The short version of reversed-phase HPLC fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-10-11 and is reviewed periodically as new material appears.
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.
Proposed mechanisms center on neurotrophic signaling rather than on classical melanocortin receptor activation. Rodent experiments have reported shifts in the expression of brain-derived neurotrophic factor and nerve growth factor after administration, together with changes in the associated receptor systems. Several authors argue that the peptide acts largely through its degradation products and their interaction with peptidergic pathways, but this remains a hypothesis rather than a settled finding. No single molecular target has been identified in a way that the field broadly accepts.
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.
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。
| Property | Value | Notes |
|---|---|---|
| Primary research models | Rodent studies | Largest share of published data |
| Reported markers | BDNF and NGF expression | Measured mainly in animal tissue |
| Common administration | Intranasal | Matches the registered formulation |
| Blood residence time | Minutes | Rapid enzymatic degradation |
| Evidence quality | Small trials, limited replication | Noted repeatedly in reviews |
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.
Dissolution is normally performed in water, phosphate-buffered saline, or normal saline, since the peptide is freely soluble in aqueous media and is rarely handled with strong organic solvents. Solution pH should be kept near neutral, because extreme acidity or alkalinity accelerates backbone hydrolysis and encourages oxidation of the methionine side chain. Once dissolved, the material is less stable than the dry powder and is commonly divided into single-use portions and frozen. Buffers containing primary amines, such as Tris, are often avoided because of possible side reactions.
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.
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.
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.
Laboratory descriptions of the material are consistent across suppliers. It appears as a white to off-white lyophilized powder that dissolves readily in water and in polar organic solvents such as dimethyl sulfoxide. Aqueous solutions are clear and colorless at low concentrations. Because the peptide contains methionine, oxidation at the sulfur atom is a recognized degradation pathway, and handling notes usually call for protected, desiccated storage. Reported purity for research-grade lots is generally above 95 percent as measured by reversed-phase high-performance liquid chromatography.
The compound is registered in Russia as a pharmaceutical product, most commonly formulated as a nasal solution, and has been used in that setting since the 1990s. Outside that jurisdiction it is generally handled as a research chemical rather than an approved medicine. Regulatory status therefore differs sharply between countries, and material sold internationally may not correspond to the Russian pharmaceutical formulation. Documentation with commercial samples is typically limited to a certificate of analysis covering purity and identity, not clinical status or local legal classification.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It corresponds to the ACTH(4-7) fragment extended at the C-terminus by a Pro-Gly-Pro tripeptide, an addition intended to slow enzymatic breakdown. The molecular formula is C37H51N9O10S and the molecular mass is approximately 814 daltons. In the literature it is often described as an ACTH(4-10) analog, although that label reflects a naming convention as much as a precise structural relationship. The compound was developed in Russia and remains most closely associated with that research tradition.
is the fourth-order tensor representing the constant of proportionality, called the viscosity or elasticity tensor, and : is the double-dot product. the fluid is assumed to be isotropic, as with gases and simple liquids, and consequently
Central memory T cells (TCM cells) express CD45RO, C-C chemokine receptor type 7 (CCR7), and L-selectin (CD62L). Central memory T cells also have intermediate to high expression of CD44. This memory subpopulation is commonly found in the lymph nodes and in the peripheral circulation. (Note- CD44 expression is usually used to distinguish murine naive from memory T cells). Effector memory T cells (TEM cells and TEMRA cells) express CD45RO but lack expression of CCR7 and L-selectin. They also have intermediate to high expression of CD44. These memory T cells lack lymph node-homing receptors and are thus found in the peripheral circulation and tissues. TEMRA stands for terminally differentiated effector memory cells re-expressing CD45RA, which is a marker usually found on naive T cells. Tissue-resident memory T cells (TRM) occupy tissues (skin, lung, etc.) without recirculating. One cell surface marker that has been associated with TRM is the intern αeβ7, also known as CD103. Virtual memory T cells (TVM) differ from the other memory subsets in that they do not originate following a strong clonal expansion event. Thus, although this population as a whole is abundant within the peripheral circulation, individual virtual memory T cell clones reside at relatively low frequencies. One theory is that homeostatic proliferation gives rise to this T cell population. Although CD8 virtual memory T cells were the first to be described, it is now known that CD4 virtual memory cells also exist.
The Knights Templar Cartel (Spanish: Caballeros Templarios) was created in Michoacán in 2011 after the presumed death of the leader of La Familia Michoacana, Nazario Moreno González. The cartel was headed by Enrique Plancarte Solís and Servando Gómez Martínez ("La Tuta"), who formed the Knights Templar due to differences with José de Jesús Méndez Vargas, who had assumed leadership of La Familia Michoacana. The cartel was reported to promote a religious doctrine as part of its identity. Sizable battles flared up in 2011 between the Knights Templar and La Familia. The organization grew from a splinter group to a dominant force in Michoacán, and following the arrest of Méndez Vargas, the cartel appeared to have taken over the bulk of La Familia's operations. In 2011 the Knights Templar appeared to have aligned with the Sinaloa Federation in an effort to root out the remnants of La Familia and to prevent Los Zetas from gaining foothold in the Michoacán region. In 2014 Plancarte Solís was killed by the Mexican Navy, and Gómez Martínez was arrested in 2015. The cartel is believed to have disbanded in 2017.
== Production == TMU is obtained by the reaction of dimethylamine with phosgene in aqueous sodium hydroxide in a 2:1 ratio. A similar method combines dimethylcarbamoyl chloride with excess dimethylamine. This reaction is highly exothermic. The removal of the resulting dimethylamine hydrochloride requires some effort.
=== Adhesion to dental metal === Tensile bond strengths to titanium plates treated with 3 experimental primers consisting of MDP in 3 concentrations were tested. The data obtained strongly suggest that MDP is effective to improve the adhesive performance of resin to titanium.
Sources: en.wikipedia.org
The symptoms of PSSD are largely shared with post-finasteride syndrome and post-retinoid sexual dysfunction, two other poorly understood conditions which have been suggested to share a common etiology with PSSD despite being associated with different types of medication. Diagnostic criteria for PSSD were proposed in 2022, but as of 2023, there is no agreement on standards for diagnosis. It is a distinct phenomenon from antidepressant discontinuation syndrome, post-acute withdrawal syndrome, and major depressive disorder, and should be distinguished from sexual dysfunction associated with depression and persistent genital arousal disorder. There are limited treatment options for PSSD as of 2023 and no evidence that any individual approach is effective. The mechanism by which SSRIs may induce PSSD is unclear. However, various neurochemical, hormonal, and biochemical changes during SSRI use—such as reduced dopamine levels, increased serotonin, inhibition of nitric oxide synthase, and the blocking of cholinergic and alpha-1 adrenergic receptors—could account for their sexual adverse effects. Additionally, SSRIs may cause peripheral changes by inhibiting serotonin receptors in peripheral nerves, which may also play a role in PSSD. As of 2023, prevalence is unknown. A 2020 review stated that PSSD is rare, underreported, and "increasingly identified in online communities". A 19 year retrospective analysis looking at people with erectile dysfunction who met most of the criteria for PSSD found that the estimated risk was 0.46%.
Amid a surge in inflation and high gas prices, Biden's approval ratings declined, with his disapproval rating surpassing his approval rating in early 2022. After 5.9% growth in 2021, real GDP growth cooled in 2022 to 2.1%, after slightly negative growth in the first half spurred recession concerns. Job creation and consumer spending remained strong, as the unemployment rate fell to match a 53-year low of 3.5% in December. Inflation peaked at 9.1% in June before easing to 3.2% by October 2023. Stocks had had their worst year since 2008 before recovering. Widespread predictions of an imminent recession did not materialize in 2022 or 2023, and by late 2023 indicators showed sharply lower inflation with economic acceleration. GDP growth hit 4.9% in the third quarter of 2023 and the year ended with stocks near record highs, with robust holiday spending. Biden signed numerous major pieces of economic legislation in the 117th Congress, including the American Rescue Plan, Infrastructure Investment and Jobs Act, CHIPS and Science Act, and the Inflation Reduction Act. He signed the CHIPS and Science Act into law on August 9, 2022. It provided billions of dollars in new funding to boost domestic research on and manufacture of semiconductors, to compete economically with China. In his third month in office, Biden also signed an executive order to increase the minimum wage for federal contractors to $15 per hour. The order went into effect for 390,000 workers in January 2022. His administration rigorously enforced antitrust law.
=== Major depressive disorder === A number of atypical antipsychotics have some benefits when used in addition to other treatments in major depressive disorder. Aripiprazole, quetiapine extended-release, and olanzapine (when used in conjunction with fluoxetine) have received the Food and Drug Administration (FDA) labelling for this indication. There is, however, a greater risk of side effects with their use compared to using traditional antidepressants. The greater risk of serious side effects with antipsychotics is why, e.g., quetiapine was denied approval as monotherapy for major depressive disorder or generalized anxiety disorder, and instead was only approved as an adjunctive treatment in combination with traditional antidepressants. A recent study on the use of antipsychotics in unipolar depression concluded that the use of those drugs in addition to antidepressants alone leads to a worse disease outcome. This effect is especially pronounced in younger patients with psychotic unipolar depression. Considering the wide use of such combination therapies, further studies on the side effects of antipsychotics as an add-on therapy are warranted.
=== Probability === Step-growth polymerization is a random process, so we can use statistics to calculate the probability of finding a chain with x-structural units ("x-mer") as a function of time or conversion.
=== First modular space station === The USSR turned its space program to the development of the low Earth orbit modular space station Mir (peace or world) assembled in orbit from 1986 to 1996. At 129,700 kilograms (285,900 lb), it held records for the largest spacecraft and the longest continuous human presence in space at 3,644 days, until the International Space Station was built starting in 1998. Mir's operation continued after the 1991 replacement of the USSR's space program with the Russian Federal Space Agency until 2001, supported by Soyuz spacecraft.
Sources: en.wikipedia.org
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.
The compound is registered as a medicine in Russia, so clinical work has concentrated there. Trials elsewhere are few and generally small. This geographic concentration is a recognized limitation in evidence reviews.
Some fraction may reach the central nervous system through olfactory pathways, and this is often cited as the rationale for the nasal route. The size of that fraction in humans is not well quantified. Blood concentrations after nasal dosing are low, which complicates measurement.
不是。Semax 是完全人工合成的七肽，自然界中没有对应的已知肽段。它的设计灵感来自促肾上腺皮质激素片段 ACTH(4-10)，但序列经过了替换和延长。