A practical reference on cyclic heptapeptide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-08-18. Anything still debated is marked as such rather than presented as settled.
Research interest has centred on photoprotection and pigmentation, with a smaller body of work on appetite and sexual function. Published human data remain limited to small, frequently uncontrolled studies, and the compound has never received marketing approval from a national medicines regulator. Most laboratory work treats it as a pharmacological tool for probing melanocortin signalling in cell culture or animal models. Whether pigmentation changes observed in people translate into measurable protection against ultraviolet-induced DNA damage remains an open question.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, the naturally occurring peptide involved in pigmentation signalling. Its sequence is conventionally written as Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, with a lactam bridge joining the aspartate side chain to the lysine side chain. The empirical formula is C50H69N15O9 and the monoisotopic mass lies near 1023.5 daltons. N-terminal acetylation and the D-configured phenylalanine both increase resistance to enzymatic breakdown compared with the parent hormone.
Pharmacologically, melanotan-2 behaves as a non-selective agonist across the melanocortin receptor family. Binding at MC1R on dermal melanocytes promotes eumelanin synthesis, which underlies the tanning response described in early human work. Activity at the centrally expressed MC4R receptor is associated with reported effects on appetite and erectile function. Because the peptide does not discriminate strongly among receptor subtypes, attributing any single observed effect to one receptor pathway is generally not possible without selective antagonists or receptor knockout models.
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controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports.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.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | Melanotan II; MT-II; N-acetyl-norleucyl-cyclo[Asp-His-D-Phe-Arg-Trp-Lys] amide | Naming follows peptide convention; the numeral distinguishes it from melanotan-1 |
| Molecular formula | C50H69N15O9 | Includes the lactam bridge; no counter-ion assumed |
| Monoisotopic mass | 1023.53 Da | Free base; salts and counter-ions shift the observed value |
| Appearance | White to off-white lyophilised powder | Batch-to-batch colour variation is not itself proof of impurity |
| Typical analytical method | RP-HPLC purity determination with ESI-MS identity confirmation | Retention time alone does not establish sequence identity |
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.
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.
39. Pain Physician. 2026 Sep;29(6):E753-E754. In Response to Comment on "Cervical Erector Spinae Plane Block vs. Epidural Steroid Injection for Cervical Radicular Pain: A Clinical Trial". Salehi S(1)(2). Author information: (1)Iran University of Medical Sciences, Tehran, Iran. (2)Department of Anesthesiology and Pain Medicine, Baqiyatallah University of Medical Sciences, Tehran, Iran.
23090Th + n → 23190Th + γ β−→25.5 h 23191Pa ( α→3.28 × 104 y 22789Ac ) 23191Pa + n → 23291Pa + γ β−→1.3 d 23292U α→69 y 232U by itself is not particularly harmful, but quickly decays to produce the strong gamma emitter 208Tl. (232Th follows the same decay chain, but its much longer half-life means that the quantities of 208Tl produced are negligible.) These impurities of 232U make 233U easy to detect and dangerous to work on, and the impracticality of their separation limits the possibilities of nuclear proliferation using 233U as the fissile material. 233Pa has a relatively long half-life of 27 days and a high cross section for neutron capture. Thus it is a neutron poison: instead of rapidly decaying to the useful 233U, a significant amount of 233Pa converts to 234U and consumes neutrons, degrading the reactor efficiency. To avoid this, 233Pa is extracted from the active zone of thorium molten salt reactors during their operation, so that it does not have a chance to capture a neutron and will only decay to 233U. The irradiation of 232Th with neutrons, followed by its processing, needs to be mastered before these advantages can be realised. Because this requires more advanced technology than the uranium and plutonium fuel cycle, research continues in this area. Others cite the low commercial viability of the thorium fuel cycle: the international Nuclear Energy Agency predicts that the thorium cycle will never be commercially viable while uranium is available in abundance—a situation which may persist "in the coming decades".
Insulin lispro, sold under the brand name Humalog among others, is a modified type of medical insulin used to treat type 1 and type 2 diabetes. It is delivered subcutaneously either by injection or from an insulin pump. Onset of effects typically occurs within 30 minutes and lasts about 5 hours. Often a longer-acting insulin like insulin NPH is also needed. Common side effects include low blood sugar. Other serious side effects may include low blood potassium. Use in pregnancy and breastfeeding is generally safe. It works the same as human insulin by increasing the amount of glucose that tissues take in and decreasing the amount of glucose made by the liver. Insulin lispro was first approved for use in the United States in 1996. It is a manufactured analogue of human insulin where two amino acids have swapped positions. In 2023, it was the 84th most commonly prescribed medication in the United States, with more than 8 million prescriptions. It is on the World Health Organization's List of Essential Medicines.
However, he also asserted that "other personality traits, including low agreeableness, low conscientiousness and low emotional stability, also attributed to Trump, are associated with greater levels of PTSD", as are "high levels of narcissism", which can also "cause people to react to even limited threats with aggression". On July 22, 2024, the Washington Post reported interviews with medical experts who believed Trump likely has an elevated genetic risk of dementia. Nephew Fred Trump III said that he sees signs of the dementia that he saw in Trump's father, Fred Trump Sr., who was diagnosed with Alzheimer's disease in October 1991, at the age of 86, eight years before he died. In August 2024, Gabriel Sherman reported in Vanity Fair suggestions that Trump was in fact "experiencing trauma from his near-death experience"; a campaign insider reportedly claimed that Trump was "watching that seven-second clip of how close he was to getting shot right in the head – over and over and over again". An August 2024 Morning Consult poll found that the number of respondents who thought Trump was too old to run jumped by seven percent, to 51%, from their previous poll once Trump's opponent changed from Joe Biden to Kamala Harris, and the number of respondents who thought Trump was in good health correspondingly fell by six percent. The poll further reported that nearly 80% of respondents "were unsure he'd be up for serving a full second term". A Marquette University poll released the same day reported that 57% of respondents felt that Trump was too old.
=== Coordinated healing === DeMarco’s animal studies showed a healing phenomenon he termed "coordinated healing". Observing that animal wounds would heal differently when treated with his formula, he tried to explain his observations: after excising a square inch of skin from a rabbit’s shaved back, he would allow it to heal normally while documenting its progress with time-lapse photography. DeMarco then performed the same experiment while treating the rabbit with his formula. He observed that the untreated wound healed haphazardly; closing in a non-circular pattern with uneven levels and with infiltrating hair growth before wound closure. In contrast, the treated rabbit shows healing in a smooth circular pattern with even levels and only after wound closure would the hair begin to regrow.
Sources: pubmed.ncbi.nlm.nih.gov
== Awards == On 29 September 2014, President Goodluck Jonathan honoured Muhammad with the national award of the Officer of the Order of the Niger (OON) for his contributions to primary health care in Nigeria. In 2013, Muhammad won the Public Administrator of the Year Award (PAYA), organized annually by the Centre for Policy Development and Political Studies, Lagos, Nigeria. The centre said after announcing the winner that of the 10 nominees for the award, Muhammad scored 3,025 votes, representing over 50 percent of the total votes cast. He was praised for his efforts in "eradication of poliomyelitis; reduction in maternal and infant mortality; initiatives in addressing human resource challenges in the primary health care sub-sector; integration and decentralization of HIV/AIDs intervention in PHC services in over 1,500 PHC facilities." Muhammad also won the Kwame Nkrumah Leadership Award and the Africa Leadership Icon in 2014 at the 71st Conference of AASU, held at OATTU Conference Centre, in Accra, Ghana. The Kwame Nkrumah Leadership Award and Africa Leadership Icon 2014 are awarded by the All-Africa Students' Union (AASU).
==== Subsidies for Affordable Care Act ("Obamacare") ==== On January 8, 2026, the House voted 230–196 to extend the higher Biden-era subsidies for another three years. Without this extension, it's estimated that monthly premiums will double for many persons who are signed up for the Affordable Care Act. One House Republican said, "I am voting in favor of this discharge and of this legislation to send it to the Senate, so that the Senate will have the opportunity to put forth a reform package that can pass Congress and become law."
Betula alleghaniensis – yellow birch (B. lutea) (eastern Canada, Great Lakes, upper eastern US, Appalachians) Betula caerulea – blue birch (northeast of North America) Betula cordifolia – mountain paper birch (eastern Canada, Great Lakes, New England US) Betula glandulosa – American dwarf birch (Siberia, Mongolia, Russian Far East, Alaska, Canada, Greenland, mountains of western US and New England, Adirondacks) Betula kenaica – Kenai birch ( Alaska, northwestern North America) Betula lenta – sweet birch, cherry birch, or black birch (Quebec, Ontario, eastern US) Betula michauxii – Newfoundland dwarf birch (Newfoundland, Labrador, Quebec, Nova Scotia) Betula minor – dwarf white birch (eastern Canada, mountains of northern New England and Adirondacks) Betula murrayana – Murray's birch (Great Lakes endemic) Betula nana – dwarf birch or bog birch (also in northern Europe and Asia) Betula neoalaskana – Alaska paper birch also known as Alaska birch or Resin birch (Alaska and northern Canada) Betula nigra – river birch or black birch (eastern US) Betula occidentalis – water birch or red birch (B. fontinalis) (Alaska, Yukon, Northwest Territories, western Canada, western US) Betula papyrifera – paper birch, canoe birch or American white birch (Alaska, most of Canada, northern US) Betula populifolia – gray birch (eastern Canada, northeastern US) Betula pumila – swamp birch (Alaska, Canada, northern US) Betula uber – Virginia round-leaf birch (southwestern Virginia)
Quinolinate synthase (EC 2.5.1.72, NadA, QS, quinolinate synthetase) is an enzyme with systematic name glycerone phosphate:iminosuccinate alkyltransferase (cyclizing). This enzyme catalyses the following chemical reaction
Sources: en.wikipedia.org
The hydrophobic effect represents the tendency of water to exclude non-polar molecules. The effect originates from the disruption of highly dynamic hydrogen bonds between molecules of liquid water. Polar chemical groups, such as OH group in methanol do not cause the hydrophobic effect. However, a pure hydrocarbon molecule, for example hexane, cannot accept or donate hydrogen bonds to water. Introduction of hexane into water causes disruption of the hydrogen bonding network between water molecules. The hydrogen bonds are partially reconstructed by building a water "cage" around the hexane molecule, similar to that in clathrate hydrates formed at lower temperatures. The mobility of water molecules in the "cage" (or solvation shell) is strongly restricted. This leads to significant losses in translational and rotational entropy of water molecules and makes the process unfavorable in terms of free energy of the system. In terms of thermodynamics, the hydrophobic effect is the free energy change of water surrounding a solute. A positive free energy change of the surrounding solvent indicates hydrophobicity, whereas a negative free energy change implies hydrophilicity. In this way, the hydrophobic effect not only can be localized but also decomposed into enthalpic and entropic contributions.
=== Negative feedback === Thrombin bound to thrombomodulin activates protein C, an inhibitor of the coagulation cascade. The activation of protein C is greatly enhanced following the binding of thrombin to thrombomodulin, an integral membrane protein expressed by endothelial cells. Activated protein C inactivates factors Va and VIIIa. Binding of activated protein C to protein S leads to a modest increase in its activity. Thrombin is also inactivated by antithrombin, a serine protease inhibitor.
==== Brown MX-5BR ==== Brown MX-5BR or Reactive Brown 10 has a formula of C40H19Cl4CrN12Na2O12S2 and a molecular weight of 1163.6 g/mol, containing two dichlorotriazine rings. Brown MX-5BR, for example, can be used to purify lysozyme, phosphinothricin acetyltransferase. It also shown that it can elute tryptophanyl-tRNA synthetase using Trp as eluant, however, tryptophanyl-tRNA and tyrosyl-tRNA synthetase are the only t-RNA that can be elute out using Brown MX-5BR.
The brain is particularly vulnerable to chemicals that are able to cross the blood-brain barrier. Body-first and brain-first models of Parkinson's disease propose that there are two distinct avenues through which environmental toxicants can enter the nervous system: (1) ingested into the gut and affecting the enteric nervous system (body-first), or (2) inhaled through the nose and affecting the olfactory bulb (brain-first). The World Health Organization (WHO) recommends reducing exposure to environmental factors associated with PD, including pesticides, trichloroethylene (TCE), and air pollution. Traumatic brain injury and Type 2 diabetes are additional risk factors. Exercise, coffee consumption, and diets rich in fruits, vegetables, whole grains, and fish are protective factors associated with lower risk of PD.
He remained home for six months until he overheard his father speaking hurriedly to a visitor about the boy's future ability to support himself. They suspected he had epilepsy. Confronted with his family's poverty, he realized the need for academic excellence. He entered his father's study and began poring over Latin grammar. He fainted three more times but eventually overcame the urge and did not faint again. This event, Jung later recalled, "was when I learned what a neurosis is".
Sources: en.wikipedia.org
It is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, containing seven amino acids with a lactam ring and a D-configured phenylalanine residue. It is supplied as a lyophilised powder for laboratory research.
The natural hormone is a linear tridecapeptide that is rapidly degraded in circulation. Melanotan-2 is shortened, cyclised, N-terminally acetylated, and carries a D-amino acid substitution, all of which slow enzymatic breakdown.
No national medicines regulator has approved melanotan-2 for therapeutic or cosmetic use. In several jurisdictions it is treated as an unapproved prescription medicine, and its legal classification differs from country to country.
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.