Semax raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-02-17 and is reviewed periodically as new material appears.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. Its design combines the ACTH(4-7) core fragment with a C-terminal Pro-Gly-Pro extension, a modification intended to improve stability and prolong activity. The molecule is hydrophilic, carries no lipid chains or glycosylation, and has a theoretical mass just over 810 daltons in its free form. All seven residues are proteinogenic amino acids, so no non-natural building blocks appear in the backbone. A free N-terminal methionine and C-terminal proline define the unmodified parent peptide.
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.
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。
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。
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | ACTH(4-7) analogue |
| Sequence | Met-Glu-His-Phe-Pro-Gly-Pro | Free N terminus, unmodified side chains |
| Molecular weight | 813.9 Da | Free base; salt forms differ |
| Appearance | White to off-white powder | Lyophilised solid |
| Solubility | Freely soluble in water | Hydrophilic; polar solvents preferred |
Regulatory status differs sharply between jurisdictions. In Russia the peptide is registered as a prescription nasal preparation, while agencies such as the United States Food and Drug Administration have not approved it for any indication. Products sold elsewhere are typically labeled for laboratory research only, and such labels shift responsibility for safe handling to the purchaser. Because the same name covers pharmaceutical-grade nasal drops and bulk research powder, identity and purity documentation becomes the main practical concern when comparing sources.
Semax is a synthetic seven-amino-acid peptide whose sequence extends the ACTH(4-10) fragment with a C-terminal proline-glycine-proline tripeptide. The commonly cited sequence is Met-Glu-His-Phe-Pro-Gly-Pro, giving a molecular formula near C37H51N9O10S and a molecular weight close to 813.9 g/mol. It belongs to the broader class of synthetic ACTH fragments studied for central nervous system effects rather than for adrenal steroid stimulation. In practice the material appears as a lyophilized white powder for laboratory work or as a dilute saline solution in clinical settings.
Development is attributed to researchers at the Institute of Molecular Genetics in Moscow during the early 1980s, building on earlier Soviet work with ACTH fragments. Russian regulatory approval followed for intranasal use, and the compound has remained commercially available there for decades. Most published human data originate from Russian and, later, some Eastern European clinical reports, which are not always accessible in English translation. Outside that region the material is generally handled as a research chemical rather than a licensed medicine.
== Metabolism == The bacteria rely on the enzyme glycerol-3-phosphate dehydrogenase (GPDH). GPDH is an alternative when managing electrons that are produced during metabolism. In the absence of the electron transport chain, T. pallidum uses GPDH to recycle the NAD+ by oxidizing glycerol-3-phosphate to dihydroxyacetone phosphate and make NAD+ to keep glycolysis and other redox-dependent energy reactions. By doing this, it helps balance the ATP yield without weighing down the protein's limited supply for essential tasks. T. pallidum uses an enzyme called pyrophosphate-dependent phosphofructokinase rather than ATP as a way to save energy and optimize its limited resources. T. pallidum manages without a complete tricarboxylic acid cycle and oxidative phosphorylation by using different efficient strategies including redox balancing and substrate-level to survive the nutrient-limited host environment. T. pallidum lacks enzyme orthologs for superoxide dismutase, however it does possess a superoxide reductase, maintaining the ability to reduce reactive oxygen species. In addition, T. pallidum encodes an alkyl hydroperoxide reductase C, which allows for the reduction of hydrogen peroxide to water and alcohols. This enzyme relies on TP0919, a protein present in the cytoplasm of T. pallidum. T.pallidum primarily relies on glucose as its primary carbon source through glycolysis, but one study has proposed the bacterium uses an acetogenic-energy conservation pathway as a way to catabolize D-lactate as an alternative carbon source.
=== Primary ion source === Three types of ion guns are employed. In one, ions of gaseous elements are usually generated with duoplasmatrons or by electron ionization, for instance noble gases (40Ar+, Xe+), oxygen (16O−, 16O2+, 16O2−), or even ionized molecules such as SF5+ (generated from SF6) or C60+ (fullerene). This type of ion gun is easy to operate and generates roughly focused but high-current ion beams. A second source type, the surface ionization source, generates 133Cs+ primary ions. Caesium atoms vaporize through a porous tungsten plug and are ionized during evaporation. Depending on the gun design, fine focus or high current can be obtained. A third source type, the liquid metal ion gun (LMIG), operates with metals or metallic alloys, which are liquid at room temperature or slightly above. The liquid metal covers a tungsten tip and emits ions under influence of an intense electric field. While a gallium source is able to operate with elemental gallium, recently developed sources for gold, indium, and bismuth use alloys which lower their melting points. The LMIG provides a tightly focused ion beam (<50 nm) with moderate intensity and is additionally able to generate short pulsed ion beams. It is therefore commonly used in static SIMS devices. The choice of the ion species and ion gun respectively depends on the required current (pulsed or continuous), the required beam dimensions of the primary ion beam, and on the sample which is to be analyzed.
In an absorption refrigeration system, thermal energy is used to drive a refrigerant through an absorber–generator solution circuit rather than relying primarily on a mechanical compressor. Absorption refrigeration has a long history: an ammonia–water machine was introduced by Ferdinand Carré in 1859, and lithium bromide–water systems were introduced for industrial applications in the 1950s. The refrigerant evaporates at low pressure and is absorbed into a liquid absorbent. The resulting solution is pumped to a higher pressure and heated in a generator, which separates refrigerant vapour from the solution. The refrigerant then condenses, expands and returns to the evaporator, while the absorbent solution returns to the absorber. Two important working-fluid pairs are ammonia–water, in which ammonia is the refrigerant and water is the absorbent, and water–lithium bromide, in which water is the refrigerant and lithium bromide is the absorbent. The choice of working pair affects operating pressure, temperature range and system performance. Because absorption systems can be driven by thermal energy, they can use sources such as industrial waste heat that might otherwise be rejected to the environment. Their performance and suitability relative to vapor-compression refrigeration depend on the working pair, cycle configuration, heat-source temperature and operating conditions.
Amphetamine, the active ingredient of Adderall, works primarily by increasing the activity of the neurotransmitters dopamine and norepinephrine in the brain. It also triggers the release of several other hormones (e.g., epinephrine) and neurotransmitters (e.g., serotonin and histamine) as well as the synthesis of certain neuropeptides (e.g., cocaine and amphetamine regulated transcript (CART) peptides). Both active ingredients of Adderall, dextroamphetamine and levoamphetamine, bind to the same biological targets, but their binding affinities (that is, potency) differ somewhat. Dextroamphetamine and levoamphetamine are both potent full agonists (activating compounds) of trace amine-associated receptor 1 (TAAR1) and interact with vesicular monoamine transporter 2 (VMAT2), with dextroamphetamine being the more potent agonist of TAAR1. Consequently, dextroamphetamine produces more CNS stimulation than levoamphetamine; however, levoamphetamine has slightly greater cardiovascular and peripheral effects. It has been reported that certain children have a better clinical response to levoamphetamine. In the absence of amphetamine, VMAT2 will normally move monoamines (e.g., dopamine, histamine, serotonin, norepinephrine, etc.) from the intracellular fluid of a monoamine neuron into its synaptic vesicles, which store neurotransmitters for later release (via exocytosis) into the synaptic cleft.
Sources: en.wikipedia.org
=== Sites of synthesis === Traditionally, RBP is synthesized within the liver with secretion being dependent upon retinol concentrations. However, the concentrations levels do not appear to have an effect upon transcription of RBP messenger RNA (mRNA) which remains constant. Literature reveals that the bovine endometrium has also been identified as a location of RBP synthesis, as well as, the conceptus and extraembryonic tissues of various livestock species.
Investigators have access to internationally recognized expertise in aging biology, comparative pathology, geriatric physiology, metabolism, pharmacology, molecular biology, and biostatistics, as well as state-of-the-art core facilities through the Nathan Shock Center of Excellence in the Basic Biology of Aging and the Claude D. Pepper Older Americans Independence Center. This integrated environment enables comprehensive mechanistic investigations that complement lifespan studies, allowing researchers to determine not only whether an intervention is effective, but also how it influences the biological processes underlying aging. The Interventions Testing Program also provides exceptional opportunities for scientific collaboration and investigator development. Faculty, postdoctoral fellows, and trainees participate in multidisciplinary research teams that span basic biology, translational science, pathology, pharmacology, and bioinformatics. Through participation in experimental design, animal studies, data analysis, and dissemination of findings, trainees gain firsthand experience conducting rigorous, large-scale preclinical aging research. These opportunities are further strengthened through integration with the Barshop Institute's NIH-funded Biology of Aging Training Program (T32), providing comprehensive education in experimental geroscience and translational aging research.
Thermoresponsive polymers can be used as stationary phase in liquid chromatography. Here, the polarity of the stationary phase can be varied by temperature changes, altering the power of separation without changing the column or solvent composition. Thermally related benefits of gas chromatography can now be applied to classes of compounds that are restricted to liquid chromatography due to their thermolability. In place of solvent gradient elution, thermoresponsive polymers allow the use of temperature gradients under purely aqueous isocratic conditions. The versatility of the system is controlled not only through changing temperature, but through the addition of modifying moieties that allow for a choice of enhanced hydrophobic interaction, or by introducing the prospect of electrostatic interaction. These developments have already introduced major improvements to the fields of hydrophobic interaction chromatography, size exclusion chromatography, ion exchange chromatography, and affinity chromatography separations as well as pseudo-solid phase extractions ("pseudo" because of phase transitions).
==== Prokaryotic regulation ==== Because of the vital role rRNA plays in the cell physiology of prokaryotes, there is much overlap in rRNA regulation mechanisms. At the transcriptional level, there are both positive and negative effectors of rRNA transcription that facilitate a cell's maintenance of homeostasis:
However, although (R)-MDMA partially substitutes for lysergic acid diethylamide (LSD) in animal drug discrimination tests, it did not produce the head-twitch response, a behavioral proxy of psychedelic effects, at any tested dose. In any case, findings in this area are conflicting. (R)-MDMA is inactive as an agonist of the human TAAR1, whereas (S)-MDMA shows very weak potency as an agonist of the receptor (EC50Tooltip half-maximal effective concentration = 74,000 nM). MDMA is a well-known serotonergic neurotoxin and this has been demonstrated both in animals and in humans. There is evidence that the serotonergic neurotoxicity of MDMA may be driven primarily by (S)-MDMA rather than (R)-MDMA. (R)-MDMA shows substantially lower or potentially no neurotoxicity compared to (S)-MDMA in animal studies. This has been the case even when doses of (R)-MDMA were increased to account for its lower potency than (S)-MDMA. However, more research is needed to confirm this in other species, such as non-human primates. In contrast to (S)-MDMA, (R)-MDMA does not produce hyperthermia in rodents, and this may be involved in its reduced risk of neurotoxicity, as hyperthermia augments and is essential for the serotonergic neurotoxicity of MDMA. The reduced potency of (R)-MDMA as a dopamine releasing agent may also be involved in its reduced neurotoxic potential, as dopamine release is likewise essential for the neurotoxicity of MDMA. The hyperthermia of MDMA may in fact be mediated by dopamine release.
Sources: en.wikipedia.org
It is a synthetic seven-amino-acid peptide built from the ACTH(4-7) sequence plus a Pro-Gly-Pro tail. It belongs to the family of short ACTH fragments studied for nervous-system effects. Its backbone contains only standard amino acids.
It contains the 4-7 fragment of adrenocorticotropic hormone extended at the C terminus. That truncation removes the region associated with steroidogenic activity. The design intent was to keep neurotrophic properties while avoiding full hormonal effects.
No natural source of the intact heptapeptide is known. It is produced by solid-phase peptide synthesis. Some related ACTH fragments arise as hormone processing products, but the Pro-Gly-Pro extension is a designed addition rather than a natural sequence.
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。