Everything below concerns synthetic heptapeptide. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-09-19. Numbers and descriptions here follow the published literature rather than marketing material.
Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. The first four residues correspond to the ACTH(4-10) fragment, while the terminal Pro-Gly-Pro extension was added to improve metabolic stability. Its molecular formula is C37H51N9O10S and its monoisotopic mass is approximately 813.9 Da. The compound is classified as a peptide research chemical and as a registered pharmaceutical product in Russia, but it does not hold marketing approval in the European Union or the United States. Naming conventions vary across supplier catalogs.
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 covers ischemic stroke, traumatic brain injury, cognitive impairment, optic nerve conditions and attention-related measures. Much of the human evidence comes from small trials conducted in one country, which limits how far the results generalize. Animal models supply the larger share of the data, and effects seen in rodents do not transfer automatically to people. Reviews have noted that methodological reporting is often incomplete, making it difficult to pool results or compare treatment schedules across studies.
Pharmacokinetic accounts emphasize rapid breakdown. After intravenous dosing the intact peptide disappears from blood within minutes, and nasal delivery produces low but measurable concentrations. Metabolites rather than the parent molecule may account for part of the observed activity, although the relative contribution is unresolved. Dosing in the literature varies widely and no optimal schedule has been agreed. These gaps are regularly cited as a reason the findings have not produced broad clinical adoption beyond the original research setting.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C37H51N9O10S | Seven-residue peptide |
| Molecular mass | 813.9 Da | Monoisotopic value |
| Appearance | White to off-white powder | Lyophilized form |
| Solubility | Freely soluble in water | Also soluble in saline and polar solvents |
| Storage (dry) | -20 °C or lower | Desiccated, protected from light |
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。
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。
Common degradation pathways include oxidation of the methionine side chain, hydrolysis of the peptide backbone, and aggregation under unfavourable pH or concentration. Stability studies typically monitor the main peak by chromatography and report total related substances as a percentage. Because no official monograph exists, acceptance criteria vary between laboratories, and reported purity values are not directly comparable across suppliers. Analysts therefore document the method, column, and detection wavelength alongside each result, and open questions remain about how much biological activity the oxidised forms retain.
Solid semax is typically supplied as a lyophilised powder that is hygroscopic and sensitive to moisture, light, and repeated temperature cycling. Long-term storage of the dry peptide is generally recommended at approximately -20 degrees Celsius, while shorter working periods may use refrigeration at 2 to 8 degrees Celsius. Vials should remain tightly closed and desiccated when brought to room temperature, because condensation can damage the material before it is weighed. Dividing a batch into aliquots is preferable to thawing one container repeatedly.
==== Anti-Jo-1 ==== Although anti-Jo-1 antibodies are often included with ANAs, they are actually antibodies to the cytoplasmic protein, Histidyl-tRNA synthetase – an aminoacyl-tRNA synthetase essential for the synthesis of histidine loaded tRNA. They are highly associated with polymyositis and dermatomyositis, and are rarely found in other connective tissue diseases. Around 20–40% of polymyositis is positive for Jo-1 antibodies and most will have interstitial lung disease, HLA-DR3 and HLA-DRw52 human leukocyte antigen (HLA) markers; collectively known as Jo-1 syndrome.
The NBOMe drugs, primarily 25I-NBOMe, were encountered as novel recreational drugs by 2010, and by 2012 had eclipsed other psychedelics like LSD and psilocybin-containing mushrooms in popularity, at least for a time. Various NBOMes, such as 25I-NBOMe, became Schedule I controlled substances in the United States in 2013.
== Biosynthesis == Current research focuses on understanding the biosynthesis of hyperforin and applying advanced techniques like omics, genome editing, and synthetic biology to enhance their pharmaceutical and medical uses. It faces production challenges that biotechnological methods, such as specialized plant root cultures and microbial biosynthesis, are being developed to overcome for scalable and modifiable manufacturing.
The original Counter-Strike has been played in competitive tournaments since 2000, with the first major event taking place at the Cyberathlete Professional League (CPL) Winter Championship in 2001. The CPL announced a transition from Quake III Arena to Counter-Strike for the Winter Championship. Prior to this, the 2000 Babbage's event featured a Counter-Strike competition sponsored by Kärna, the parent company of Razer, offering a $15,000 prize pool. However, Kärna experienced financial difficulties, leading to delays in prize payouts. On March 14, 2001, the CPL issued a statement confirming that alternative arrangements would be made if the payments were not received by April 2, 2001.
Sources: en.wikipedia.org
== Limitations == FFF does not work for small molecules, because of their fast diffusion. For an effective separation, the sample has to be concentrated very close to the accumulation wall (a distance less than 10 μm), which requires the drift velocity caused by the force field to be two orders of magnitude higher compared to the diffusion coefficient. The maximum field strength which can be generated in an FFF channel determines the lower size range of separation. For current instrumentation this is approximately 1 nm. Although FFF is an extremely versatile technique, there is no "one size fits all" method for all applications. Different FFF methods need specialized instrumentation. Currently only the so-called asymmetric flow field-flow fractionation (AF4) has gained widespread use. Other methods like centrifugal, thermal or electrical FFF still have a niche existence. FFF behaves differently from column chromatography and can be counter-intuitive for HPLC or SEC users. Understanding of the working principle of FFF is vital for a successful application of the method.
Ag+(aq) + 2 NH3(aq) ⇌ Ag(NH3)2+ AgCl(s) ⇌ Ag+(aq) + Cl−(aq) If these reactions both occurred in the same reaction vessel, the solubility of the silver chloride (AgCl) would be increased by the presence of NH3 because formation of the diammineargentum(I) complex (Ag(NH3)2+) consumes a significant portion of the free silver ions from the solution. By Le Chatelier's principle, this causes the equilibrium reaction for the dissolving of the silver chloride, which has silver ion as a product, to shift to the right. This new solubility can be calculated given the values of Kf and Ksp for the original reactions. The solubility is found essentially by combining the two separate equilibria into one combined equilibrium reaction and this combined reaction is the one that determines the new solubility. So Kc, the new solubility constant, is denoted by:
These non-peptide inhibitors can be more stable than inhibitors containing peptide bonds, because they will not be substrates for peptidases and are less likely to be degraded. In drug design it is important to consider the concentrations of substrates to which the target enzymes are exposed. For example, some protein kinase inhibitors have chemical structures that are similar to ATP, one of the substrates of these enzymes. However, drugs that are simple competitive inhibitors will have to compete with the high concentrations of ATP in the cell. Protein kinases can also be inhibited by competition at the binding sites where the kinases interact with their substrate proteins, and most proteins are present inside cells at concentrations much lower than the concentration of ATP. As a consequence, if two protein kinase inhibitors both bind in the active site with similar affinity, but only one has to compete with ATP, then the competitive inhibitor at the protein-binding site will inhibit the enzyme more effectively.
=== Erectile dysfunction === Smoking is a key cause of erectile dysfunction (ED). The incidence of erectile dysfunction (difficulty achieving and maintaining a penile erection) is approximately 85 percent higher in men who smoke compared to men who do not smoke. Smoking causes impotence because it promotes arterial narrowing and damages cells lining the inside of the arteries, thus leading to reduce penile blood flow.
[RO−P(O)2−O−P(O)2−O−PO3]4− + H2O → [RO−P(O)2−O−PO3]3− + [HPO4]2− + H+ [RO−P(O)2−O−P(O)2−O−PO3]4− + H2O → [RO−PO3]2− + [HO3P−O−PO3]3− + H+ For ATP hydrolysis that takes place with the physiological concentrations of ATP, ADP, and inorganic phosphate (Pi) within the living cell, the change in Gibbs free energy is given by:
Sources: en.wikipedia.org
A new Familia 1000 coupé arrived in November 1965, with a 985 cc SOHC "PC" engine, and was joined by the larger Mazda Luce in 1966. Around the same time, the 800 engine was upgraded, adding three horsepower. As a number of new 1-litre vehicles were introduced by Mazda's competitors, another 987 cc OHV engine (PB) appeared in January 1967, powering new 1000 saloon and van versions. The 1-litre saloons and vans are recognizable by their broader, rounded-off rectangular headlights. Production of the saloon continued until November 1967, while the van versions continued until they were replaced in February 1968. Around 400,000 of the first Familias were built, 130,473 of which were saloons and coupés. Around 10,000 of the first generation Familias were exported, mainly to Australia and Oceania.
== E == Setsuro Ebashi (1922–2006). Japanese biochemist at the University of Tokyo who discovered troponin. Richard H. Ebright (b. 1959). American molecular biologist at Rutgers University, known for work on protein-DNA interaction, aspects of transcription, and antibacterial drug discovery. John Tileston Edsall (1902–2002). American protein chemist at Harvard, very influential in protein research, and author (with Edwin Cohn) of Proteins, Amino Acids and Peptides. Member Natl. Acad. Sci. USA. Konstantin Efetov (b. 1958). Ukrainian biochemist at Crimea State Medical University, known for work in molecular immunology, evolutionary biology, and biosystematics. Gertrude B. Elion (1918–1999). American biochemist and pharmacologist at Duke University, known for using rational drug design for the discovery of new drugs. Nobel Prize in Physiology or Medicine (1988). Conrad Elvehjem (1901–1962). American biochemist and nutritionist at the University of Wisconsin, known for identifying two vitamins, nicotinic acid, and nicotinamide. Gladys Anderson Emerson (1903–1984). American historian, biochemist and nutritionist at UCLA, the first to isolate Vitamin E in a pure form. Akira Endo (1933–2024). Japanese biochemist at the Tokyo University of Agriculture and Technology. His research into the relationship between fungi and cholesterol biosynthesis led to the development of statin drugs. Foreign associate Natl. Acad. Sci. USA. Donald Engelman (b. 1941). American biochemist at Yale, involved in the creation of new cancer drugs and treatments. Member Natl. Acad. Sci.
== Stable isotope analysis == Stable isotope biogeochemistry uses variations in isotopic signatures and relates them to biogeochemical processes. The science is based on the preferential fractionation of lighter or heavier isotopes, which results in enriched and depleted isotopic signatures compared to a standard value. Essential elements for life such as carbon, nitrogen, oxygen, and sulfur are the primary stable isotope systems used to interrogate archeological discoveries. Isotopic signatures from multiple systems are typically used in tandem to create a comprehensive understanding of the analyzed material. These systems are most commonly used to trace the geographic origin of archaeological remains and investigate the diets, mobility, and cultural practices of ancient humans.
The Southern Oscillation is the atmospheric component of ENSO. This component is an oscillation in surface air pressure between the tropical eastern and the western Pacific Ocean waters. The strength of the Southern Oscillation is measured by the Southern Oscillation Index (SOI). The SOI is computed from fluctuations in the surface air pressure difference between Tahiti (in the Pacific) and Darwin, Australia (on the Indian Ocean). El Niño episodes have negative SOI, meaning there is lower pressure over Tahiti and higher pressure in Darwin. La Niña episodes on the other hand have positive SOI, meaning there is higher pressure in Tahiti and lower in Darwin. Low atmospheric pressure tends to occur over warm water and high pressure occurs over cold water, in part because of deep convection over the warm water. El Niño episodes are defined as sustained warming of the central and eastern tropical Pacific Ocean, thus resulting in a decrease in the strength of the Pacific trade winds, and a reduction in rainfall over eastern and northern Australia. La Niña episodes are defined as sustained cooling of the central and eastern tropical Pacific Ocean, thus resulting in an increase in the strength of the Pacific trade winds, and the opposite effects in Australia when compared to El Niño. Although the Southern Oscillation Index has a long station record going back to the 1800s, its reliability is limited due to the latitudes of both Darwin and Tahiti being well south of the Equator, so that the surface air pressure at both locations is less directly related to ENSO.
Sources: en.wikipedia.org
It is a synthetic peptide of seven amino acids. Its backbone corresponds to a fragment of adrenocorticotropic hormone extended at the carboxyl end. The material is distributed as a lyophilized solid for laboratory use.
The extension was introduced to slow enzymatic breakdown of the peptide in biological systems. Natural ACTH fragments are degraded rapidly by peptidases. Adding the tripeptide was intended to extend the window during which the molecule remains intact.
Most published work consists of animal experiments conducted in a small number of laboratories. Human data are limited in number and size. Whether the observed effects translate into reliable clinical benefit is still unresolved.
The main proposal is modulation of neurotrophic factors such as brain-derived neurotrophic factor, supported largely by animal experiments. Receptor-level targets have not been firmly established. Most reviews describe the mechanism as only partially characterized.