cyclic peptide is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2025-08-31. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
| 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 |
== Honors and awards == Pauling received numerous honorary degrees (around 47 by his death), starting with his alma mater in 1933, and including prestigious institutions like Cambridge University, Oxford University, Princeton University, Reed College, and Yale University. Awards and honors received during his career include the following:
== Philanthropy == The Dunkin' Joy in Childhood Foundation is an independent 501(c)3 charitable organization founded in 2006 to provide the simple joys of childhood to kids battling hunger or illness. The Foundation partners with food banks, children's hospitals, and nonprofit organizations to fund joyful environments and experiences for children across the country. Since its founding, the Foundation has granted more than $70 million to hundreds of national and local charities. Kari Bornhorst McHugh served as Executive Director from March 2017 to August 2021. In December 2018, McHugh launched the Dogs for Joy program, the first initiative of its scale to place full-time specially trained facility dogs in children's hospitals nationwide, backed by more than $2 million in initial grants. As part of the launch, McHugh brought in Cooper Dunkin', a Black Lab/Golden Retriever mix trained by Canine Assistants, who served as the Foundation's Chief Joy Officer and program ambassador, visiting children's hospitals across the country. In 2020, the Foundation launched Joyful Spaces, a program funding the creation and renovation of playgrounds, healing gardens, and play spaces at children's hospitals. Also during the COVID-19 pandemic, the Foundation introduced Hero Recharge, created in partnership with outdoor adventure nonprofit First Descents to support healthcare workers, which received an honorable mention in the Corporate Social Responsibility category of Fast Company's 2021 World Changing Ideas Awards.
The constitution, which was promulgated in 1924, 1936 and 1977, did not limit state power. No separation of powers existed in the Soviet Union, as the state system was based on the unified state power of the highest organ of state authority, that is, the All-Union Supreme Soviet which worked under the party's leadership. The system was governed less by statute than by informal conventions, and no settled mechanism of leadership succession existed. Bitter and at times deadly power struggles took place in the Politburo after the deaths of Lenin and Stalin, as well as after Khrushchev's dismissal, itself due to a decision by both the Politburo and the Central Committee. All leaders of the Communist Party before Gorbachev died in office, except Georgy Malenkov and Khrushchev, who were both dismissed from the party leadership amid internal struggle within the party. Between 1988 and 1990, facing considerable opposition, Mikhail Gorbachev enacted reforms shifting power away from the highest bodies of the party and making the Supreme Soviet less dependent on them. The Congress of People's Deputies was established, the majority of whose members were directly elected in competitive elections held in March 1989, the first in Soviet history. The Congress now elected the Supreme Soviet, which became a full-time parliament, and much stronger than before. For the first time since the 1920s, it refused to rubber stamp proposals from the party and Council of Ministers.
Granzyme B also cleaves many of the proteins responsible for apoptosis in the absence of caspase activity. The other granzymes activate cell death by caspase-dependent and caspase-independent mechanisms. In addition to killing their target cells, granzymes can target and kill intracellular pathogens. Granzymes A and B induce lethal oxidative damage in bacteria by cleaving components of the electron transport chain, while granzyme B cleaves viral proteins to inhibit viral activation and replication. The granzymes bind directly to the nucleic acids DNA and RNA; this enhances their cleavage of nucleic acid binding proteins. More recently, in addition to T lymphocytes, granzymes have been shown to be expressed in other types of immune cells such as dendritic cells, B cells and mast cells. In addition, granzymes may also be expressed in non-immune cells such as keratinocytes, pneumocytes and chondrocytes. As many of these cell types either do not express perforin or do not form immunological synapses, granzyme B is released extracellularly. Extracellular granzyme B can accumulate in the extracellular space in diseases associated with dysregulated or chronic inflammation leading to the degradation of extracellular matrix proteins and impaired tissue healing and remodelling. Extracellular granzyme B has been implicated in the pathogenesis of atherosclerosis, aneurysm, vascular leakage, chronic wound healing, and skin aging.
== Background == An estimated 50% of oxidoreductases catalyze the transfer of a hydride using the nicotinamide adenine dinucleotide cofactor NAD(P). Nicotinamide adenine dinucleotide phosphate (NADPH) is used in anabolic reactions while nicotinamide adenine dinucleotide (NAD) is used in catabolic reactions. In the field of biocatalysis, NAD(P)-dependent oxidoreductases are widely used for the production of chiral alcohols, amines, and other valuable compounds. Yet the reduced forms of the cofactor, NADH and NADPH, needed for the catalysis, is too expensive to be used in stoichiometric amounts. Therefore a cofactor recycling system is usually employed.
Sources: en.wikipedia.org
Conditions in the predominant agricultural sector kept deteriorating between 1929 and 1939, which resulted in rural unrest and a progressive radicalization of the Polish peasant movement that became increasingly inclined toward militant anti-state activities. It was firmly repressed by the authorities. According to Norman Davies, the failures of the Sanation government (combined with the objective economic realities) caused a radicalization of the Polish masses by the end of the 1930s, but he warns against drawing parallels with the incomparably more oppressive Nazi Germany or the Stalinist Soviet Union.
Cristalino [kɾistaˈlino] ("crystalline"): aged tequila that has been filtered to remove its color before bottling, similar to chill filtering of whisky Rosa ("pink"): a young version of the spirit "lightly aged in red wine barrels"
As such, the transdermal route cannot easily achieve adequate circulating progesterone levels, and this makes transdermal progesterone impractical for systemic therapy. Clinical studies have found only very low circulating levels of progesterone with the use of transdermal progesterone, and these levels are thought to be insufficient to confer endometrial protection against estrogens. The range of circulating levels of progesterone that has been observed in clinical studies with various formulations and doses of transdermal progesterone is 0.38 to 3.5 ng/mL. Although very low levels of progesterone have been observed in venous blood with transdermal progesterone, very high and in fact greatly supraphysiological levels of progesterone have unexpectedly been found in saliva and capillary blood. In one study, the levels of progesterone in saliva and capillary blood were 10- and 100-fold greater than levels in venous blood, respectively. Levels of salivary progesterone that have been observed have ranged from 2.9 to 2,840 ng/mL. The high salivary and capillary blood levels of progesterone suggest that despite low circulating levels of progesterone, systemic distribution of progesterone and considerable exposure of some tissues to the hormone may be occurring with transdermal progesterone somehow. However, the few clinical studies that have assessed the effects of transdermal progesterone on the endometrium have had mixed findings, and further research is needed to determine whether it can confer adequate endometrial protection as a component of menopausal hormone therapy.
=== 15 June === At least 35 people were killed by RSF shelling on an IDP shelter at the agriculture ministry building in El Fasher. The SAF claimed to have repelled an RSF assault on El Fasher, destroying two armored troop carriers, two armored combat vehicles, and killing and injuring dozens of soldiers.
Sources: en.wikipedia.org
Grinners Food Systems Limited, the franchiser of Greco Pizza (since 1981) and Captain Sub, is a Truro, Nova Scotia-based company. It is owned by Trucorp Investments Incorporated. Trucorp, headquartered in Dieppe, New Brunswick, also owns Bonte Foods Limited, Frank and Gino's Restaurants, and Chris Brothers food products. Established in Moncton, New Brunswick in 1977, Greco Pizza is one of Atlantic Canada's largest pizza chains. Menu items include pizza, donair, salads, garlic fingers, and the restaurant's proprietary dipping sauces. Many of the over 170 locations in Quebec, Ontario, New Brunswick, Nova Scotia, and Newfoundland operate co-branded with Captain Submarine. Both are quick-service restaurants. Captain Submarine was acquired by Grinner's in 2002, when it only had nine locations (21 fewer than it had in the 1980s). Many of the stores franchised since then also sell Greco Pizza items. The purchase brought the number of Grinners franchised restaurants from 111 to 120.
=== Natural resources and energy === Belize is known to have a number of economically important minerals, but none in quantities large enough to warrant mining. These minerals include dolomite, barite (source of barium), bauxite (source of aluminium), cassiterite (source of tin), and gold. In 1990 limestone, used in road construction, was the only mineral resource exploited for domestic or export use. In 2006, the cultivation of newly discovered crude oil in the town of Spanish Lookout has presented new prospects and problems for this developing nation. Access to biocapacity in Belize is much higher than world average. In 2016, Belize had 3.8 global hectares of biocapacity per person within its territory, much more than the world average of 1.6 global hectares per person. In 2016 Belize used 5.4 global hectares of biocapacity per person – their ecological footprint of consumption. This means they use more biocapacity than Belize contains. As a result, Belize is running a biocapacity deficit.
=== 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.
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.
It is a synthetic cyclic heptapeptide and an analogue of alpha-melanocyte-stimulating hormone. The molecule is produced by chemical synthesis rather than extracted from a biological source.