A practical reference on cyclic heptapeptide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-02-19 and is reviewed periodically as new material appears.
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controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports.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.
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.
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.
| 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 |
Human data remain limited and mostly short-term. Reports describe small trials and observational accounts rather than large controlled studies, so questions about dose-response relationships and long-term effects on melanocytes stay open. Whether repeated exposure alters naevus behaviour is not settled in the published record. Researchers also note that self-administered use outside clinical settings makes actual exposure difficult to quantify. Statements about efficacy and safety should therefore be read as preliminary rather than established.
Melanotan II is a synthetic cyclic heptapeptide that acts as an agonist at melanocortin receptors. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous peptide involved in pigment production. The analogue carries a lactam bridge that constrains the ring and slows enzymatic breakdown relative to the native hormone. In research literature it appears under several abbreviations, and naming conventions are not fully standardized. Published descriptions usually place it within the broader melanocortin agonist family.
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.
North Raleigh is an expansive, diverse, and fast-growing suburban area of the city that is home to established neighborhoods to the south along with many newly built subdivisions and along its northern fringes. The area generally falls North of Millbrook Road. It is primarily suburban with large shopping areas. Primary neighborhoods and subdivisions in North Raleigh include Bartons Creek Bluffs, Bedford, Bent Tree, Black Horse Run, Brier Creek, Brookhaven, Coachman's Trail, Crossgate, Crosswinds, Dominion Park, Durant Trails, Ethan's Glenn, Falls River, Greystone Village, Harrington Grove, Hidden Valley, Lake Park, Long Lake, North Haven, North Ridge, Oakcroft, Shannon Woods, Six Forks Station, Springdale Estates, Stonebridge, Stone Creek, Stonehenge, Summerfield, The Sanctuary, Valley Estates, Wakefield, Weathersfield, Windsor Forest, and Wood Valley. The area is served by a number of primary transportation corridors including Glenwood Avenue US 70, I-540, Wake Forest Road, Millbrook Road, Lynn Road, Six Forks Road, Spring Forest Road, Creedmoor Road, Leesville Road, Norwood Road, Strickland Road, and North Hills Drive.
The switch of the nervous system: Based on the evidence listed below, it has been recently conjectured in, that macro glia (and astrocytes in particular) act both as a lossy neurotransmitter capacitor and as the logical switch of the nervous system. I.e., macroglia either block or enable the propagation of the stimulus along the nervous system, depending on their membrane state and the level of the stimulus.
Although the ancient Egyptians did not always distinguish frankincense from other resins such as myrrh, references to incense from the land of Punt have been dated to the third millennium BCE. Incense trees being transported for cultivation in Thebes are depicted in the so-called "Punt Colonnade" at the mortuary temple of Hatshepsut. The Ebers Papyrus, from around 1500 BCE, provides some of the earliest evidence for frankincense used with intent as a possible therapy. The incense offering occupied a prominent position in the sacrificial legislation of the ancient Hebrews. The Book of Exodus (30:34–38) prescribes frankincense, blended with equal amounts of three aromatic spices, to be ground and burnt in the sacred altar before the Ark of the Covenant in the wilderness Tabernacle, where it was meant to be a holy offering—not to be enjoyed for its fragrance. The Book of Jeremiah (6:20) relates that frankincense was imported from Sheba during the 6th century BC Babylonian captivity. Frankincense is mentioned in the New Testament as one of the three gifts (with gold and myrrh) that the magi "from the East" presented to the Christ Child (Matthew 2:11).
Based on computational work by Bach, the strain energy for Z-cyclooctenes is 7.0 kcal/mol compared to 12.4 kcal/mol for cyclooctane due to a loss of two transannular interactions. E-cyclooctene has a highly twisted double bond resulting in a strain energy of 17.9 kcal/mol. As such, the highly strained trans-cyclooctene is used as a reactive dienophile. The diene is a 3,6-diaryl-s-tetrazine which has been substituted in order to resist immediate reaction with water. The reaction proceeds through an initial cycloaddition followed by a reverse Diels Alder to eliminate N2 and prevent reversibility of the reaction. Not only is the reaction tolerant of water, but it has been found that the rate increases in aqueous media. Reactions have also been performed using norbornenes as dienophiles at second order rates on the order of 1 M−1•s−1 in aqueous media. The reaction has been applied in labeling live cells and polymer coupling.
Sources: en.wikipedia.org
Today, there are several retailers of baker's yeast; one of the earlier developments in North America is Fleischmann's Yeast, in 1868. During World War II, Fleischmann's developed a granulated active dry yeast which did not require refrigeration, had a longer shelf life than fresh yeast, and rose twice as fast. Baker's yeast is also sold as a fresh yeast compressed into a square "cake". This form perishes quickly, so must be used soon after production. A weak solution of water and sugar can be used to determine whether yeast is expired. In the solution, active yeast will foam and bubble as it ferments the sugar into ethanol and carbon dioxide. Some recipes refer to this as proofing the yeast, as it "proves" (tests) the viability of the yeast before the other ingredients are added. When a sourdough starter is used, flour and water are added instead of sugar; this is referred to as proofing the sponge. When yeast is used for making bread, it is mixed with flour, salt, and warm water or milk. The dough is kneaded until it is smooth, and then left to rise, sometimes until it has doubled in size. The dough is then shaped into loaves. Some bread doughs are knocked back after one rising and left to rise again (this is called dough proofing) and then baked. A longer rising time gives a better flavor, but the yeast can fail to raise the bread in the final stages if it is left for too long initially.
Hair analysis to detect addictive substances has been used by court systems in the United States, United Kingdom, Canada, and other countries worldwide. In the United States, hair testing has been accepted in court cases as forensic evidence following the Frye Rule, the Federal Rules of Evidence, and the Daubert Rule. As such, hair testing results are legally and scientifically recognized as admissible evidence. Hair testing is commonly used in the USA as pre-employment drug test. The detection time for this test is roughly 3 months, which is the time, that takes head hair to grow ca. 1.5 inches, that are collected as a specimen. Longer detection times are possible with longer hair samples. A 2014 collaborative US study of 359 adults with moderate-risk drug use found, that a large number of participants, who reported drug use in the last 3 months, had negative hair tests. The tests were done using an immunoassay followed by a confirmatory GC-MS. For marijuana, only about half of self-disclosed users had a positive hair test. Under-identification of drug use by hair testing (or over-reporting) was also widespread for cocaine, amphetamines, and opioids. Because such under-identification was more common among participants, who self-reported an infrequent use, the authors suggested, that the immunoassay did not have the sensitivity required for such infrequent uses. It is worth noting, that most earlier studies reported, that hair tests found ca. 50-fold higher prevalence of illicit drug use, than self reports.
It also possible that the cells involved in these pathological states favor the reversed action of 5-HEDH, conversion of 5-oxo-ETE to 5(S)-HETE, as a consequence of reductions in oxidative stress and thereby NADP+/NADPH ratios; such cells might then actually "detoxify" 5-oxo-ETE and contribute to resolving the pathological states.
Amitabha Chattopadhyay is an Indian scientist working in the areas of membrane and receptor biology and biophysics . He is presently a CSIR Bhatnagar Fellow at the Center for Cellular and Molecular Biology and served as the founding dean of biological sciences at the Academy of Scientific and Innovative Research (AcSIR). In addition, he is a distinguished visiting professor at the Indian Institute of Technology Bombay, adjunct professor at the Jawaharlal Nehru University (New Delhi), Tata Institute of Fundamental Research, Indian Institute of Science Education and Research (Kolkata), Swinburne University of Technology (Australia), and honorary professor at the Jawaharlal Nehru Centre for Advanced Scientific Research (Bangalore). He was elected a Fellow of the Royal Society of Chemistry in 2013 and Royal Society of Biology in 2017. Chattopadhyay has authored more than 300 research papers and has an h-index of 65. In 2016, Chattopadhyay won The World Academy of Sciences in Biology for his seminal contribution in understanding the role of membrane cholesterol in the organization and function in healthy and diseased conditions.
Bohrium is a synthetic chemical element; it has symbol Bh and atomic number 107. It is named after Danish physicist Niels Bohr. As a synthetic element, it can be created in particle accelerators but is not found in nature. All known isotopes of bohrium are highly radioactive; the most stable known isotope is 270Bh with a half-life of approximately 2.4 minutes, though the unconfirmed 278Bh may have a longer half-life of about 11.5 minutes. In the periodic table, it is a transactinide element in the d-block. It is a member of the 7th period and belongs to the group 7 elements as the fifth member of the 6d series of transition metals. Chemistry experiments have confirmed that bohrium behaves as the heavier homologue to rhenium in group 7. The chemical properties of bohrium are characterized only partly, but they compare well with the chemistry of the other group 7 elements.
Sources: en.wikipedia.org
Addiction psychiatry, addiction medicine Brain injury medicine Child and adolescent psychiatry Consultation-liaison psychiatry Forensic psychiatry Geriatric psychiatry Hospice and palliative medicine Sleep medicine
On 7 January 2026, US senator Ruben Gallego introduced a resolution in the US senate to block Trump from invading Greenland. A few days later, Democratic and Republican senators introduced the bipartisan No Funds for NATO Invasion Act, which prohibits the use of federal funds for the invasion of any NATO member state or NATO-protected territory, as well as the bipartisan NATO Unity Protection Act to "prohibit the use of US Department of Defense or Department of State funds to blockade, occupy, annex or otherwise assert control over the sovereign territory of a NATO member state without that ally's consent or authorization from the North Atlantic Council", introduced by Republican senator Lisa Murkowski and Democratic senator Jeanne Shaheen. According to Murkowski, the Act seeks to stop Trump's threats against Greenland. Timothy Broglio, the Archbishop for the Military Services, USA, and former president of the United States Conference of Catholic Bishops, said Trump's actions tarnish the image of the US and that it would be morally acceptable for US soldiers to disobey "morally questionable" orders to attack Greenland. Former Trump spokesperson Sarah Matthews said Trump's Greenland threats were "the most mentally ill, deranged thing" he had done.
==== Conditionality as the middle way – not-self and emptiness ==== The early Buddhist texts also associate dependent arising with emptiness and not-self. The early Buddhist texts outline different ways in which dependent origination is a middle way between different sets of "extreme" views (such as "monist" and "pluralist" ontologies or materialist and dualist views of mind-body relation). In the Kaccānagottasutta (SN 12.15, parallel at SA 301), the Buddha states that "this world mostly relies on the dual notions of existence and non-existence" and then explains the right view as follows:
=== Differential diagnosis === Before a diagnosis of allergic disease can be confirmed, other plausible causes of the presenting symptoms must be considered. Vasomotor rhinitis, for example, is one of many illnesses that share symptoms with allergic rhinitis, underscoring the need for professional differential diagnosis. Once a diagnosis of asthma, rhinitis, anaphylaxis, or other allergic disease has been made, there are several methods for discovering the causative agent of that allergy.
AAA (ATPases Associated with diverse cellular Activities) proteins (more commonly referred to as "triple-A ATPases") are a large group of protein family sharing a common conserved module of approximately 230 amino acid residues. This is a large, functionally diverse protein family belonging to the AAA+ protein superfamily of ring-shaped P-loop NTPases, which exert their activity through the energy-dependent remodeling or translocation of macromolecules. AAA proteins couple chemical energy provided by ATP hydrolysis to conformational changes which are transduced into mechanical force exerted on a macromolecular substrate. AAA proteins are functionally and organizationally diverse, and vary in activity, stability, and mechanism. Members of the AAA family are found in all organisms and they are essential for many cellular functions. They are involved in processes such as DNA replication, protein degradation, membrane fusion, microtubule severing, peroxisome biogenesis, signal transduction and the regulation of gene expression.
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.
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.