This is a working overview of Pro-Gly-Pro tail, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-08-01. Anything still debated is marked as such rather than presented as settled.
The parent fragment ACTH(4-10) carries the sequence Met-Glu-His-Phe-Arg-Trp-Gly. Semax replaces the arginine and tryptophan positions with a proline-glycine-proline tail, giving Met-Glu-His-Phe-Pro-Gly-Pro. That change removes residues associated with adrenal stimulation, so the peptide does not drive cortisol release the way full ACTH does. This distinction shapes how the compound is grouped in the literature, where it sits with neuropeptides and peptide neuromodulators rather than with corticosteroids.
Regulatory status varies sharply by country. Semax is registered for medical use in Russia, where it appears in formularies as a nasal solution, and it also holds registration in a small number of neighbouring states. It has no approval from the United States Food and Drug Administration or the European Medicines Agency, and it is not a scheduled controlled substance in most jurisdictions. Elsewhere it circulates mainly as laboratory material, so purity documentation comes from suppliers rather than from a national pharmacopoeia.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Analogue of the ACTH(4-10) fragment |
| Amino acid sequence | Met-Glu-His-Phe-Pro-Gly-Pro | Single-letter form MEHFPGP |
| Molecular formula | C37H51N9O10S | Free peptide, nominal mass near 814 Da |
| First registration | 1994, Russia | Nasal formulation for neurological indications |
| Typical purity grade | 95% or higher by HPLC | Research material; higher grades used as reference standards |
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.
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.
Russian regulatory authorities approved the peptide for nasal administration, and it remains listed in the national pharmacopoeia under several trade names. Documented indications include acute ischemic stroke, transient ischemic attacks, traumatic brain injury, and certain ophthalmological and neurological conditions. Physicians also prescribe it for cognitive complaints in older patients, although the evidence base for that use is thinner. Outside Russia and a few neighboring states, the substance is not an approved medicine and is sold instead as a research chemical.
Later generations of the molecule include an N-acetylated form and an amidated form, both marketed online alongside the parent peptide. These variants differ in terminal chemistry and stability, and they are frequently discussed in the same breath even though they have not been compared in controlled trials. Supply outside formal healthcare systems comes largely from laboratories that synthesize peptides to order. Purity and identity of these materials vary widely, and no single body oversees the international trade.
Semax is a synthetic heptapeptide developed in the Soviet Union during the 1980s by researchers at the Institute of Molecular Genetics in Moscow. It was designed as a truncated analog of adrenocorticotropic hormone, retaining only the fragment spanning residues four through ten. Investigators sought a peptide that would preserve the cognitive effects associated with ACTH while eliminating the hormonal stimulation of the adrenal cortex. The compound entered clinical use in Russia during the following decade.
== Production of intracellular components == Of primary interest among the intracellular components are microbial enzymes: catalase, amylase, protease, pectinase, cellulase, hemicellulase, lipase, lactase, streptokinase and many others. Recombinant proteins, such as insulin, hepatitis B vaccine, interferon, granulocyte colony-stimulating factor, streptokinase and others are also made this way. The largest difference between this process and the others is that the cells must be ruptured (lysed) at the end of fermentation, and the environment must be manipulated to maximize the amount of the product. Furthermore, the product (typically a protein) must be separated from all of the other cellular proteins in the lysate to be purified.
The Federal Assembly of Yugoslavia, representing the FR Yugoslavia (1992–2003) was composed of two chambers: the Council of Citizens and the Council of Republics. Whereas the Council of Citizens served as an ordinary assembly, representing the people, the Council of Republics was made equally by representatives from the federation's constituent republics, to ensure federal equality between Serbia and Montenegro. The first president from 1992 to 1993 was Dobrica Ćosić, a former communist Yugoslav partisan during World War II and later one of the fringe contributors of the controversial Memorandum of the Serbian Academy of Sciences and Arts. Despite being head of the country, Ćosić was forced out of office in 1993 due to his opposition to Serbian President Slobodan Milošević. Ćosić was replaced by Zoran Lilić who served from 1993 to 1997, and then followed by Milošević becoming Yugoslav President in 1997 after his last legal term as Serbian president ended in 1997. The FR Yugoslavia was dominated by Milosevic and his allies, until the presidential election in 2000. There were accusations of vote fraud and Yugoslav citizens took to the streets and engaged in riots in Belgrade demanding that Milošević be removed from power. Shortly afterwards Milošević resigned and Vojislav Koštunica took over as Yugoslav president and remained president until the state's reconstitution as the State Union of Serbia and Montenegro.
The pharmacokinetics of progesterone are dependent on its route of administration. The medications is approved in the form of oil-filled capsules containing micronized progesterone for oral administration, termed oral micronized progesterone or OMP. It is also available in the form of vaginal or rectal suppositories or pessaries, topical creams and gels, oil solutions for intramuscular injection, and aqueous solutions for subcutaneous injection. Routes of administration that progesterone has been used by include oral, intranasal, transdermal/topical, vaginal, rectal, intramuscular, subcutaneous, and intravenous injection. Vaginal progesterone is available in the form of progesterone capsules, tablets or inserts, gels, suppositories or pessaries, and rings. The bioavailability of progesterone was commonly overestimated due to the immunoassay method of analysis failing to distinguish between progesterone itself and its metabolites. Newer methods have adjusted the oral bioavailbility estimate from 6.2 to 8.6% down to less than 2.4%.
Statistical, likelihood-based approaches: Statistical, likelihood-based iterative expectation-maximization algorithms such as the Shepp–Vardi algorithm are now the preferred method of reconstruction. These algorithms compute an estimate of the likely distribution of annihilation events that led to the measured data, based on statistical principles. The advantage is a better noise profile and resistance to the streak artifacts common with FBP, but the disadvantage is greater computer resource requirements. A further advantage of statistical image reconstruction techniques is that the physical effects that would need to be pre-corrected for when using an analytical reconstruction algorithm, such as scattered photons, random coincidences, attenuation and detector dead-time, can be incorporated into the likelihood model being used in the reconstruction, allowing for additional noise reduction. Iterative reconstruction has also been shown to result in improvements in the resolution of the reconstructed images, since more sophisticated models of the scanner physics can be incorporated into the likelihood model than those used by analytical reconstruction methods, allowing for improved quantification of the radioactivity distribution. Research has shown that Bayesian methods that involve a Poisson likelihood function and an appropriate prior probability (e.g., a smoothing prior leading to total variation regularization or a Laplacian distribution leading to
=== Mechanism === Younes and Loveland define fission as, "...a collective motion of the protons and neutrons that make up the nucleus, and as such it is distinguishable from other phenomena that break up the nucleus. Nuclear fission is an extreme example of large-amplitude collective motion that results in the division of a parent nucleus into two or more fragment nuclei. The fission process can occur spontaneously, or it can be induced by an incident particle." The energy from a fission reaction is produced by its fission products, though a large majority of it, about 85 percent, is found in fragment kinetic energy, while about 6 percent each comes from initial neutrons and gamma rays and those emitted after beta decay, plus about 3 percent from neutrinos as the product of such decay.
Sources: en.wikipedia.org
=== Entry into the cytoplasm === Ricin B chain binds complex carbohydrates on the surface of eukaryotic cells containing either terminal N-acetylgalactosamine or beta-1,4-linked galactose residues. In addition, the mannose-type glycans of ricin are able to bind to cells that express mannose receptors. RTB has been shown to bind to the cell surface on the order of 106–108 ricin molecules per cell surface. The profuse binding of ricin to surface membranes allows internalization with all types of membrane invaginations. The holotoxin can be taken up by clathrin-coated pits, as well as by clathrin-independent pathways including caveolae and macropinocytosis. Intracellular vesicles shuttle ricin to endosomes that are delivered to the Golgi apparatus. The active acidification of endosomes is thought to have little effect on the functional properties of ricin. Because ricin is stable over a wide pH range, degradation in endosomes or lysosomes offers little or no protection against ricin. Ricin molecules are thought to follow retrograde transport via early endosomes, the trans-Golgi network, and the Golgi to enter the lumen of the endoplasmic reticulum (ER). For ricin to function cytotoxically, RTA must be reductively cleaved from RTB to release a steric block of the RTA active site. This process is catalysed by the protein PDI (protein disulphide isomerase) that resides in the lumen of the ER. Free RTA in the ER lumen then partially unfolds and partially buries into the ER membrane, where it is thought to mimic a misfolded membrane-associated protein.
=== Photodegradation === Additionally, DBNPA is prone to light-induced degradation, especially when exposed to ultraviolet (UV) radiation. Photocatalytic breakdown leads to debromination and the formation of less reactive intermediates, further accelerating its degradation in aqueous systems.
Above all, we are in need of a renewed Enlightenment, which will base itself on the proposition that the proper study of mankind is man and woman [referencing Alexander Pope]. This Enlightenment will not need to depend, like its predecessors, on the heroic breakthroughs of a few gifted and exceptionally courageous people. It is within the compass of the average person. The study of literature and poetry, both for its own sake and for the eternal ethical questions with which it deals, can now easily depose the scrutiny of sacred texts that have been found to be corrupt and confected. The pursuit of unfettered scientific inquiry, and the availability of new findings to masses of people by electronic means, will revolutionize our concepts of research and development. Very importantly, the divorce between the sexual life and fear, and the sexual life and disease, and the sexual life and tyranny, can now at last be attempted, on the sole condition that we banish all religions from the discourse. And all this and more is, for the first time in our history, within the reach if not the grasp of everyone. Hitchens was accused of "anti-Catholic bigotry" by others, including Brent Bozell and UCLA Law Professor Stephen Bainbridge. When Joe Scarborough on 12 March 2004 asked Hitchens whether he was "consumed with hatred for conservative Catholics", Hitchens responded that he was not and that he just thinks that "all religious belief is sinister and infantile".
=== Surgical techniques === The effectiveness of a rhinoplastic reconstruction of the external nose derives from the contents of the surgeon's armamentarium of skin-flap techniques applicable to correcting defects of the nasal skin and of the mucosal lining; some management techniques are the bilobed flap, the nasolabial flap, the paramedian forehead flap, and the septal mucosal flap.
Sources: en.wikipedia.org
The most controversial of these responses by Ja Rule was leaked in April 2003 in the track Loose Change; in which Ja Rule directly attacked Eminem and Dr. Dre for their affiliation with 50 Cent, notably aiming several insults at Eminem's daughter Hailie. On Eminem's 2005 track "Like Toy Soldiers" he mentioned how he had tried to coerce 50 Cent into ending his feud with Ja Rule, until Ja Rule leaked his diss track attacking him and his daughter. Eminem and D12 quickly responded with Hailie's revenge, a diss track that was critically lauded as one of the best in the genre for its aggression and ferocity. Further attacks came in the form of other rappers such as Obie Trice and Busta Rhymes, the latter of whom joined 50 Cent and Eminem on a remake of Tupac Shakur's "Hail Mary". In the track; Eminem proclaimed a narrative that drew criticism towards Ja Rule for his supposed influence of Tupac's image to benefit himself. In another move to damage Ja Rule's contributions to other collaborative efforts, Eminem later barred him from appearing on any remixed posthumous tracks by Tupac Shakur on the 2004 album Loyal to the Game. Former D12 affiliate Royce Da 5'9 who was involved with an ongoing feud with the group; took side with Murder Inc on his diss track Malcolm X in which he attacked both D12 and G-Unit, even threatening to sign with Murder Inc. Following the release of his track, Royce later made amends with Proof of D12 following the two being arrested in connection to a nightclub fight.
Patients with no history of red cell antibodies may qualify for computer-assisted crossmatch, which does not involve combining patient serum with donor cells. If an antibody is suspected, potential donor units must first be screened for the corresponding antigen by phenotyping them. Antigen negative units are then tested against the patient plasma using an antiglobulin/indirect crossmatch technique at 37 degrees Celsius to enhance reactivity and make the test easier to read. In urgent cases where crossmatching cannot be completed, and the risk of dropping hemoglobin outweighs the risk of transfusing uncrossmatched blood, O-negative blood is used, followed by crossmatch as soon as possible. O-negative is also used for children and women of childbearing age. It is preferable for the laboratory to obtain a pre-transfusion sample in these cases so a type and screen can be performed to determine the actual blood group of the patient and to check for alloantibodies.
chimerism The presence of two or more populations of cells with distinct genotypes in an individual organism, known as a chimera, which has developed from the fusion of cells originating from separate zygotes; each population of cells retains its own genome, such that the organism as a whole is a mixture of genetically non-identical tissues. Genetic chimerism may be inherited (e.g. by the fusion of multiple embryos during pregnancy) or acquired after birth (e.g. by allogeneic transplantation of cells, tissues, or organs from a genetically non-identical donor); in plants, it can result from grafting or errors in cell division. It is similar to but distinct from mosaicism.
Sources: en.wikipedia.org
Registered medical products are most often 0.1% nasal drops. Research suppliers ship lyophilized powder, usually in milligram quantities, which is dissolved before use. The active peptide is the same in both cases; presentation and excipients differ.
No. The peptide is synthetic, although it is modelled on a fragment of a naturally occurring hormone. ACTH(4-10) is generated when ACTH is cleaved, but the Pro-Gly-Pro extension is not a known endogenous sequence. It is therefore a designed analogue rather than a natural metabolite.
The label reflects reported effects on attention, memory and recovery after neurological injury in regional clinical reports. Those reports are mostly small and have not been widely replicated outside the region. The classification is descriptive and does not imply a single defined mechanism.
It is described as a synthetic analogue of the ACTH(4–10) fragment, a short segment of adrenocorticotropic hormone. Its sequence differs from that fragment and includes two proline residues, which influence stability and behaviour in solution.