The short version of ACTH 片段 fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-10-06. Anything still debated is marked as such rather than presented as settled.
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。
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 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.
| Property | Value | Notes |
|---|---|---|
| 结构类别 | 线性合成七肽 | 无环化结构，不含二硫键 |
| 氨基酸序列 | Met-Glu-His-Phe-Pro-Gly-Pro | N 端为甲硫氨酸 |
| 分子量 | 约 814 Da | 游离碱形式的计算值 |
| 外观 | 白色至类白色粉末 | 具吸湿性 |
| 溶解性 | 易溶于水 | 亦可溶于甲醇等极性溶剂 |
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.
=== Closing ceremony === The closing ceremony took place before the World Cup final at MetLife Stadium in New Jersey, and featured performances by Laura Pausini, Nicole Scherzinger, Robbie Williams, IShowSpeed, and Post Malone, as well as an appearance from Tom Cruise. Jennifer Hudson performed "The Star-Spangled Banner".
== Awards and honours == 2007 Elected to the British Mass Spectrometry Society 2018 Elected Chair of the Management Advisory Panel for the EPSRC National Mass Spectrometry Facility 2022 Royal Society of Chemistry Analytical Division Theophilus Redwood Award
The significance of these additional actions for Auvelity's antidepressant effects remains unclear. The combined pharmacological actions of DXM and bupropion make Auvelity function similarly to an SNDRI (serotonin-norepinephrine-dopamine reuptake inhibitor), simultaneously enhancing all three monoamine neurotransmitter systems. This characteristic may contribute to its relatively rapid antidepressant onset. The role of NMDA antagonism in Auvelity appears to be relatively limited. Ketamine and related compounds do indeed owe their rapid antidepressant effects to NMDA receptor antagonism. However, subsequent studies of numerous NMDA antagonists have found that most do not exhibit antidepressant efficacy. The reason appears to be that antidepressant activity requires exceptionally stringent molecular properties for NMDA receptor antagonism, particularly highly specific receptor-binding kinetics. In practice, neither DXM nor dextrorphan fulfills these requirements. This likely explains why Auvelity requires approximately 8 days to produce antidepressant effects, whereas esketamine can begin working within only a few hours. Therefore, although Auvelity substantially shortens the onset of action compared with conventional oral antidepressants, its mechanism underlying the accelerated antidepressant response appears to have only a limited relationship to the rapid antidepressant mechanism of ketamine.
Sources: en.wikipedia.org
=== Stille–Kelly coupling === Using the seminal publication by Eaborn in 1976, which forms arylstannanes from arylhalides and distannanes, T. Ross Kelly applied this process to the intramolecular coupling of arylhalides. This tandem stannylation/aryl halide coupling was used for the syntheses of a variety of dihydrophenanthrenes. Most of the internal rings formed are limited to 5 or 6 members, however some cases of macrocyclization have been reported. Unlike a normal Stille coupling, chlorine does not work as a halogen, possibly due to its lower reactivity in the halogen sequence (its shorter bond length and stronger bond dissociation energy makes it more difficult to break via oxidative addition). Starting in the middle of the scheme below and going clockwise, the palladium catalyst (1) oxidatively adds to the most reactive C-X bond (13) to form 14, followed by transmetalation with distannane (15) to yield 16 and reductive elimination to yield an arylstannane (18). The regenerated palladium catalyst (1) can oxidative add to the second C-X bond of 18 to form 19, followed by intramolecular transmetalation to yield 20, followed by reductive elimination to yield the coupled product (22).
The reaction happens with two metal cofactors (Mg or Mn) coordinated to the two aspartate residues on C1. They perform a nucleophilic attack of the 3'-OH group of the ribose on the α-phosphoryl group of ATP. The two lysine and aspartate residues on C2 selects ATP over GTP for the substrate, so that the enzyme is not a guanylyl cyclase. A pair of arginine and asparagine residues on C2 stabilizes the transition state. In many proteins, these residues are nevertheless mutated while retaining the adenylyl cyclase activity. There are ten known isoforms of adenylyl cyclases in mammals: These are also sometimes called simply AC1, AC2, etc., and, somewhat confusingly, sometimes Roman numerals are used for these isoforms that all belong to the overall AC class III. They differ mainly in how they are regulated, and are differentially expressed in various tissues throughout mammalian development.
Both agonist and antagonist bond the same active site. Adding agonist dose can reverse the effect of reversible competitive antagonism. Irreversible competitive antagonism occurs when the antagonist binds to the same spot on the receptor as the agonist but dissociates from the receptors very slowly or not. As a result, when the agonist is delivered, there is no change in the antagonist occupancy. Since a receptor can only hold one molecule at a time, competitive antagonists can reduce the agonist occupancy (percentage of receptors to which the agonist is bound). Raising the agonist concentration can bring back the agonist occupancy and the subsequent tissue response due to their competition. Thus, the opposition is surmountable. The amount to which the competitive antagonist causes the agonist log concentration–effect curve to shift to the right while maintaining its maximum slope is a measure of the dosage ratio. The antagonist concentration causes the dosage ratio to rise linearly.
Sources: en.wikipedia.org
=== Dynamics of surfactants at interfaces === The dynamics of surfactant adsorption is of great importance for practical applications such as in foaming, emulsifying or coating processes, where bubbles or drops are rapidly generated and need to be stabilized. The dynamics of absorption depend on the diffusion coefficient of the surfactant. As the interface is created, the adsorption is limited by the diffusion of the surfactant to the interface. In some cases, there can exist an energetic barrier to adsorption or desorption of the surfactant. If such a barrier limits the adsorption rate, the dynamics are said to be ‘kinetically limited'. Such energy barriers can be due to steric or electrostatic repulsions. The surface rheology of surfactant layers, including the elasticity and viscosity of the layer, play an important role in the stability of foams and emulsions.
== Overview == When an elastic material is deformed due to an external force, it experiences internal resistance to the deformation so that it is restored to its original state if the external force is no longer applied. There are various elastic moduli, such as Young's modulus, the shear modulus, and the bulk modulus, all of which are measures of the inherent elastic properties of a material as a resistance to deformation under an applied load. The various moduli each apply to different kinds of deformation. For instance, Young's modulus applies to extension or ←compression of a body, whereas the shear modulus applies to its shear. Young's modulus and shear modulus only apply to solids, whereas the bulk modulus applies to solids, liquids, and gases. The elasticity of materials is described by a stress–strain curve, which shows the relation between stress (the average restorative internal force per unit area) and strain (the relative deformation). The curve is generally nonlinear, but it can (by use of a Taylor series) be approximated as linear for sufficiently small deformations (in which higher-order terms are negligible). If the material is isotropic, the linearized stress–strain relationship is called Hooke's law, which is often presumed to apply up to the elastic limit for most metals or crystalline materials whereas nonlinear elasticity is generally required to model large deformations of rubbery materials even in the elastic range.
Plasma renin activity (PRA), also known as the renin (active) assay or random plasma renin, is a measure of the activity of the plasma enzyme renin, which plays a major role in the body's regulation of blood pressure, thirst, and urine output. Measure of direct renin concentration (DRC) is technically more demanding, and hence PRA is used instead. DRC assays are still in evolution, and generally a conversion factor of PRA (ng/mL/h) to DRC (mU/L) is 8.2. A recently developed and already commonly used automated DRC assay uses the conversion factor of 12. PRA is sometimes measured, specially in case of certain diseases which present with hypertension or hypotension. PRA is also raised in certain tumors. A PRA measurement may be compared to a plasma aldosterone concentration as an aldosterone-to-renin ratio (ARR).
Sources: en.wikipedia.org
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。
Semax 对应 ACTH 第 4 至第 10 位的片段，并在两端做了替换与延长，使其不再具备促肾上腺皮质激素的典型内分泌活性。这一改动同时改变了它在体内的稳定性与分布特征。
俄罗斯将其列为处方药物，需要医生开具处方。多数其他国家把它当作研究化合物，不能作为药品销售或宣称疗效。具体合法性取决于当地法规。
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.