Everything below concerns amino acid substitution. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-09-13. Numbers and descriptions here follow the published literature rather than marketing material.
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controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports.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.
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.
| 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 |
== Sequence == More than 100 AKH sequences are known. The typical makeup of hormones in this family includes a length between 8 and 10 amino acids, blocked N (pyroglutamic acid) and C (amidation) termini, with hydrophic residues at position 2, asparagine or threonine at position 3, phenylalanine or tyrosine at position 4, and serine or threonine at position 5. AKH sequence characteristics also include tryptophan at position 8 and in about two-thirds of the known AKHs, proline at position 6. AKHs can be modified (C-mannosylated tryptophan, proline hydroxylation, threonine phosphorylation, possible proline isomerisation, threonine O-sulfonation). Mass spectrometry is increasingly used for de novo sequencing of these hormones. Sequence prediction from genomic and transcriptomic data assist in hormone identification . AKH sequences differ slightly in insect families (Scarabaeoidea, Cucujiformia, Lepidoptera, Diptera, Hemiptera, Polyphaga).
He was elected a Foreign Member of the Royal Society (1957). His honorary memberships of foreign academies and scientific societies included: the Romanian Physical Society in Bucharest, the Royal Spanish Society for Chemistry and Physics and the Spanish National Research Council, and the Academies in Allahabad, Bangalore, Berlin, Boston, Bucharest, Copenhagen, Göttingen, Halle, Helsinki, Lisbon, Madrid, Mainz, Munich, Rome, Stockholm, the Vatican, and Vienna. He was an honorary fellow of University College London,
Pitting also may be caused by a variety of systemic diseases, including reactive arthritis and other connective tissue disorders, sarcoidosis, pemphigus, alopecia areata, and incontinentia pigmenti. Because pitting is caused by defective layering of the superficial nail plate by the proximal nail matrix, any localized dermatitis (e.g., atopic dermatitis or chemical dermatitis) that disrupts orderly growth in that area also can cause pitting.
=== Other symptoms and comorbidities === Myoglobinuria (reddish-brown urine) may be seen due to the breakdown of skeletal muscle known as rhabdomyolysis (a condition in which muscle cells breakdown, sending their contents into the bloodstream). In 2020, the largest study to-date of 269 GSD-V patients, 39.4% reported no previous episodes of myoglobinuria and 6.8% had normal CK (including those with fixed muscle weakness); so an absence of myoglobinuria and normal CK should not rule out the possibility of the disease. Between 33-51.4% develop fixed muscle weakness, typically of the trunk and upper body, with the onset of muscle weakness usually occurring later in life (40+ years of age). Younger people may display unusual symptoms, such as difficulty chewing, swallowing, or utilizing normal oral motor functions. Idiopathic leg pains were common in children, usually occurring at night, often presumed to be "growing pains" and not investigated further. Several comorbidities were found in GSD-V individuals at a higher rate than in the general population, including (but not limited to): hypertension (17%), endocrine diseases (15.7%), musculoskeletal/rheumatic disease (12.9%), hyperuricemia/gout (11.6%), gastrointestinal diseases (11.2%), neurological disease (10%), respiratory disease (9.5%), and coronary artery disease (8.3%). They may have a pseudoathletic appearance of muscle hypertrophy (24%), particularly of the legs, and may have lower bone mineral content and density in the legs.
Sources: en.wikipedia.org
According to these rules, compounds with the most ionic character will have large positive ions with a low charge, bonded to a small negative ion with a high charge. More generally HSAB theory can be applied, whereby the compounds with the most ionic character are those consisting of hard acids and hard bases: small, highly charged ions with a high difference in electronegativities between the anion and cation. This difference in electronegativities means that the charge separation, and resulting dipole moment, is maintained even when the ions are in contact (the excess electrons on the anions are not transferred or polarized to neutralize the cations). Although chemists classify idealized bond types as being ionic or covalent, the existence of additional types such as hydrogen bonds and metallic bonds, for example, has led some philosophers of science to suggest that alternative approaches to understanding bonding are required. This could be by applying quantum mechanics to calculate binding energies.
Peptide computing is a form of computing which uses peptides, instead of traditional electronic components. The basis of this computational model is the affinity of antibodies towards peptide sequences. Similar to DNA computing, the parallel interactions of peptide sequences and antibodies have been used by this model to solve a few NP-complete problems. Specifically, the hamiltonian path problem (HPP) and some versions of the set cover problem are a few NP-complete problems which have been solved using this computational model so far. This model of computation has also been shown to be computationally universal (or Turing complete). This model of computation has some critical advantages over DNA computing. For instance, while DNA is made of four building blocks, peptides are made of twenty building blocks. The peptide-antibody interactions are also more flexible with respect to recognition and affinity than an interaction between a DNA strand and its reverse complement. However, unlike DNA computing, this model is yet to be practically realized. The main limitation is the availability of specific monoclonal antibodies required by the model.
Acquired progressive lymphangioma (benign lymphangioendothelioma) Acral fibrokeratoma (acquired digital fibrokeratoma, acquired periungual fibrokeratoma) Acrochordon (cutaneous papilloma, cutaneous tag, fibroepithelial polyp, fibroma molluscum, fibroma pendulum, papilloma colli, skin tag, soft fibroma, Templeton skin tag) Adenoma sebaceum Adult type of generalized eruption of cutaneous mastocytosis African cutaneous Kaposi sarcoma African lymphadenopathic Kaposi sarcoma Aggressive infantile fibromatosis AIDS-associated Kaposi sarcoma Ainhum (bankokerend, dactylolysis spontanea, sukhapakla) Angiofibroma Angiokeratoma Angiokeratoma of Fordyce (angiokeratoma of the scrotum and vulva) Angiokeratoma of Mibelli (Mibelli's angiokeratoma, telangiectatic warts) Angioleiomyoma (vascular leiomyoma) Angiolipoleiomyoma Angiolipoma Angioma serpiginosum Angiosarcoma Aponeurotic fibroma (calcifying aponeurotic fibroma, juvenile aponeurotic fibroma) Atypical fibroxanthoma Benign lipoblastomatosis (embryonic lipoma) Buschke–Ollendorff syndrome (dermatofibrosis lenticularis disseminata) Capillary aneurysms Carcinoid Cellular angiofibroma Cherry angioma (De Morgan spot, senile angioma) Chondrodermatitis nodularis chronica helicis (chondrodermatitis nodularis helicis) Chondroid lipoma Chordoma Classic Kaposi sarcoma Collagenous fibroma (desmoplastic fibroblastoma) Composite hemangioendothelioma Connective tissue nevus (collagenoma, elastoma, shagreen patch) Cutaneous endometriosis Cutaneous meningioma (heterotopic meningeal tissue, rudimentary meningocele) Cutaneous myelofibrosis Cutaneous myxoma Cutis marmorata telangiectatica congenita (congenital generalized phlebectasia, Van Lohuizen syndrome) Dermal dendrocyte hamartoma Dermatofibroma (benign fibrous histiocytoma, dermal dendrocytoma, fibrous dermatofibroma, fibrous histiocytoma, fibroma simplex, histiocytoma, nodular subepidermal fibrosis, sclerosing hemangioma) Dermatofibrosarcoma protuberans Desmoid tumor Diffuse cutaneous mastocytosis Diffuse infantile fibromatosis Dupuytren's contracture (Dupuytren's diathesis, Dupuytren's disease, palmar fibromatosis) Eccrine angiomatous hamartoma Elastofibroma dorsi Endovascular papillary angioendothelioma (Dabska tumor, Dabska-type hemangioendothelioma, hobnail hemangioendothelioma, malignant endovascular papillary angioendothelioma, papillary intralymphatic angioendothelioma) Epithelioid cell histiocytoma Epithelioid hemangioendothelioma Epithelioid sarcoma Erythrodermic mastocytosis Extraskeletal chondroma (chondroma of soft parts) Familial myxovascular fibromas Fascial hernia Fibroma of tendon sheath Fibromatosis colli (sternomastoid tumor of infancy) Fibrous hamartoma of infancy Fibrous papule of the nose (benign solitary fibrous papule, fibrous papule of the face) Folded skin with scarring (Michelin tire baby syndrome) Fordyce's spot (Fordyce's disease) Ganglion cyst Ganglioneuroma Gardner fibroma Genital leiomyoma (dartoic leiomyoma) Giant cell fibroblastoma Giant cell tumor of the tendon sheath (giant cell synovioma, localized nodular tenosynovitis, pigmented villonodular synovitis) Glomeruloid hemangioma Glomus tumor (glomangioma, solid glomus tumor, solitary glomus tumor) Granular cell tumor (Abrikossoff's tumor, Abrikossov's tumor, granular cell myoblastoma, granular cell nerve sheath tumor, granular cell schwannoma) Hamartoma Hemangiopericytoma Hemangiosarcoma Hibernoma (fetal lipoma, lipoma of embryonic fat, lipoma of immature adipose tissue) Hypertrophic scar Immunosuppression-associated Kaposi sarcoma Infantile digital fibromatosis (inclusion body fibromatosis, infantile digital myofibroblastoma, Reye tumor) Infantile hemangiopericytoma (congenital hemangiopericytoma) Infantile myofibromatosis (congenital generalized fibromatosis, congenital multicentric fibromatosis) Infantile systemic hyalinosis (juvenile systemic hyalinosis) Intradermal spindle cell lipoma Intravascular papillary endothelial hyperplasia (Masson's hemangio-endotheliome vegetant intravasculaire, Masson's lesion, Masson's pseudoangiosarcoma, Masson's tumor, papillary endothelial hyperplasia) Juvenile hyaline fibromatosis (fibromatosis hyalinica multiplex juvenilis, Murray–Puretic–Drescher syndrome) Kaposiform hemangioendothelioma (infantile kaposiform hemangioendothelioma) Kasabach–Merritt syndrome (hemangioma with thrombocytopenia) Keloid (Keloidal scar) Keratinizing metaplasia Keratocyst Klippel–Trenaunay syndrome (angioosteohypertrophy syndrome, hemangiectatic hypertrophy) Knuckle pads (heloderma) Leiomyosarcoma Lipoma Liposarcoma (atypical lipoma, atypical lipomatous tumor) Lymphangiectasis (lymphangioma) Lymphangiomatosis Malignant fibrous histiocytoma Malignant peripheral nerve sheath tumor (malignant schwannoma, neurofibrosarcoma, neurosarcoma) Mast cell sarcoma Meningocele Metastatic carcinoma Microvenular hemangioma (microcapillary hemangioma) Midline nevus flammeus (angel's kiss, salmon patch) Multifocal lymphangioendotheliomatosis (congenital cutaneovisceral angiomatosis with thrombocytopenia, multifocal lymphangioendotheliomatosis with thrombocytopenia) Multinucleate cell angiohistocytoma Multiple cutaneous and uterine leiomyomatosis syndrome (leiomyomatosis cutis et uteri, multiple leiomyomatosis, Reed's syndrome) Multiple cutaneous leiomyoma (pilar leiomyoma) Neural fibrolipoma Neuroblastoma (infantile neuroblastoma, neuroepithelioma) Neuroma cutis Neurothekeoma (bizarre cutaneous neurofibroma, cutaneous lobular neuromyxoma, myxoma of the nerve sheath, myxomatous perineurioma, nerve sheath myxoma) Nevus flammeus (capillary malformation, port-wine stain) Nevus flammeus nuchae (stork bite) Nevus lipomatosus superficialis (nevus lipomatosis of Hoffman and Zurhelle) Nevus oligemicus Nodular fasciitis (nodular pseudosarcomatous fasciits, pseudosarcomatous fasciitis, subcutaneous pseudosarcomatous fibromatosis) Oral submucous fibrosis Pachydermodactyly Palisaded encapsulated neuroma Paraneoplastic syndrome Pearly penile papules (hirsuties coronae glandis, hirsutoid papillomas) Peyronie's disease (induratio penis plastica) Phakomatosis pigmentovascularis Piloleiomyoma Plantar fibromatosis (Ledderhose's disease) Pleomorphic fibroma Pleomorphic lipoma Plexiform fibrohistiocytic tumor Porokeratotic eccrine ostial and dermal duct nevus Progressive nodular histiocytoma Proliferating angioendotheliomatosis Prominent inferior labial artery Pseudo-ainhum
Brinkley initiated a boom in male impotence treatments in the U.S. in the 1920s and 1930s, with radio programs that recommended expensive goat gland implants and "mercurochrome" injections as the path to restored male virility, including operations by surgeon Serge Voronoff. Modern drug therapy for ED made a significant advance in 1983, when British physiologist Giles Brindley dropped his trousers and demonstrated to a shocked Urodynamics Society audience showing his papaverine-induced erection. The current most common treatment for ED, the oral PDE5 inhibitor known as sildenafil (Viagra) was approved for use for Pfizer by the FDA in 1998, which at the time of release was the fastest selling drug in history. Sildenafil largely replaced SSRI treatments for ED at the time and proliferated new types of specialised pharmaceutical marketing which emphasised social connotations of ED and Viagra rather than its physical effects.
===== U.S. Congress ===== In the aftermath of the recall, there was a call from consumers for an investigation into Menu Foods reaction to the poisonings, and the federal government's stand on pet food safety and quality control and the FDA's response to the recall. On 1 April 2007, Senator Dick Durbin (D – Illinois) called on the FDA to "account for weak links in the pet food inspection system." Earlier in the week, Representative Rosa DeLauro (D – Connecticut) asked for an analysis of the FDA's oversight of pet food manufacturing facilities and a report of actions taken since the recall. On 6 April 2007, Senator Durbin criticized the federal inspection process for both human and pet food and called for the hearings on the matter. According to the Los Angeles Times who interviewed Durbin 8 April, Durbin said he would like to see the FDA set national standards and inspection rules for pet food manufacturing facilities, and to see "federal law changed to allow the FDA to order a recall of food intended for human or pet consumption rather than rely on companies to do it voluntarily." Durbin was working with Senator Herb Kohl (D – Wisconsin), the Chairman of the United States Senate Appropriations Subcommittee on Agriculture, Rural Development, Food and Drug Administration, and Related Agencies. Senator Kohl initiated hearings in the Senate Appropriations Subcommittee along with Senator Durbin and Senator Bob Bennett (R – Utah). Senator Robert Byrd (D – West Virginia), from the United States Senate Committee on Appropriations was there as well.
Sources: en.wikipedia.org
For example, ammonia (NH3) is soluble in both water (aq) and the organic solvent trichloromethane (CHCl3) - two immiscible solvents. If ammonia is first dissolved in water, and then an equal volume of trichloromethane is added, and the two liquids shaken together, the following equilibrium is established:
== Further reading == Appanna, Varun P.; Auger, Christopher; Thomas, Sean C.; Omri, Abdelwahab (13 June 2014). "Fumarate metabolism and ATP production in Pseudomonas fluorescens exposed to nitrosative stress". Antonie van Leeuwenhoek. 106 (3): 431–438. doi:10.1007/s10482-014-0211-7. PMID 24923559. S2CID 1124142. Cabrefiga, J.; Frances, J.; Montesinos, E.; Bonaterra, A. (1 October 2014). "Improvement of a dry formulation of Pseudomonas fluorescens EPS62e for fire blight disease biocontrol by combination of culture osmoadaptation with a freeze-drying lyoprotectant". Journal of Applied Microbiology. 117 (4): 1122–1131. doi:10.1111/jam.12582. PMID 24947806.
Martha Sharp "Sunny" von Bülow (née Crawford; September 1, 1931 − December 6, 2008) was an American heiress and socialite. Her second husband, Claus von Bülow, was convicted in 1982 of attempting to murder her by insulin overdose, but the conviction was overturned on appeal. A second trial found him not guilty, after experts opined that there was no insulin injection and that her symptoms were attributable to overuse of prescription drugs. The story was dramatized in the book and film Reversal of Fortune. Sunny von Bülow lived almost 28 years in a persistent vegetative state, from December 1980 until her death in a New York City nursing home on December 6, 2008.
ICT appears to be vanishing as a result of greater genetic diversity within the affected populations in conjunction with educational programs to ensure that tinned cooking utensils are used instead of copper pots and pans being directly exposed to cooked foods. The preponderance of cases of early childhood cirrhosis identified in Germany over a period of 10 years were not associated with either external sources of copper or with elevated hepatic metal concentrations Only occasional spontaneous cases of ICT arise today.
The restaurant has achieved popularity which has led to celebration by some when brought to new locations, and the opening of a new restaurant often becomes an event. When one opened in Scottsdale, Arizona, there was a four-hour wait for food, and news helicopters whirled above the parking lot. When the first location in the state of Colorado opened in Aurora in 2020 wait times exceeded fourteen hours and local police had to assist with traffic control.
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.
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.