Everything below concerns alpha-MSH analogue. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-10-04. Numbers and descriptions here follow the published literature rather than marketing material.
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controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports.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.
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.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, which separates the target peptide from truncated or oxidised impurities. Mass spectrometry, most often coupled to liquid chromatography, confirms molecular mass and detects substitutions that chromatography alone may miss. Amino acid analysis and peptide mapping supply additional structural evidence, while nuclear magnetic resonance is reserved for full structural confirmation. Laboratories that examine samples sold online report wide variation in actual content, with some vials containing little or none of the labelled material.
Melanotan-2 appears on the World Anti-Doping Agency prohibited list within the peptide hormone class, and several national regulators treat it as an unapproved prescription substance. Some countries restrict importation or sale for personal use. Because the compound is widely traded as a research chemical, the practical legal picture differs between jurisdictions and shifts over time. Human safety data covering long periods are limited, and whether repeated pigmentation changes carry any lasting risk to melanocytes remains an open question.
| 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 |
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.
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.
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.
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.
Melanotan-2 has not received marketing authorisation from major regulatory agencies for any therapeutic indication. Several jurisdictions classify it as a prescription-only medicine or a controlled substance when supplied for human use. Because approved products do not exist, material sold online usually sits outside pharmaceutical supply chains and formal quality oversight. Regulators have issued public notices describing the compound as unapproved. Enforcement varies, and the legal position differs between countries, which complicates any single general statement about its status.
Scientific discussion of Melanotan-2 spans pharmacology, dermatology, and public-health literature. Laboratory studies examine its receptor binding and cellular effects, while clinical reports describe outcomes observed after unregulated use. These two bodies of work differ in rigour and intent. Peer-reviewed trials of the compound as a medicine are limited, so much of the available information comes from case reports and surveillance data. Authors frequently note the gap between experimental findings and real-world use.
==== Cofactors ==== Protein enzymes catalyze various chemical reactions, but over half of them incorporate cofactors to facilitate and diversify their catalytic activities. Cofactors are essential in biology, as they are based largely on nucleotides rather than amino acids. Ribozymes use nucleotide cofactors to create metabolism, with two basic choices: non-covalent binding or covalent attachment. Both approaches have been demonstrated using directed evolution to reinvent RNA dupes of protein-catalyzed processes. Lorsch and Szostak investigated ribozymes that could phosphorylate themselves and use ATP-γS as a substrate. However, only one of the seven classes of selected ribozymes had detectable ATP affinity, indicating that the ability to bind ATP was compromised. NAD+- dependent redox ribozymes were also evaluated. The selected ribozyme had a rate of enhancement of more than 107 fold and was proven to catalyze the reverse reaction - benzaldehyde reduction by NADH. Since the usage of adenosine as a cofactor is prevalent in current metabolism and is likely to have been common in the RNA world, these discoveries are essential for the evolution of metabolism in the RNA world.
Racemic menthol can also be formed by hydrogenation of thymol, menthone, or pulegone. In both cases with further processing (crystallizative entrainment resolution of the menthyl benzoate conglomerate) it is possible to concentrate the L-enantiomer, however this tends to be less efficient, although the higher processing costs may be offset by lower raw material costs. A further advantage of this process is that D-menthol becomes inexpensively available for use as a chiral auxiliary, along with the more usual L-antipode.
==== Physical performance ==== Amphetamine is used by some athletes for its psychological and athletic performance-enhancing effects, such as increased endurance and alertness; however, non-medical amphetamine use is prohibited at sporting events that are regulated by collegiate, national, and international anti-doping agencies. In healthy people at oral therapeutic doses, amphetamine has been shown to increase muscle strength, acceleration, athletic performance in anaerobic conditions, and endurance (i.e., it delays the onset of fatigue), while improving reaction time. Amphetamine improves endurance and reaction time primarily through reuptake inhibition and release of dopamine in the central nervous system. Amphetamine and other dopaminergic drugs also increase power output at fixed levels of perceived exertion by overriding a "safety switch", allowing the core temperature limit to increase in order to access a reserve capacity that is normally off-limits. At therapeutic doses, the adverse effects of amphetamine do not impede athletic performance; however, at much higher doses, amphetamine can induce effects that severely impair performance, such as rapid muscle breakdown and elevated body temperature.
=== Exceptions === Some jellyfish species, including Turritopsis dohrnii, Laodicea undulata, and Aurelia sp.1, are able to revert to the polyp stage even after reproducing (so-called reversible life cycle), rather than dying as in other jellyfish. Consequently, these species are considered biologically immortal and have no maximum lifespan. There may be no natural limit to the hydra's life span, but it is not yet clear how to estimate the age of a specimen. Flatworms, or Platyhelminthes, are known to be "almost immortal" as they have a great regeneration capacity, continuous growth, and binary fission type cellular division. Lobsters are sometimes said to be biologically immortal because they do not seem to slow down, weaken, or lose fertility with age. However, due to the energy needed for moulting, they cannot live indefinitely.
Sources: en.wikipedia.org
The dugite (Pseudonaja affinis) is a highly venomous Australian brown snake species. The venom of this species contains highly potent presynaptic and postsynaptic neurotoxins and procoagulants. The murine LD50 is 0.66 mg/kg SC. The average venom yield per bite is 18 mg (dry weight of milked venom) according to Meier and White (1995). Rate of envenomation is 20–40% and the untreated mortality rate is 10–20% by cardiac arrest, kidney failure, or cerebral hemorrhage.
== Aftermath == The recapture of Constantinople signalled the restoration of the Byzantine Empire, and on 15 August, the day of the Dormition of the Theotokos, Emperor Michael VIII entered the city in triumph and was crowned at the Hagia Sophia. The rights of the legitimate emperor, John IV Laskaris, for whom Palaiologos had been ostensibly ruling as a guardian, were brushed aside, and the boy subsequently was blinded and imprisoned.
Often, the patient consumes about 3–4 times the RDA's specification. Toxicity of vitamin A is believed to be associated with the methods of increasing vitamin A in the body, such as food modification, fortification, and supplementation, all of which are used to combat vitamin A deficiency. Toxicity is classified into two categories: acute and chronic. The former occurs a few hours or days after ingestion of a large amount of vitamin A. Chronic toxicity takes place when about 4,000 IU/kg or more of vitamin A is consumed for a long time. Symptoms of both include nausea, blurred vision, fatigue, weight loss, and menstrual abnormalities. Excess vitamin A is suspected to be a contributor to osteoporosis. This seems to happen at much lower doses than those required to induce acute intoxication. Only preformed vitamin A can cause these problems because the conversion of carotenoids or retinyl esters into vitamin A is downregulated when physiological requirements are met; but excessive uptake of carotenoids can cause carotenosis. Excess preformed vitamin A during early pregnancy is associated with a significant increase in birth defects. These defects may be severe, even life-threatening. Even twice the daily recommended amount can cause severe birth defects. The FDA recommends that pregnant women get their vitamin A from foods containing beta carotene and that they ensure that they consume no more than 5,000 IU of preformed vitamin A (if any) per day.
== Medical uses == Ciclosporin is indicated to treat and prevent graft-versus-host disease in bone marrow transplantation and to prevent rejection of kidney, heart, and liver transplants. It is also approved in the US for treating of rheumatoid arthritis and psoriasis, persistent nummular keratitis following adenoviral keratoconjunctivitis, and as eye drops for treating dry eyes caused by Sjögren's disease and meibomian gland dysfunction. In addition to these indications, ciclosporin is also used in severe atopic dermatitis, It has been used in severe rheumatoid arthritis and related diseases. Ciclosporin has also been used in people with acute severe ulcerative colitis and hives that do not respond to treatment with steroids.
Portugal's manufacturing industry accounted for 21.2% of the country's total GDP as of 2024, down from an annual average of 26% over the period between 1953 and 1973. The lower contribution of manufacturing to Portugal's economy has led to lower real GDP growth rates between 1974 and 2019 than during the period between 1950 and 1973. As of 2025, Portugal's automobile industry produced the biggest share of the country's exports. The automobile industry accounts for 20.2% of the country manufacturing exports and 82.8% of the total value of its exports employing 43.247 workers in 2020. Portugal's service sector accounted for 76.5% of the country's total economic output as of 2024. Tourism, retail, and telecommunication are all major industries. Tourism represented 11.8% of the Portugal's total GDP as of 2025. Portugal attracted nearly 30 million international tourists in 2025, ranking 15th in the world in that year for inbound tourism.
Sources: en.wikipedia.org
=== Genome === The Liliaceae include a species with one of the largest genome size within the angiosperms, Fritillaria assyriaca (1C=127.4 pg), while Tricyrtis macropoda is as small as 4.25 pg. Chromosome numbers vary by genus. Some genera like Calochortus (x=6-10), Prosartes (6,8,9,11), Scoliopus (7,8), Streptopus (8, 27) and Tricyrtis (12–13) have a small and variable number of chromosomes while subfamily Lilioideae have a larger and more stable chromosome number (12) as have the Medeoleae (7).
fixative Any chemical compound or solution that causes the fixation of cells, tissues, or other microscopic structures by any mechanism, thus preserving them for long-term, detailed study by methods such as embedding, staining, and microscopy. Common fixatives include dilute solutions of ethanol, acetic acid, formaldehyde, and osmium tetroxide, among others.
An aminoacyl-tRNA synthetase (aaRS or ARS), also called aminoacyl-tRNA ligase, is an enzyme that attaches the appropriate amino acid onto its corresponding tRNA. It does so by catalyzing the transesterification of a specific cognate amino acid or its precursor to one of all its compatible cognate tRNAs to form an aminoacyl-tRNA. In humans, for each of the 20 standard amino acids of the genetic code, there are typically separate aminoacyl-tRNA synthetases that make the corresponding aa-tRNA (see § Genes in humans). This is sometimes called "charging" or "loading" the tRNA with an amino acid. Once the tRNA is charged, a ribosome can transfer the amino acid from the tRNA onto a growing peptide, according to the genetic code. Aminoacyl tRNA therefore plays an important role in RNA translation, the expression of genes to create proteins.
Many forms of human-derived agriculture fit the broad definition of "utilizing a biotechnological system to make products". The cultivation of plants may be viewed as the earliest biotechnological enterprise. Agriculture has been theorized to have become the dominant way of producing food since the Neolithic Revolution. Through early biotechnology, the earliest farmers selected and bred the best-suited crops (e.g., those with the highest yields) to produce enough food to support a growing population. As crops and fields became increasingly large and difficult to maintain, it was discovered that specific organisms and their by-products could effectively fertilize, restore nitrogen, and control pests. Throughout the history of agriculture, farmers have inadvertently altered the genetics of their crops through introducing them to new environments and breeding them with other plants — one of the first forms of biotechnology. These processes were also included in the early fermentation of beer. These processes were introduced in early Mesopotamia, Egypt, China and India, and still use the same basic biological methods. In brewing, malted grains (containing enzymes) convert starch from grains into sugar and then adding specific yeasts to produce beer. In this process, carbohydrates in the grains broke down into alcohols, such as ethanol. Later, other cultures developed the process of lactic acid fermentation, which produced other preserved foods, such as soy sauce. Fermentation was also used in this time period to produce leavened bread.
Regulatory T cells are crucial for the maintenance of immune tolerance. Their major role is to shut down T cell–mediated immunity toward the end of an immune reaction and to suppress autoreactive T cells that escaped the process of negative selection in the thymus. Two major classes of CD4+ Treg cells have been described—FOXP3+ Treg cells and FOXP3− Treg cells. Regulatory T cells can develop either during normal development in the thymus, and are then known as thymic Treg cells, or can be induced peripherally and are called peripherally derived Treg cells. These two subsets were previously called "naturally occurring" and "adaptive" (or "induced"), respectively. Both subsets require the expression of the transcription factor FOXP3 which can be used to identify the cells. Mutations of the FOXP3 gene can prevent regulatory T cell development, causing the fatal autoimmune disease IPEX. Several other types of T cells have suppressive activity, but do not express FOXP3 constitutively. These include Tr1 and Th3 cells, which are thought to originate during an immune response and act by producing suppressive molecules. Tr1 cells are associated with IL-10, and Th3 cells are associated with TGF-beta. Recently, Th17 cells have been added to this list.
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.
The lyophilised solid is best kept cold, dry and dark, typically at minus twenty degrees Celsius. Moisture and repeated warming cycles are the main causes of degradation. Solutions prepared from the powder are less stable and are normally used quickly.