Neurotrophic signalling 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 2026-04-22. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Development took place during the 1980s at institutes of the Russian Academy of Sciences, where peptide fragments of ACTH were screened for cognitive and neuroprotective effects. The compound received regulatory approval in Russia as a nasal preparation, marketed for conditions such as ischemic stroke, transient ischemic attacks, and optic nerve disorders. Registration in other countries has not followed. Most published clinical reports originate from a small number of Russian research groups, and independent replication outside that setting remains limited. The regulatory status therefore differs sharply between Russia and the rest of the world.
Laboratory work points toward modulation of neurotrophic signaling, particularly expression of brain-derived neurotrophic factor and nerve growth factor in hippocampal tissue. Studies also describe effects on monoamine turnover, inflammatory mediators, and oxidative markers. These observations come mainly from animal models and cultured cells, so the causal chain in humans is not firmly established. Whether the reported molecular changes translate into measurable clinical benefit is an open question. Reviews generally present the mechanism as plausible rather than demonstrated.
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.
| Property | Value | Notes |
|---|---|---|
| Sequence | Met-Glu-His-Phe-Pro-Gly-Pro | Heptapeptide; ACTH(4-10) analog extended at C-terminus |
| Molecular mass | ~813.9 Da | Free peptide, unmodified |
| Appearance | White to off-white powder | Typical lyophilized solid |
| Solubility | Soluble in water and saline | Also soluble in common aqueous buffers |
| Storage (solid) | -20 °C, desiccated | Protect from moisture and repeated thawing |
Scientific literature on semax is unevenly distributed. A substantial share of published work originates from a small number of laboratories in Russia, while independent replication elsewhere is limited. Human data consist mostly of small trials with short follow-up, and several reported outcomes rely on subjective rating scales. Questions about how much intact peptide reaches the central nervous system after nasal administration, and how long it persists there, are still unresolved. The compound is best described as an active research subject rather than a settled pharmacological agent.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It was derived from the ACTH(4-10) fragment, a short segment of adrenocorticotropic hormone that lacks the hormonal activity associated with the full-length peptide. Researchers at the Institute of Molecular Genetics in Moscow developed the compound during the 1980s. It has been registered as a pharmaceutical product in Russia and several neighbouring countries, where it is supplied as a nasal solution, and it is also sold internationally as a research chemical.
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.
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。
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.
Norepinephrine has been reported to exist in a wide variety of animal species, including protozoa, placozoa and cnidaria (jellyfish and related species), but not in ctenophores (comb jellies), whose nervous systems differ greatly from those of other animals. It is generally present in deuterostomes (vertebrates, etc.), but in protostomes (arthropods, molluscs, flatworms, nematodes, annelids, etc.) it is replaced by octopamine, a closely related chemical with a closely related synthesis pathway. In insects, octopamine has alerting and activating functions that correspond (at least roughly) with the functions of norepinephrine in vertebrates. It has been argued that octopamine evolved to replace norepinephrine rather than vice versa; however, the nervous system of amphioxus (a primitive chordate) has been reported to contain octopamine but not norepinephrine, which presents difficulties for that hypothesis.
Repatriating the survivors of the 16 October strike on a semi-submersible to their home countries for prosecution avoids a civilian court challenge to continued detention without evidence, and a military court challenge to the legal justification for treating prisoners as unlawful combatants if they were not engaged in armed conflict.
== Biosynthesis == Its complete biosynthetic pathway includes glycolysis, the tricarboxylic acid (TCA) or citric acid cycle (Krebs cycle), and the aspartate metabolic pathway. It forms by two reductions of aspartic acid via the intermediacy of aspartate semialdehyde. Specifically, the enzyme homoserine dehydrogenase, in association with NADPH, catalyzes a reversible reaction that interconverts L-aspartate-4-semialdehyde to L-homoserine. Homoserine kinase and homoserine O-succinyltransferase convert homoserine to phosphohomoserine and O-succinyl homoserine, respectively. Homoserine is produced from aspartate via the intermediate aspartate-4-semialdehyde, which is produced from β-phosphoaspartate. By the action of homoserine dehydrogenases, the semialdehyde is converted to homoserine.
Amitriptyline/chlordiazepoxide, sold under the brand names Limbitrol and Limbitrol DS, is a combination of amitriptyline (Elavil), a tricyclic antidepressant, and chlordiazepoxide (Librium), a benzodiazepine, which is approved for the treatment of depression associated with anxiety in the United States. It is taken orally and contains 12.5 to 25 mg amitriptyline and 5 to 10 mg chlordiazepoxide per tablet.
Sources: en.wikipedia.org
=== Geographic distribution === AI activity is heavily concentrated in London and the South East. In 2024, London, the South East, and the East of England accounted for approximately 75% of all registered AI company offices. London has been described by industry investors as "the third largest city in the world for starting AI companies". However, the number of AI firms is growing across all UK regions, with annual growth rates of between 20% and 50%, and at least double the number of AI companies now operating in the West Midlands, North West, East Midlands, Wales, and Yorkshire and Humber compared to 2022.
Some consider the armpits to be an erogenous zone, despite the similarity of the axillae (armpits) to normal-haired skin in both the density of nerves and hair follicles. Exaggerated or anticipated digital (fingers, toes) or oral (mouth, lips, tongue) stimulation is believed to be responsible for the heightened sensual response. If pheromones exist for humans, they would likely be secreted by a mixture of liquid from the apocrine glands with other organic compounds in the body. George Preti, an organic chemist at the Monell Chemical Senses Center in Philadelphia and Winnefred Cutler of the University of Pennsylvania's psychology department, discovered that women with irregular menstrual cycles became regular when exposed to male underarm extracts. They hypothesized that the only explanation was that underarms contain pheromones, as there was no other explanation for the effects, which mirrored how pheromones affect other mammals.
Although a single injection of long-acting penicillin or other beta-lactam antibiotic cures the disease and is widely available, and the disease is highly localised, many eradication campaigns ended in complacency and neglect; even in areas where transmission was successfully interrupted, re-introduction from infected areas occurred. Yaws eradication remained a priority in South-East Asia. In 1995, the WHO estimated 460,000 worldwide cases. In the Philippines, yaws stopped being listed as a notifiable disease in 1973; as of 2020, it is still present in the country. India implemented a successful yaws eradication campaign that resulted in the 2016 certification by the WHO that India was free of yaws. In 1996 there were 3,571 yaws cases in India; in 1997 after a serious elimination effort began the number of cases fell to 735. By 2003, the number of cases was 46. The last clinical case in India was reported in 2003 and the last latent case in 2006; certification by the WHO was achieved in 2016. In 2012 the WHO officially targeted yaws for eradication by 2020 following the development of orally administered azithromycin as a treatment, but missed that target. The Morges approach (named after Morges, Switzerland, where a meeting on it was held) involved mass treatment with azithromycin. This was safe, but ran into problems with antibiotic resistance, and did not fully interrupt transmission.
==== Apoptosis inhibition ==== Sendai virus P gene encodes a nested set of proteins (C', C, Y1 and Y2), which are named to collectively as the C proteins (see the section "Genome structure" below). C proteins of SeV are able to suppress apoptosis. The antiapoptotic activity of the C proteins supports SeV infection in the host cells.
=== Angiogenesis for cardiovascular disease === Angiogenesis represents an excellent therapeutic target for the treatment of cardiovascular disease. It is a potent, physiological process that underlies the natural manner in which our bodies respond to a diminution of blood supply to vital organs, namely neoangiogenesis: the production of new collateral vessels to overcome the ischemic insult. A large number of preclinical studies have been performed with protein-, gene- and cell-based therapies in animal models of cardiac ischemia, as well as models of peripheral artery disease. Reproducible and credible successes in these early animal studies led to high enthusiasm that this new therapeutic approach could be rapidly translated to a clinical benefit for millions of patients in the Western world with these disorders. A decade of clinical testing both gene- and protein-based therapies designed to stimulate angiogenesis in underperfused tissues and organs, however, has led from one disappointment to another. Although all of these preclinical readouts, which offered great promise for the transition of angiogenesis therapy from animals to humans, were in one fashion or another, incorporated into early stage clinical trials, the FDA has, to date (2007), insisted that the primary endpoint for approval of an angiogenic agent must be an improvement in exercise performance of treated patients.
Sources: en.wikipedia.org
=== CD38 === CD38 is an enzyme that triggers inflammatory responses and type II CD38 contains an ecto-NADase or extracellular NADase, whereas type II CD38 contains an intracellular cADPR. CD38 consumes NAD, which can produce second messengers that help regulate immune activity. Cells that are programmed for cell death or apoptosis releases NAD+, and type II CD38 help recycle the extracellular NAD+ released from apoptosis, where both products of NADase, ADP-ribose and nicotinamide, can be used to resynthesize NAD+ via the NAD+ synthesis pathway. ADP-ribose must be converted to adenosine in order to enter the NAD+ synthesis pathway, where ADP-ribose first gets converted to AMP and then AMP gets converted to adenosine via non-classical adenosine generational pathway. The other product nicotinamide is membrane permeable, which allows the molecule to re-enter the NAD synthesis pathway more easily. CD38 NADase is also found in tissues and cells other than T cells, and CD38 is one of the main forms of NADase activity in mammals.
The activity of the cell is regulated by extracellular signals. Signal propagation inside and/or along the interior of cells depends on PPIs between the various signaling molecules. The recruitment of signaling pathways through PPIs is called signal transduction and plays a fundamental role in many biological processes and in many diseases including Parkinson's disease and cancer.
== External links == Separation of Mixtures Using Different Techniques Archived 2013-06-05 at the Wayback Machine, instructions for performing classroom experiments Separation of Components of a Mixture Archived 2013-06-05 at the Wayback Machine, instructions for performing classroom experiments
=== Hydrophilic - Lipophilic Balance === This part of the article aims at disambiguating of the notion of HLB, "Hydrophile - Lipophile Balance", attributed to Sucrose Fatty Acid Ester surfactants (also named sucrose esters or sugar esters). The attribution of HLB values to sucrose esters emulsifiers at the origin is unclear, since no bibliographic source can be found on how the attribution has been made. There is no early scientific data, dating back to the 1990s or earlier, supporting experimentally the current HLB scale attributed to sucrose esters. However, a clear numerical correlation is found between the Griffin HLB scale defined for non-ionic poly(ethylene oxide) (PEO) surfactants and the HLB scale attributed to marketed sucrose esters. For polyethylene oxide non ionic surfactants the HLB is defined by the Griffin's scale (Equation 1):
Sources: en.wikipedia.org
Semax is a synthetic seven-amino-acid peptide derived from a fragment of corticotropin. It is used in Russia as a nasal preparation, while elsewhere it is studied as a research compound. It is not approved as a medicine in most countries.
Its sequence corresponds to the 4-10 region of corticotropin extended by three residues. This fragment lacks the region responsible for adrenal steroid release, so it is explored for neural rather than hormonal effects. The relationship explains the compound's classification among ACTH-derived peptides.
It holds approval in Russia for several neurological indications as a nasal spray or drop formulation. Regulatory agencies in the United States and the European Union have not approved it. Products sold elsewhere are generally labeled for research use only.
It originated at the Institute of Molecular Genetics in Moscow during the 1980s. The work was carried out by a Russian research group that specialized in peptide neuropharmacology.