neurotrophic factor comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2025-09-10. 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.
Semax is a synthetic peptide created in the Soviet Union during the early 1980s by researchers working in Moscow. It was built from the short adrenocorticotropic hormone fragment known as ACTH(4-10), and the chain was then extended with three additional amino acids. The resulting molecule was named semax and entered clinical use in Russia in 1994. It is generally described as a nootropic and neuroprotective agent rather than as a hormone analogue.
Practical handling follows from those properties. Bulk material is best divided into single-use portions soon after receipt, because each thaw exposes the whole container to moisture and temperature cycling. Vials should be allowed to reach room temperature before opening to prevent condensation on the powder. Low-binding plasticware reduces loss of dilute solutions, and sterile filtration is used when a preparation must remain free of microbial growth. Records of batch number, reconstitution date and storage history are what allow a later analytical result to be interpreted meaningfully.
Identity and purity of Semax are established mainly by reversed-phase high-performance liquid chromatography coupled with mass spectrometry. The chromatographic trace gives a purity estimate as a percentage of total peak area, while electrospray or matrix-assisted laser desorption ionization confirms the molecular mass against the calculated value. Amino acid analysis and sequence-specific fragmentation provide further confirmation when a supplier's chain of custody is unclear. Vendors frequently quote a purity figure without stating the detection wavelength or the integration method, which limits how far one number can be compared with another.
Stability depends heavily on physical state. Lyophilized powder held dry, cold and dark retains its content over long periods, whereas dissolved peptide begins to change within days at room temperature. The most cited degradation route is oxidation of the methionine residue, which converts the peptide to a sulfoxide form that elutes differently on chromatography. Hydrolysis of amide bonds and adsorption onto container walls contribute smaller losses. Buffers that exclude oxygen from the headspace slow the oxidation pathway, but no single condition prevents all change indefinitely.
| 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 |
Clinical evidence consists largely of small trials with modest sample sizes, often without independent replication. Reported endpoints include cognitive scores, recovery after stroke, and visual function, but study designs vary widely and few trials meet contemporary reporting standards. Systematic reviewers have noted a high risk of bias in several of these reports. No large multicenter trial conducted outside Russia has been published. The compound is therefore best described as investigational in most jurisdictions, with its clinical role still unresolved.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. Its chain combines the first seven residues of corticotropin with a C-terminal proline-glycine-proline extension, a modification intended to slow enzymatic breakdown. The free peptide has a molecular mass near 813.9 daltons. It belongs to the class of ACTH-derived fragments studied for central nervous system activity rather than for adrenal steroid stimulation. This structural relationship to a natural hormone fragment is the usual starting point for describing the compound in the literature.
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.
该化合物于二十世纪八十年代在俄罗斯被开发，相关工作由俄罗斯科学院分子遗传学研究所的研究团队主导。开发目标并非复制 ACTH 的完整激素活性，而是寻找保留其神经作用方向、同时去除促肾上腺皮质激素释放效应的短肽片段。研究记录显示，这一方向促成了多个相关短肽的合成与筛选，而 Semax 是其中被研究最广泛的一个。当地文献常以 Семакс 这一名称指代它。
研究兴趣主要集中在神经营养因子相关的路径上，包括脑源性神经营养因子与神经生长因子的表达变化。部分实验报告称在特定条件下观察到这些因子的水平上升，但具体信号通路和剂量依赖关系仍未完全厘清。多数公开数据来自细胞模型和动物实验，人体对照研究数量有限。因此，该化合物的作用机制在文献中属于活跃讨论，而非已经确立的定论。
Semax 是一种人工合成的七肽，氨基酸序列为 Met-Glu-His-Phe-Pro-Gly-Pro，单字母缩写记作 MEHFPGP。它被归类为促肾上腺皮质激素片段 ACTH(4-10) 的结构类似物，但并不天然存在于生物体内。母体片段 ACTH(4-10) 的序列为 Met-Glu-His-Phe-Arg-Trp-Gly，Semax 替换了中间两个残基，并在羧基端延长了 Pro-Gly-Pro 三肽。这种延长被普遍认为能提升分子对肽酶的耐受性。
== History == The existence of a compensatory mechanism for telomere shortening was first found by Soviet biologist Alexey Olovnikov in 1973, who also suggested the telomere hypothesis of aging and the telomere's connections to cancer and perhaps some neurodegenerative diseases. Telomerase in the ciliate Tetrahymena was discovered by Carol W. Greider and Elizabeth Blackburn in 1984. Together with Jack W. Szostak, Greider and Blackburn were awarded the 2009 Nobel Prize in Physiology or Medicine for their discovery. Later the cryo-EM structure of telomerase was first reported in T. thermophila, to be followed a few years later by the cryo-EM structure of telomerase in humans. The role of telomeres and telomerase in cell aging and cancer was established by scientists at biotechnology company Geron with the cloning of the RNA and catalytic components of human telomerase and the development of a polymerase chain reaction (PCR) based assay for telomerase activity called the TRAP assay, which surveys telomerase activity in multiple types of cancer. The negative stain electron microscopy (EM) structures of human and Tetrahymena telomerases were characterized in 2013. Two years later, the first cryo-electron microscopy (cryo-EM) structure of telomerase holoenzyme (Tetrahymena) was determined. In 2018, the structure of human telomerase was determined through cryo-EM by UC Berkeley scientists.
== Fast atom bombardment == Fast atom bombardment (FAB) is a method involving using a beam of high energy atoms to strike a surface and generate ions. These solid analyte particles must be dissolved into some form of matrix, or non-volatile liquid to protect and assist in the ionization of the solid analyte. It has been shown that as the matrix is depleted, the ion formation diminishes, so choosing the right matrix compound is vital. The overall goal of the matrix compound is to present the sample to the atom beam at a high mobile surface concentration. For maximum sensitivity, the sample should form a perfect monolayer at the surface of a substrate having low volatility. This monolayer effect can be seen in that once a certain concentration of analyte in matrix is reached, any concentration above that is seen to exhibit no effect, because once the monlayer is formed, any additional analyte is beneath the monolayer, and thus not affected by the atom beam. The concentration needed to cause this effect is seen to change as the amount of non-volatile matrix changes. So concentration of solid analyte needs to be considered in the preparation of the solution for analysis so that signal from "hidden" analyte is not missed. To choose the matrix for each solid analyte, three criteria must be considered.
Electrosmog is colloquially understood as the exposure of humans and the environment to electric, magnetic and electromagnetic fields, some of which are believed to have undesirable biological effects. Electromagnetic environmental compatibility (EMC) refers to the effects on living organisms, some of which are considered electrosensitive. Fears of such effects have existed since the beginning of technological use in the mid-19th century. In 1890, for example, officials of the Royal General Directorate in Bavaria were forbidden to attend the opening ceremony of Germany's first alternating current power plant, the Reichenhall Electricity Works, or to enter the machine room. With the establishment of the first radio telegraphy and its telegraph stations, the U.S. magazine The Atlanta Constitution reported in April 1911 on the potential dangers of radio telegraph waves, which, in addition to "tooth loss," were said to cause hair loss and make people "crazy" over time. Full-body protection was recommended as a preventive measure. During the second half of the 20th century, other sources of electromagnetic fields have become the focus of health concerns, such as power lines, photovoltaic systems, microwave ovens, computer and television screens, security devices, radar equipment, and more recently, cordless telephones (DECT), cell phones, their base stations, energy-saving lamps, and Bluetooth connections. Electrified railroad lines, tram overhead lines and subway tracks are also strong sources of electrosmog.
Peptidoglycan is involved in binary fission during bacterial cell reproduction. L-form bacteria and mycoplasmas, both lacking peptidoglycan cell walls, do not proliferate by binary fission, but by a budding mechanism. In the course of early evolution, the successive development of boundaries (membranes, walls) protecting first structures of life against their environment must have been essential for the formation of the first cells (cellularisation). The invention of rigid peptidoglycan (murein) cell walls in bacteria (domain Bacteria) was probably the prerequisite for their survival, extensive radiation and colonisation of virtually all habitats of the geosphere and hydrosphere.
=== Other polymers === Other sugar polymers include vegetable gums such as pectin from Citrus peel, guar gum from the guar bean, and locust bean gum from the carob bean. Agar, alginin and carrageenan are polysaccharides extracted from algae, xanthan gum is a polysaccharide secreted by the bacterium Xanthomonas campestris, and carboxymethyl cellulose is a synthetic gum derived from cellulose. Proteins used as food thickeners include collagen, egg whites, and gelatin. Other thickening agents act on the proteins already present in a food; for example sodium pyrophosphate, which acts on casein in milk during the preparation of instant pudding.
Sources: en.wikipedia.org
=== Syndesmotic tear === The severity of acute syndesmosis injury is rated from grade I to III by several authors. A grade I injury is a partial anteroinferior tibiofibular ligament tear, meaning the exorotation and squeeze tests are negative for this grade. Grade II injury is a complete anteroinferior tibiofibular ligament and inferior interosseous ligament tear, meaning that squeeze test and exorotation are positive. This results in the injury being stabilized with immobilization but not operatively stabilized. A grade III injury is a complete anteroinferior tibiofibular ligament tear including a (partial) interosseous ligament tear and deltoid ligament avulsion, meaning the joint is unstable and positive on the exorotation and squeeze tests. This grade requires operative stabilization. If the syndesmosis is torn apart as result of bone fracture, surgeons will sometimes fix the relevant bones together with a syndesmotic screw, temporarily replacing the syndesmosis, or with a tightrope fixation, which is called syndesmosis procedure. The screw inhibits normal movement of the bones and, thereby, the corresponding joint(s). When the natural articulation is healed, the screw may be removed. The tightrope fixation with elastic fiberwire suture on the other hand allows physiologic motion of the ankle and may be permanent.
Gelatin contains many functional groups like NH2, SH, and COOH which allow for gelatin to be modified using nanoparticles and biomolecules. Gelatin is an Extracellular Matrix protein which allows it to be applied for applications such as wound dressings, drug delivery and gene transfection. Starch: Starch is an inexpensive biodegradable biopolymer and copious in supply. Nanofibers and microfibers can be added to the polymer matrix to increase the mechanical properties of starch improving elasticity and strength. Without the fibers, starch has poor mechanical properties due to its sensitivity to moisture. Starch being biodegradable and renewable is used for many applications including plastics and pharmaceutical tablets. Cellulose: Cellulose is very structured with stacked chains that result in stability and strength. The strength and stability comes from the straighter shape of cellulose caused by glucose monomers joined by glycogen bonds. The straight shape allows the molecules to pack closely. Cellulose is very common in application due to its abundant supply, its biocompatibility, and is environmentally friendly. Cellulose is used vastly in the form of nano-fibrils called nano-cellulose. Nano-cellulose presented at low concentrations produces a transparent gel material. This material can be used for biodegradable, homogeneous, dense films that are very useful in the biomedical field. Alginate: Alginate is the most copious marine natural polymer derived from brown seaweed.
Monoclonal antibodies that can be used to block pro-inflammatory cytokines Antigen-specific immunotherapy which allows immune cells to specifically target the abnormal cells that cause autoimmune disease Co-stimulatory blockade that works to block the pathway that leads to the autoimmune response Regulatory T cell therapy that utilizes this special type of T cell to suppress the autoimmune response Thymoquinone, a compound found in the flower Nigella sativa, has been studied for potential in treating several autoimmune diseases due to its effects on inflammation.
Fat storage – marrow adipose tissue (MAT) acts as a storage reserve of fatty acids. Acid-base balance – bone buffers the blood against excessive pH changes by absorbing or releasing alkaline salts. Detoxification – bone tissues can also store heavy metals and other foreign elements, removing them from the blood and reducing their effects on other tissues. These can later be gradually released for excretion. Endocrine organ – bone controls phosphate metabolism by releasing fibroblast growth factor 23 (FGF-23), which acts on kidneys to reduce phosphate reabsorption. Bone cells also release a hormone called osteocalcin, which contributes to the regulation of blood sugar (glucose) and fat deposition. Osteocalcin increases both the insulin secretion and sensitivity, in addition to boosting the number of insulin-producing cells and reducing stores of fat. Calcium balance – the process of bone resorption by the osteoclasts releases stored calcium into the systemic circulation and is an important process in regulating calcium balance. As bone formation actively fixes circulating calcium in its mineral form, removing it from the bloodstream, resorption actively unfixes it thereby increasing circulating calcium levels. These processes occur in tandem at site-specific locations.
Sources: en.wikipedia.org
=== Increase in age === When an individual ages, the outermost layer of skin becomes thin despite the number of cell layers remaining unchanged. The number of cells that contain pigment decreases, and the melanocytes that remain increase in size. This is why aging skin looks thin, pale, and translucent. Large spots may be pigmented when some areas are exposed to sunlight. The various alterations in the skin and underlying connective tissue may decrease its strength and elasticity. Also, the blood vessels in the outer skin become more delicate and can result in bruises and bleeding under the skin's surface. The subcutaneous glands also excrete decreased amounts of oil as you age. Men experience this shortage mostly after reaching the age of 80 years. Women may slowly begin excreting less oil after menopause, making it difficult to keep the skin moist. The subcutaneous fat layer also decreases, reducing the insulation and padding capability of the skin. This can put the individual at risk of an injury and makes maintaining body temperature difficult. The sweat glands also reduce the amount of sweat they produce, making the individual's body harder to cool.
Overview, University of Kansas Archived 26 December 2010 at the Wayback Machine Connective tissue atlas, University of Iowa Heritable disorders of connective tissue US National Institute of Arthritis and Musculoskeletal and Skin Diseases Connective tissue photomicrographs
=== Silicides and borides === Americium monosilicide (AmSi) and "disilicide" (nominally AmSix with: 1.87 < x < 2.0) were obtained by reduction of americium(III) fluoride with elementary silicon in vacuum at 1050 °C (AmSi) and 1150−1200 °C (AmSix). AmSi is a black solid isomorphic with LaSi, it has an orthorhombic crystal symmetry. AmSix has a bright silvery lustre and a tetragonal crystal lattice (space group I41/amd), it is isomorphic with PuSi2 and ThSi2. Borides of americium include AmB4 and AmB6. The tetraboride can be obtained by heating an oxide or halide of americium with magnesium diboride in vacuum or inert atmosphere.
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.
Suppliers normally quote a percentage of total chromatographic peak area, most often from reversed-phase HPLC. That figure says nothing about what the remaining percentage contains, and it depends on the detection wavelength used. A mass spectrometry result is a separate and stronger check on identity.