice for small synthetic peptides rather than a product-specific monograph. Lyophilized powder is typically kept at minus twenty degrees Celsius or colder, protected from light and moisture, because warmth and humidity accelerate degradation. Once reconstituted, solutions are usually refrigerated and used within a short window, as hydrolysis and microbial growth both become concerns. Repeated freeze-thaw cycles are generally avoided. These conventions come from laboratory peptide chemistry and not from formal stability studies on this specific compound.
Analytical confirmation of identity relies on mass spectrometry, most often coupled to liquid chromatography. Reversed-phase high-performance liquid chromatography separates the peptide from related impurities and provides a purity estimate based on peak area. Electrospray ionization mass spectrometry then confirms the expected molecular mass, while tandem mass spectrometry can map the fragment sequence. For research-grade material, these two techniques together form the standard minimum. Purity figures reported by vendors are frequently not traceable to an independent laboratory.
Independent verification is central to quality control because the compound is not produced under pharmaceutical manufacturing standards. Third-party laboratories can measure purity, identity, residual solvents, and microbial contamination, though the scope of testing varies between services. Reported analyses of vendor samples have shown batch-to-batch variation in peptide content and the presence of truncated or oxidized species. How much of this variation reflects synthesis conditions versus storage and shipping is not well characterized. No harmonized reference standard exists for the material as sold.
Two structural changes distinguish the synthetic peptide from the natural hormone. A norleucine residue replaces methionine at one position, and a D-configured phenylalanine replaces the natural L-form at another. Both substitutions slow enzymatic breakdown, which extends the molecule's persistence relative to the parent hormone. The lactam bridge further constrains the backbone into a stable conformation. These features are standard design strategies in peptide chemistry and are not unique to this compound; they appear across many research peptides built for improved stability.
The compound was developed in the late 1980s and early 1990s by academic researchers investigating melanocortin signaling and pigmentation. Early work explored whether synthetic analogs could reproduce effects of the natural hormone under controlled conditions. The molecule never advanced through the full regulatory pathway required for approval as a medicine. From the mid-2000s onward it appeared in unregulated consumer markets, often distributed through informal channels. That gap between research origins and commercial availability shapes how the compound is discussed today.
Melanotan-2 is a synthetic peptide designed as an analog of alpha-melanocyte-stimulating hormone, a signaling molecule produced in the pituitary and skin. Its structure is a linear chain of seven amino acids that folds into a ring through an internal lactam bridge joining two side chains. The compound is sometimes written as MT-II or MEL-2 in informal and commercial contexts. It belongs to the melanocortin peptide family, a group of short signaling molecules that share a conserved core sequence recognized by melanocortin receptors.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilized form |
| Solubility | Freely soluble in water | Dissolves readily in aqueous buffer |
| Typical storage temperature | -20 °C or below | Protect from light and moisture |
| Typical analytical method | Reversed-phase HPLC and LC-MS | Purity estimate plus mass confirmation |
| Unit of measure | Milligram per vial | Content varies by vendor |
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.
Regulatory status varies by jurisdiction, and the substance is frequently described as unapproved for therapeutic use. Some authorities classify it alongside prescription-only medicines or controlled categories, while others address it through general consumer protection rules. Analytical surveys have reported mismatches between label claims and measured content in products sold online, although the scope of such testing is limited. Whether these discrepancies are widespread remains an open question. Discussion in the literature therefore tends to combine chemistry, supply-chain observation and policy analysis.
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 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.
Measurement tools, such as goniometers and inclinometers, aid in standardized quantification of joint motion relative to normative values or ranges. Tests that follow functional movements, such as reaching overhead, squatting, or rotating the neck, are used to evaluate whether reduced ROM translates into activity limitation. When hypomobility is regional, clinicians can use condition-specific values to compare the patient's ROM values against. For instance, in the shoulder, adhesive capsulitis (frozen shoulder) is defined by marked loss of both active and passive motion (particularly external rotation and abduction). For the knee, postoperative arthrofibrosis is typically diagnosed when extension loss exceeds 10° or flexion is limited to less than 100°, with more severe forms showing a flexion deficit of 25° or greater. In the spine, decreased ROM is assessed using values developed for ankylosing spondylitis and related disorders. The Modified Schober Test measures lumbar flexion. An increase of less than 5 cm indicates limited motion, chest expansion of 2.5 cm or less suggests thoracic restriction, and an occiput-to-wall distance greater than 2 cm shows thoracic or cervical extension limitation. The Bath Ankylosing Spondylitis Metrology Index (BASMI) provides a composite score summarizing these spinal mobility measures and is widely used to quantify skeletal hypomobility.
== Prediction == Because viscosity depends continuously on temperature and pressure, it cannot be fully characterized by a finite number of experimental measurements. Predictive formulas become necessary if experimental values are not available at the temperatures and pressures of interest. This capability is important for thermophysical simulations, in which the temperature and pressure of a fluid can vary continuously with space and time. A similar situation is encountered for mixtures of pure fluids, where the viscosity depends continuously on the concentration ratios of the constituent fluids For the simplest fluids, such as dilute monatomic gases and their mixtures, ab initio quantum mechanical computations can accurately predict viscosity in terms of fundamental atomic constants, i.e., without reference to existing viscosity measurements. For the special case of dilute helium, uncertainties in the ab initio calculated viscosity are two order of magnitudes smaller than uncertainties in experimental values. For slightly more complex fluids and mixtures at moderate densities (i.e. sub-critical densities) Revised Enskog Theory can be used to predict viscosities with some accuracy. Revised Enskog Theory is predictive in the sense that predictions for viscosity can be obtained using parameters fitted to other, pure-fluid thermodynamic properties or transport properties, thus requiring no a priori experimental viscosity measurements. For most fluids, high-accuracy, first-principles computations are not feasible.
=== D-amino acids === Some amino acids contain the opposite absolute chirality, chemicals that are not available from normal ribosomal translation and transcription machinery. Most bacterial cells walls are formed by peptidoglycan, a polymer composed of amino sugars crosslinked with short oligopeptides bridged between each other. The oligopeptide is non-ribosomally synthesised and contains several peculiarities including D-amino acids, generally D-alanine and D-glutamate. A further peculiarity is that the former is racemised by a PLP-binding enzymes (encoded by alr or the homologue dadX), whereas the latter is racemised by a cofactor independent enzyme (murI). Some variants are present, in Thermotoga spp. D-Lysine is present and in certain vancomycin-resistant bacteria D-serine is present (vanT gene).
Biko's given name "Bantu" means "people" in IsiXhosa; Biko interpreted this in terms of the saying "Umntu ngumntu ngabantu" ("a person is a person by means of other people"). As a child he was nicknamed "Goofy" and "Xwaku-Xwaku", the latter a reference to his unkempt appearance. He was raised in his family's Anglican Christian faith. In 1950, when Biko was four, his father fell ill, was hospitalised in St. Matthew's Hospital, Keiskammahoek, and died, making the family dependent on his mother's income. Biko spent two years at St. Andrews Primary School and four at Charles Morgan Higher Primary School, both in Ginsberg. Regarded as a particularly intelligent pupil, he was allowed to skip a year. In 1963 he transferred to the Forbes Grant Secondary School in the township. Biko excelled at maths and English and topped the class in his exams. In 1964 the Ginsberg community offered him a bursary to join his brother Khaya as a student at Lovedale, a prestigious boarding school in Alice, Eastern Cape. Within three months of Steve's arrival, Khaya was accused of having connections to Poqo, the armed wing of the Pan Africanist Congress (PAC), an African nationalist group which the government had banned. Both Khaya and Steve were arrested and interrogated by the police; the former was convicted, then acquitted on appeal. No clear evidence of Steve's connection to Poqo was presented, but he was expelled from Lovedale. Commenting later on this situation, he stated: "I began to develop an attitude which was much more directed at authority than at anything else.
Sources: en.wikipedia.org
More than 80% of newborns develop jaundice within several days of birth. Jaundice, or yellowing of the skin and eyes, occurs when bilirubin, a byproduct of the breakdown/recycling of red blood cells, builds up in the newborn's bloodstream faster than the liver can break it down and excrete it through the baby's urine and stool. By continuing to breastfeed frequently (start at 8-12 times per day), the infant's body can usually rid itself of the bilirubin excess by encouraging more urine and stool production. However, in some cases, the infant may need additional treatments, such as UV light therapy or additional feedings (see Supplementation) to keep the condition from progressing into more severe problems. There are two types of newborn jaundice related to breastfeeding. Breastfeeding jaundice is quite common and may occur in the first week of life in conjunction with ongoing weight loss. The cause is thought to be low caloric intake. Formula-fed infants tend to lose less weight after birth compared to breastfed infants, supporting the hypothesis that breastfeeding jaundice is related to caloric intake rather than volume intake. Individual risk factors, such as breastfeeding, are not predictive of developing severe jaundice: Breastfeeding is a risk factor for severely high levels of bilirubin, but the risk factor is very common, and the risk of severely high bilirubin remains small. Breast milk jaundice is jaundice that persists despite appropriate weight gain.
In 1969, Wenger was recruited to nearby third division club Mutzig. The club was famed for playing the "best amateur football" in Alsace and managed by Max Hild, who would later go on to become Wenger's mentor. Wenger's emergence at Mutzig aged 20 was considered too late for him to build a reputable playing career. Football was not seen as his future; the plan was for him to run the family's spare parts business. He was, however, of the age to start increasing his tactical knowledge of the sport. He frequently read France Football and alongside Hild made trips to Germany to watch Bundesliga matches and observe the different managerial styles. During Wenger's three years at Mutzig, the club beat Strasbourg 3–0 to win the Coupe d'Alsace. He also represented Alsace in a competition held annually between the regional leagues. Wenger took his studies further, and in 1971 enrolled at the Faculté des sciences économiques et de gestion (Faculty of Economic and Management Sciences) at the University of Strasbourg to read politics and economics after a brief stint in medicine. In 1973 he joined semi-professional club Mulhouse and balanced his football career with his education. Wenger completed an economics degree a year later. He was selected to represent the national French students squad and visited Nigeria, Lebanon, and Uruguay – where the World Students Championship was held in 1976.
The 2014 State Department's annual Trafficking in Persons (TIP) report appeared to classify the Khobragade incident as an example of human trafficking, stating: "An Indian consular officer at the New York consulate was indicted in December 2013 for visa fraud related to her alleged exploitation of an Indian domestic worker." In response, India has shown no urgency to allow visits to India by the newly appointed US anti-human trafficking ambassador Susan P. Coppedge and the US special envoy for LGBT rights Randy Berry. Under Section 377 of the Indian Penal Code homosexuality was illegal in India. Indian Ambassador to the US, Arun K. Singh reiterated India's commitment to work within an international framework to tackle the problem of trafficking but rejected any "unilateral assessments" by another country saying "We will never accept it" and downplayed the importance of the visits: "When you ask a U.S. official when somebody will be given a visa, they always say 'we will assess when visa is applied for.' ... I can do no better than to reiterate the U.S. position." In February 2016, the Obama administration notified the US Congress that it intended to provide Pakistan eight nuclear-capable F-16 fighters and assorted military goods including eight AN/APG-68(V)9 airborne radars and eight ALQ-211(V)9 electronic warfare suites despite strong reservations from US lawmakers regarding the transfer of any nuclear weapons capable platforms to Pakistan. Shashi Tharoor, an elected representative from the Congress party in India, questioned the substance of India–U.S.
Sources: en.wikipedia.org
For example, it was shown that the reaction of oganesson with F2 to form the compound OgF2 would release an energy of 106 kcal/mol of which about 46 kcal/mol come from these interactions. For comparison, the spin–orbit interaction for the similar molecule RnF2 is about 10 kcal/mol out of a formation energy of 49 kcal/mol. The same interaction stabilizes the tetrahedral Td configuration for OgF4, as distinct from the square planar D4h one of XeF4, which RnF4 is also expected to have; this is because OgF4 is expected to have two inert electron pairs (7s and 7p1/2). As such, OgF6 is expected to be unbound, continuing an expected trend in the destabilisation of the +6 oxidation state (RnF6 is likewise expected to be much less stable than XeF6). The Og–F bond will most probably be ionic rather than covalent, rendering the oganesson fluorides non-volatile. OgF2 is predicted to be partially ionic due to oganesson's high electropositivity. Oganesson is predicted to be sufficiently electropositive to form an Og–Cl bond with chlorine. A compound of oganesson and tennessine, OgTs4, has been predicted to be potentially stable chemically.
== Species distribution == Carboxypeptidase E is found in all species of vertebrates that have been examined, and is also present in many other organisms that have been studied (nematode, sea slug). Carboxypeptidase E is not found in the fruit fly (Drosophila), and another enzyme (presumably carboxypeptidase D) fills in for carboxypeptidase E in this organism. In humans, CPE is encoded by the CPE gene.
=== Functioning as signal transducer === Within the last decade, many independent labs have demonstrated that, in addition to the classical ion transporting, this membrane protein can also relay extracellular ouabain-binding signalling into the cell through regulation of protein tyrosine phosphorylation. For instance, a study investigated the function of Na+/K+-ATPase in foot muscle and hepatopancreas in land snail Otala lactea by comparing the active and estivating states. They concluded that reversible phosphorylation can control the same means of coordinating ATP use by this ion pump with the rates of the ATP generation by catabolic pathways in estivating O. lactea. The downstream signals through ouabain-triggered protein phosphorylation events include activation of the mitogen-activated protein kinase (MAPK) signal cascades, mitochondrial reactive oxygen species (ROS) production, as well as activation of phospholipase C (PLC) and inositol triphosphate (IP3) receptor (IP3R) in different intracellular compartments. Protein-protein interactions play a very important role in Na+-K+ pump-mediated signal transduction. For example, the Na+-K+ pump interacts directly with Src, a non-receptor tyrosine kinase, to form a signaling receptor complex. Src is initially inhibited by the Na+-K+ pump. However, upon subsequent ouabain binding, the Src kinase domain is released and then activated. Based on this scenario, NaKtide, a peptide Src inhibitor derived from the Na+-K+ pump, was developed as a functional ouabain–Na+-K+ pump-mediated signal transduction.
Sources: en.wikipedia.org
The lyophilized powder is generally held at minus twenty degrees Celsius or below, away from light and moisture. Reconstituted solutions are typically refrigerated and used quickly. These practices derive from general peptide handling rather than a formal stability study.
Reversed-phase liquid chromatography estimates purity, and mass spectrometry confirms molecular mass. Together they distinguish the intended peptide from truncated or modified forms. Sequence-level confirmation may use tandem mass spectrometry or amino acid analysis.
Because it is not made under pharmaceutical standards, purity and content can vary between vendors and batches. Independent testing has documented labeling discrepancies. A certificate of analysis from an accredited laboratory offers more assurance than a vendor's own claim.
It is a synthetic seven-amino-acid peptide modeled on alpha-melanocyte-stimulating hormone. It carries two non-natural substitutions and a cyclic bridge that increase its stability relative to the natural hormone. It circulates as a research chemical and is not an approved medicine.