If you have been reading about neuropeptide and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-01-22. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
Identity and purity are confirmed with reversed-phase high-performance liquid chromatography, typically monitored at 214 nanometres where the peptide bond absorbs. Mass spectrometry, either electrospray or MALDI-TOF, verifies molecular mass against the theoretical value and detects truncation or adduct formation. Amino acid analysis and peptide mapping provide additional confirmation when required. The most frequently reported impurities are deletion sequences from incomplete coupling, methionine sulfoxide from oxidation, and dimeric species formed through non-covalent aggregation. Impurity profiles depend strongly on the synthesis and purification route chosen by the producer.
| 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 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.
Lyophilized material is chemically stable for extended periods when kept dry, cold, and protected from light. The powder is hygroscopic, so vials should be warmed to room temperature before opening to reduce condensation on the contents. Once dissolved, the peptide is far less stable because peptide bonds are susceptible to hydrolysis and the methionine residue can oxidize. Solutions are typically aliquoted and held at 2-8 °C for short intervals or frozen for longer ones, and repeated freeze-thaw cycles should be avoided.
Routine characterization relies on reversed-phase high-performance liquid chromatography to establish purity and on mass spectrometry to confirm molecular identity. Electrospray ionization and matrix-assisted laser desorption ionization are both used for mass verification. Amino acid analysis and peptide mapping can detect sequence errors. Common impurities include truncated sequences, methionine sulfoxide formed by oxidation, and deamidated products. Chromatograms are usually recorded near 214 nm, where the peptide backbone absorbs, and purity is reported as the percentage area of the principal peak.
For even higher stresses, materials exhibit plastic behavior, that is, they deform irreversibly and do not return to their original shape after stress is no longer applied. For rubber-like materials such as elastomers, the slope of the stress–strain curve increases with stress, meaning that rubbers progressively become more difficult to stretch, while for most metals, the gradient decreases at very high stresses, meaning that they progressively become easier to stretch. Elasticity is not exhibited only by solids; non-Newtonian fluids, such as viscoelastic fluids, will also exhibit elasticity in certain conditions quantified by the Deborah number. In response to a small, rapidly applied and removed strain, these fluids may deform and then return to their original shape. Under larger strains, or strains applied for longer periods of time, these fluids may start to flow like a viscous liquid. Because the elasticity of a material is described in terms of a stress–strain relation, it is essential that the terms stress and strain be defined without ambiguity. Typically, two types of relation are considered. The first type deals with materials that are elastic only for small strains. The second deals with materials that are not limited to small strains. Clearly, the second type of relation is more general in the sense that it must include the first type as a special case.
The composition of Euryapsida was uncertain. Ichthyosaurs were, at times, considered to have arisen independently of the other euryapsids, and given the older name Parapsida. Parapsida was later discarded as a group for the most part (ichthyosaurs being classified as incertae sedis or with Euryapsida). However, four (or three if Euryapsida is merged into Diapsida) subclasses remained more or less universal for non-specialist work throughout the 20th century. It has largely been abandoned by recent researchers: In particular, the anapsid condition has been found to occur so variably among unrelated groups that it is not now considered a useful distinction.
== Regulation == IGFBP-3 levels in human serum are, like IGF-1, dependent on growth hormone (GH); for example, serum IGFBP-3 is increased in acromegaly and low in GH-deficient children. However, IGFBP-3 gene expression in human liver is GH-independent. Because it is stabilized in human serum by forming complexes with IGF-1 and ALS, which are both GH-dependent, serum IGFBP-3 also appears regulated by GH. Its production by some non-hepatic tissues may also be directly GH-regulated. Immunoassays for serum IGFBP-3 are often used as part of the diagnosis of childhood GH-deficiency. The most widely studied IGFBP3 polymorphism, at nucleotide-202 in the promoter region, is significantly associated with circulating IGFBP-3 levels, although the mechanism is unclear. In some studies circulating IGFBP-3 also appears to be nutritionally regulated, although this may not be seen at the mRNA level. IGFBP-3 has been identified in human lymph, nipple aspirate, milk, amniotic fluid, follicular fluid, seminal plasma, urine, peritoneal dialysate, synovial fluid, tear fluid, and cerebrospinal fluid, in addition to serum. Many factors increase IGFBP-3 production by cells, including transforming growth factor-β (TGFβ), tumor necrosis factor-α, vitamin D, retinoic acid, IGF-1, and stimuli such as chemotherapy that activate the tumor suppressor p53. Estrogen inhibits IGFBP-3 production, and its tissue levels are lower in estrogen receptor (ER)-positive breast cancers than in ER-negative cancers.
== Structural studies == As of late 2007, 8 structures have been solved for this class of enzymes, with PDB accession codes PDB: 1OPM, PDB: 1PHM, PDB: 1SDW, PDB: 1YI9, PDB: 1YIP, PDB: 1YJK, PDB: 1YJL, and PDB: 3PHM.
== See also == Pneumoconiosis – Scarring of the lungs due to inhaling dust over long periods Asbestosis – Pneumoconiosis caused by inhalation and retention of asbestos fibers Health effects arising from the September 11 attacks – Health issues and effects during and after the September 11 attacks Hawks Nest Tunnel disaster – 1930-35 industrial disaster in West Virginia, U.S. Dust pneumonia Frances Perkins Occupational dust exposure
Sources: en.wikipedia.org
== Etymology == The name Malaysia is a combination of the word Malays and the Latin-Greek suffix -ia/-ία, which can be translated as 'land of the Malays'. Similar-sounding variants have also appeared in accounts older than the 11th century, as toponyms for areas in Sumatra or referring to a larger region around the Strait of Malacca. The Sanskrit text Vayu Purana, thought to have been in existence since the first millennium CE, mentioned a land named 'Malayadvipa', which was identified by certain scholars as the modern Malay Peninsula. Other notable accounts are by Ptolemy's 2nd-century Geographia, which used the name Malayu Kulon for the west coast of Golden Chersonese, and the 7th-century Yijing's account of Malayu. At some point, the Melayu Kingdom took its name from the Sungai Melayu. Melayu then became associated with Srivijaya, and remained associated with various parts of Sumatra, especially Palembang, where the founder of the Malacca Sultanate is thought to have come from. It is only thought to have developed into an ethnonym as Malacca became a regional power in the 15th century. Islamisation established an ethnoreligious identity in Malacca, with the term Melayu beginning to appear as interchangeable with Melakans. It may have specifically referred to local Malay speakers who were loyal to the Malaccan Sultan. The initial Portuguese use of Malayos reflected this, referring only to the ruling people of Malacca.
== Cause == Sickle cell-Hb Lepore Boston syndrome is a type of sickle cell disease (HbS) that differs from homozygous sickle cell disease where both parents carry sickle hemoglobin. In this variant one parent has the sickle cell hemoglobin the second parent has Hb Lepore Boston, the only one of the three variants described in association with HbS.
It also raised concerns among those who had bought the ATI Radeon HD 2900 XT graphics card, which came with a voucher for The Black Box, but Valve clarified that only the retail version of The Black Box had been cancelled. While Valve never expressed its reasons for this decision, industry writers speculated that it might have been to increase profits on retail copies or to avoid customer confusion between similar game packages and their availability across the platforms.
== Aerobic vs anaerobic == Anaerobic organisms require an oxygen-free environment. When culturing anaerobic microbes, broths are often flushed with nitrogen gas to extinguish oxygen present, and growth can also occur on media in a chamber without oxygen present. Sodium resazurin can be added to indicate redox potential. Cultures are to be incubated in an oxygen-free environment for 48 hours at 35 °C before growth is examined.
Sources: en.wikipedia.org
=== Fluorohistidine tags === A polyfluorohistidine tag has been reported for use in in vitro translation systems. In this system, an expanded genetic code is used in which histidine is replaced by 4-fluorohistidine. The fluorinated analog is incorporated into peptides via the relaxed substrate specificity of histidine-tRNA ligase and lowers the overall pKa of the tag. This allows for the selective enrichment of polyfluorohistidine tagged peptides in the presence of complex mixtures of traditional polyhistidine tags by altering the pH of the wash buffers.
=== Research === TRH has been evaluated for the treatment of various neurological disorders. It has been attempted for treatment of various epileptic disorders. TRH has been shown to improve outcomes of CNS injuries in experimental models. Efficacy for the treatment ALS and spinal muscle atrophy has not been demonstrated. Many individuals with depression exhibit a blunted endocrine response to TRH due to unknown reasons, and the response is correlated with clinical outcomes. Involvement of TRH in the pathogenesis of depression has nevertheless not been well established. TRH has undergone research for its ostensible antidepressant properties, however, results regarding efficacy have been inconsistent. One study on a small sample of people with treatment-resistant depression found short-lived anti-depressant and anti-suicidal effects when TRH was administered intrathecally. An orally bioavailable prodrug is being researched. In 2012, the U.S. Army awarded a research grant to develop a TRH nasal spray for suicide prevention amongst veterans. TRH acts as a wakefulness-promoting agent, causing awakening from sleep or sedation.
=== Circulatory disorders === Diabetic vasculopathy Sepsis with peripheral necrosis Peripheral artery disease which can lead to gangrene A severe deep vein thrombosis (phlegmasia cerulea dolens) can cause compartment syndrome and gangrene
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.
Reversed-phase HPLC gives the main purity figure, most often with UV detection near 214 nanometres. Mass spectrometry then confirms the molecular mass. Together the two methods distinguish a correct sequence from a closely related impurity.