Everything below concerns reversed-phase HPLC. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-06-13. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Outside regulated medicine, melanotan II circulates through online vendors as a research chemical, often marketed for tanning. Products sold this way vary widely in purity, concentration, and labeling accuracy, and independent testing has documented discrepancies. Published reports describe both pigment effects and adverse reactions, including nausea, flushing, and darkening of existing moles. Long-term safety data are sparse, and no large controlled trial has established a risk profile. Questions about cumulative effects on melanocytes remain unresolved in the literature.
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.
Melanotan-2 is handled in the laboratory as a lyophilised powder that dissolves readily in water, dimethyl sulfoxide and dimethylformamide, with limited solubility in ethanol. Stock solutions prepared in an organic solvent often precipitate when diluted into aqueous buffer, so gradual dilution with mixing is standard practice. The peptide carries a tryptophan residue and a histidine residue, both sensitive to oxidation and to alkaline conditions. Working solutions are therefore kept near neutral to slightly acidic pH, protected from light, and consumed within the same working session whenever that is practical.
Solid peptide kept dry at minus twenty degrees Celsius, shielded from light and moisture, is generally considered stable for extended periods. Solutions are divided into single-use aliquots and held at minus twenty or minus eighty degrees Celsius, because repeated freeze-thaw cycles promote aggregation and loss of material to container surfaces. Hydrolysis of the backbone and oxidation of tryptophan are the principal degradation routes in aqueous solution, and both accelerate at ambient temperature. Hygroscopic uptake after a vial is opened can also shift the actual mass weighed, which affects any concentration calculated from it.
Routine characterisation relies on reversed-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres, using a C18 column and a water-acetonitrile gradient containing trifluoroacetic acid. Electrospray ionisation mass spectrometry confirms the expected molecular mass and can reveal truncated or oxidised by-products that co-elute poorly. Sequence and stereochemistry require additional work, such as peptide mapping or amino acid analysis, because a chromatographic purity figure alone does not distinguish a diastereomer from the target peptide. Independent testing of research-grade material frequently shows measured content below the stated label, so a certificate of analysis is best read together with the method that produced it.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Belongs to the melanocortin agonist family |
| Key substitutions | Nle4 and D-Phe7 | Improve resistance to enzymatic degradation |
| Molecular formula | C50H69N15O9 | Approximately 1024 g/mol |
| Regulatory status | Not approved as a medicine | Distributed as a research chemical |
| Common synonyms | Melanotan II, MT-II, MT-2 | Spelling varies across sources |
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.
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.
Identity testing for a synthetic peptide relies on several complementary methods. Reversed-phase high-performance liquid chromatography separates the target from related impurities and reports purity as a percentage of total peak area. Mass spectrometry confirms molecular mass and can reveal deletions or truncations. Amino acid analysis and peptide mapping provide sequence-level confirmation, while counter-ion content and residual solvents are measured separately. A purity figure alone does not establish identity, so a complete dataset combines chromatographic and spectrometric evidence.
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.
The compound emerged from research programs in the 1980s that examined analogues of alpha-melanocyte-stimulating hormone for pigmentation and photoprotection. Investigators modified the native sequence to extend activity duration and potency. A related analogue, afamelanotide, was developed within the same broad line of inquiry and eventually gained approval in certain jurisdictions for a rare light-sensitivity condition. Melanotan-2 itself did not progress through the same regulatory route and has no approved therapeutic indication.
Melanocortin receptors comprise five subtypes with distinct tissue distributions and functions. Melanotan-2 is described in the literature as a non-selective agonist that engages several of these subtypes, including MC1R, MC3R, MC4R, and MC5R. MC1R is the subtype most directly linked to melanin production in skin cells. Because the compound is not subtype-selective, its observed effects in experimental settings are generally attributed to activity across multiple receptor pathways rather than to a single target.
On 25 August, Israel began strikes in southern Lebanon against Hezbollah targets. Israel framed its strikes as "preemptive". Hezbollah said that it fired over 320 Katyusha rockets to IDF sites in northern Israel and the Golan Heights as the first phase of response to the assassination of Fuad Shukr. A woman was slightly injured due to sharpnel from the attack in Acre. Some homes were also damaged in Northern Israel. Israel sent a hundred fighter jets during its operations. Israeli Defense Minister Yoav Gallant described the strikes as "very successful", stating that "over fifty percent, maybe two-thirds" of Hezbollah's strikes were prevented. An Israeli drone strike in Qasimia in southern Lebanon wounded two people including one Hezbollah militant.
The use of different fuels in nuclear reactors results in different spent nuclear fuel (SNF) composition, with varying activity curves. The most abundant material being U-238 with other uranium isotopes, other actinides, fission products and activation products. Long-lived radioactive waste from the back end of the fuel cycle is especially relevant when designing a complete waste management plan for SNF. When looking at long-term radioactive decay, the actinides in the SNF have a significant influence due to their characteristically long half-lives. Depending on what a nuclear reactor is fueled with, the actinide composition in the SNF will be different. An example of this effect is the use of nuclear fuels with thorium. Th-232 is a fertile material that can undergo a neutron capture reaction and two beta minus decays, resulting in the production of fissile U-233. The SNF of a cycle with thorium will contain U-233. Its radioactive decay will strongly influence the long-term activity curve of the SNF for around a million years. A comparison of the activity associated to U-233 for three different SNF types can be seen in the figure on the top right. The burnt fuels are thorium with reactor-grade plutonium (RGPu), thorium with weapons-grade plutonium (WGPu), and Mixed oxide fuel (MOX, no thorium). For RGPu and WGPu, the initial amount of U-233 and its decay for around a million years can be seen. This has an effect on the total activity curve of the three fuel types.
== Procedure == After fasting overnight, a catheter is passed into the patient's duodenum. The patient receives sequential intravenous injections of first secretin then either CKK or a synthetic 8-residue peptide representing the C-terminal 8 of CKK (ceruletide). Duodenal fluid is collected at 15 minute intervals for at least an hour, and the properties of the fluid are used to assess exocrine function of the pancreas. The CCK test may be administered in conjunction with an ultrasound test to visually monitor gall bladder contraction. While the test is usually administered in a supine position, Dr. William Smedley of Wilkes Barre, Pennsylvania has detected previously missed gallbladder abnormalities by administering the test in an erect position. The concentration and output of bicarbonate with the secretin-CCK test is similar to what has been observed with the standard secretin test. The secretin-induced rapid flow of water results in lower and often unreliable enzyme concentrations. CCK also induces gallbladder contraction and the release of bile, which may further dilute enzyme concentrations. As a result, the quantification of total enzyme output (units/min) must be determined through continuous collection of duodenal fluid with or without the use of perfusion markers. Measurement of more than one enzyme (i.e. amylase, lipase, and tryptase) and bicarbonate may improve sensitivity since some patients may possess deficiencies of one parameter and not the others.
Sources: en.wikipedia.org
== Metabolism == Anaerobic metabolism is a natural part of metabolic energy expenditure. Fast twitch muscles (as compared to slow twitch muscles) operate using anaerobic metabolic systems, such that any use of fast twitch muscle fibers leads to increased anaerobic energy expenditure. Intense exercise lasting upwards of four minutes (e.g. a mile race) may still have considerable anaerobic energy expenditure. An example is high-intensity interval training, an exercise strategy that is performed under anaerobic conditions at intensities that reach an excess of 90% of the maximum heart rate. Anaerobic energy expenditure is difficult to accurately quantify. Some methods estimate the anaerobic component of an exercise by determining the maximum accumulated oxygen deficit or measuring the lactic acid formation in muscle mass. In contrast, aerobic exercise includes lower intensity activities performed for longer periods of time. Activities such as walking, jogging, rowing, and cycling require oxygen to generate the energy needed for prolonged exercise (i.e., aerobic energy expenditure). For sports that require repeated short bursts of exercise, the aerobic system acts to replenish and store energy during recovery periods to fuel the next energy burst. Therefore, training strategies for many sports demand that both aerobic and anaerobic systems be developed. The benefits of adding anaerobic exercise include improving cardiovascular endurance as well as build and maintaining muscle strength and losing weight.
==== Gateway theory ==== An association has been found between adolescent exposure to nicotine by smoking conventional cigarettes and the subsequent onset of using other dependence-producing substances. Strong temporal and dose-dependent associations have been reported, and a plausible biological mechanism (via rodent and human modeling) suggests that long-term changes in the neural reward system take place as a result of adolescent smoking. Adolescent smokers of conventional cigarettes have disproportionately high rates of comorbid substance use, and longitudinal studies have suggested that early adolescent smoking may be a starting point or "gateway" for substance use later in life, with this effect more likely for persons with attention deficit hyperactivity disorder (ADHD). Although factors such as genetic comorbidity, innate propensity for risk-taking, and social influences may underlie these findings, both human neuroimaging and animal studies suggest a neurobiological mechanism also plays a role. In addition, behavioral studies in adolescent and young adult smokers have revealed an increased propensity for risk-taking, both generally and in the presence of peers, and neuroimaging studies have shown altered frontal neural activation during a risk-taking task as compared with nonsmokers.
Medical societies issue guidelines for when physicians should use MRI on patients and recommend against overuse. MRI can detect health problems or confirm a diagnosis, but medical societies often recommend that MRI not be the first procedure for creating a plan to diagnose or manage a patient's complaint. A common case is to use MRI to seek a cause of low back pain; the American College of Physicians, for example, recommends against imaging (including MRI) as unlikely to result in a positive outcome for the patient.
Sources: en.wikipedia.org
== Routine biochemistry analysers == These are machines that process a large portion of the samples going into a hospital or private medical laboratory. Automation of the testing process has reduced testing time for many analytes from days to minutes. The history of discrete sample analysis for the clinical laboratory began with the introduction of the "Robot Chemist" invented by Hans Baruch and introduced commercially in 1959. The AutoAnalyzer is an early example of an automated chemistry analyser using a special flow technique named "continuous flow analysis (CFA)", invented in 1957 by Leonard Skeggs, PhD and first made by the Technicon Corporation. The first applications were for clinical (medical) analysis. The AutoAnalyzer profoundly changed the character of the chemical testing laboratory by allowing significant increases in the numbers of samples that could be processed. Samples used in the analyser include, but are not limited to, blood, serum, plasma, urine, cerebrospinal fluid, and other fluids from within the body. The design based on separating a continuously flowing stream with air bubbles largely reduced slow, clumsy, and error-prone manual methods of analysis. The types of tests include enzyme levels (such as many of the liver function tests), ion levels (e.g. sodium and potassium, and other tell-tale chemicals (such as glucose, serum albumin, or creatinine). Simple ions are often measured with ion selective electrodes, which let one type of ion through, and measure voltage differences.
The unaltered proteins were then treated with recombinant FGE from Mycobacterium tuberculosis in vitro in which the aldehyde group was successfully installed at the glycosylation site of Fc (Fig. 3A). Next, the introduction of N-acetylglucoseamine (GlcNAc) to the aldehyde tagged proteins via oxime formation was carried out through the treatment with aminooxy GlcNAc (AO-GlcNAc) (Fig. 3B). The conjugation was confirmed by liquid chromatography-electrospray ionisation-mass spectrometry (LC-ESI-MS) and lectin blot with the GlcNAc-binding wheat germ agglutinin attached to AlexaFluor 647. Having successfully introduced GlcNAc, the monomer was extended with a glycan structure containing GlcNAc, mannose (Man) and galactose (Gal) (Fig. 3C). A mutant endoglycosidase EndoS (EndoS-D233Q) was utilised as it is highly specific for IgG Fc N-linked GlcNAc residues and does not elongate Asn-GlcNAc sites on other proteins or on denatured IgGs. Product formation was again monitored by LC-ESI-MS and lectin blot probing, with the sialic acid-binding sambucus nigra agglutinin attached to fluorescein isothiocyanate. A successful chemical glycosylation of the Fc IgG fragment was achieved which resembles the natural occurring glycosylation pattern. The study discussed above focused on the IgG antibody, however, the application of the aldehyde tag for glycan conjugation could potentially be extended to other proteins.
=== Arizona State University === In June 2014, Starbucks announced a partnership with Arizona State University (ASU) that would allow Starbucks employees in their Junior and Senior years of college to complete four years of college at Arizona State University's online program for only around US$23,000. Starbucks employees admitted into the program would receive a scholarship from the college, that would cover 44% of their tuition. The remaining balance and all other expenses would be paid by the student or through traditional financial aid. In April 2015, Starbucks and ASU announced an expansion of the College Achievement Program. The program would now allow all eligible part-time and full-time employees working in a U.S. Starbucks to enroll in the program for full-tuition reimbursement. After the completion of each semester, Starbucks reimburses the student their portion of the tuition. The student can then use the reimbursement to pay any loans or debt incurred during the semester.
Sources: en.wikipedia.org
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.
No regulatory agency has approved it for any indication. It is encountered as a research chemical sold outside pharmaceutical supply chains. Products marketed this way are not subject to the manufacturing and labeling requirements that apply to approved drugs.
Reports describe increased skin pigmentation as well as side effects such as nausea, flushing, and changes to existing moles. Much of the evidence comes from small studies and case reports rather than large trials. The long-term safety profile is therefore uncertain.
Purity is normally stated as an area percentage from high-performance liquid chromatography, for example ninety-five or ninety-eight percent. That figure describes the proportion of ultraviolet-absorbing material eluting as the main peak. It says nothing about water content, counterions, residual solvents or mass fraction of the peptide itself.