The short version of Semax fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-09-11. Anything still debated is marked as such rather than presented as settled.
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.
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.
各国监管态度分化明显。俄罗斯按处方药管理，部分东欧国家留有使用记录；欧盟与美国未批准其作为药物上市，市面流通品通常标注为研究用化学品。身份差异意味着标示含量、纯度与无菌性缺少统一核查。体育领域还牵涉反兴奋剂名录，跨境携带则受目的地药品法规约束。
Semax 是人工设计的七肽，序列为 Met-Glu-His-Phe-Pro-Gly-Pro，骨架取自促肾上腺皮质激素片段 ACTH(4-10)。它于二十世纪八十年代在苏联的分子遗传学研究机构内合成。设计目标是保留该片段与注意力和记忆相关的活性，同时剔除促皮质激素释放等内分泌作用。此后俄罗斯将其登记为药品并进入临床使用。
当时的短肽研究普遍关注能否穿越血脑屏障、在低剂量下产生中枢效应，Semax 属于这一路线。鼻内给药是其主要使用方式，俄语文献报道的适应症涵盖缺血性卒中、短暂性脑缺血发作、认知功能减退以及视神经病变。这些研究大多发表在当地期刊上，样本规模与终点设置同西方试验惯例存在差异，国际同行对其临床证据的强度看法不一。
| Property | Value | Notes |
|---|---|---|
| Purity assay | RP-HPLC, UV 214 nm | Typical research grade 95 percent or higher |
| Mass confirmation | ESI-MS or MALDI-TOF | Compared with theoretical value |
| Main degradation route | Methionine oxidation | Sulfoxide formation in solution |
| Powder storage | -20 °C, desiccated | Amber vial, minimal headspace |
| Working solution | Sterile water or saline | Prepare fresh; avoid repeated thawing |
Dissolution is normally performed in water, phosphate-buffered saline, or normal saline, since the peptide is freely soluble in aqueous media and is rarely handled with strong organic solvents. Solution pH should be kept near neutral, because extreme acidity or alkalinity accelerates backbone hydrolysis and encourages oxidation of the methionine side chain. Once dissolved, the material is less stable than the dry powder and is commonly divided into single-use portions and frozen. Buffers containing primary amines, such as Tris, are often avoided because of possible side reactions.
Purity assessment relies mainly on reversed-phase high-performance liquid chromatography, which separates the target heptapeptide from truncated sequences, deletion analogues, and oxidised forms. Mass spectrometry, usually coupled to liquid chromatography, confirms identity through the expected molecular ion and reveals modifications such as methionine sulfoxide formation. Amino acid analysis can verify composition, and tandem mass spectrometry supports sequence confirmation. Ultraviolet detection near 254 to 280 nanometres is convenient because the phenylalanine and histidine residues absorb in that region. Nuclear magnetic resonance is rarely used for routine release testing.
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.
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.
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Once separated, both Gα and Gβγ are free to participate in their own distinct signaling pathways. Gβγ does not go through any conformational changes when it dissociates from Gα and it acts as a signaling molecule as a dimer. The Gβγ dimer has been found to interact with many different effector molecules by protein-protein interactions. Different combinations of the Gβ and Gγ subtypes can influence different effectors and work exclusively or synergistically with the Gα subunit. Gβγ signaling is diverse, inhibiting or activating many downstream events depending on its interaction with different effectors. Researchers have discovered that Gβγ regulates ion channels, such as G protein-gated inward rectifier channels, as well as calcium channels. In human PBMC, Gβγ complex has been shown to activate phosphorylation of ERK1/2. Another example of Gβγ signaling is its effect of activating or inhibiting adenylyl cyclase leading to the intracellular increase or decrease of the secondary messenger cyclic AMP. For more examples of Gβγ signaling see table. However, the full extent of Gβγ signaling has not yet been discovered.
diffusion The net movement of atoms or molecules from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in chemical potential of the diffusing species and depends on the random walk of particles; hence it results in mixing or mass transport without required directed bulk motion.
Enzyme assays are laboratory procedures that measure the rate of enzyme reactions. Since enzymes are not consumed by the reactions they catalyse, enzyme assays usually follow changes in the concentration of either substrates or products to measure the rate of reaction. There are many methods of measurement. Spectrophotometric assays observe the change in the absorbance of light between products and reactants; radiometric assays involve the incorporation or release of radioactivity to measure the amount of product made over time. Spectrophotometric assays are most convenient since they allow the rate of the reaction to be measured continuously. Although radiometric assays require the removal and counting of samples (i.e., they are discontinuous assays), they are usually extremely sensitive and can measure very low levels of enzyme activity. An analogous approach is to use mass spectrometry to monitor the incorporation or release of stable isotopes as the substrate is converted into product. Occasionally, an assay fails and approaches are essential to resurrect a failed assay. The most sensitive enzyme assays use lasers focused through a microscope to observe changes in single enzyme molecules as they catalyse their reactions. These measurements either use changes in the fluorescence of cofactors during an enzyme's reaction mechanism, or of fluorescent dyes added onto specific sites of the protein to report movements that occur during catalysis.
A nerve is an enclosed, cable-like bundle of nerve fibers (called axons). Nerves have historically been considered the basic units of the peripheral nervous system. A nerve provides a common pathway for the electrochemical nerve impulses called action potentials that are transmitted along each of the axons to peripheral organs or, in the case of sensory nerves, from the periphery back to the central nervous system. Each axon is an extension of an individual neuron, along with other supportive cells such as some Schwann cells that coat the axons in myelin. Each axon is surrounded by a layer of connective tissue called the endoneurium. The axons are bundled together into groups called fascicles, and each fascicle is wrapped in a layer of connective tissue called the perineurium. The entire nerve is wrapped in a layer of connective tissue called the epineurium. Nerve cells (often called neurons) are further classified as either sensory or motor. In the central nervous system, the analogous structures are known as nerve tracts.
Sources: en.wikipedia.org
The Bradford assay uses the spectral properties of Coomassie brilliant blue G-250 to estimate the amount of protein in a solution. A protein sample is added to a solution of the dye in phosphoric acid and ethanol. Under the acid conditions the dye is normally a brownish colour but on binding to the protein the blue form of the dye is produced. The optical absorbance of the solution is measured at a wavelength of 595 nm. The dye is noted for its high level of sensitivity: 5 μg of protein can be detected. However, among the disadvantages of the method is its variability of color development with different proteins: the absorbance change per unit mass of proteins varies with the type of the protein. On binding to a protein, the negatively charged Coomassie brilliant blue G-250 dye molecule will give an overall negative charge to the protein. This property can be used to separate proteins or protein complexes using polyacrylamide gel electrophoresis under non-denaturing conditions in a technique called blue native PAGE. The mobility of the complex in the polyacrylamide gel will depend on both the size of the protein complex (i.e., the molecular weight) and the amount of dye bound to the protein. Coomassie blue staining can also be used as a loading control staining method in western blot analysis. It is applied as an anionic pre-antibody stain.
==== Centrifugal extractors ==== Centrifugal extractors mix and separate in one unit. Two liquids will be intensively mixed between the spinning rotor and the stationary housing at speeds up to 6000 RPM. This develops great surfaces for an ideal mass transfer from the aqueous phase into the organic phase. At 200–2000 g, both phases will be separated again. Centrifugal extractors minimize the solvent in the process, optimize the product load in the solvent and extract the aqueous phase completely. Counter current and cross current extractions are easily established.
=== Medicine and surgery === Prothrombin complex concentrate and fresh frozen plasma are prothrombin-rich coagulation factor preparations that can be used to correct deficiencies (usually due to medication) of prothrombin. Indications include intractable bleeding due to warfarin. Manipulation of prothrombin is central to the mode of action of most anticoagulants. Warfarin and related drugs inhibit vitamin K-dependent carboxylation of several coagulation factors, including prothrombin. Heparin increases the affinity of antithrombin to thrombin (as well as factor Xa). The direct thrombin inhibitors, a newer class of medication, directly inhibit thrombin by binding to its active site. Recombinant thrombin is available as a powder for reconstitution into aqueous solution. It can be applied topically during surgery, as an aid to hemostasis. It can be useful for controlling minor bleeding from capillaries and small venules, but ineffective and not indicated for massive or brisk arterial bleeding.
(editor) (2017) Handbook on Navier-Stokes Equations Theory and Applied Analysis, Nova Science Publisher ISBN 978-1-53610-292-5 Döring, C.E. and J.D. Gibbon, J.D. (1995) Applied analysis of the Navier-Stokes equations, Cambridge University Press, ISBN 0-521-44557-4 Basset, Alfred Barnard (1888) Hydrodynamics Volume I and II, Cambridge: Delighton, Bell and Company Fox, R. W.; McDonald, A. T.; and Pritchard, P. J. (2004) Introduction to Fluid Mechanics, John Wiley and Sons, ISBN 0-471-20231-2 Foias, C.; Mainley, O.; Rosa, R.; and Temam, R. (2004) Navier–Stokes Equations and Turbulence, Cambridge University Press, ISBN 0-521-36032-3 Lions, P-L. (1998) Mathematical Topics in Fluid Mechanics Volume 1 and 2, Clarendon Press, ISBN 0-19-851488-3 Deville, M. O. and Gatski, T. B. (2012) Mathematical Modeling for Complex Fluids and Flows, Springer, ISBN 978-3-642-25294-5 Kochin, N. E.; Kibel, I. A.; and Roze, N. V. (1964) Theoretical Hydromechanics, John Wiley & Sons, Limited Lamb, Horace (1879) Hydrodynamics, Cambridge University Press White, Frank M. (2006), Viscous Fluid Flow, McGraw-Hill, ISBN 978-0-07-124493-0
=== Osteological specimens === Museum collections, especially those of natural history, may contain human osteological specimens such as individual bones, bone fragments, entire skeletons, and teeth from both ancient and contemporary sources. Reconstruction of bone fragments should be conducted with great care and consideration. Due to the porous nature of bones, few adhering substances can be used on bone with an adequate level of reversibility, which is a key factor of conservation treatments.
Sources: en.wikipedia.org
== Further reading == Larsen PR, Williams RL (2003). Williams textbook of endocrinology (10th ed.). Philadelphia: WB Saunders. ISBN 978-0-7216-9184-8. Doppman, John L. (15 August 1995). "Localization of Insulinomas to Regions of the Pancreas by Intra-arterial Stimulation with Calcium". Annals of Internal Medicine. 123 (4): 269–273. doi:10.7326/0003-4819-123-4-199508150-00004. PMID 7611592. S2CID 20993342. Vella, Adrian. "Insulinoma". UpToDate.
In mammals, progesterone, like all other steroid hormones, is synthesized from pregnenolone, which itself is derived from cholesterol. Cholesterol undergoes double oxidation to produce 22R-hydroxycholesterol and then 20α,22R-dihydroxycholesterol. This vicinal diol is then further oxidized with loss of the side chain starting at position C22 to produce pregnenolone. This reaction is catalyzed by cytochrome P450scc. The conversion of pregnenolone to progesterone takes place in two steps. First, the 3β-hydroxyl group is oxidized to a keto group and second, the double bond is moved to C4, from C5 through a keto/enol tautomerization reaction. This reaction is catalyzed by 3β-hydroxysteroid dehydrogenase/δ5-4-isomerase. Progesterone in turn is the precursor of the mineralocorticoid aldosterone, and after conversion to 17α-hydroxyprogesterone, of cortisol and androstenedione. Androstenedione can be converted to testosterone, estrone, and estradiol, highlighting the critical role of progesterone in testosterone synthesis. Pregnenolone and progesterone can also be synthesized by yeast. Approximately 30 mg of progesterone is secreted from the ovaries per day in reproductive-age women, while the adrenal glands produce about 1 mg of progesterone per day.
=== FastPP === In fast parallel proteolysis the researcher adds a thermostable protease (thermolysin) and takes out samples in parallel upon heating in a thermal gradient cycler. Optionally, for instance for proteins expressed at low levels, a western blot is then run to determine at what temperature a protein becomes degraded. For pure or highly enriched proteins, direct SDS-PAGE detection is possible facilitating Commassie-fluorescence based direct quantification. FastPP exploits that proteins become increasingly susceptible to proteolysis when unfolded and that thermolysin cleaves at hydrophobic residues which are typically found in the core of proteins. To reduce the workload, western blots could be replaced by SDS-PAGE gel polyhistidine-tag staining, provided that the protein has such a tag and is expressed in adequate amounts. FastPP can be used on unpurified, complex mixtures of proteins and proteins fused with other proteins, such as GST or GFP, as long as the sequence that is the target of the western blot, e.g., His-tag, is directly linked to the protein of interest. However, commercially available thermolysin is dependent on calcium ions for activity and denatures itself just above 85 degrees Celsius. So calcium must be present and calcium chelators absent in the buffer - other compounds that interfere with the function (such as high concentrations of detergents) of the protease could also be problematic. FASTpp has also been used to monitor binding-coupled folding of intrinsically disordered proteins (IDPs).
1883. A Treatise on the Motion of Vortex Rings: An essay to which the Adams Prize was adjudged in 1882, in the University of Cambridge. London: Macmillan and Co., pp. 146. Recent reprint: ISBN 0-543-95696-2. 1888. Applications of Dynamics to Physics and Chemistry. London: Macmillan and Co., pp. 326. Recent reprint: ISBN 1-4021-8397-6. 1893. Notes on recent researches in electricity and magnetism: intended as a sequel to Professor Clerk-Maxwell's 'Treatise on Electricity and Magnetism'. Oxford University Press, pp. xvi & 578. 1991, Cornell University Monograph: ISBN 1-4297-4053-1. Thomson, Joseph John (1893). Notes on recent researches in electricity and magnetism. Oxford: Clarendon Press. Thomson, Joseph John (1900). Discharge of electricity through gases (in German). Leipzig: Johann Ambrosius Barth. Thomson, Joseph John (1904). Electricity and matter (in English). Oxford : Clarendon Press. Thomson, Joseph John (1905). Electricity and matter (in Italian). Milano: Hoepli. Thomson, Joseph John (1908). Corpuscular theory of matter (in German). Braunschweig: Vieweg und Sohn. 1921 (1895). Elements of the Mathematical Theory of Electricity And Magnetism. London: Macmillan and Co. Scan of 1895 edition. A Text book of Physics in Five Volumes, co-authored with J.H. Poynting: (1) Properties of Matter, (2) Sound, (3) Heat, (4) Light, and (5) Electricity and Magnetism. Dated 1901 and later, and with revised later editions. Dahl, Per F. (1997). Flash of the Cathode Rays: A History of J J Thomson's Electron. Bristol and Philadelphia: Institute of Physics Publishing. ISBN 0-7503-0453-7.
=== Pharmacodynamics === 5-MAPB acts as a serotonin–norepinephrine–dopamine releasing agent with EC50Tooltip half-maximal effective concentration values for induction of monoamine release of 64 nM for serotonin, 24 nM for norepinephrine, and 41 nM for dopamine using rat brain synaptosomes. It is also a partial agonist of the serotonin 5-HT2A, 5-HT2B, and 5-HT2C receptors. In addition, unlike MDMA, it is a relatively potent agonist of the serotonin 5-HT1B receptor, with EC50 values of 161 nM for (S)-5-MAPB and 981 nM for (R)-5-MAPB.
Sources: en.wikipedia.org
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.
The main chemical risks are methionine oxidation and backbone hydrolysis in solution. Moisture and repeated temperature cycling accelerate both processes. Dry powder held cold and desiccated is considerably more stable than any reconstituted preparation.
It holds a medicine registration in Russia, where it has been used clinically for decades. In most other countries it is treated as a research chemical. That split explains the uneven distribution of clinical literature.
不存在。它是依据 ACTH 的一段序列人工设计的分子，天然蛋白质中找不到与之完全相同的七肽。名称属于研究代号，而非天然物质名。