Everything below concerns melanocortin receptor. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-05-20. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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 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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Free base; salt forms add to total mass |
| Molecular mass | About 1024 daltons | Calculated for the free base |
| Structural class | Cyclic heptapeptide | Contains D-phenylalanine and norleucine |
| Parent hormone | Alpha-melanocyte-stimulating hormone | Endogenous tridecapeptide of 13 residues |
| Receptor profile | Non-selective melanocortin agonist | Interacts with MC1R, MC3R, MC4R and MC5R |
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.
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.
However, CSP expressing secretions and tissues are not only the female moth pheromone gland, but also antennal branches, mandibles and salivae, cephalic capsula, eyes, proboscis, thorax and abdomen, head, epidermis, fat body, gut, wings and legs, i.e. a wide range of reproductive and non reproductive, sensory and non-sensory fluids and tissues of the insect body [28-31]. Nearly all CSPs are up regulated in most of all tissues from the insect body, particularly in the gut, epidermis and fat body, following insecticide exposure [32].
radical Also free radical. Any atom, molecule, or ion that has at least one unpaired valence electron. With few exceptions, such unpaired electrons make radicals highly chemically reactive, and therefore organic radicals are usually short-lived.
The United States was one of the "Four Policemen" who met to plan the post-war world, alongside the United Kingdom, the Soviet Union, and China. The U.S. emerged relatively unscathed from the war, with even greater economic power and international political influence.
Sources: en.wikipedia.org
This study was only looking at people who have erectile dysfunction. This limitation makes it difficult to obtain a true figure as people who took SSRIs and did not have erectile dysfunction were not included. Reports of PSSD have occurred with almost every SSRI (dapoxetine is an exception). In 2019, the Pharmacovigilance Risk Assessment Committee of the European Medicines Agency (EMA) recommended that packaging leaflets of selected SSRIs and SNRIs should be amended to include information regarding a possible risk of persistent sexual dysfunction. Following the EMA assessment, a safety review by Health Canada "could neither confirm nor rule out a causal link ... which was long lasting in rare cases", but recommended that "healthcare professionals inform patients about the potential risk of long-lasting sexual dysfunction despite discontinuation of treatment". A 2023 review stated that ongoing sexual dysfunction after SSRI discontinuation was possible, but that cause and effect were undetermined. The 2023 review cautioned that reports of sexual dysfunction cannot be generalized to wider practice as they are subject to a "high risk of bias", but agreed with the EMA assessment that cautionary labeling on SSRIs was warranted. On May 20, 2024, a lawsuit was filed by the organization Public Citizen, representing Dr. Antonei Csoka, against the United States Food and Drug Administration (FDA) for failing to act on a citizen petition submitted in 2018.
Duterte accused David of being involved in illegal drugs and stealing church donations, after which the CBCP came to David's defense and vouched for his integrity. Citing continued criticism from Catholic bishops, Duterte's verbal attacks on the Catholic Church escalated in mid-2018 to early 2019, during which he challenged the Catholic Church to show evidence of the existence of God, while expressing his belief in "one Supreme God" and "a universal mind somewhere which controls the universe". In one of his harshest vitriol in June 2018, he remarked that God was "stupid" for permitting the serpent to tempt Eve in the creation story in the Bible; though the controversial statement was later clarified by his spokesperson as Duterte's "personal opinion", it contributed to Duterte's quarterly approval rating dipping to its lowest at 45%. Efforts by the Church to rally public support against the administration's war on drugs, however, were less effective due to Duterte's domestic popularity and high trust ratings.
=== Characterisation and family === After his first scenes aired, Kipa-Williams wrote a detailed biography from his character's perspective on social media. He revealed that Ari's full name is Ariki Wiremu Parata, and that he moved to Australia from New Zealand twelve years prior to his debut appearance. He continued: "I've had a few challenges and those challenges brought me to Summer Bay... I love my whanau (family), I'll do anything for them, but never cross me. I didn't know the guy who died but my heart goes out to the family. As for me, I guess you'll find out if I stay in the bay or if I go when Home and Away returns in 2020." The character's profile on TVNZ confirmed that Ari had served time in prison, which he tries to keep to himself. Kipa-Williams revealed that Ari was involved in "a life of crime", but made the decision to change and leave it behind him. However, "he wrestles with his past" and is constantly "frustrated" with the few opportunities available to him because of his criminal record. Ari is "fiercely protective" of the family, especially since his brother's death, and he has become the patriarch of the family. Although this has left him feeling "a little out of his depth". Ari dislikes confrontation and he struggles to express his emotions, but he is keen to change "his path." Kipa-Williams stated "he has made some strong choices but he is a little bit lost.
Sources: en.wikipedia.org
Aβ is formed after sequential cleavage of the amyloid precursor protein (APP), a transmembrane glycoprotein of undetermined function. APP can be cleaved by the proteolytic enzymes α-, β- and γ-secretase; Aβ protein is generated by successive action of the β and γ secretases. The γ secretase, which produces the C-terminal end of the Aβ peptide, cleaves within the transmembrane region of APP and can generate a number of isoforms of 30–51 amino acid residues in length. The most common isoforms are Aβ40 and Aβ42; the longer form is typically produced by cleavage that occurs in the endoplasmic reticulum, while the shorter form is produced by cleavage in the trans-Golgi network.
The entries in BTO are updated bi-annually as part of the major update of BRENDA. It is available via the BRENDA website in the category “Ontology Explorer”. The enzyme source terms can be searched via the BTO query form. As a result, the user receives a list of EC numbers which are directly connected to the enzyme information of BRENDA. It is also possible to search via the BRENDA “Source Tissue” search form (“Classic View”). The result page displays all enzymes which are isolated or detected in the searched tissue term, directly linked to BTO. BTO and BRENDA are freely accessible for academic users. It can be freely downloaded via the “Ontology Explorer” of the BRENDA website or in the OBO format from “Obofoundry”. BTO (BRENDA Tissue Ontology) BRENDA Ontology Explorer BRENDA-website ExplorEnz – Enzyme Nomenclature Obofoundry Gene Ontology Consortium EBI-EMBL Bioportal des National Center for Biomedical Ontology, Stanford, USA
Artificially acquired passive immunity is a short-term immunization induced by the transfer of antibodies, which can be administered in several forms; as human or animal blood plasma, as pooled human immunoglobulin for intravenous (IVIG) or intramuscular (IG) use, and in the form of monoclonal antibodies (MAb). Passive transfer is used prophylactically in the case of immunodeficiency diseases, such as hypogammaglobulinemia. It is also used in the treatment of several types of acute infection, and to treat poisoning. Immunity derived from passive immunization lasts for only a short period of time, and there is also a potential risk for hypersensitivity reactions, and serum sickness, especially from gamma globulin of non-human origin. The artificial induction of passive immunity has been used for over a century to treat infectious disease, and before the advent of antibiotics, was often the only specific treatment for certain infections. Immunoglobulin therapy continued to be a first line therapy in the treatment of severe respiratory diseases until the 1930s, even after sulfonamide lot antibiotics were introduced.
Sources: en.wikipedia.org
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.
Melanotan-1, also called afamelanotide, is a linear analogue with greater selectivity for MC1R and has received approval in some jurisdictions for a specific photosensitivity disorder. Melanotan-2 is cyclic, less selective, and reaches central receptors more readily. The two are often confused in online discussion despite different pharmacology and regulatory status.
Alpha-MSH is an endogenous tridecapeptide derived from pro-opiomelanocortin. Melanotan-2 reproduces its core receptor-binding sequence inside a shortened, stabilised ring. The result is a molecule with a longer effective half-life and higher potency than the parent hormone.
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.