Everything below concerns RP-HPLC. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-01-07. Numbers and descriptions here follow the published literature rather than marketing material.
The C-terminal Pro-Gly-Pro extension is not incidental. Proline-rich tails are known to resist several common peptidases, and the published literature attributes the longer half-life of Semax, relative to unmodified ACTH fragments, to this feature. The modification also removes the melanocyte-stimulating and corticosteroidogenic activity that characterizes longer ACTH-derived sequences. Because the molecule is small and hydrophilic, it is typically formulated as an aqueous solution for intranasal or parenteral delivery. Acetylation or amidation at the termini appears in closely related research peptides and shifts the mass by a fixed increment.
Reported pharmacological work centers on neurotrophic signaling, including changes in BDNF and NGF expression in hippocampal tissue in animal models. Human data come largely from studies conducted in Russia, and how well those results generalize to other populations remains an open question. Regulatory status differs sharply by jurisdiction: Semax is a registered prescription medicine in Russia, while it holds no approved marketing status in the United States or the European Union. Outside such jurisdictions it is generally handled as a research chemical, which affects both documentation and quality expectations.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular weight | ~813.9 Da (free heptapeptide) | N-acetylated form is about 42 Da heavier |
| Residue count | 7 (heptapeptide) | Four residues from ACTH(4-10), three added |
| Appearance | White to off-white powder | Usually supplied lyophilized |
| Solubility class | Freely soluble in water | Also dissolves in DMSO and polar organic solvents |
| Related parent fragment | ACTH(4-10) | Parent motif is Met-Glu-His-Phe |
The compound was developed during the 1980s at the Institute of Molecular Genetics in Moscow as part of research on fragments of adrenocorticotropic hormone. Early work examined short ACTH-derived sequences that retained neurotrophic effects while lacking the endocrine activity of the full hormone. Semax entered clinical use in Russia during the 1990s, where it received registration for several neurological indications. Outside that region it remained primarily a laboratory research material rather than an approved therapeutic. English-language literature on it grew more slowly and frequently cited the original Russian studies.
Terminology around the compound varies by source. It appears in catalogues and papers as Semax, as the heptapeptide ACTH(4-7)-Pro-Gly-Pro, and under various alphanumeric laboratory codes used by individual suppliers. These names refer to the same sequence but may imply different salt forms, purity grades, or counter-ions. Peptide databases usually list the free base mass, while product descriptions sometimes report acetate or trifluoroacetate salts with a different formula weight. Because naming conventions for research peptides are not standardised across vendors, checking the declared sequence and measured mass is more reliable than relying on a trade name alone.
Pharmacokinetic accounts emphasize rapid breakdown. After intravenous dosing the intact peptide disappears from blood within minutes, and nasal delivery produces low but measurable concentrations. Metabolites rather than the parent molecule may account for part of the observed activity, although the relative contribution is unresolved. Dosing in the literature varies widely and no optimal schedule has been agreed. These gaps are regularly cited as a reason the findings have not produced broad clinical adoption beyond the original research setting.
Proposed mechanisms center on neurotrophic signaling rather than on classical melanocortin receptor activation. Rodent experiments have reported shifts in the expression of brain-derived neurotrophic factor and nerve growth factor after administration, together with changes in the associated receptor systems. Several authors argue that the peptide acts largely through its degradation products and their interaction with peptidergic pathways, but this remains a hypothesis rather than a settled finding. No single molecular target has been identified in a way that the field broadly accepts.
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.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It is described in the literature as an analogue of the ACTH(4–10) fragment, a short N-terminal portion of adrenocorticotropic hormone that retains some neurotropic activity without the full hormonal effects of the parent peptide. The molecule carries a methionine residue at the N-terminus and two proline residues near the C-terminus, features that shape both its interactions with receptor systems and its chemical stability. The free peptide corresponds to the formula C37H51N9O10S and a molecular mass near 813.9 Da.
Conformations are the same in solution and when adsorbed. Diastereomers bind to surfaces (silica gel in normal phase chromatography) mainly with hydrogen bonding. Significant resolution of diastereomers is only expected when molecules can adsorb to silica through two contact points (two hydrogen bonds). This interaction can be perturbed by substituents. Diastereomers with bulky substituents on the alpha carbon (R2) and on the nitrogen (R1) can shield the hydrogen bonding with the surface, thus the molecule will be eluted before similar molecules with smaller substituents. Helmchen's postulates have been proven to be applicable to other functional groups such as: carbamates, esters, and epoxides.
Vacuum pumps are used to manufacture light bulbs, in the freeze drying process in the medical, food and biological industries, and in the atomic energy industry. Compressed air allowed for better and more powerful pneumatic tools that helped the growth of big cities. Many important buildings in today's society are possible because of these tools, such as skyscrapers, hotels, tenements, and stadiums. The use of reciprocating air pumps is vital in the construction of the internal combustion engine.
=== Insulin === The method usually employed is a dose of slow-acting insulin twice daily to keep the blood sugar within a recommended range for the entire day. With this method, it is important for the cat to avoid large meals or high-carbohydrate food. Meals may also be timed to coincide with peak insulin activity. Once-daily doses are not recommended, since insulin usually metabolizes faster in cats than in humans or dogs. For example, an insulin brand that lasts 24 hours in people may only be effective for about 12 in a cat. Cats may be treated with animal insulin (bovine-based insulin is most similar to cat insulin) or with human synthetic insulin. The best choice of insulin brand and type varies from animal to animal and may require some trial and error. The human synthetic insulin, Humulin N /Novolin N/ NPH, is usually a poor choice for cats, since cats metabolize insulin about twice as fast. The Lente and Ultralente versions were popular for feline use until summer 2005, when they were discontinued. Until the early 1990s, the most recommended type for pets was bovine/porcine-derived PZI, but that type was phased out over the 1990s and is now difficult to find in many countries. There are sources in the US and UK, and many vets are now starting to recommend them again for pets, but they have been discontinued by most manufacturers as of 2007-2008. A new synthetic PZI analogue called ProZinc is now available. Caninsulin (known in the US as Vetsulin) is a brand of porcine-based insulin approved for cats which is available with a veterinarian's prescription.
Another example is spironolactone, a potassium-sparing diuretic of the steroidal spirolactone group, which interferes with the aldosterone receptor (among others) leading to lower blood pressure by the mechanism described above. Aldosterone was first isolated by Sylvia Tait (Simpson) and Jim Tait in 1953; in collaboration with Tadeusz Reichstein.
Cellular thermal shift assay (CETSA®) is a biophysical technique applicable on living cells as well as tissue biopsies. CETSA® is based on the discovery that protein melting curves can also be generated in intact cells and that drug binding leads to very significant thermal stabilization of proteins. Upon denaturation, proteins are aggregated and can thus be removed by centrifugation after lysis of the cells. The stable proteins are found in the supernatant can be detected; e.g., by western blot, alpha-LISA, or mass spectrometry. The CETSA®-technique is highly stringent, reproducible, and not prone to false positives. However, it is possible for a sample, or small molecule compound, to bind a protein in a given target's pathway. If that protein induces further stabilization of the original target protein through a cascade event, it could manifest as direct target engagement. An advantage of this method is that it is label-free and thus applicable for studies of drug binding in a wide range of cells and tissues. CETSA® can also be conducted on cell lysates versus intact cells, helping to determine sample penetration of the cell membrane.
Sources: en.wikipedia.org
Prospects in Analytical Atomic Spectrometry – tendencies in five main branches of atomic spectrometry (absorption, emission, mass, fluorescence and ionization spectrometry) Learning by Simulations – various atomic absorption and emission spectra Atomic Spectroscopy: A Compendium of Basic Ideas, Notation, Data, and Formulas
In 1989, the communist governments in Poland and Hungary became the first to negotiate the organization of competitive elections. In Czechoslovakia and East Germany, mass protests unseated entrenched communist leaders. The communist regimes in Bulgaria and Romania also crumbled, in the latter case as the result of a violent uprising. Attitudes had changed enough that US Secretary of State James Baker suggested that the American government would not be opposed to Soviet intervention in Romania, on behalf of the opposition, to prevent bloodshed. The tidal wave of change culminated with the fall of the Berlin Wall in November 1989, which symbolized the collapse of European communist governments and graphically ended the Iron Curtain divide of Europe. The 1989 revolutionary wave swept across Central and Eastern Europe and peacefully overthrew all of the Soviet-style Marxist–Leninist states: East Germany, Poland, Hungary, Czechoslovakia and Bulgaria; Romania was the only Eastern-bloc country to topple its communist regime violently and execute its head of state.
=== Food waste reduction === Approximately one-third of all food produced globally is wasted. Innovative food tech solutions are being developed to address this issue. For example, Apeel Sciences has developed an edible coating that extends the shelf life of fruits and vegetables, reducing spoilage and waste.
FM (frequency modulation) – in FM the frequency of the radio carrier signal is varied slightly by the audio signal. FM broadcasting is permitted in the FM broadcast bands between about 65 and 108 MHz in the very high frequency (VHF) range. Radio waves in this band travel by line-of-sight so FM reception is limited by the visual horizon to about 30–40 miles (48–64 km), and can be blocked by hills. However it is less susceptible to interference from radio noise (RFI, sferics, static), and has higher fidelity, better frequency response, and less audio distortion than AM. In the US, radiated power (ERP) of FM stations varies from 6–100 kW. Digital radio involves a variety of standards and technologies for broadcasting digital radio signals over the air. Some systems, such as HD Radio and DRM, operate in the same wavebands as analog broadcasts, either as a replacement for analog stations or as a complementary service. Others, such as DAB/DAB+ and ISDB_Tsb, operate in wavebands traditionally used for television or satellite services.
Sources: en.wikipedia.org
requirement for the safety factor). In a tokamak, instabilities also arise from resistive MHD. For instance, tearing modes are instabilities that arise within the framework of non-ideal MHD. This is an active field of research because these instabilities are the starting point for disruptions.
=== 15 July === The Russian-installed governor of Sevastopol claimed that a house was damaged by falling drone debris near Cape Fiolent. The Russian defence ministry claimed that six drones were shot down over Crimea. The HUR and volunteer hackers carried out a cyberattack on websites in Russia belonging to entities involved in the war effort against Ukraine. In Russia, the governor of Lipetsk Oblast claimed that an electrical substation was struck by a drone in Stanovlyansky District, while the governor of Bryansk Oblast claimed that 15 drones were shot down over five districts. Lithuania and Vilnius Combined Heat and Power Plant gave Ukraine equipment for a thermal power plant.
In the US, newborn screening (NBS) is mandated in all states, though in some states parents may decline it for religious or philosophical reasons. Few parents opt for the program due to health concerns, and a lack of awareness of the ability to opt out. After the initial testing is complete, the residual dried blood spots (DBS) on newborn screening cards may be used for secondary purposes, including being shared with law enforcement and sold for research. The decreasing costs of whole genome sequencing have also raised concerns that blood spots may be sequenced in the future, limiting any de-identification procedures. While CLIA does specify minimum retention requirements, it does not specify a federal maximum retention period. Retention periods for NBS cards vary by state; for example, New Jersey stores them for 23 years, and Texas may keep them indefinitely. The absence of parental awareness and consent for these activities, and a lack of transparency and federal regulations, has led to significant public concern and apprehension.
Beta blockers have a variety of drug interactions. An example is that various beta blockers including propranolol, carvedilol, nebivolol, timolol, and metoprolol are metabolized by the cytochrome P450 enzyme CYP2D6 and may be potentiated by CYP2D6 inhibitors like fluoxetine, paroxetine, duloxetine, and bupropion. This may increase the risk of adverse effects like bradycardia and hypotension.
=== Legal status === In February 2023, the Committee for Medicinal Products for Human Use of the European Medicines Agency adopted a positive opinion, recommending the granting of a marketing authorization for the medicinal product Hyftor, intended for the treatment of angiofibroma. The applicant for this medicinal product is Plusultra pharma GmbH. Hyftor was authorized for medical use in the European Union in May 2023. Sirolimus, as Rapamune solution, was approved for medical use in the United States in 1999; and as Rapamune tablets in August 2000. Sirolimus, as Fyarro, was approved for medical use in the United States in November 2021. Sirolimus, as Hyftor, was approved for medical use in the United States in March 2022.
Sources: en.wikipedia.org
The sequence is Met-Glu-His-Phe-Pro-Gly-Pro, a seven-residue peptide. The first four residues correspond to the ACTH(4-10) fragment, and Pro-Gly-Pro is added at the C-terminus. N-acetylated versions also appear in the literature and differ in mass.
Semax is a synthetic analog of the ACTH(4-10) fragment rather than a copy of the full hormone. Truncation plus the added tail removes the steroidogenic portion of ACTH. That distinction explains why it is studied for nervous-system effects instead of adrenal stimulation.
It is registered as a prescription product in Russia and has been used there clinically, chiefly by the intranasal route. No approval exists in the United States or the European Union. Availability elsewhere typically falls under research-chemical distribution, with varying purity documentation.
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.