cyclic heptapeptide raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2025-10-16 and is reviewed periodically as new material appears.
Early published reports described melanotan-2 as a tanning agent without sun protection, which means darkening is not the same as protection against ultraviolet radiation. Later studies explored the peptide in erectile dysfunction, hemorrhagic shock, and some skin conditions. No regulator in the United States or Europe has approved it for clinical use. Many products labelled melanotan-2 are sold without approval and their identity and purity are unverified. Its long-term safety in humans remains an open question.
Melanotan-2, also written Melanotan II, is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, and the lactam bridge between the aspartate and lysine side chains constrains the peptide into a ring. This structural change increases receptor affinity and metabolic stability relative to the native hormone. The compound was created in the 1980s as a research tool for studying pigmentation biology.
Melanocytes are the pigment-producing cells of the skin, and they carry melanocortin-1 receptors on their surface. When the receptor is activated, cyclic adenosine monophosphate rises inside the cell and raises the activity of enzymes such as tyrosinase, which increases melanin output. Melanotan-2 binds melanocortin-1 receptors in vitro and in animal models, and this binding is generally described as the basis for the tanning effect. Other receptors account for different effects: melanocortin-4 receptors contribute to appetite and erectile signalling, while melanocortin-3 and melanocortin-5 receptors contribute to energy balance and exocrine function.
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 |
|---|---|---|
| Compound class | Synthetic cyclic heptapeptide | Alpha-MSH analogue containing a D-phenylalanine residue |
| Molecular formula | C50H69N15O9 | Average molecular mass approximately 1024.2 g/mol |
| Appearance | White to off-white lyophilised powder | Normally supplied as a freeze-dried solid in a sealed vial |
| Solubility | Freely soluble in water and polar solvents | Dissolves readily in aqueous buffers and in alcohol-water mixtures |
| Receptor targets | MC1R, MC3R, MC4R, MC5R | Acts as a non-selective melanocortin receptor agonist |
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.
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.
== Release == Library of Ruina was initially released for Windows via Steam's early access program on May 15, 2020, before being fully released for Windows and Xbox One on August 10, 2021. Versions for Nintendo Switch and PlayStation 4 were made available by publisher Arc System Works on April 25, 2024.
Graduation from an accredited school with the appropriate degree Completion of supervised clinical experience or internship Passing a written examination and, in some states, an oral examination All U.S. state and Canadian province licensing boards are members of the Association of State and Provincial Psychology Boards (ASPPB), which created and maintains the Examination for Professional Practice in Psychology (EPPP). Many states require other examinations in addition to the EPPP, such as a jurisprudence (i.e. mental health law) examination and/or an oral examination. Most states also require a certain number of continuing education credits per year in order to renew a license, which can be obtained through various means, such as taking audited classes and attending approved workshops. Clinical psychologists require the psychologist license to practice, although other mental health provider licenses can be obtained with a master's degree, such as Marriage and Family Therapist (MFT), Licensed Professional Counselor (LPC), and Licensed Psychological Associate (LPA).
Mephenoxalone (trade names Dorsiflex, Moderamin, Control-OM) is a muscle relaxant and mild anxiolytic. It inhibits neuron transmission, relaxing skeletal muscles by inhibiting the reflex arc. As the effect of muscle relaxation, mephenoxalone affects mental condition, and is also a treatment for nervousness and anxiety.
== Lineage Foundation for Good == In October 2021, Lineage announced the launch of Lineage Foundation for Good, the independent philanthropic arm of Lineage. The Foundation was created by a $3 million gift from Lineage to support the company's philanthropic efforts and support initiatives and organizations that align to its mission and work towards innovative and sustainable solutions to help reduce food waste and fight food insecurity. In 2022, Lineage facilitated donations of over 2.7 million pounds of food products from customers, issued almost $3 million in grants, and recorded over 5,000 volunteer hours via the Lineage Foundation for Good during its first year as a public charity. The same year, Lineage Hardship Fund launched to provide assistance to team members impacted by hardships, providing over $622,000 in 2022 to support 152 team members and their families through the Lineage Foundation for Good. The Foundation has partnered with organizations including Feeding America and Global FoodBanking Network to help provide meals to those in need. In 2023, Lineage and the Foundation sponsored DC Central Kitchen's Capital Food Fight and partnered with Forgotten Harvest to supply nearly 12,000 metro Detroit households with holiday meal boxes. Also in 2023, the Foundation announced a new partnership with Jared Goff, quarterback for the Detroit Lions and global ambassador for the Foundation, to donate meals for every touchdown the quarterback threw and to provide meals to families in need during the holidays.
Sources: en.wikipedia.org
There are two recorded instances of the parasitic cookiecutter shark targeting white sharks off Guadalupe, though the scarcity of such records suggests white sharks are not a primary food source for them. As many as 116 parasite species infest white sharks, including copepod crustaceans—such as Nesippus orientalis, Nemesis lamna, and Dinemoura latifolia—which attach to the skin, fins, mouth, and gills. The white shark is the primary host of two species of tapeworms from the genus Clistobothrium; Clistobothrium carcharodoni and Clistobothrium tumidum. The former is believed to be transmitted to white sharks through the consumption of infected cetacean prey, while the transmission source of C. tumidum is unknown. The intensity of C. carcharodoni infestations can be remarkably high; in one documented case, as many as 2,533 specimens were recovered from the spiral valve of a single individual.
=== Minerals === At the bottom of the chain, minerals were unable to move, sense, grow, or reproduce. Their attributes were being solid and strong, while the gemstones possessed magic. The king of gems was the diamond.
There are 120 genes on the R1 plasmid, and these genes can be sorted into three different groups. The largest group, as seen in green in Figure 1, is the conjugative plasmid backbone. The region pictured in purple is primarily a Tn21-like transposon, and the smallest region pictured in yellow contains sequences resembling those of Klebsiella oxytoca.
The sucrose lysis test is a diagnostic laboratory test used for diagnosing paroxysmal nocturnal hemoglobinuria (PNH), as well as for hypoplastic anemias and any hemolytic anemia with an unclear cause. The test works by using sucrose, which creates a low ionic strength environment that allows complement to bind to red blood cells. In individuals with PNH, some red blood cells are especially vulnerable to lysis caused by complement. The test may also produce suspicious results in other hematologic conditions, including megaloblastic anemia and autoimmune hemolytic anemia. False-negative results can occur when complement activity is absent in the serum. A simpler alternative called the sugar water test also involves mixing blood with sugar and observing for hemolysis, using the same principle as the sucrose lysis test.
== German Mass Spectrometry Society (Deutsche Gesellschaft für Massenspektrometrie, DGMS) == The major awards of the German Mass Spectrometry Society (Deutsche Gesellschaft für Massenspektrometrie, DGMS) are the Mattauch-Herzog Award for Mass Spectrometry, Wolfgang Paul Lecture, Mass Spectrometry in the Life Sciences Award, and Life Science Prize.
Sources: en.wikipedia.org
=== Pharmacokinetics === 4-Fluorodeprenyl is metabolized to 4-fluoromethamphetamine and 4-fluoroamphetamine, both of which are active. The levels of substituted amphetamine metabolites in the brain is three times higher following 4-fluoroselegiline administration compared to an equivalent dose of selegiline.
=== Effector === The arcuate nucleus of the hypothalamus, a part of the brain, is the main regulatory organ for the human appetite. Many brain neurotransmitters affect appetite, especially dopamine and serotonin. Dopamine acts primarily through the reward centers of the brain, whereas serotonin primarily acts through effects on neuropeptide Y (NPY)/agouti-related peptide (AgRP) [stimulate appetite] and proopiomelanocortin (POMC) [induce satiety] neurons located in the arcuate nucleus. Similarly, the hormones leptin and insulin suppress appetite through effects on AgRP and POMC neurons. Hypothalamocortical and hypothalamolimbic projections contribute to the awareness of hunger, and the somatic processes controlled by the hypothalamus include vagal tone (the activity of the parasympathetic autonomic nervous system), stimulation of the thyroid (thyroxine regulates the metabolic rate), the hypothalamic-pituitary-adrenal axis and a large number of other mechanisms. Opioid receptor-related processes in the nucleus accumbens and ventral pallidum affect the palatability of foods. The nucleus accumbens (NAc) is the area of the brain that coordinates neurotransmitter, opioid and endocannabinoid signals to control feeding behaviour. The few important signalling molecules inside the NAc shell modulate the motivation to eat and the affective reactions for food. These molecules include the dopamine (DA), acetylcholine (Ach), opioids and cannabinoids and their action receptors inside the brain, DA, muscarinic and μ-opioid receptor (MOR) and CB1 receptors respectively.
M−OH + R3SiCl → M−OSiR3 + HCl M−OH + R3SiOCH3 → M−OSiR3 + CH3OH M is typically Si, but could be many other elements. The process is assumed to follow the pathways that apply to silylation of molecular substrates, such as alcohols.
=== Bond strain === This is the principal effect of induced fit binding, where the affinity of the enzyme to the transition state is greater than to the substrate itself. This induces structural rearrangements which strain substrate bonds into a position closer to the conformation of the transition state, so lowering the energy difference between the substrate and transition state and helping catalyze the reaction. However, the strain effect is, in fact, a ground state destabilization effect, rather than transition state stabilization effect. Furthermore, enzymes are very flexible and they cannot apply large strain effect. In addition to bond strain in the substrate, bond strain may also be induced within the enzyme itself to activate residues in the active site.
Sources: en.wikipedia.org
No. It is a laboratory-made peptide, while the natural hormone is alpha-melanocyte-stimulating hormone, a longer peptide produced by the pituitary gland and by skin cells. Melanotan-2 mimics only a short active region of that hormone and contains non-natural residues such as D-phenylalanine.
No approved regulatory indication exists in major markets. An approval exists for a different peptide, afamelanotide, which is used for a rare photosensitivity disorder called erythropoietic protoporphyria. Melanotan-2 itself remains a research compound with no cleared clinical role.
Melanocortin-1 receptors on melanocytes are the receptor most closely linked to pigment production. The peptide is not selective, however, and also activates melanocortin-3, melanocortin-4, and melanocortin-5 receptors. That lack of selectivity is the usual explanation offered for both its range of observed effects and its off-target effects.
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.