A practical reference on cyclic heptapeptide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-11-18. Anything still debated is marked as such rather than presented as settled.
Regulatory treatment varies by country. In the United States the peptide is not approved as a medicine, and products offered for human use may be treated as unapproved new drugs; some states also restrict sale. Australia, the United Kingdom, and European Union member states apply comparable restrictions to unapproved peptide products. Border agencies have seized shipments labelled as research chemicals. Classification may change over time, and the legal position for personal importation is not clearly settled in most published guidance.
Lyophilised melanotan-2 is supplied as a solid, which is more stable than a solution. The material is hygroscopic, so weighing is done quickly, in low humidity, with the container kept sealed. Reconstitution usually uses water for injection or bacteriostatic water, added down the wall of the vial to limit foaming. A reconstituted solution is held at 2 to 8 °C and kept away from light. Repeated freezing and thawing of the same vial is avoided because ice crystal formation and concentration effects degrade the peptide.
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.
| Property | Value | Notes |
|---|---|---|
| Lyophilised storage | −20 °C, dry, protected from light | Vials are sealed and allowed to reach room temperature before opening |
| Reconstituted storage | 2 to 8 °C, protected from light | Short-term holding; avoid repeated freeze-thaw cycles |
| Reconstitution solvent | Water for injection or bacteriostatic water | Added slowly along the vial wall to reduce foaming and shear |
| Purity measurement | RP-HPLC with area normalisation | Acetonitrile-water gradient monitored at roughly 214 nm |
| Identity confirmation | Electrospray ionisation mass spectrometry | Observed mass compared against the calculated peptide mass |
Verification of a purchased sample requires documentation linking a batch to a certificate of analysis, and that document should be read for the methods used rather than the headline purity figure. A single chromatographic percentage does not establish identity. Independent laboratories can perform identity and content assays, but no such test establishes that a product is suitable for human use. Claims about efficacy rest largely on small, early studies rather than on replicated controlled trials, and that gap remains open.
Identity testing for a cyclic peptide of this size usually relies on reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The mass spectrum confirms molecular weight, while the chromatographic trace indicates the proportion of related impurities. Tandem mass spectrometry can provide sequence-level information when fragmentation data are compared against a reference standard. Nuclear magnetic resonance is sometimes used to confirm the lactam bridge, although it requires more material and greater operator expertise than routine chromatographic methods.
Lyophilised peptide powder is comparatively stable when kept dry, cold and protected from light. Once dissolved, the molecule is exposed to hydrolysis, oxidation and microbial growth, and degradation accelerates at higher temperatures and in alkaline solution. Repeated freeze-thaw cycles concentrate solutes and promote aggregation. Handling guidance for research peptides commonly clusters around freezer temperatures for powder and short refrigerated use for reconstituted solutions, with pH control and sterile technique applied throughout.
The peptide was developed during the 1980s by researchers investigating melanocortin signalling and skin pigmentation pathways. Early work focused on analogues of alpha-melanocyte-stimulating hormone that would resist enzymatic breakdown more effectively than the parent molecule. Melanotan-2 emerged from that programme as a shortened, cyclised variant. Reports describing its synthesis and receptor activity later appeared in the scientific literature. Commercial availability grew through unregulated channels rather than through pharmaceutical approval.
Structurally, Melanotan-2 retains the core recognition motif of alpha-melanocyte-stimulating hormone while adding a lactam bridge that links two side chains and constrains the molecule into a ring. This modification lowers susceptibility to enzymatic degradation. The compound acts as an agonist at melanocortin receptors, particularly subtypes associated with melanin production. Because the same receptor family influences several physiological processes, researchers note that its activity is not confined to pigmentation alone. Receptor selectivity continues to be examined in published studies.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its sequence incorporates modified residues that increase potency and extend biological activity relative to the native hormone. The compound binds receptors of the melanocortin family and is examined mainly in laboratory research. It does not occur naturally and exists only as a manufactured chemical entity produced by solid-phase synthesis.
Lyophilised melanotan-2 is comparatively robust when kept dry, cold and dark, and a desiccated powder stored at minus twenty degrees Celsius or below is generally expected to retain its chemical integrity for extended periods. In solution the peptide is far less stable, with degradation proceeding through oxidation of tryptophan and histidine residues, hydrolysis adjacent to the lactam bridge, and aggregation at higher concentrations. Repeated freeze-thaw cycling accelerates loss of the parent peak. Working aliquots are therefore prepared once, held cold, and used without letting the stock return to ambient temperature.
Quality assessment of research-grade peptide rests mainly on reversed-phase high-performance liquid chromatography for purity and on mass spectrometry for identity confirmation. A single main peak above a stated threshold, commonly ninety-eight percent by peak area, is the usual release criterion applied by suppliers. Independent analyses commissioned by laboratories and consumer organisations have repeatedly reported discrepancies between label claims and measured content, including truncated sequences, residual trifluoroacetate, and lower-than-declared peptide mass. Those findings do not establish that every supplier is unreliable, but they indicate that purity figures printed on a vial are claims requiring verification rather than settled facts.
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.
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.
== Role in cancer == Studies indicate significant HB-EGF gene expression elevation in a number of human cancers as well as cancer-derived cell lines. Evidence indicates that HB-EGF plays a significant role in the development of malignant phenotypes contributing to the metastatic and invasive behaviors of tumors. The proliferative and chemotactic effects of HB-EGF results from the target influence on particular cells including fibroblasts, smooth muscles cells, and keratinocytes. For numerous cell types such as breast and ovarian tumor cells, human epithelial cells and keratinocytes HB-EGF is a potent mitogen resulting in evidenced upregulation of HB-EGF in such specimens. Both in vivo and in vitro studies of tumor formation in cancer derived cell lines indicate that expression of HB-EGF is essential for tumor development. As a result, studies implementing the use of specific HB-EGF inhibitors and monoclonal antibodies against HB-EGF show the potential for the development of novel therapies for treating cancers by targeting HB-EGF expression.
== Early life == Jones was born in Cincinnati, Ohio on May 17, 1893, to an Irish father and Black American mother. Little is known about his mother who left his life when Jones was a child. His father, John Jones, was a railroad worker who struggled to raise him on his own. Jones was raised by a Catholic priest, Father Ryan, at a rectory in Cincinnati, Ohio, near Covington. Father Ryan took in Jones around the age of seven, and two years later, John Jones died. Jones left school at age 11 after the sixth grade. He went to nearby Cincinnati, Ohio, working odd jobs including a role as a garage cleaning boy. By age 14, Jones was working as an automobile mechanic and was later named garage foreman. Jones was largely self taught.
The company's continued presence in Russia stands in stark contrast to the actions of many of its Western counterparts, who have pulled out or scaled down their operations to align with global sanctions and the broader call for economic isolation of Russia. As the conflict in Ukraine rages on, Dr. Reddy's decision to remain in Russia raises serious concerns about the ethical implications of doing business with a country under international sanctions, while the rest of the world seeks to hold Russia accountable for its actions. Other viewpoints, particularly those outside the European and American centric western viewpoint, take the position that denying life saving pharmaceutical treatment by seeking to stop the flow of pharmaceutical goods to the common people in those countries whose actions are perceived as hostile, violent and inappropriate, such as Russia, is a deeply immoral act, and that by continuing to provide lifesaving medication to everyday citizens who have no connection to their government's foreign policy Dr. Reddy is acting in a deeply ethical way.
Treponema pallidum was first microscopically identified in syphilitic chancres by Fritz Schaudinn and Erich Hoffmann at the Charité in Berlin in 1905. Historically, this bacterium was identified in the clinical laboratory through visualization in dark-field microscopy. This bacterium can be detected with special stains, such as the Dieterle stain. T. pallidum is also detected by serology, including nontreponemal VDRL, rapid plasma reagin, treponemal antibody tests (FTA-ABS), T. pallidum immobilization reaction, and syphilis TPHA test.
Gish's debating opponents said that he used a rapid-fire approach during a debate, presenting arguments and changing topics quickly. Eugenie Scott, executive director of the National Center for Science Education, dubbed this approach the "Gish gallop", describing it as "where the creationist is allowed to run on for 45 minutes or an hour, spewing forth torrents of error that the evolutionist hasn't a prayer of refuting in the format of a debate". She also criticized Gish for failing to answer objections raised by his opponents. However, Gish said a similar thing about his debate opponents, especially Kenneth Miller. Gish accused Miller of using spread debating, i.e. speaking very fast and bringing up so many points that there was no chance to answer them all. Gish was also criticized for using a standardized presentation during debates. While undertaking research for a debate with Gish, Michael Shermer noted that Gish re-used similar openings, assumptions about his opponent, slides, and even jokes. For example, during the debate, Gish attempted to prove that Shermer was indeed an atheist and therefore immoral, even though Shermer said he was not an atheist and was willing to accept the existence of a divine creator. Massimo Pigliucci, who debated Gish five times, said that Gish ignored evidence contrary to his religious beliefs. Robert Schadewald accused Gish of stonewalling arguments with fabricated data.
Sources: en.wikipedia.org
Heroin, the common name for diacetylmorphine, is the first of several semi-synthetic opioids to be derived from morphine, a component of natural opium. It is formed by the acetylation of morphine in order to increase the lipid solubility. Heroin (diacetylmorphine) is a morphine prodrug; it is metabolized by the liver into morphine after administration. One of the major metabolites of heroin, 6-monoacetylmorphine (6-MAM), is also a morphine prodrug.
a 5-year surveillance study to determine if resistance emerges, with the final report due in December 2022 a study of the IV form in pregnant rats to determine distribution to the reproductive tract, due June 2018, with further studies required if there is significant distribution. Melinta merged with Cempra in August, 2017. Melinta has entered into commercialization and distribution agreements with both Menarini Therapeutics (March 2017) and Eurofarma Laboratórios (January 2015) for international commercialization of delafloxacin. The agreement with Menarini allows them to commercialize and distribute in 68 countries, including Europe, China, and South Korea among others. A similar agreement with Eurofarma allows for commercialization in Brazil.
== Pharmacokinetics == Unlike erythromycin, telithromycin is acid-stable and can therefore be taken orally while being protected from gastric acids. It is fairly rapidly absorbed, and diffused into most tissues and phagocytes. Due to the high concentration in phagocytes, telithromycin is actively transported to the site of infection. During active phagocytosis, large concentrations of telithromycin is released. The concentration of telithromycin in the tissues is much higher than in plasma. Telithromycin fulfills a role that has arisen due to the rise of microbial resistance to existing macrolides and appears to be effective against macrolide-resistant Streptococcus pneumoniae. The defining differentiating characteristic of the ketolides as opposed to other macrolides is the removal of the neutral sugar, L-cladinose from the 3 position of the macrolide ring and the subsequent oxidation of the 3-hydroxyl to a 3-keto functional group.
Clinical psychologists engage in a wide range of activities. Some focus solely on research into the assessment, treatment, or cause of mental illness and related conditions. Some teach, whether in a medical school or hospital setting, or in an academic department (e.g., psychology department) at an institution of higher education. The majority of clinical psychologists engage in some form of clinical practice, with professional services including psychological assessment, provision of psychotherapy, development and administration of clinical programs, and forensics (e.g., providing expert testimony in a legal proceeding). In clinical practice, clinical psychologists may work with individuals, couples, families, or groups in a variety of settings, including private practices, hospitals, mental health organizations, schools, businesses, and non-profit agencies. Clinical psychologists who provide clinical services may also choose to specialize. Some specializations are codified and credentialed by regulatory agencies within the country of practice. In the United States, such specializations are credentialed by the American Board of Professional Psychology (ABPP).
=== President and Past Presidents (since 1953) === 2022–2024 Julia Laskin 2020–2022 Susan Richardson 2016–2018 Vicki Wysocki 2014–2016 Jennifer Brodbelt 2012–2014 Susan Weintraub 2006–2008 Barbara S. Larsen 2002–2004 Catherine E. Costello 1996–1998 Veronica M. Bierbaum 1982–1984 Catherine Fenselau
Sources: en.wikipedia.org
Commission A2: Liquefaction and Separation of Gases The work of "Commission A2: Liquefaction and Separation of Gases" reflects worldwide activities in the domain of separation of gases and liquefaction. Apart from the personal involvement of Commission members in various projects, the commission is present at conferences, workshops and seminars: LNG International Exhibition and Conference, GASTECH, Cryogenics, Cryogen Expos, European Cryogenic Course and others. The commission is close to academia, industry and end users of separated and liquefied gases. Commission members work closely with Commission A1 Cryophysics, Cryoengineering and Commission C1 Cryobiology, Cryomedicine and Health Products.
=== 1980s === The compact disk was invented in the 1980s, initially to store and play digital audio recordings but a few years later also as general data storage. Vacuum is used for the metallization of CD surfaces. In 1984, Edwards' Henry Wycliffe invented the Drystar roots/claw dry pump, patented by Edwards. The Drystar was a positive-displacement roots/claw pump that does not require oil for lubrication. The semiconductor industry in particular moved away quickly from oil-sealed pumps in favour of the new dry pumps. In the harsh semiconductor processes, oil-sealed pumps required frequent servicing and oil changes: this new dry pump technology enabled more complex production processes in the semiconductor industry.
==== MeSH D13.695.201 – deoxyribonucleotides ==== MeSH D13.695.201.100 – deoxyadenine nucleotides MeSH D13.695.201.150 – deoxycytosine nucleotides MeSH D13.695.201.150.200 – deoxycytidine monophosphate MeSH D13.695.201.175 – deoxyguanine nucleotides MeSH D13.695.201.200 – deoxyuracil nucleotides MeSH D13.695.201.200.270 – fluorodeoxyuridylate MeSH D13.695.201.486 – nucleoside diphosphate sugars MeSH D13.695.201.789 – thymine nucleotides MeSH D13.695.201.789.788 – thymidine monophosphate
Leach testified that through her role Fred had gradually begun to view her as a confidante and had confided in her that on the evening prior to his 25 February arrest he and Rose had formed a pact whereby he would take full responsibility for all the murders, many of which he had described to her as being "some of Rose's mistakes." Fred had further divulged that Rose had indeed murdered Charmaine while he had been incarcerated, and had also murdered Robinson. He had also confided that Rose had participated in the mutilation and dismemberment of Robinson, having personally removed the foetus from Robinson's womb after her death. In reference to the remaining eight murders for which Rose had been charged, Leach testified Fred had confided that Rose had "played a major part" in these murders. Upon cross-examination, Leach did concede to Ferguson she had earlier lied under oath about having sold her story to a national newspaper for £100,000, although she was adamant about the sincerity of her testimony. While delivering this testimony, Leach collapsed and the trial was adjourned for six days. She returned to complete her cross-examination on 13 November.
Sources: en.wikipedia.org
Low temperature slows hydrolysis and oxidation, the two main routes by which the peptide backbone and side chains are modified. A lyophilised powder stored at −20 °C is more stable than one kept at room temperature, and once the material is dissolved the degradation rate rises, making refrigeration more important.
Liquid chromatography coupled to mass spectrometry is the most common approach because it combines a retention time with a mass measurement. A chromatographic peak alone cannot establish which peptide is present, so mass determination or amino acid analysis is used as an orthogonal confirmation alongside the separation.
This depends on buffer, pH, and concentration, and published stability data for this peptide are limited. In practice laboratories work through a refrigerated solution within a few weeks and discard samples that show cloudiness or visible particles. Freezing and thawing repeatedly is generally discouraged.
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.