reversed-phase 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 2026-07-04. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. It was developed as a fragment analog of adrenocorticotropic hormone, modeled specifically on the ACTH(4-10) region. The first four residues reproduce that fragment, while a Pro-Gly-Pro tripeptide is appended at the C-terminus. Work on the compound originated in Russia, where it entered clinical use as an intranasal preparation. Its sequence places it among short regulatory peptides studied for effects on the central nervous system rather than on the adrenal axis.
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.
Semax is supplied as a lyophilized powder that appears white to off-white. It dissolves readily in water, phosphate-buffered saline, and other aqueous media, which simplifies preparation of working solutions for laboratory use. The nasal products registered in Russia are dilute aqueous solutions, typically around 0.1 percent peptide by weight. Organic solvents are rarely necessary and can complicate handling. Because the peptide is hygroscopic, weighing should be performed quickly and with minimal exposure to ambient humidity.
Solid material is normally kept at minus 20 degrees Celsius in a sealed, desiccated container. Reconstituted solutions are less stable and are usually divided into single-use aliquots before freezing. Repeated freeze-thaw cycles are avoided because they promote aggregation and loss of activity. Light exposure is minimized by using amber glassware or foil wrapping. Published stability data for this peptide are sparse, so recommended storage conditions rest mainly on general practice for short synthetic peptides rather than on dedicated study.
| 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 |
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.
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.
Published research has focused mainly on neurological and cognitive endpoints in animal models, with proposed mechanisms involving brain-derived neurotrophic factor and related signalling pathways. A substantial share of the human data originates from a limited number of research groups, and independent replication in other countries remains sparse. Regulatory status reflects that distribution: the peptide is registered as a medicine in Russia and appears in some neighbouring markets, while elsewhere it is handled as a research chemical without approved therapeutic labelling. Questions about dose-response relationships, long-term effects, and comparability across studies are still open.
Lyophilised powder is normally kept at -20 °C in a desiccated container, with some suppliers recommending -80 °C for long-term archival storage. Repeated freeze-thaw cycles are the most common cause of avoidable loss, so aliquoting before freezing reduces variability between working sessions. Dissolved peptide is far less stable than the dry solid and is usually prepared fresh or held briefly at 4 °C. Aqueous solutions support both hydrolysis of the backbone and oxidation of the N-terminal methionine, and these two routes dominate degradation under ordinary laboratory conditions.
If by next Thursday, May 21, 1942, Mexico has not received from the country responsible for the aggression complete satisfaction, as well as guarantees that the indemnities for the damages suffered will be duly covered, the government of the Republic will immediately adopt the measures required by national honor. Mexico received no response except for a new attack on May 20. Another oil tanker, the SS Faja de Oro, was sunk in the Gulf of Mexico by a German torpedo. On May 22, the president called an extraordinary session of the Congress of the Union to grant the executive the power to declare a state of war between Mexico and the Axis countries. Before the congress, Avila Camacho said the following:
== RM-ODP and UML == Currently there is growing interest in the use of UML for system modelling. However, there is no widely agreed approach to the structuring of such specifications. This adds to the cost of adopting the use of UML for system specification, hampers communication between system developers and makes it difficult to relate or merge system specifications where there is a need to integrate IT systems. Although the ODP reference model provides abstract languages for the relevant concepts, it does not prescribe particular notations to be used in the individual viewpoints. The viewpoint languages defined in the reference model are abstract languages in the sense that they define what concepts should be used, not how they should be represented. This lack of precise notations for expressing the different models involved in a multi-viewpoint specification of a system is a common feature for most enterprise architectural approaches, including the Zachman Framework, the "4+1" model, or the RM-ODP. These approaches were consciously defined in a notation- and representation-neutral manner to increase their use and flexibility. However, this makes more difficult, among other things, the development of industrial tools for modeling the viewpoint specifications, the formal analysis of the specifications produced, and the possible derivation of implementations from the system specifications. In order to address these issues, ISO/IEC and the ITU-T started a joint project in 2004: "ITU-T Rec.
=== The presence of all structural varieties in the library === Formation of all structural variants that can be deduced from the BBs is an important feature of the S&P synthesis. Only the S&P method can achieve this in a single process. On the other hand, the presence of all possible structural varieties in a library assures that the library is a combinatorial one and is prepared by combinatorial synthesis.
Ivory usage in the last thirty years has moved towards mass production of souvenirs and jewelry. In Japan, the increase in wealth sparked consumption of solid ivory hanko – name seals – which before this time had been made of wood. These hanko can be carved out in a matter of seconds using machinery and were partly responsible for massive African elephant decline in the 1980s, when the African elephant population went from 1.3 million to around 600,000 in ten years. Carving of walrus ivory is permitted for Arctic Indigenous peoples in the USA, but the export of raw ivory is prohibited; surveys by a team led by EcoVerde Global Consulting showed that raw walrus tusks from the USA are illegally exported to Indonesia (Bali) where they are carved in traditional motifs and exported back to the US market.
==== Post-traumatic stress disorder and phobias ==== Propranolol is being investigated as a potential treatment for PTSD. Propranolol works to inhibit the actions of norepinephrine (noradrenaline), a neurotransmitter that enhances memory consolidation. In one small study, individuals given propranolol immediately after trauma experienced fewer stress-related symptoms and lower rates of PTSD than respective control groups who did not receive the drug. Due to the fact that memories and their emotional content are reconsolidated in the hours after they are recalled or re-experienced, propranolol can also diminish the emotional impact of already formed memories; for this reason, it is also being studied in the treatment of specific phobias, such as arachnophobia, dental fear, and social phobia. It has also been found to be helpful for some individuals with misophonia. Ethical and legal questions have been raised surrounding the use of propranolol-based medications for use as a "memory damper", including altering memory-recalled evidence during an investigation, modifying the behavioral response to past (albeit traumatic) experiences, the regulation of these drugs, and others. However, Hall and Carter have argued that many such objections are "based on wildly exaggerated and unrealistic scenarios that ignore the limited action of propranolol in affecting memory, underplay the debilitating impact that PTSD has on those who suffer from it, and fail to acknowledge the extent to which drugs like alcohol are already used for this purpose".
Sources: en.wikipedia.org
==== Public opinion polls ==== An opinion poll of Canadians conducted by Léger in August 2020 found that a majority (68%) would not take the Russian vaccine if offered a free dose, compared to 14% who said they would take it. When Americans were asked the same question, 59% would not take the Russian vaccine if offered a free dose, compared to 24% who said they would take it. In June 2021, according to a poll conducted by Ost-Ausschuss der Deutschen Wirtschaft (German Eastern Business Association), a majority (60%) of Germans would use the Russian vaccine Sputnik V if they had the opportunity to do so. With 71% approval, the values in East Germany are significantly higher, but with 58% of the respondents there is also a solid majority in West Germany. 38% of respondents, on the other hand, would not want to use Sputnik V. In July 2020, opinion polls suggested around 90% of the Russian population had doubts about the vaccine but by September this had dropped to around half the Russian population. In May 2021, the Levada Center released a poll of 1,614 respondents from 50 regions which showed that 26% of Russians were prepared to be vaccinated with Sputnik V, while 62% were not prepared to be vaccinated. Ten percent of respondents had already been vaccinated.
== Transcripts == The gene GLS encodes three separate isoforms. Isoform 1 (or KGA) and isoform 3 (or Glutaminase C) are functional enzymes, while isoform 2 (or GAM) shows no enzyme activity. Isoform 1 is expressed in the brain and kidneys, while isoform 3 is mostly expressed in the brain, heart and pancreas. Neither isoform is expressed in the liver, distinguishing it from the glutaminase encoded by GLS2. Despite predictions that suggested that isoform 3 should undergo nonsense-mediated decay, it is highly expressed.
MassLynx is a software package to control analytical equipment produced by Waters Corporation. It was developed to simplify interaction with mass spectrometry equipment. It is used to control equipment including liquid chromatography systems such as the ACQUITY UPLC series of UHPLC systems and mass spectrometers such as the Xevo TQ-S. MassLynx is used for hardware control, creating, editing and executing run sequences as well as configuration of acquisition methods. Data treatment is performed in other software such as TargetLynx or ChromaLynx.
==== Other terminal prostaglandin synthases ==== Terminal prostaglandin syntheses have been identified that are responsible for the formation of other prostaglandins. For example, two types of prostaglandin-D synthase, hematopoietic-type PGDS and lipocalin-type PGDS, are responsible for the formation of PGD2 from PGH2. Similarly, prostacyclin (PGI2) synthase (PGIS) converts PGH2 into PGI2. A thromboxane synthase (TxAS) has also been identified. Prostaglandin-F synthase (PGFS) catalyzes the formation of 9α,11β-PGF2α,β from PGD2 and PGF2α from PGH2 in the presence of NADPH. This enzyme has recently been crystallized in complex with PGD2 and bimatoprost (a synthetic analogue of PGF2α).
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.
Solid peptide is best kept frozen at about minus 20 degrees Celsius in a sealed container with desiccant. It should be allowed to reach room temperature before opening to prevent condensation. Repeated warming and cooling of the same vial is discouraged.