This is a working overview of alpha-MSH analog, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-10-08 and is reviewed periodically as new material appears.
Published human data come mostly from small, short studies rather than large controlled trials. Reported outcomes include increased skin pigmentation and, in some reports, effects on appetite and libido, but sample sizes are small and follow-up is limited. Whether long-term use produces durable pigment changes or adverse effects is not established. Because products sold outside pharmacies are not standardized, the actual content of any given vial is often unknown. Independent testing of such material is uncommon.
Melanotan II is a synthetic cyclic heptapeptide analog derived from the core sequence of alpha-melanocyte-stimulating hormone. Researchers at the University of Arizona synthesized it during the 1980s while studying pigmentation and appetite signaling. The compound is not an approved medicine in any major jurisdiction and appears mainly in laboratory and research-chemical settings. Its structure incorporates a lactam bridge between side chains, which constrains the ring and slows enzymatic breakdown relative to the natural hormone.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Analog of alpha-melanocyte-stimulating hormone |
| Primary receptor family | Melanocortin receptors MC1R through MC5R | Binding is not subtype-selective |
| Development period | 1980s | Synthesized during pigmentation and appetite research |
| Regulatory status | Not an approved medicine | No major regulator has authorized human use |
| Related compound | Afamelanotide | Linear analog studied for photoprotection |
The compound was developed in the late 1980s and 1990s by academic researchers investigating photoprotection. The rationale held that stimulating melanin production might reduce ultraviolet damage to skin and lower skin cancer risk. Early work examined receptor binding, pigment response, and short-term tolerability in small studies. That program did not produce an approved drug, and formal development stalled after early-phase trials. Whether induced pigmentation confers meaningful photoprotection remains an open question.
Outside regulated medicine, melanotan II circulates through online vendors as a research chemical, often marketed for tanning. Products sold this way vary widely in purity, concentration, and labeling accuracy, and independent testing has documented discrepancies. Published reports describe both pigment effects and adverse reactions, including nausea, flushing, and darkening of existing moles. Long-term safety data are sparse, and no large controlled trial has established a risk profile. Questions about cumulative effects on melanocytes remain unresolved in the literature.
Melanotan II is a synthetic peptide analog modeled on alpha-melanocyte-stimulating hormone, a naturally occurring signaling peptide involved in pigmentation. Its structure is a cyclic heptapeptide containing two non-natural substitutions, norleucine at position four and D-phenylalanine at position seven. These modifications resist enzymatic breakdown and extend the molecule's activity relative to the native hormone. The compound binds melanocortin receptors and is studied mainly as a pharmacological tool rather than a therapeutic product. It has never received approval as a medicine in any major jurisdiction.
Solid peptide material is generally stable when kept cold and dry. Common practice is storage at -20 degrees Celsius or lower, with desiccant and protection from light. Repeated freeze-thaw cycles and exposure to moisture are associated with degradation, aggregation, or loss of material. Once dissolved, stability depends on solvent, concentration, and temperature, and solutions are usually treated as short-lived unless stability data support longer periods. Handling notes typically emphasise minimising time at ambient temperature.
Identity and purity are assessed with chromatographic and mass spectrometric techniques. Reversed-phase high-performance liquid chromatography separates the target peptide from related impurities and degradation products, and the resulting retention time is compared against a reference standard. Mass spectrometry, often coupled to liquid chromatography, confirms molecular mass. Amino acid analysis or peptide mapping can provide additional sequence-level confirmation when required. Results are only as reliable as the reference materials used alongside them.
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.
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.
Lyophilized peptide powder is generally stored frozen, protected from light and moisture. Tryptophan residues are susceptible to oxidation, and the lactam bridge can hydrolyze under strongly acidic or basic conditions. Solutions prepared for laboratory work degrade faster than dry powder, and repeated freeze-thaw cycles accelerate loss. Common practice is to aliquot solutions before freezing and to avoid alkaline buffers. Reported stability windows vary with concentration, buffer, and temperature, so exact shelf lives are method-specific rather than universal.
Regulatory status differs by country, and in many places supplying the compound for human consumption is unlawful. Vendors frequently label material as intended for research use only, a designation that shifts stated purpose but does not create a legal pathway for personal use. Certificates of analysis accompanying such products vary widely in detail and provenance. Third-party testing exists but is voluntary, and results are rarely linked to a specific lot in a publicly verifiable way.
fluorescence in situ hybridization (FISH) A type of in situ hybridization assay where the oligonucleotide probes are labelled with a chemical compound that is naturally fluorescent when exposed to light at particular wavelengths, making it possible to detect the in situ locations of complementary sequences with fluorescence microscopy. FISH is commonly used to visualize the physical locations of specific genes on chromosomes.
== Properties == LCRs are more abundant in eukaryotes, but they also have a significant presence in many prokaryotes. On average, 0.05 and 0.07% of the bacterial and archaeal proteomes (total amino acids of LCRs in a given proteome/total amino acids of that proteome) form LCRs whereas for five model eukaryotic proteomes (human, fruitfly, yeast, fission yeast, Arabidopsis) this coverage was significantly higher (on average, 0.4%; between 2 and 23 times higher than prokaryotes). Eukaryotic LCRs tend to be longer than prokaryotic LCRs. The average size of a eukaryotic LCR is 42 amino acids long, whereas bacterial, archaeal and phage LCRs are 38, 36 and 33 amino acids long, respectively. In the Archaea, the halobacterium Natrialba magadii has the highest number of LCRs and the highest enrichment for LCRs. In Bacteria, Enhygromyxa salina, a delta proteobacterium that belongs to myxobacteria has the highest number of LCRs and the highest enrichment for LCRs. Intriguingly, four of the top five bacteria with the highest enrichment for LCRs are also myxobacteria. The three most enriched amino acids within LCRs of Bacteria are proline, glycine and alanine, whereas in Archaea they are threonine, aspartate and proline. In Phages, they are alanine, glycine and proline. Glycine and proline emerge as very enriched amino acids in all three evolutionary lineages, whereas alanine is highly enriched in Bacteria and Phages but not enriched in Archaea.
This gas flow passes through the centre of the plasma, where it forms a channel that is cooler than the surrounding plasma but still much hotter than a chemical flame. Samples to be analyzed are introduced into this central channel, usually as a mist of liquid formed by passing the liquid sample into a nebulizer. To maximise plasma temperature (and hence ionisation efficiency) and stability, the sample should be introduced through the central tube with as little liquid (solvent load) as possible, and with consistent droplet sizes. A nebuliser can be used for liquid samples, followed by a spray chamber to remove larger droplets, or a desolvating nebuliser can be used to evaporate most of the solvent before it reaches the torch. Solid samples can also be introduced using laser ablation. The sample enters the central channel of the ICP, evaporates, molecules break apart, and then the constituent atoms ionise. At the temperatures prevailing in the plasma a significant proportion of the atoms of many chemical elements are ionized, each atom losing its most loosely bound electron to form a singly charged ion. The plasma temperature is selected to maximise ionisation efficiency for elements with a high first ionisation energy, while minimising second ionisation (double charging) for elements that have a low second ionisation energy.
== Other animals == A neuroendocrine system has been observed in all animals with a nervous system and all vertebrates have a hypothalamus–pituitary axis. All vertebrates have a thyroid, which in amphibians is also crucial for transformation of larvae into adult form. All vertebrates have adrenal gland tissue, with mammals unique in having it organized into layers. All vertebrates have some form of a renin–angiotensin axis, and all tetrapods have aldosterone as a primary mineralocorticoid.
==== Ciprofloxacin ==== Due to the constraints and confined environments that astronauts are exposed to for long durations of time, they are at risk for higher rates of infection. Ciprofloxacin is a common drug used to treat infections, especially bacterial of nature, and is used to study antibiotics delivery in outer space due to its good bioavailability, infrequent dose intake, multiple-dose intake abilities (oral or intravenous), and stability. This study also employs a bed-rest model called the antiorthostatis bed rest (ABR) model, where subjects lie at a 12° angle downwards to simulate space flight weightlessness. Six individuals were employed to take one dose of 250 mg ciprofloxacin, once at weightlessness and once at normal conditions, separated between fifteen days. Blood was examined at intervals of 0, 0.25, 0.5, 0.75, 1, 1.5, 2, 3, 4, 8, and 12 hours and urine samples were also collected at 0, 3, 6, 8, and 12 hours after each dose. It was found that ciprofloxacin's penetration in the tissue was lower in microgravity conditions than normal, indicating tissue penetration to be an issue in outer space for ciprofloxacin. In addition, compared to doses stored at ground versus in space, there was visible discoloration in samples stored in outer space and the expiration period in outer space was much shorter than on the ground.
Sources: en.wikipedia.org
Graft copolymerization: The growing polystyrene chain reacts with a double bond of the polybutadiene. As a result, several polystyrene chains are attached to one polybutadiene. S represents in the figure the styrene repeat unit B the butadiene repeat unit. However, the middle block often does not consist of such depicted butane homo-polymer but of a styrene-butadiene co-polymer: SSSSSSSSSSSSSSSSSSSBBSBBSBSBBBBSBSSBBBSBSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS By using a statistical copolymer at this position, the polymer becomes less susceptible to cross-linking and flows better in the melt. For the production of SBS, the first styrene is homopolymerized via anionic copolymerization. Typically, an organometallic compound such as butyllithium is used as a catalyst. Butadiene is then added and after styrene again its polymerization. The catalyst remains active during the whole process (for which the used chemicals must be of high purity). The molecular weight distribution of the polymers is very low (polydispersity in the range of 1.05, the individual chains have thus very similar lengths). The length of the individual blocks can be adjusted by the ratio of catalyst to monomer. The size of the rubber sections, in turn, depends on the block length. The production of small structures (smaller than the wavelength of the light) ensure transparency. In contrast to PS-I, however, the block copolymer does not form any particles but has a lamellar structure.
COL1A1/2-related osteogenesis imperfecta is inherited in an autosomal dominant manner. The proportion of cases caused by a De novo COL1A1 or COL1A2 mutations are the cause of osteogenesis imperfecta in the vast majority of perinatally lethal osteogenesis imperfecta, and progressively deforming osteogenesis imperfecta. In classic non-deforming osteogenesis imperfecta with blue sclerae or common variable osteogenesis imperfecta with normal sclerae, nearly 60% of cases are de novo. COL1A1/2-related osteogenesis imperfecta is identified by repeated fractures with trivial trauma, defective dentinogenesis imperfecta (DI), and hearing loss. The clinical features of COL1A1/2-related osteogenesis imperfecta can be highly variable ranging from severe and lethal perinatal fractures to individuals with minimal tendency to repeated fractures and skeletal deformities and with a normal stature and life span. In between the clinical spectrum may include individuals with various degrees of disabling skeletal deformities and short stature. The radiographic findings of osteogenesis imperfecta include; long bone deformations such as bowing of the tibias and femurs, pencil-like deformity and tapering of bones, cortical thinning and rarefaction, pathologic fractures at various degrees of healing, bone shortening and vertebral wedging. Accordingly, COL1A1/2-related osteogenesis imperfecta has been classified into four sub-types (I, II, III, and IV) built upon the diversity of the radioclinical features.
Ibogaine affects many different neurotransmitter systems simultaneously and hence has complex pharmacology. The specific targets mediating the effects of ibogaine are not fully clear. The drug is a cyclized derivative of serotonin, and hence may be expected to have serotonergic actions, but shows relatively low affinity for serotonin receptors. In any case, it appears that the serotonin 5-HT2A, 5-HT2C, sigma σ2, and μ- and/or κ-opioid receptors may be involved in the subjective effects of ibogaine based on animal studies. Conversely, the NMDA, serotonin 5-HT1A and 5-HT3, and sigma σ1 receptors do not appear to be involved. Ibogaine's major active metabolite noribogaine has similar discriminative stimulus properties compared to ibogaine in rodent drug discrimination tests, but only partially substitutes for ibogaine. It appears that the stimulus properties of ibogaine may be primarily mediated by noribogaine. Noribogaine is most potent as a serotonin reuptake inhibitor. It acts as a moderate κ-opioid receptor agonist and weak μ-opioid receptor agonist or weak partial agonist. The action of ibogaine at the κ-opioid receptor may indeed contribute significantly to the psychoactive effects attributed to ibogaine ingestion; Salvia divinorum, another plant recognized for its strong hallucinogenic properties, contains the chemical salvinorin A, which is a highly selective κ-opioid agonist. Noribogaine is more potent than ibogaine in rat drug discrimination assays when tested for the subjective effects of ibogaine.
=== Natural hypoallergenic milk for infants with cows' milk protein allergy === Pasteurized donkey milk is used as a natural hypoallergenic milk because it is tolerated by about 90% of infants with food allergies, e.g., cows' milk protein allergy (CMPA), a common food allergy in childhood with a prevalence of approximately 3% during the first 3 years of life. However, an infant's tolerance to donkey milk must be evaluated under medical supervision, and after carrying out specific allergy tests. Natural hypoallergenic formula is preferred over those of soy or produced from protein hydrolysates because it has a pleasant taste and may not cause allergies in people who also have allergic reactions to soy proteins or protein hydrolysates.
Sources: en.wikipedia.org
==== Laos and Cambodia ==== Separate accords were signed by the signatories with the Kingdom of Laos and the Kingdom of Cambodia in relation to Laos and Cambodia respectively. Following the terms of the agreement, Laos would be governed by the Royal Lao Government, while Cambodia would be ruled by the royal court of Norodom Sihanouk. Despite retaining its monarchy, the agreement also allowed for "VWP-affiliated Laotian forces" to run the provinces of Xam Neua and Phongsaly, further expanding North Vietnamese influence within Indochina. The Viet Minh and North Vietnamese never really withdrew from the border areas of Laos and the Pathet Lao continued to operate almost as a branch organization of the Viet Minh. Two months after the conference, the North Vietnamese formed Group 100 with headquarters at Na Mèo. Due to the agreement, communist forces in Cambodia would remain out of power. With this backdrop around a thousand of UIF cadres left for Vietnam along with the departing Viet Minh forces, on Polish ships provided by the ICSC on the Mekong river.
Papers suggest that the lack of cell cycle arrest and apoptosis gives more cells the chance to be reprogrammed. Decreased levels of p53 were also shown to be a crucial aspect of blastema formation in the legs of salamanders. p53 regulation is very important in acting as a barrier between stem cells and a differentiated stem cell state, as well as a barrier between stem cells being functional and being cancerous.
An association between hearing loss and high level exposures to PFNA was also reported in 2020. PFOA is classified as carcinogenic to humans (Group 1) by the International Agency for Research on Cancer (IARC), with significant associations with the onset of liver, pancreatic, and uterine cancers. IARC also classified PFOS as possibly carcinogenic to humans (Group 2b) based on "strong" mechanistic evidence. Evidence suggests PFOA, perfluorohexanesulfonic acid (PFHxS), and perfluorononanoic acid (PFNA) cause hepatotoxicity in humans and links PFAS exposure to male infertility.
Sources: en.wikipedia.org
No regulator in a major market has approved it for human use. It appears in research settings and in products marketed outside pharmacy channels. Legal status for personal possession varies by country.
Afamelanotide is a linear analog that has received approval in some jurisdictions for a specific photoprotection indication. Melanotan II is cyclic and less selective across melanocortin receptors. The two are related but are not interchangeable in regulatory or clinical terms.
A compound that activates several receptor subtypes may produce effects beyond pigmentation. Selectivity influences which tissues respond and shapes the side-effect profile described in reports. Designing subtype-selective analogs is a stated goal of melanocortin research.
The dry powder is more stable during transport and storage than a solution. It also allows a known amount of material to be reconstituted at a chosen concentration.