RP-HPLC is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-01-15. Where a claim depends on a specific study, the study is described rather than over-claimed.
Identity and purity of semax are established with reversed-phase high-performance liquid chromatography coupled to ultraviolet detection, usually at 214 nanometres. Mass spectrometry, most often electrospray ionisation in positive mode, confirms the molecular mass and reveals truncated sequences. Amino acid analysis and peptide mapping after enzymatic digestion provide additional structural confirmation. Laboratories typically report purity as the percentage area of the main peak, a figure that does not capture isomeric or oxidised variants unless the method resolves them.
The peptide is prone to several degradation pathways. Oxidation of the methionine residue produces a sulfoxide that elutes close to the parent peak in many chromatographic systems. Hydrolysis of peptide bonds and deamidation of susceptible residues in related sequences also reduce purity over time. Lyophilised material kept dry at minus twenty degrees Celsius and shielded from light is the most stable form commonly described in laboratory practice.
Material sold for laboratory use varies widely in stated purity and documentation. A certificate of analysis should list the analytical method, the column and detector used, and the observed purity value. Independent verification by an outside laboratory is the practical way to confirm identity when documentation is absent or internally inconsistent. Regulatory status differs by country, and a product legal in one jurisdiction may be unapproved or controlled in another.
Semax is a synthetic seven-amino-acid peptide whose sequence extends the ACTH(4-10) fragment with a C-terminal proline-glycine-proline tripeptide. The commonly cited sequence is Met-Glu-His-Phe-Pro-Gly-Pro, giving a molecular formula near C37H51N9O10S and a molecular weight close to 813.9 g/mol. It belongs to the broader class of synthetic ACTH fragments studied for central nervous system effects rather than for adrenal steroid stimulation. In practice the material appears as a lyophilized white powder for laboratory work or as a dilute saline solution in clinical settings.
Development is attributed to researchers at the Institute of Molecular Genetics in Moscow during the early 1980s, building on earlier Soviet work with ACTH fragments. Russian regulatory approval followed for intranasal use, and the compound has remained commercially available there for decades. Most published human data originate from Russian and, later, some Eastern European clinical reports, which are not always accessible in English translation. Outside that region the material is generally handled as a research chemical rather than a licensed medicine.
Regulatory status differs sharply between jurisdictions. In Russia the peptide is registered as a prescription nasal preparation, while agencies such as the United States Food and Drug Administration have not approved it for any indication. Products sold elsewhere are typically labeled for laboratory research only, and such labels shift responsibility for safe handling to the purchaser. Because the same name covers pharmaceutical-grade nasal drops and bulk research powder, identity and purity documentation becomes the main practical concern when comparing sources.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilised solid |
| Solubility class | Freely soluble in water | Also dissolves in aqueous buffers |
| Typical storage temperature | -20 °C | Dry, desiccated, protected from light |
| Typical analytical method | RP-HPLC with UV detection | Often paired with LC-MS |
| Water content | Reported as Karl Fischer value | Freeze-dried material is hygroscopic |
Published studies are dominated by animal models of stroke, ischemia, and cognitive impairment, with a smaller number of human trials conducted in Russia. Many of the human reports are small, single-center, and published in Russian-language journals, which limits independent scrutiny. Outcome measures vary between studies and often rely on clinician-rated scales rather than objective biomarkers. Systematic reviews have noted the methodological weaknesses and called for larger, preregistered trials before firm conclusions can be drawn.
Claims about enhanced focus, memory, or mood in healthy people rest mostly on anecdotal reports and community discussion rather than on controlled data. It remains unclear whether any cognitive benefit observed in patients recovering from brain injury would extend to uninjured users. Dose-response relationships, long-term safety, and interactions with other drugs are not well characterized in the peer-reviewed literature. Questions about optimal route of administration and treatment duration likewise remain open.
The compound was developed in the 1980s at the Institute of Molecular Genetics in Moscow, where it emerged from research on short ACTH fragments and their effects on the central nervous system. Russian pharmaceutical listings describe it as a nootropic and neuroprotective agent, most often formulated as nasal drops. It is not a marketed medicine in the United States or the European Union, and no pharmacopoeial monograph covers it. Consequently, most published clinical experience with the substance originates from a small number of research centres, mainly in Russia and neighbouring countries.
Pharmacological accounts link semax to melanocortin signalling and to modulation of neurotrophic factor expression, particularly brain-derived neurotrophic factor and nerve growth factor. Much of this evidence comes from rodent studies using intranasal delivery, a route chosen because it allows peptides to reach the central nervous system with limited systemic exposure. Whether the same mechanisms operate in humans at comparable magnitude remains an open question. The precise receptor or receptors responsible for the reported behavioural and neuroprotective effects have not been conclusively identified.
Clinical reports describe use in ischaemic stroke, transient ischaemic attack, optic nerve conditions, and cognitive complaints, but most of these studies are small and were conducted in a single region. Systematic reviews have generally described the evidence base as limited in size and variable in methodological quality. Randomised controlled data suitable for international regulatory assessment are scarce. As a result, major treatment guidelines outside Russia do not include the peptide, and interest in it remains largely research-driven rather than routine clinical.
Just like the GT-X, the engine power of the European market GT-R was also lowered to produce 185 PS (136 kW; 182 hp). As per the first GT-X, 300 units special version of GT-R were produced known as GT-Ae. These shared the power output of the GT-R, but were 30 kg (66 lb) lighter, fitted with closer ratio gearboxes, and featured a larger top spoiler with a gap between the hatch and the spoiler to direct air to the new lower spoiler. The wiring for ABS, air conditioning, power mirrors, power windows, power locks, and sunroof was removed. Instead of using the GT-R's leather interior, the lighter cloth interior of the GT-X was used.
== Medical uses == Dielectric heating (diathermy) is used in medicine; the frequencies used typically lie in the ultrasonic, shortwave, and microwave ranges. Careless application, especially when the patient has implanted metal conductors (e.g. cardiostimulator leads), can cause burns of skin and deeper tissues and even death. Microwave damage to tissues can be intentionally exploited as a therapeutic technique, e.g. radiofrequency ablation and radiofrequency lesioning. Controlled destruction of tissue is performed for treatment of arrhythmia. Microwave coagulation can be used for some kinds of surgeries, e.g., stopping bleeding after a severe liver injury. Microwave heating seems to cause more damage to bacteria than equivalent thermal-only heating. However food reheated in a microwave oven typically reaches lower temperature than classically reheated, therefore pathogens are more likely to survive. Microwave heating of blood, e.g. for transfusion, is contraindicated, as it can cause hemolysis and hyperkalemia. Microwave heating is one of the methods for inducing hyperthermia for hyperthermia therapy. High-energy microwaves are used in neurobiology experiments to kill small laboratory animals (mice, rats) in order to fix brain metabolites without the loss of anatomical integrity of the tissue. The instruments used are designed to focus most of the power to the animal's head. The unconsciousness and death is nearly instant, occurring in less than one second, and the method is the most efficient one to fix brain tissue chemical activity.
=== Strontium unit: radiation dose === The strontium unit, formerly known as the Sunshine Unit (symbol S.U.), is a unit of biological contamination by radioactive substances (specifically strontium-90). It is equal to one picocurie of Sr-90 per gram of body calcium. Since about 2% of the human body mass is calcium, and Sr-90 has a half-life of 28.78 years, releasing 6.697+2.282 MeV per disintegration, this works out to about 1.065×10−12 grays per second. The permissible body burden was established at 1,000 S.U.
Sources: en.wikipedia.org
=== Other Heseltine comments === Heseltine criticised the Coalition's policy on Europe, but he did support the tightening of immigration laws. He also supported George Osborne's Budget measures in 2013 and Iain Duncan Smith's welfare reforms, but showed concerns over the legalisation of same-sex marriage. In June 2013, he voted against Lord Dear's wrecking amendment, thus ratifying the same-sex marriage act.
=== Ga–Go === Elmer L. Gaden (1923–2012). American biochemical engineer at the University of Virginia, known as the father of biochemical engineering. Michael H. Gelb (b. 1957). American biochemist at the University of Washington who studies study enzymatic processes of biomedical significance. Susan Gerbi, (b. 1944). American biochemist at Brown University working on RNA and DNA. Jonathan Gershenzon (b. 1955). American biochemist at the Max Planck Institute for Chemical Ecology in Jena, known for work on the biochemistry of secondary plant metabolites. Quentin Gibson FRS (1918–2011). British-American biochemist at Sheffield and later Cornell University who worked on haem proteins. Member Natl. Acad. Sci. USA. Walter Gilbert FRS (foreign member) (b. 1932). American biochemist at Harvard, awarded the Nobel Prize in Chemistry (1980) for work on DNA sequencing. Member Natl. Acad. Sci. USA. H. Bentley Glass (1906–2005). American biochemist at the State University of New York at Stony Brook. Member Natl. Acad. Sci. USA Joseph L. Goldstein (b. 1940). American biochemist at the University of Texas, awarded the Nobel Prize in Physiology or Medicine (1985) for studies of cholesterol. Member Natl. Acad. Sci. USA. Eugene Goldwasser (1922–2010). American biochemist at the University of Chicago, known for identifying the hormone erythropoietin. Michael M. Gottesman (b. 1946). American biochemist at the NIH, whose achievements includes the discovery of P-glycoprotein. Member Natl. Acad. Sci. USA. Alfred Gottschalk (1894–1973).
In 2011, the United States Environmental Protection Agency introduced the gallon gasoline equivalent as a unit of energy because their research showed most U.S. citizens do not understand the standard units. The gallon gasoline equivalent is defined as 33.7 kWh, or about 1.213×108 joules. Energy efficiency of electric and alternative-fuel vehicles can be given as miles per gallon gasoline equivalent.
== Causes == AMP deaminase is an enzyme that converts adenosine monophosphate (AMP) to inosine monophosphate (IMP), freeing an ammonia molecule in the process. It is a part of the metabolic process that converts sugar, fat, and protein into cellular energy. In order to use energy, a cell converts one of the above fuels into adenosine triphosphate (ATP) via the mitochondria. Cellular processes, especially muscles, then convert the ATP into adenosine diphosphate (ADP), freeing the energy to do work. During heavy or prolonged mild to moderate activity, other enzymes convert two molecules of ADP into one ATP molecule and one AMP molecule, making more ATP available to supply energy. AMP is normally converted into IMP by myoadenylate deaminase—so myoadenylate deaminase deficiency reduces energy that would be available to the cell through the purine nucleotide cycle. Instead of being converted to IMP, the AMP builds up in the cells of affected individuals, spills into the blood, and is eventually metabolized in the liver. In persons with a defective enzyme, 5'-nucleotidase removes the ribose and phosphorus from AMP, increasing levels of adenosine measured in muscle cells by ~16–25×, after exercise.
Sources: en.wikipedia.org
Reversed-phase high-performance liquid chromatography is the standard method, with detection in the ultraviolet range. Peak area percentage yields a purity figure for the main component. Mass spectrometry is normally run alongside to confirm molecular identity.
Dry lyophilised powder is generally kept at minus twenty degrees Celsius, protected from light and moisture. Repeated freeze-thaw cycles are avoided because they encourage aggregation and moisture uptake. Solutions are less stable than the solid form and degrade faster at room temperature.
A certificate documents what the supplier measured, not what an independent party confirmed. Methods, instruments and acceptance criteria can differ between suppliers. Third-party testing is the usual way to resolve discrepancies.
It is a short synthetic peptide built from seven amino acids: methionine, glutamic acid, histidine, phenylalanine and three prolines. The sequence derives from the 4-10 fragment of adrenocorticotropic hormone with an added proline-glycine-proline tail. No plant or animal extract is involved; the material is produced by solid-phase peptide synthesis.