Everything below concerns lactam bridge. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-03-07. Where a claim depends on a specific study, the study is described rather than over-claimed.
Melanotan II binds several melanocortin receptor subtypes rather than a single target. MC1R on melanocytes drives melanin synthesis, while MC3R and MC4R participate in energy balance, appetite, and sexual response pathways. This lack of selectivity explains why reported effects extend beyond skin darkening. Substitutions at positions four and seven, including norleucine and D-phenylalanine, increase potency and resistance to peptidases. Understanding which receptor mediates which effect remains an active area of investigation.
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.
No regulatory authority has approved melanotan-2 for human use, and several countries classify it as a prescription-only or controlled substance, which restricts lawful supply. Material sold online is generally labelled as a research chemical and is not required to meet pharmaceutical standards of identity or purity. Published human data consist mainly of small uncontrolled studies, case reports and adverse-event notifications, so the evidence base is descriptive rather than confirmatory. Whether repeated melanocyte stimulation alters long-term naevus behaviour remains an open question that no completed trial has resolved.
Melanotan-2 is a synthetic cyclic heptapeptide designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous tridecapeptide that regulates pigment production. Two modifications distinguish it from the natural hormone: norleucine replaces methionine at the N-terminus, which limits oxidation, and a D-phenylalanine substitution raises receptor affinity. The ring is closed through an aspartate-lysine lactam bridge, giving the molecule a constrained conformation. The free base has a molecular mass near 1024 daltons, and commercial material is usually supplied as an acetate salt. It appears in the literature as a research peptide rather than an approved therapeutic agent.
Receptor studies place melanotan-2 among non-selective melanocortin agonists, binding MC1R, MC3R, MC4R and MC5R rather than a single subtype. Activation of MC1R on cutaneous melanocytes raises tyrosinase activity and shifts pigment synthesis toward eumelanin, which is darker and more photostable than pheomelanin. Central receptors, particularly MC4R, are associated with appetite suppression and with reported effects on sexual function. Because subtype selectivity is low, the same molecule engages pigment, metabolic and vascular pathways at once, and this breadth is a common explanation offered for the range of adverse events described in user reports.
| 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 |
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.
The compound was developed in the late 1980s and early 1990s by academic researchers investigating melanocortin signaling and pigmentation. Early work explored whether synthetic analogs could reproduce effects of the natural hormone under controlled conditions. The molecule never advanced through the full regulatory pathway required for approval as a medicine. From the mid-2000s onward it appeared in unregulated consumer markets, often distributed through informal channels. That gap between research origins and commercial availability shapes how the compound is discussed today.
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.
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.
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.
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.
== Distribution == Nolina lindheimeriana is endemic just to the Edwards Plateau region of western central Texas in the USA. The species has been reported in Zacatecas state, Mexico, well outside the distribution area usually designated, and various online sources report its presence there. Sources for the information in the citation just given do not mention its presence in Zacatecas. Searching for online herbarium collections of Nolina lindheimeriana on file at UNAM (MEXU), the National Autonomous University of Mexico, returns only collections from Texas.
The Chinese Physical Society (CPS) is a professional society of physicists established in 1932. It is part of the China Association for Science and Technology. Current membership is at around 40,000. CPS has been a member of the International Union of Pure and Applied Physics (IUPAP) since 1984 and of the Association of Asia Pacific Physical Societies (AAPPS) since 1990.
The remaining 143 MPs joined the Thinkakhao Chaovilai Party, who held no seats, and the party was renamed to the People's Party on 9 August. Additionally, Padipat also received a 10-year ban and the Fair Party dropped to one MP. Phitsanulok 1st district was won by Pheu Thai candidate Jadet Jantar on 15 September, defeating the People's Party who won the seat as Move Forward in 2023. On 5 October 2024, party-list and sole MP for the New Party Kritdithat Sangthanyothin was expelled from the party. The following day, New Social Power's sole MP Chao Writthit Kachornpongkitti of Nan 1st district was also expelled. Buncha Dechjerongsirikul, party-list MP and leader of the Party of Thai Counties, left the party on 15 October. Preeda Boonpleng, sole MP of the Thai Teachers for People Party, was expelled on 21 October. All four MPs joined the Kla Tham Party by the end of October, increasing Kla Tham's number of seats to four. On 11 December 2024, Thamanat Prompow and his faction of 19 other MPs were expelled by the Palang Pracharath Party and officially joined Kla Tham on 19 December, boosting Kla Tham to 24 seats and making it a medium size party. In 2025, Kla Tham saw further defections to it. On 18 April 2025, Ekarat Changlao of Khon Kaen was expelled by Bhumjaithai amid a embezzlement scandal and joined Kla Tham. On 27 April 2025, Bhumjaithai lost a seat when Kla Tham candidate Kongkiat Katesombat won a by-election in Nakhon Si Thammarat 8th district after Bhumjaithai MP Mukdawan Loengseenil was disqualified for electoral fraud.
=== CANDU reactors === Natural uranium, with 0.72% 235U, is usable as nuclear fuel in reactors designed specifically for this, such as the heavy-water CANDU reactor. By making use of non-enriched uranium, such reactor designs give a nation access to nuclear power for the purpose of electricity production without necessitating the development of fuel enrichment capabilities, which are often seen as a prelude to weapons production.
The efficacy of dapagliflozin to improve kidney outcomes and reduce cardiovascular death in people with chronic kidney disease was evaluated in a multicenter, double-blind study of 4,304 participants. In February 2023, the EU authorized dapagliflozin for extended use to cover heart failure patients across the full spectrum of left ventricular ejection fraction (LVEF), including those with mildly reduced and preserved ejection fraction.
Sources: en.wikipedia.org
Smoking cessation may decrease the metabolism of acetaminophen, beta-blockers, caffeine, oxazepam, pentazocine, propoxyphene, theophylline, and tricyclic antidepressants, leading to higher plasma concentrations of these drugs. Possible alteration of nicotine absorption through the skin from the transdermal nicotine patch by drugs that cause vasodilation or vasoconstriction. Possible alteration of nicotine absorption through the nasal cavity from the nicotine nasal spray by nasal vasoconstrictors (e.g., xylometazoline). Possible alteration of nicotine absorption through oral mucosa from nicotine gum and lozenges by food and drink that modify salivary pH.
== Clinical trials == The drug is currently under development by AbbVie. Navitoclax is used as mono-therapy as well as in combination with chemotherapies (paclitaxel, docetaxel, gemcitabine, and irinotecan), olaparib, erlotinib, venetoclax, and rituximab in advanced hematological malignancies (in both pediatric and adult patients) and solid tumors including ovarian cancer, breast cancer, lung cancer. Additionally, an ongoing global multi-center, randomized, open-label, phase 3 study evaluating efficacy and safety of navitoclax in combination with ruxolitinib versus best available therapy in adult patients with relapsed/refractory myelofibrosis was initiated on 31 August 2020. The study is expected to conclude in 2026.
==== Iodine ==== Iodine used for water purification is commonly added to water as a solution, in crystallized form, or in tablets containing tetraglycine hydroperiodide that release 8 mg of iodine per tablet. The iodine kills many, but not all, of the most common pathogens present in natural fresh water sources. Carrying iodine for water purification is an imperfect but lightweight solution for those in need of field purification of drinking water. Kits are available in camping stores that include an iodine pill and a second pill (vitamin C or ascorbic acid) that will remove the iodine taste from the water after it has been disinfected. The addition of vitamin C, in the form of a pill or in flavored drink powders, precipitates much of the iodine out of the solution, so it should not be added until the iodine has had sufficient time to work. This time is 30 minutes in relatively clear, warm water, but is considerably longer if the water is turbid or cold. If the iodine has precipitated out of the solution, then the drinking water has less available iodine in the solution. Tetraglycine hydroperiodide maintains its effectiveness indefinitely before the container is opened; although some manufacturers suggest not using the tablets more than three months after the container has initially been opened, the shelf life is in fact very long provided that the container is resealed immediately after each time it is opened. Similarly to potassium iodide (KI), sufficient consumption of tetraglycine hydroperiodide tablets may protect the thyroid against uptake of radioactive iodine.
=== Europe === In Europe, the number of individuals affected by osteoarthritis has increased from 27.9 million in 1990 to 50.8 million in 2019. Hand osteoarthritis was the second most prevalent type, affecting an estimated 12.5 million people. In 2019, knee osteoarthritis was the 18th most common cause of years lived with disability (YLDs) in Europe, accounting for 1.28% of all YLDs. This has increased from 1.12% in 1990.
Sources: en.wikipedia.org
=== Assessment and physical examination === Catatonia is often overlooked and under-diagnosed. Most patients present with an underlying psychiatric disorder, which can obscure recognition of catatonia. For example, psychotic symptoms may dominate the clinical picture, while classic catatonic features (such as mutism or posturing) are absent. Motor abnormalities can also be misleading; in mania, increased motor activity is typically goal-directed, whereas in excited catatonia, activity is non–goal-directed and repetitive. Careful observation of motor behavior is therefore crucial for diagnosis. Catatonia remains a clinical diagnosis with no specific laboratory test to diagnose it. However, supportive investigations may help identify underlying causes:
=== Instability === A 2021 Federal Reserve review of the bank found several deficiencies in its risk management procedures. The bank failed to fix six citations issued by the Fed and was placed under a full supervisory review in July 2022. In the autumn, San Francisco Fed officials met with SVB senior leaders to discuss the bank's ability to raise cash in a crisis and possible exposure to losses as interest rates rose. Fed officials determined the bank was using flawed models that led SVB officers to incorrectly believe rising interest rates would increase the bank's interest revenue to substantially stabilize its financial condition. By early 2023, the Fed placed SVB in a "horizontal review" of its risk management procedures. In the week before the collapse, Moody's Investors Service reportedly informed SVB Financial, the bank's holding company, that it was facing a potential double-downgrade of its credit rating because of its unrealized losses. On March 8, 2023, SVB announced it had sold over $21 billion worth of its investments, borrowed $15 billion, and would hold an emergency sale of its stock to raise $2.25 billion, including $500 million to General Atlantic. JPMorgan Chase and Bank of America turned down opportunities to acquire the bank. Despite the steps taken by the bank, Moody's downgraded SVB on March 8.
===== Cuba ===== On 15 September, Lula and four of his cabinet minister visited Cuba where they met with Cuban president and first secretary of the Communist Party of Cuba Miguel Díaz-Canel. During his visit, Lula also attended a summit of the Group of 77 plus China in Havana where he lamented the United States embargo against Cuba stating that the island "is the victim of an illegal economic embargo, Brazil is against any unilateral coercive measure". Lula also criticized the inclusion of Cuba in the US list of states sponsors of terrorism.
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.
No regulatory agency has authorised melanotan-2 as a medicine for any indication. It circulates mainly as a research chemical or through unregulated channels. As a result, identity, purity and content are not independently guaranteed.