This is a working overview of afamelanotide, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-01-14 and is reviewed periodically as new material appears.
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.
Handling guidance for melanotan II follows general practice for small synthetic peptides rather than a product-specific monograph. Lyophilized powder is typically kept at minus twenty degrees Celsius or colder, protected from light and moisture, because warmth and humidity accelerate degradation. Once reconstituted, solutions are usually refrigerated and used within a short window, as hydrolysis and microbial growth both become concerns. Repeated freeze-thaw cycles are generally avoided. These conventions come from laboratory peptide chemistry and not from formal stability studies on this specific compound.
Analytical confirmation of identity relies on mass spectrometry, most often coupled to liquid chromatography. Reversed-phase high-performance liquid chromatography separates the peptide from related impurities and provides a purity estimate based on peak area. Electrospray ionization mass spectrometry then confirms the expected molecular mass, while tandem mass spectrometry can map the fragment sequence. For research-grade material, these two techniques together form the standard minimum. Purity figures reported by vendors are frequently not traceable to an independent laboratory.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Melanocortin receptor agonist |
| Molecular formula | C50H69N15O9 | Neutral form, mass near 1024.2 g/mol |
| Primary targets | MC1R, MC3R, MC4R, MC5R | Binding is non-selective across subtypes |
| Related compounds | Alpha-MSH, melanotan I, afamelanotide | Structurally or functionally related peptides |
| Common abbreviations | MT-II, MT-2 | Naming in the literature is not uniform |
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.
Lyophilized peptide powder is generally stored frozen, protected from light and moisture. Tryptophan residues are susceptible to oxidation, and the lactam bridge can hydrolyze under strongly acidic or basic conditions. Solutions prepared for laboratory work degrade faster than dry powder, and repeated freeze-thaw cycles accelerate loss. Common practice is to aliquot solutions before freezing and to avoid alkaline buffers. Reported stability windows vary with concentration, buffer, and temperature, so exact shelf lives are method-specific rather than universal.
Regulatory status differs by country, and in many places supplying the compound for human consumption is unlawful. Vendors frequently label material as intended for research use only, a designation that shifts stated purpose but does not create a legal pathway for personal use. Certificates of analysis accompanying such products vary widely in detail and provenance. Third-party testing exists but is voluntary, and results are rarely linked to a specific lot in a publicly verifiable way.
These isoenzymes include MM, MB, and BB, which all carry out the same function given different amino acid sequences. The functions of these isoenzymes are to convert creatine, using ATP, into phosphocreatine expelling ADP. Mini columns were filled with DEAE-Sephadex A-50 and further eluted with tris- buffer sodium chloride at various concentrations (each concentration was chosen advantageously to manipulate elution). Human tissue extract was inserted in columns for separation. All fractions were analyzed to see total CK activity and it was found that each source of CK isoenzymes had characteristic isoenzymes found within. Firstly, CK- MM was eluted, then CK-MB, followed by CK-BB. Therefore, the isoenzymes found in each sample could be used to identify the source, as they were tissue specific. Using the information from results, correlation could be made about the diagnosis of patients and the kind of CK isoenzymes found in most abundant activity. From the finding, about 35 out of 71 patients studied suffered from heart attack (myocardial infarction) also contained an abundant amount of the CK-MM and CK-MB isoenzymes. Findings further show that many other diagnosis including renal failure, cerebrovascular disease, and pulmonary disease were only found to have the CK-MM isoenzyme and no other isoenzyme. The results from this study indicate correlations between various diseases and the CK isoenzymes found which confirms previous test results using various techniques.
This schedule is an approximation, as actual healing rates vary depending on when in an animal's annual hair-growth cycle the brand is applied. Complete healing and final brand appearance can take up to five months in animals branded during a winter phase of hair growth and in as little as one or two months on animals with spring coats.
== Epidemiology == PMOS is the most common hormonal disorder (endocrine disorder) among women of reproductive age. When someone is infertile due to a lack of ovulation, PMOS is the most common cause. According to the World Health Organization (WHO), PMOS affects over 6 to 13% of reproductive-aged women. A 2022 review noted a prevalence between 5% and 18%. The prevalence of PMOS depends on the choice of diagnostic criteria. Using the Rotterdam criteria, around 10–13% of women have PMOS. Based on the NIH criteria, the global prevalence was 5.5%, increasing to approximately 7.1% when using the Androgen Excess Society criteria. Irrespective of the criteria, the prevalence of PMOS is increasing, likely due to an aging population, more awareness, and increasing obesity rates. Prevalence seems fairly even among people with different ethnicities, but may be higher in people from Southeast Asia and the Eastern Mediterranean. But PMOS can express differently. For instance, in African and Hispanic American people with PMOS, there is more insulin resistance compared to other ethnic groups. The same is true for South Asian people with PMOS, who also have more metabolic symptoms and higher BMIs. East Asian women typically have less hirsutism and lower BMI compared to other groups. While early small-scale studies found that transmasculine people were more likely to have PMOS than cis women, this was not found in a larger, more rigorous study.
Sources: en.wikipedia.org
Copper is absorbed, transported, distributed, stored, and excreted in the body according to complex homeostatic processes which ensure a constant and sufficient supply of the micronutrient while simultaneously avoiding excess levels. If an insufficient amount of copper is ingested for a short period of time, copper stores in the liver will be depleted. Should this depletion continue, a copper health deficiency condition may develop. If too much copper is ingested, an excess condition can result. Both of these conditions, deficiency and excess, can lead to tissue injury and disease. However, due to homeostatic regulation, the human body is capable of balancing a wide range of copper intakes for the needs of healthy individuals. Many aspects of copper homeostasis are known at the molecular level. Copper's essentiality is due to its ability to act as an electron donor or acceptor as its oxidation state fluxes between Cu1+ (cuprous) and Cu2+ (cupric). As a component of about a dozen cuproenzymes, copper is involved in key redox (i.e., oxidation-reduction) reactions in essential metabolic processes such as mitochondrial respiration, synthesis of melanin, and cross-linking of collagen. Copper is an integral part of the antioxidant enzyme copper-zinc superoxide dismutase, and has a role in iron homeostasis as a cofactor in ceruloplasmin.
=== Ethos water === Ethos water, a brand of bottled water acquired by Starbucks in 2003, is sold at locations throughout North America. Ethos bottles feature prominent labeling stating "helping children get clean water", referring to the fact that US$0.05 from each US$1.80 bottle sold (US$0.10 per bottle in Canada) is used to fund clean water projects in underdeveloped areas. Although sales of Ethos water have raised over US$6.2 million for clean water efforts, the brand is not incorporated as a charity. Critics have argued that the claim on the label misleads consumers into thinking that Ethos is primarily a charitable organization when it is actually a for-profit brand and only 5 cents per bottle supports clean-water projects. The founders of Ethos have stated that the brand is intended to raise awareness of third-world clean water issues and provide socially responsible consumers with an opportunity to support the cause by choosing Ethos over other brands. Starbucks has since redesigned the American version of the Ethos water bottles, stating the amount of money donated per bottle in the description.
=== Receptor Genetics === Four RXFPs in humans are located in different linkage groups. Additionally there are two RXFP pseudogenes ("RXFP3-3" and "RXFP2-like") which have functional counterparts in other species.
Sources: en.wikipedia.org
Calcium carbonate is poorly soluble in pure water (47 mg/L at normal atmospheric CO2 partial pressure as shown below). The equilibrium of its solution is given by the equation (with dissolved calcium carbonate on the right):
==== European Union ==== The European Board of Internal Medicine (EBIM) was formed as a collaborative effort between the European Union of Medical Specialists (UEMS) - Internal Medicine Section and the European Federation of Internal Medicine (EFIM) to provide guidance on standardizing training and practice of internal medicine throughout Europe. The EBIM published training requirements in 2016 for postgraduate education in internal medicine, and efforts to create a European Certificate of Internal Medicine (ECIM) to facilitate the free movement of medical professionals with the EU are currently underway. The internal medicine specialist is recognized in every country in the European Union and typically requires five years of multi-disciplinary post-graduate education. The specialty of internal medicine is seen as providing care in a wide variety of conditions involving every organ system and is distinguished from family medicine in that the latter provides a broader model of care the includes both surgery and obstetrics in both adults and children.
Purification of the crude synthesis solution increases usability of the products by improving the chances of successfully obtaining full-length oligo sequences. Successfully synthesized long oligo-sequences are scarce; the solution predominantly contains truncated or failed oligo-sequences. By tagging only full-length oligonucleotides with polymerizable tagging phosphoramidite (PTP) and incorporating them into polyacrylamide gel, truncated, or untagged, sequences are washed away, and the desired sequences are retained. This purification method is coined catching-by-polymerization (CBP) and allows for successful recovery of synthesized sequences. Utilizing these methods, successful direct chemical synthesis of ultra-long (800-mer and 1728-mer) oligonucleotides has been achieved.
=== Alcohol use disorder === Naltrexone has been best studied as a treatment for alcoholism, or alcohol use disorder (AUD). Naltrexone has been shown to decrease the quantity and frequency of alcohol consumption by reducing the release of dopamine, a neurotransmitter associated with the euphoria that often accompanies alcohol use. Studies comparing naltrexone to a placebo have shown a small but statistically significant decrease in relapse likelihood. Its overall benefit has been described as "modest". Acamprosate may be more effective for AUD management overall, while naltrexone may decrease the desire for alcohol to a greater extent. A method pioneered by scientist John David Sinclair (dubbed commercially the "Sinclair Method") in the 1980s advocates "pharmacological extinction" of problem drinking behavior by administering naltrexone alongside controlled alcohol consumption. In effect, he argues that naltrexone-induced opioid antagonism sufficiently disrupts reflexive reward mechanisms inherent in the consumption of alcohol and, given enough repetition, will dissociate positive associations formerly made with the consumption of alcohol. A 2001 review of eight studies of naltrexone treatment in the setting of AUD concluded that, "although all found benefits from naltrexone with the coping therapy, none of them found any significant benefit of naltrexone over placebo when combined with support for abstinence."
Sources: en.wikipedia.org
It is a synthetic cyclic heptapeptide and a non-selective melanocortin receptor agonist. Structurally it is modelled on alpha-melanocyte-stimulating hormone, a peptide that occurs naturally in the body.
Activation of MC1R increases pigment synthesis independently of ultraviolet exposure, which is the mechanism usually cited for darkening without sun exposure. Ultraviolet light still influences skin response through separate biological pathways.
Because the peptide binds several melanocortin receptor subtypes, its effects are not confined to pigmentation. This complicates interpretation of both intended and unintended outcomes reported in studies.
The lyophilized powder is generally held at minus twenty degrees Celsius or below, away from light and moisture. Reconstituted solutions are typically refrigerated and used quickly. These practices derive from general peptide handling rather than a formal stability study.