amino acid substitution 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 2026-02-28. Numbers and descriptions here follow the published literature rather than marketing material.
Activity is attributed to agonism at melanocortin receptors, particularly MC1R and MC4R. Activation of MC1R on melanocytes increases melanin synthesis, which underlies the reported tanning effect. MC4R engagement in the central nervous system is linked to appetite suppression and to effects on sexual arousal reported in early clinical studies. Those studies were small and were not designed to establish efficacy or long-term safety. Receptor selectivity among the melanocortin subtypes is not absolute, which complicates attribution of any effect to a single pathway.
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.
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.
Lyophilised peptide powder is comparatively stable when kept dry, cold and protected from light. Once dissolved, the molecule is exposed to hydrolysis, oxidation and microbial growth, and degradation accelerates at higher temperatures and in alkaline solution. Repeated freeze-thaw cycles concentrate solutes and promote aggregation. Handling guidance for research peptides commonly clusters around freezer temperatures for powder and short refrigerated use for reconstituted solutions, with pH control and sterile technique applied throughout.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Analogue of alpha-melanocyte-stimulating hormone |
| Common synonyms | MT-II; melanotan 2 | No internationally accepted non-proprietary name |
| Typical presentation | Lyophilised powder in a sealed vial | Often supplied alongside a separate diluent |
| Regulatory status | Unapproved therapeutic substance | Customs seizure reported in several jurisdictions |
| Reported route in use | Subcutaneous injection | Self-administered outside clinical settings |
Melanotan II is a synthetic cyclic heptapeptide with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, corresponding to a molecular formula of C50H69N15O9 and a monoisotopic mass near 1024 daltons. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, a peptide hormone produced by cleavage of proopiomelanocortin. A lactam bridge between the aspartate and lysine side chains closes the ring, and the C-terminal amide removes a free carboxyl group. Both modifications increase resistance to enzymatic degradation compared with the linear parent hormone. Four substitutions distinguish it from afamelanotide, the linear analogue studied under the name melanotan I.
Receptor-binding studies classify melanotan II as a non-selective melanocortin agonist. It interacts with MC1R, MC3R, MC4R and MC5R, with reported affinities in the low nanomolar range and no strong subtype preference. Activation of MC1R on dermal melanocytes shifts pigment synthesis toward eumelanin, the dark polymer deposited in melanosomes and transferred to keratinocytes. Because the same peptide engages MC4R in the hypothalamus, it also appears in animal work on food intake and erectile response, which is why it is discussed in both pigment and metabolic research. Which receptor populations dominate after systemic exposure in humans is not fully established.
Published pharmacokinetic information is limited and comes mainly from small studies rather than registrational trials. Plasma half-life is usually described as short, on the order of tens of minutes, followed by rapid tissue distribution and clearance of the intact peptide. Metabolites and low concentrations of parent compound have been reported in urine, a detail relevant to anti-doping and forensic testing. Whether repeated exposure changes receptor sensitivity or clearance over time remains an open question. Values differ noticeably between analytical assays, so published numbers should be read as approximate rather than definitive.
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.
Identification in laboratories relies on reversed-phase liquid chromatography coupled with tandem mass spectrometry, with product-ion spectra compared against a certified reference standard. High-resolution mass spectrometry supplies accurate mass confirmation, and peptide mapping after enzymatic digestion separates melanotan II from closely related analogues. Quantitation of seized material is complicated by unknown counter-ions and residual trifluoroacetate left from purification. Immunoassays raised against alpha-melanocyte-stimulating hormone can cross-react, so chromatographic confirmation is normally required. Urinary detection windows are short, and reported limits of detection differ substantially between laboratories.
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.
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.
Because the substance circulates mainly through informal markets, verification is a recurring theme in technical discussion. Independent analyses have found that labeled content and actual content can diverge, and that purity varies between samples. Analytical laboratories use reversed-phase chromatography to separate components and mass spectrometry to confirm identity. Isotope-labeled internal standards improve quantification in complex matrices. Such methods describe what a sample contains but say nothing about its sterility, lawful status, or suitability for any use. Open questions remain about how consistently testing is applied across the supply chain.
Regulatory treatment of this peptide varies by country. It holds no marketing authorization as a medicine in the United States, the European Union, or most other jurisdictions. Some countries classify products containing it as prescription-only or unlicensed medicines, which restricts lawful supply. Authorities have issued public notices warning that unregulated products may contain undeclared or incorrect ingredients. The molecule also appears on prohibited lists for competitive sport. These measures address supply oversight rather than any approved therapeutic role.
== Spin-off characters == Leslian Marie Gold (レスリー星人マリー・ゴールド, Resurī Seijin Marī Gōrudo): An S.P.D. officer from Planet Leslie with the power to temporarily stop time who serves as Deka Gold (デカゴールド, Deka Gōrudo) and appears exclusively in the film Tokusou Sentai Dekaranger The Movie: Full Blast Action. While working undercover as a nightclub singer to investigate the Gas Drinkers' attack on Leslie, she encounters and falls in love with Ban. Marie Gold is portrayed by Chiharu Niiyama (新山 千春, Niiyama Chiharu) while her singing voice is provided by Sae (小枝). Kight Reidlich (カイト・レイドリッヒ, Kaito Reidorihhi): The corrupt chief of the Space Police's Galactic District Police Bureau who appears exclusively in the direct-to-video anniversary special Tokusou Sentai Dekaranger: 10 Years After. Two years prior, Kruger discovered Reidlich had been selling confidential information to the space mafia Qurlian Family (キルリアンファミリー, Kirurian Famirī), but the latter captured him and used his Master License's Mirage Dimension to pose as Kruger and frame him for killing the Qurlians and their Clementian hostage. However, the hostage's daughter Carrie witnessed everything and seeks the Dekarangers' help in stopping Reidlich in the present. After the Dekarangers expose him and rescue Kruger, Reidlich sacrifices his underlings, Assam Asimov and Mugi Grafton, to power his Neo Hyper Muscle Gear and overwhelm the Dekarangers, only to be deleted by them and Deka Master. Kight Reidlich is voiced by Rikiya Koyama (小山 力也, Koyama Rikiya).
Liraglutide is sold under the brand name Victoza in the US, UK, UAE, Kuwait, India, Iran, Canada, Europe, Japan and the Philippines. It has been launched in Germany, Italy, Denmark, the Netherlands, Sweden, Japan, Canada, the United States, France, Indonesia, Malaysia and Singapore. Liraglutide is also known to be sold as Saxenda in Australia, Brazil, Canada, Germany, Indonesia, Iran, Ireland, Israel, Norway, Czech Republic, Poland, Portugal, South Korea, Switzerland, The United Kingdom and the US, and also as Enligria and Quinliro in Russia.
== Contraindications == Contraindications of progesterone include hypersensitivity to progesterone or progestogens, prevention of cardiovascular disease (a Black Box warning), thrombophlebitis, thromboembolic disorder, cerebral hemorrhage, impaired liver function or disease, breast cancer, reproductive organ cancers, undiagnosed vaginal bleeding, missed menstruations, miscarriage, or a history of these conditions. Progesterone should be used with caution in people with conditions that may be adversely affected by fluid retention such as epilepsy, migraine headaches, asthma, cardiac dysfunction, and renal dysfunction. It should also be used with caution in patients with anemia, diabetes mellitus, a history of depression, previous ectopic pregnancy, and unresolved abnormal Pap smear. Use of progesterone is not recommended during pregnancy and breastfeeding. However, the medication has been deemed usually safe in breastfeeding by the American Academy of Pediatrics, but should not be used during the first four months of pregnancy. Some progesterone formulations contain benzyl alcohol, and this may cause a potentially fatal "gasping syndrome" if given to premature infants.
Sources: en.wikipedia.org
=== Americas === Skin whitening practices have also been well documented in South America and the Caribbean. Sociologists such as Jack Menke noted that early skin-lightening practices among indigenous women were motivated by the attentions of conquistadores. Recovered journals from women in Suriname indicated that they used vegetable mixtures to lighten their skin, which produced painful side effects. Various studies have linked the prevalence of skin whitening in Latin American nations to their histories and legacies of colonization and slavery. Witness accounts in colonial Jamaica reported that women practiced "flaying" and "skinning" on themselves, using astringent lotions to appear lighter. Caribbean creole women were also observed to treat their skin with cashew nut oil, which burned the external layers of skin. Skin whitening practices grew in popularity, partly as a consequence of blanqueamiento in Latin America. The ideologies behind blanqueamiento promoted the idea of social hierarchy, based on Eurocentric features and skin tone.
Severe aortic stenosis with or without symptoms Aortic regurgitation with NYHA functional class III-IV symptoms Mitral stenosis with NYHA functional class II-IV symptoms Mitral regurgitation with NYHA functional class III-IV symptoms Aortic and/or mitral valve disease resulting in severe pulmonary hypertension (pulmonary pressure greater than 75% of systemic pressures) Aortic and/or mitral valve disease with severe LV dysfunction (EF less than 0.40) Mechanical prosthetic valve requiring anticoagulation Marfan syndrome with or without aortic regurgitation
== Biography == Born at Port Stanley in 1942 to New Zealanders Harold and Moya (née Boak) Baker, he spent his early life in the Falkland Islands, where his father was the superintendent of education. The family returned to New Zealand in 1948. He was educated at King's College, Auckland from 1956 to 1960. After studying chemistry at the University of Auckland, completing his PhD in 1967, he conducted postdoctoral research on the structure of insulin with Nobel laureate Dorothy Hodgkin at the University of Oxford. He then took up an academic post at Massey University, where he determined the structure of the kiwifruit enzyme actinidin. In 1997 he moved back to the University of Auckland where he became professor of structural biology and later direct of the Maurice Wilkins Center for Molecular Diversity. He also served as president of the International Union of Crystallography between 1996 and 1999. Baker was elected a Fellow of the Royal Society of New Zealand in 1987, and won the society's Hector Medal in 1997. He was awarded the Rutherford Medal, the highest honour in New Zealand science, in 2006. In the 2007 Queen's Birthday Honours, he was appointed a Companion of the New Zealand Order of Merit, for services to science.
Sources: en.wikipedia.org
Note: + = Positive, - =Negative P. aeruginosa is a Gram-negative, aerobic (and at times facultatively anaerobic), rod-shaped bacterium with unipolar motility. It has been identified as an opportunistic pathogen of both humans and plants. P. aeruginosa is the type species of the genus Pseudomonas. Identification of P. aeruginosa can be complicated by the fact individual isolates often lack motility. The colony morphology itself also displays several varieties. The main two types are large, smooth, with a flat edge and elevated center and small, rough, and convex. A third type, mucoid, can also be found. The large colony can typically be found in clinal settings while the small is found in nature. The third, however, is present in biological settings and has been found in respiratory and in the urinary tract. Furthermore, mutations in the gene lasR drastically alter colony morphology and typically lead to failure to hydrolyze gelatin or hemolyze. In certain conditions, P. aeruginosa can secrete a variety of pigments, including pyocyanin (blue), pyoverdine (yellow and fluorescent), pyorubin (red), and pyomelanin (brown). These can be used to identify the organism.
Surface energy is conventionally defined as the work that is required to build an area of a particular surface. Another way to view the surface energy is to relate it to the work required to cleave a bulk sample, creating two surfaces. If the new surfaces are identical, the surface energy γ of each surface is equal to half the work of cleavage, W: γ = (1/2)W11. If the surfaces are unequal, the Young-Dupré equation applies: W12 = γ1 + γ2 – γ12, where γ1 and γ2 are the surface energies of the two new surfaces, and γ12 is the interfacial energy. This methodology can also be used to discuss cleavage that happens in another medium: γ12 = (1/2)W121 = (1/2)W212. These two energy quantities refer to the energy that is needed to cleave one species into two pieces while it is contained in a medium of the other species. Likewise for a three species system: γ13 + γ23 – γ12 = W12 + W33 – W13 – W23 = W132, where W132 is the energy of cleaving species 1 from species 2 in a medium of species 3. A basic understanding of the terminology of cleavage energy, surface energy, and surface tension is very helpful for understanding the physical state and the events that happen at a given surface, but as discussed below, the theory of these variables also yields some interesting effects that concern the practicality of adhesive surfaces in relation to their surroundings.
The nucleophilic phosphine attacks the azide at the electrophilic terminal nitrogen. Through a four-membered transition state, N2 is lost to form an aza-ylide. The unstable ylide is hydrolyzed to form phosphine oxide and a primary amine. However, this reaction is not immediately bioorthogonal because hydrolysis breaks the covalent bond in the aza-ylide.
Rest It is suggested that the patient take a break from the activity that caused the injury in order to give the injury time to heal. Ice The injury should be iced on and off in 20 minute intervals, avoiding direct contact of the ice with the skin. Compression Bandaging the injury will compress it, and prevent any further bleeding or swelling from occurring. Elevation Elevating the injury above the heart while resting will aid in the reduction of swelling.
Sources: en.wikipedia.org
No. No major regulatory agency has granted a marketing authorisation for melanotan II as a medicine. Products sold under this name are generally presented as laboratory reagents and are not subject to the batch-release testing applied to approved drugs.
It was developed in the 1980s by researchers investigating analogues of alpha-melanocyte-stimulating hormone for pigmentation and related endpoints. Early work included small human studies during the 1990s. Development did not progress to licensing, and the compound remained a research and grey-market item.
Peptides are prone to truncation, oxidation and aggregation during synthesis and handling. Without independent testing, a buyer cannot confirm the identity or the content of a vial. Analytical surveys of unapproved peptide products have repeatedly found discrepancies between label claims and measured composition.
Mass spectrometry combined with liquid chromatography provides both molecular weight confirmation and a measure of related impurities. Tandem mass spectrometry adds sequence information. A purity percentage reported without a mass measurement does not confirm what the material is.