Everything below concerns lactam bridge. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-06-04. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic cyclic heptapeptide | Analog of alpha-MSH with an internal lactam bridge |
| Molecular weight | Approximately 1024 daltons | Free base value; salt forms differ |
| Appearance | White to off-white powder | Usually supplied as a lyophilized solid |
| Solubility | Freely soluble in water | Poorly soluble in nonpolar solvents |
| Typical storage | −20 °C, dry, protected from light | Repeated freeze-thaw cycles degrade peptides |
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.
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.
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.
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.
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.
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.
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.
Freeman's performance generated a positive response; Owen Gleiberman of Entertainment Weekly wrote: "Freeman plays nearly every scene in a doleful hush; he makes you lean in to hear his words, to ferret out the hints of anger and regret that haunt this weary knight." The critic from Variety magazine called Freeman's acting "supremely nuanced". While filming Outbreak, Freeman expressed an interest in starting a film production company. He turned to McCreary, the producer of Bopha!, to be his business partner. Freeman explained that he wanted to achieve representation on screen, explore challenging issues and reveal hidden truths, so they chose to name their firm Revelations Entertainment. A year later, he appeared in Chain Reaction as Paul Shannon, a science-fiction thriller co-starring Keanu Reeves and Rachel Weisz. The film was a critical and commercial disappointment. Next, he was cast opposite Robin Wright in 1996's Moll Flanders, a period drama based on the novel of the same name. The film received a mixed reception; Greg Evans from Variety magazine said Freeman gave a "sweet" performance, while The New York Times critic thought he was miscast.
=== Dorsal genital slits in some African tribes === A variety of "dorsal slit" circumcision was once predominant amongst the Maasai tribe of Kenya and Tanzania, and is still practised and found in many of the more remote regions of the very large area known as "Maasailand" generally. However, the Maasai operation is different in this: rather than a dorsal slit from the opening of the prepuce to the corona, a heart shaped "oval" is excised from the dorsum of the prepuce and the glans is pushed through this hole. Later the edges of the cut prepuce will heal. The prepuce is first cut off, leaving only a small part where the main veins are located, which is pulled down and the small hole through which the glans in pushed through is created. The remaining part is left hanging down, but the glans exposed. Formerly tribes that copied the Maasai like the numerous Kikuyu, Embu and Meru of Kenya also practised the same form of circumcision. Photos of the operation and result are numerously found in specialized African books, such as Carol Beckwith and Tepelit Ole Saitoti's Maasai. There are words for the resultant "preputial flap" in the Maa and Gikuyu languages, and possibly in other African tongues. In Gikuyu the word, now archaic, is likely to be ngwati.
=== Laser restoration of historical monuments === The companies Jaulard and Trivella (companies from France and Italy respectively), together with the laser specialists Quantel (France) and Unilaser (from France and Portugal) have developed the LAMA project of a laser that can be carried by hand and used to clean the facades and sculpted ornaments of historical monuments. The process makes it easier to select the area to be cleaned without damaging "the outer skin" of the stone and outperforms all other existing systems at a fifth of the cost.
The SeV genome is non-segmented, negative-sense RNA, of about 15.384 n. in length, and contains the noncoding 3′ leader and 5′ trailer regions, which are about 50 nucleotides in length. As in other respiroviruses from family Paramyxoviridae, in SeV they work as cis-acting elements essential for replication. A 3′ leader sequence acts as a transcriptional promoter. Between these non-coding regions are located six genes, which encode the nucleocapsid (NP) protein, phosphoprotein (P), matrix protein (M), fusion protein (F), hemagglutinin-neuraminidase (HN) and large (L) protein in this order from the 3′ terminus. The RNA-dependent RNA polymerase of the SeV consists of the large protein (L) and the phosphoprotein (P). The structural gene sequence of SeV is as follows: 3′-NP-P-M-F-HN-L-5′. Intergenomic regions between these genes are three nucleotides long as in other respiroviruses. Additional proteins, which are frequently called non structural or accessory proteins can be produced from the P gene, using alternative reading frames. The Sendai virus P/C mRNA contains five ribosomal initiation sites between positions 81 and 201 from the 5' end. One of these sites initiates in the P open reading frame, whereas four others initiate a nested set of C proteins (C', C, Y1, Y2). These C proteins are initiated in the + 1 reading frame to that of P at different translation starting sites. Sendai virus uses ribosome shunting to express Y1 and Y2 proteins that initiate at the fourth and fifth start sites on the P/C mRNA (respectively).
Sources: en.wikipedia.org
Because pellagra outbreaks occurred in regions where maize was a dominant food crop, the most convincing hypothesis during the late 19th century, as espoused by Cesare Lombroso, was that the maize either carried a toxic substance or was a carrier of disease. Louis Sambon, an Anglo-Italian doctor working at the London School of Tropical Medicine, was convinced that pellagra was carried by an insect, along the lines of malaria. Later, the lack of pellagra outbreaks in Mesoamerica, where maize is a major food crop, led researchers to investigate processing techniques in that region. Pellagra was studied mostly in Europe until the late 19th century, when it became epidemic especially in the Southern United States. In the early 1900s, pellagra reached epidemic proportions in the American South. Between 1906 and 1940 more than 3 million Americans were affected by pellagra with more than 100,000 deaths, yet the epidemic resolved itself right after dietary niacin fortification. Pellagra deaths in South Carolina numbered 1,306 during the first 10 months of 1915; 100,000 Southerners were affected in 1916. At this time, the scientific community held that pellagra was probably caused by a germ or some unknown toxin in corn.
With the advantage of being located near the Arabian Peninsula, Somali traders have increasingly begun to challenge Australia's traditional dominance over the Gulf Arab livestock and meat market, offering quality animals at very low prices. In response, Gulf Arab states have started to make strategic investments in the country, with Saudi Arabia building livestock export infrastructure and the United Arab Emirates purchasing large farmlands. Somalia is also a major world supplier of frankincense and myrrh. The modest industrial sector, based on the processing of agricultural products, accounts for 10% of Somalia's GDP. According to the Somali Chamber of Commerce and Industry, over six private airline firms also offer commercial flights to both domestic and international locations, including Daallo Airlines, Jubba Airways, African Express Airways, East Africa 540, Central Air and Hajara. In 2008, the Puntland government signed a multimillion-dollar deal with Dubai's Lootah Group, a regional industrial group operating in the Middle East and Africa. According to the agreement, the first phase of the investment is worth Dhs 170 m and will see a set of new companies established to operate, manage and build Bosaso's free trade zone and sea and airport facilities. The Bosaso Airport Company is slated to develop the airport complex to meet international standards, including a new 3,400 m (11,200 ft) runway, main and auxiliary buildings, taxi and apron areas, and security perimeters.
=== Regional cuisines === Chilies are present in many cuisines, including curries. In Peru, Papa a la huancaina is a dish of potatoes in a sauce of fresh cheese and aji amarillo chilies. In Thailand, kaeng tai pla fish curry is flavoured with a tai pla sauce made with garlic, shallots, galangal, kaffir lime, turmeric, fish paste, and bird's eye chilies. In Jamaica, jerk chicken is spiced with powerful habanero chilies and allspice. Goan vindaloo curry uses the extremely hot ghost pepper or bhut jolokia to create "perhaps [India's] hottest dish". In Bhutan, ema datshi, entirely made of chili mixed with local cheese, is the national dish. Many Mexican dishes use chilies of different types, including the jalapeño, poblano, habanero, serrano, chipotle, ancho, pasilla, guajillo, de árbol, cascabel and mulato. These offer a wide range of flavours including citrus, earthy, fruity, and grassy. They are used in many dishes and the spicy mole sauce and Mexican salsa sauces. In Yoruba cuisine, chillies are well used in many dishes including Ewa Agoyin and Obe ata.
==== Elimination and duration ==== Levels of progesterone with oral progesterone have been measured by the unreliable method of IA as remaining elevated for 12 to 24 hours. Regardless of the assay method, peak levels of progesterone following a dose of oral progesterone occur after about 1 to 3 hours. The elimination half-life of progesterone in circulation is very short at a range of about 3 to 90 minutes. Previous studies using IA have reported an overestimated elimination half-life of oral progesterone of about 16 to 18 hours. Subsequent, reliable studies using high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) and similar methods reported elimination half-lives of progesterone with oral progesterone of about 4.6 to 5.2 hours and 9.98 hours when it was taken with food. Due to the short half-life and duration of action of oral progesterone, it may be taken in divided doses two or three times per day.
=== 11 June === The SAF announced its withdrawal from the Libya-Egypt-Sudan border triangle following attacks by the LNA and the RSF the previous day. Eight people were killed by RSF shelling in Abu Shouk IDP camp.
Sources: en.wikipedia.org
=== As applied to chronic wounds === During the year 2000, the concept was applied to systematizing the treatment of chronic wounds. The 2000 proposals recommended that wound management address the identifiable impediments to healing in order to achieve more successful outcomes. Three publications appeared that year that focused on the concept of managing the healing processes of a wound exudate, bioburden and devitalized tissue. Initially, emphasis was placed on debridement, moisture balance and bacterial balance as the three guiding principles of good wound care, while at the same time recognizing that the provision of care includes a vast array of patient, clinical and environmental variables.
== Serological surveys == A 2016 research paper by Metcalf et al., amongst whom were Neil Ferguson and Jeremy Farrar, stated that serological surveys are often used by epidemiologists to determine the prevalence of a disease in a population. Such surveys are sometimes performed by random, anonymous sampling from samples taken for other medical tests or to assess the prevalence of antibodies of a specific organism or protective titre of antibodies in a population. Serological surveys are usually used to quantify the proportion of people or animals in a population positive for a specific antibody or the titre or concentrations of an antibody. These surveys are potentially the most direct and informative technique available to infer the dynamics of a population's susceptibility and level of immunity. The authors proposed a World Serology Bank (or serum bank) and foresaw "associated major methodological developments in serological testing, study design, and quantitative analysis, which could drive a step change in our understanding and optimum control of infectious diseases."
=== Hunger and satiety hormones === Unlike the surgical sleeve gastrectomy, the ESG does not appear to affect central appetite signaling through the hunger hormone, ghrelin. This is thought to be because the surgical sleeve removes the fundus, the primary site of ghrelin production, and the relatively thinner-walled fundus is avoided in the ESG for safety concerns. Furthermore, in cases where the fundus was sutured in ESG, this did not benefit weight loss outcomes.
It is often desirable to know the unordered amino acid composition of a protein prior to attempting to find the ordered sequence, as this knowledge can be used to facilitate the discovery of errors in the sequencing process or to distinguish between ambiguous results. Knowledge of the frequency of certain amino acids may also be used to choose which protease to use for digestion of the protein. The misincorporation of low levels of non-standard amino acids (e.g. norleucine) into proteins may also be determined. A generalized method often referred to as amino acid analysis for determining amino acid frequency is as follows:
According to the Federal Office for Radiation Protection, the few available results from investigations in the frequency range of active whole-body scanners that work with millimeter wave or terahertz radiation do not yet allow a conclusive assessment from a radiation protection perspective (as of 24 May 2017). In the vicinity of the plant, where employees or other third parties may be present, the limit value of the permissible annual dose for a single person in the population of one millisievert (1 mSv, including pregnant women and children) is not exceeded, even in the case of permanent presence. In the case of X-ray scanners for hand luggage, it is not necessary to set up a radiation protection area by Section §19 RöV, as the radiation exposure during a hand luggage check for passengers does not exceed 0.2 microsievert (μSv), even under unfavorable assumptions. For this reason, employees involved in baggage screening are not considered to be occupationally exposed to radiation in accordance with Section §31 X-ray Ordinance and therefore do not have to wear a dosimeter.
Sources: en.wikipedia.org
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.
Melanotan-1, also called afamelanotide, is a shorter linear analog with a different amino acid sequence and no lactam ring. It has been evaluated in formal clinical programs, while melanotan-2 has not. The two are distinct molecules and are not interchangeable.
No. Bremelanotide is a related but distinct cyclic peptide that reached approved status for one specific clinical indication. Melanotan-2 is a separate molecule with its own sequence and properties. Shared ancestry in the melanocortin family does not make them the same substance.
No. It is a synthetic analogue carrying four amino acid changes, a lactam ring and an amidated C-terminus. The natural hormone is a linear thirteen-amino-acid peptide processed from proopiomelanocortin.