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 2026-08-01 and is reviewed periodically as new material appears.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Analogue of alpha-melanocyte-stimulating hormone |
| Common synonyms | MT-II; melanotan 2 | No internationally accepted non-proprietary name |
| Typical presentation | Lyophilised powder in a sealed vial | Often supplied alongside a separate diluent |
| Regulatory status | Unapproved therapeutic substance | Customs seizure reported in several jurisdictions |
| Reported route in use | Subcutaneous injection | Self-administered outside clinical settings |
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.
Receptor binding at MC1R on melanocytes raises intracellular cyclic AMP and increases expression of tyrosinase and related enzymes. The downstream result is greater synthesis of eumelanin, the dark pigment, without ultraviolet exposure acting as the trigger. The compound is not selective, however, and also engages MC3R, MC4R and MC5R, which are expressed in the central nervous system and elsewhere. That lack of selectivity is the explanation usually offered for effects reported outside pigmentation, including appetite suppression and nausea. Selectivity remains a central theme in comparative studies of related peptides.
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.
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.
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.
=== Naturally occurring inhibitors === The plant alkaloid berberine inhibits the transcription of the PCSK9 gene in immortalized human hepatocytes in vitro, and lowers serum PCSK9 in mice and hamsters in vivo. It has been speculated that this action contributes to the ability of berberine to lower serum cholesterol. Annexin A2, an endogenous protein, is a natural inhibitor of PCSK9 activity.
The main street in the city centre, Via Roma, runs atop a tunnel built during the fascist era (when Via Roma itself was totally refurbished and took on its present-day aspect). The tunnel was supposed to host the underground line, but it is now used as an underground car park. A project to build an underground system was ready in the 1970s, with government funding for it and for similar projects in Milan and Rome. Whilst the other two cities went ahead with the projects, Turin's local government led by mayor Diego Novelli shelved the proposal as it believed it to be too costly and unnecessary. The city has an international airport known as Caselle International Airport Sandro Pertini (airport code: TRN), in Caselle Torinese, about 13 km (8 mi) from Turin's centre—connected to the city by rail (from Dora Station) and bus (from Porta Nuova and Porta Susa railway stations). From 2010 to 2023 a bicycle sharing system, the ToBike, was operational. The metropolitan area is served by Turin metropolitan railway service. Central districts are served by tram; lines 3, 4, and 9 are light rail.
== Non-enzymatic transamination == A second type of transamination reaction can be described as a nucleophilic substitution of one amine or amide anion on an amine or ammonium salt. For example, the attack of a primary amine by a primary amide anion can be used to prepare secondary amines:
Sources: en.wikipedia.org
=== Temperature: Gas Mark === Gas Mark is a temperature scale, predominantly found on British ovens, that scales linearly with temperature above 135 °C (Gas Mark 1) and scales with the log of Celsius below 135 °C.
== Properties == N-Methylethanolamine is a clear, colorless, hygroscopic, amine-like smelling liquid which is miscible with water and ethanol in any ratio. Aqueous solutions react strongly basic and are therefore corrosive. The substance is easily biodegradable and has no potential of bioaccumulation due to its water miscibility. NMEA is not mutagenic, but in the presence of nitrite, carcinogenic nitrosamines can be formed from the compound, as it is a secondary amine.
On the same day, China's special representative for Afghanistan, Yu Xiaoyong, told Taliban Foreign Minister Amir Khan Muttaqi that China had contacted Pakistan and was working to reduce tensions between the Taliban and Pakistan. On 9 March, Taliban officials said that they had destroyed a border outpost of Pakistani forces in the Goshta District of Nangarhar province. On the same day, Pakistani officials stated that their ground forces had destroyed an Afghan Taliban border outpost along the border, while the PAF destroyed an ammunition depot at Shaheen Base in Paktika province. On the same day, Pakistan's Information Minister said that Pakistan's military operations inside Afghanistan were aimed at militant hideouts and did not target civilian areas. He said the strikes were based on precise intelligence, dismissed casualty figures released by the Taliban as fabricated, and argued that United Nations reports of civilian casualties relied largely on information provided by the Taliban administration. On 10 March, Pakistani officials stated that they had destroyed important posts and centers of Taliban forces in the Arandu and Kurram sectors, forcing them to abandon their positions. Taliban officials said that Pakistani forces had carried out strikes in parts of Paktika, Paktia, Khost, and Nuristan provinces, killing three civilians and injuring three others. In Pakistan's Mohmand district, Pakistani Taliban militants clashed with police, resulting in no casualties on either side. A soldier was killed and eight injured in a militant attack in Kurram District.
Sources: en.wikipedia.org
==== September ==== The Syrian Observatory for Human Rights reported that Firas Hamayel, a commander in the National Guard, was killed in an ambush in Suwayda. On 21 September, Ayoob Kara, former member of the Israeli Knesset, announced the independence of Suwayda, declaring "We proclaim September 21, 2025, as the historic day of Suwayda’s separation from Syria and from the terrorist government of Ahmed Al-Sharaa". On 26 September, the Syrian Druze militias established a local women's self-defense army as a response to the precarious security situation. More than 500 women are involved. Minors have been forcibly trained to use weapons. On 27 September, the Syrian transitional government bombed the city of Mecdel with a drone and also bombed the city of Kanaker.
Though the allograft (skin transplanted from a member of the same species) is replaced by granulation tissue and is not actually incorporated into the healing wound, it encourages cellular proliferation and provides a structure for epithelial cells to crawl across. On the most difficult chronic wounds, allografts may not work, requiring skin grafts from elsewhere on the patient, which can cause pain and further stress on the patient's system. Collagen dressings are another way to provide the matrix for cellular proliferation and migration, while also keeping the wound moist and absorbing exudate. Additionally Collagen has been shown to be chemotactic to human blood monocytes, which can enter the wound site and transform into beneficial wound-healing cells. Since levels of protease inhibitors are lowered in chronic wounds, some researchers are seeking ways to heal tissues by replacing these inhibitors in them. Secretory leukocyte protease inhibitor (SLPI), which inhibits not only proteases but also inflammation and microorganisms like viruses, bacteria, and fungi, may prove to be an effective treatment. Research into hormones and wound healing has shown estrogen to speed wound healing in elderly humans and in animals that have had their ovaries removed, possibly by preventing excess neutrophils from entering the wound and releasing elastase. Thus the use of estrogen is a future possibility for treating chronic wounds.
Mavatrep (JNJ‐39439335) is a TRPV1 receptor selective competitive antagonist. It is an investigational analgesic that may be a potential treatment for pain and/or inflammation. Phase I trials have been completed in healthy Japanese and Caucasian volunteers. Potential common adverse effects include thermohypoesthesia, chills, feeling cold, and feeling hot.
==== Multicenter ESG Randomized Trial (MERIT) ==== The recently published MERIT study is the first and only randomized controlled trial of the ESG for treatment of obesity and included 209 adult subjects with class I and II obesity (BMI 30–40 kg/m2). It was conducted from Dec. 2017 to Jun. 2019, spanned nine centers in the United States, and comprised 85 adults in the ESG arm and 124 adults in the control arm (lifestyle modification only). Subjects in the ESG arm lost 13.6% of body weight and 49.2% of excess body weight at one year, compared to 0.8% total body weight loss and 3.2% excess weight loss in the control arm at the same time point.
Sources: en.wikipedia.org
No. No major regulatory agency has granted a marketing authorisation for melanotan II as a medicine. Products sold under this name are generally presented as laboratory reagents and are not subject to the batch-release testing applied to approved drugs.
It was developed in the 1980s by researchers investigating analogues of alpha-melanocyte-stimulating hormone for pigmentation and related endpoints. Early work included small human studies during the 1990s. Development did not progress to licensing, and the compound remained a research and grey-market item.
Peptides are prone to truncation, oxidation and aggregation during synthesis and handling. Without independent testing, a buyer cannot confirm the identity or the content of a vial. Analytical surveys of unapproved peptide products have repeatedly found discrepancies between label claims and measured composition.
It is a synthetic cyclic peptide designed as an analog of alpha-melanocyte-stimulating hormone. It acts on melanocortin receptors and is best known from research into pigmentation. It is not an approved pharmaceutical product.