Everything below concerns neuropeptide. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2025-08-21. 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. It is described in the literature as an analogue of the ACTH(4–10) fragment, a short N-terminal portion of adrenocorticotropic hormone that retains some neurotropic activity without the full hormonal effects of the parent peptide. The molecule carries a methionine residue at the N-terminus and two proline residues near the C-terminus, features that shape both its interactions with receptor systems and its chemical stability. The free peptide corresponds to the formula C37H51N9O10S and a molecular mass near 813.9 Da.
The compound was developed in the 1980s at the Institute of Molecular Genetics in Moscow, where it emerged from research on short ACTH fragments and their effects on the central nervous system. Russian pharmaceutical listings describe it as a nootropic and neuroprotective agent, most often formulated as nasal drops. It is not a marketed medicine in the United States or the European Union, and no pharmacopoeial monograph covers it. Consequently, most published clinical experience with the substance originates from a small number of research centres, mainly in Russia and neighbouring countries.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C37H51N9O10S | Free acid form of the heptapeptide; depends on terminal groups |
| Molecular mass | About 813.9 g/mol | Average mass used for mass spectrometry confirmation |
| Appearance | White to off-white solid | Supplied as a lyophilised powder; hygroscopic |
| Solubility class | Freely soluble in aqueous media | Water, saline, and phosphate buffers; limited organic solubility |
| Typical storage temperature | -20 degrees Celsius | Long term and dry; short working periods may use 2 to 8 degrees Celsius |
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 proposed mechanism centres on neurotrophic signalling rather than direct receptor activation. Semax is reported to increase expression of brain-derived neurotrophic factor and nerve growth factor in several brain regions, and to shift the balance between excitatory and inhibitory neurotransmitter systems. Interaction with melanocortin receptors has been suggested because of the parent ACTH fragment. Many of these findings come from rodent studies, and the extent to which they translate to human physiology remains an open question.
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。
Development of the compound took place in the Soviet Union during the 1980s, largely through peptide research groups affiliated with the Shemyakin-Ovchinnikov Institute and Moscow State University. Investigators screened fragments of adrenocorticotropic hormone for activity on the central nervous system while attempting to separate cognitive effects from hormonal ones. The shortened sequence was selected because it retained behavioral activity in animal models without stimulating corticosteroid release. Early publications described the molecule as an ACTH(4-10) analog.
Published research on this peptide originates mainly from Russian laboratories, and the wider international literature is comparatively thin. Studies have used rodent models of stroke, hypoxia, and memory tasks, with a smaller number of human trials reported. Reported outcomes include changes in attention and memory measures, along with effects on neurotrophic factor expression in some experiments. Small sample sizes, inconsistent dosing protocols, and limited independent replication are widely noted limitations, so the strength of the clinical evidence remains an open question.
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.
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.
They proposed a formation theory accounting for the dependence of microstructure on anodising conditions, and demonstrated the formation of porous gallium arsenide — the first porous III–V semiconductor — confirming the generality of the mechanism. In 1986, the same group also demonstrated that chemical stain etching produces porous silicon identical in structure to that formed by anodisation, unifying the two formation routes. This work on the formation mechanism and microstructure provided the basis for much of the subsequent research into the material's properties and applications—in fields as diverse as optoelectronics and photonics, chemical and biological sensing, biomedicine and drug delivery, photovoltaics, energy storage and microelectromechanical systems—and the model continues to be cited as a standard reference for porous silicon formation. Despite the discovery of porous silicon in the 1950s and the elucidation of its formation mechanism in the mid-1980s, the material attracted little wider attention until the end of the decade, when its nanoscale structure—a network of nanometre-sized pores within a crystalline silicon skeleton—was recognised as the source of optical, electronic and surface properties quite different from those of bulk silicon, triggering the rapid growth of interest that established porous silicon as a versatile nanostructured material with applications across optoelectronics, sensing, biomedicine, photovoltaics, energy storage and microelectronics.
== Eponym == Donohue syndrome was first identified in 1948 by Canadian pathologist William L. Donohue (1906–1985). The name leprechaunism has been largely abandoned because of the perception of the name by some parents of patients as insulting.
is the standard entropy change. Since the enthalpy should be approximately the same for the two reactions, the difference between the two stability constants is due to the effects of entropy. In equation (1) there are two particles on the left and one on the right, whereas in equation (2) there are three particles on the left and one on the right. This difference means that less entropy of disorder is lost when the chelate complex is formed with bidentate ligand than when the complex with monodentate ligands is formed. This is one of the factors contributing to the entropy difference. Other factors include solvation changes and ring formation. Some experimental data to illustrate the effect are shown in the following table.
Sources: en.wikipedia.org
== Medical uses == Gepotidacin is indicated for the treatment of females aged twelve years of age and older weighing at least 40 kilograms (88 lb) with uncomplicated urinary tract infections (uUTI) caused by Escherichia coli, Klebsiella pneumoniae, Citrobacter freundii complex, Staphylococcus saprophyticus, and Enterococcus faecalis. In December 2025, the indication for gepotidacin was expanded to include the treatment of uncomplicated urogenital gonorrhea in people who weigh at least 99 pounds (45 kg).
Contraction is achieved by the muscle's structural unit, the muscle fiber, and by its functional unit, the motor unit. Muscle fibers are excitable cells stimulated by motor neurons. The motor unit consists of a motor neuron and the many fibers that it makes contact with. A single muscle is stimulated by many motor units. Muscle fibers are subject to depolarization by the neurotransmitter acetylcholine, released by the motor neurons at the neuromuscular junctions. In addition to the actin and myosin myofilaments in the myofibrils that make up the contractile sarcomeres, there are two other important regulatory proteins – troponin and tropomyosin, that make muscle contraction possible. These proteins are associated with actin and cooperate to prevent its interaction with myosin. Once a cell is sufficiently stimulated, the cell's sarcoplasmic reticulum releases ionic calcium (Ca2+), which then interacts with the regulatory protein troponin. Calcium-bound troponin undergoes a conformational change that leads to the movement of tropomyosin, subsequently exposing the myosin-binding sites on actin. This allows for myosin and actin ATP-dependent cross-bridge cycling and shortening of the muscle.
=== Lipid extraction === Most methods of lipid extraction and isolation from biological samples exploit the high solubility of hydrocarbon chains in organic solvents. Given the diversity in lipid classes, it is not possible to accommodate all classes with a common extraction method. The traditional Bligh/Dyer procedure uses chloroform/methanol-based protocols that include phase partitioning into the organic layer. However, several protocols now exist, with newer methods overcoming the shortcomings of older ones and solving problems associated with, for example, targeted lipid isolation or high throughput data collection . Most protocols work relatively well for a variety of physiologically relevant lipids but they have to be adapted for species with particular properties and low-abundance and labile lipid metabolites .
Sources: en.wikipedia.org
Since in terms of their socio-economic situation, Arab Christians in Israel have high socio-economic status and are more akin to the Jewish population in this regard than to the Muslim Arab or Druze population. The local Druze community has complained that despite their sons serving in the Israeli army and police forces, the government fails to reward the Druze community adequately. Meanwhile, Christian youth receive high-quality education, secure better jobs, leading to a noticeable disparity in living standards between the two groups. Additionally, Arab Christians are among the most educated groups in Israel. Statistically, Arab Christians in Israel have the highest rates of educational attainment among all religious communities. Many Druze and Muslims attend Christian schools in Israel, because Christian schools are high-performing and among the best schools in the country, and while those schools represent only 4% of the Arab schooling sector, about 34% of Arab university students come from Christian schools, and about 87% of the Israeli Arabs in the high tech sector have been educated in Christian schools. Moreover, a significant number of Druze students attend prestigious Christian schools such as the Orthodox Arab College-School and the Sisters of Nazareth School in Haifa, Mar Elias Educational Institutions in I'billin, the Latin Patriarchate School in Rameh, Bishop Timothy National School in Kafr Yasif, and the Melkite Catholic Episcopal School and the Sisters of Nazareth School in Shefa-Amr.
Common recreational drugs include caffeine, commonly found in coffee, tea, soft drinks, and chocolate; alcohol, commonly found in beer, wine, cocktails, and distilled spirits; nicotine, commonly found in tobacco, tobacco-based products, and electronic cigarettes; cannabis and hashish (with legality of possession varying inter/intra-nationally); and the controlled substances listed as controlled drugs in the Single Convention on Narcotic Drugs (1961) and the Convention on Psychotropic Substances (1971) of the United Nations (UN). Since the early 2000s, the European Union (EU) has developed several comprehensive and multidisciplinary strategies as part of its drug policy in order to prevent the diffusion of recreational drug use and abuse among the European population and raise public awareness on the adverse effects of drugs among all member states of the European Union, as well as conjoined efforts with European law enforcement agencies, such as Europol and EMCDDA, in order to counter organized crime and illegal drug trade in Europe.
=== Upcycling === A March 2022 joint study by scientists Sewon Oh and Erin Stache at Cornell University in Ithaca, New York found a new processing method of upcycling polystyrene to benzoic acid. The process involved irradiation of polystyrene with iron chloride and acetone under white light and oxygen for 20 hours. The scientists also demonstrated a similar scalable commercial process of upcycling polystyrene into valuable small-molecules (like benzoic acid) taking just a few hours.
Sources: en.wikipedia.org
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.
It appears in Russian pharmaceutical listings as a nasal formulation, but it is not an authorised medicine in the United States or the European Union. Outside those markets it is normally encountered as a research chemical rather than a prescription product.
Laboratory and animal work points to melanocortin signalling and changes in neurotrophic factor levels, especially brain-derived neurotrophic factor. The exact receptor targets and the degree to which these findings transfer to humans are still unresolved.
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.