The short version of Lyophilized powder fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-09-24 and is reviewed periodically as new material appears.
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.
Pharmacological accounts link semax to melanocortin signalling and to modulation of neurotrophic factor expression, particularly brain-derived neurotrophic factor and nerve growth factor. Much of this evidence comes from rodent studies using intranasal delivery, a route chosen because it allows peptides to reach the central nervous system with limited systemic exposure. Whether the same mechanisms operate in humans at comparable magnitude remains an open question. The precise receptor or receptors responsible for the reported behavioural and neuroprotective effects have not been conclusively identified.
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.
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.
| 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 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。
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 is normally supplied as a lyophilized powder, and that form is the most stable. Suppliers commonly recommend storage at -20 °C in a desiccated container protected from light, with short-term handling at room temperature limited to weighing and transfer. Powder that has absorbed moisture degrades faster, so vials should be warmed to ambient temperature before opening to prevent condensation on the contents. Hygroscopic behavior is typical of short hydrophilic peptides, and humidity control matters more than temperature alone for long-term retention.
Once dissolved, the peptide is considerably less stable than the solid. Aqueous solutions are usually prepared at neutral to slightly acidic pH, filtered, and divided into single-use aliquots before freezing. Repeated freeze-thaw cycles are a common cause of avoidable loss and are best prevented by never refreezing a thawed aliquot. Adsorption to plastic and glass surfaces can lower the measured concentration of dilute solutions, particularly below roughly 0.1 mg/mL. Buffer choice, salt content, and container material all influence how much peptide remains detectable after storage.
Chronic exposure to high level of nitrogen dioxide results in the allosteric inhibition of glutathione peroxidase and glutathione S-transferase, both of which are important enzymes found in the mucous membrane antioxidant defense system, that catalyse nucleophilic attack by reduced glutathione (GSH) on non-polar compounds that contain an electrophilic carbon and nitrogen. These inhibition mechanisms generates free radicals that causes peroxidation from the lipids in the mucous membrane leading to increased peroxidized erythrocyte lipids, a reaction that proceeds by a free radical chain reaction mechanism that result in oxidative stress. The oxidative stress on the mucous membrane causes the dissociation of the GSTp-JNK complex, oligomerization of GSTP and induction of the JNK pathway, resulting in apoptosis or inflammation of the bronchioles and pulmonary alveolus in mild cases. On migrating to the bloodstream, nitrogen dioxide poisoning results in an irreversible inhibition of the erythrocyte membrane acetylcholinesterase which may lead to muscular paralysis, convulsions, bronchoconstriction, the narrowing of the airways in the lungs (bronchi and bronchioles) and death by asphyxiation. It also causes a decrease in glucose-6-phosphate dehydrogenase which may results in glucose-6-phosphate dehydrogenase deficiency known as favism, a condition that predisposes to hemolysis (spontaneous destruction of red blood cells).
Residues in α-helices typically adopt backbone (φ, ψ) dihedral angles around (−60°, −45°), as shown in the image at right. In more general terms, they adopt dihedral angles such that the ψ dihedral angle of one residue and the φ dihedral angle of the next residue sum to roughly −105°. As a consequence, α-helical dihedral angles, in general, fall on a diagonal stripe on the Ramachandran diagram (of slope −1), ranging from (−90°, −15°) to (−70°, −35°). For comparison, the sum of the dihedral angles for a 310 helix is roughly −75°, whereas that for the π-helix is roughly −130°. The general formula for the rotation angle Ω per residue of any polypeptide helix with trans isomers is given by the equation
The science behind food and food production involves studying how food behaves and how it can be improved. Researchers analyze longevity and composition (i.e., ingredients, vitamins, minerals, etc.) of foods, as well as how to ensure food safety.
Sources: en.wikipedia.org
The enyzme cyclises nicotinamide adenine dinucleotide (a cation) to give initially nicotinamide and cyclic ADP-ribose as intermediate. The latter is then hydrolyzed to adenosine diphosphate ribose (ADP-ribose). This makes it different from NAD+ glycohydrolase (EC 3.2.2.5), where the hydrolysis gives ADP-ribose directly. The enzyme was characterised from beef spleen. The enzyme is also present in bacteria and humans. This enzyme is a hydrolase, specifically a glycosylase that hydrolyses N-glycosyl compounds. Other names of this enzyme include nicotinamide adenine dinucleotide (phosphate) nucleosidase, triphosphopyridine nucleotidase, NAD(P) nucleosidase, NAD(P)ase, and nicotinamide adenine dinucleotide (phosphate) glycohydrolase.
About 43% of the population lives on less than 1 US dollar a day, with around 24% of those found in urban areas and 54% living in rural areas. The Ministry of Finance of Somalia projected the 2025 GDP to be $13.3 billion. Somalia's economy consists of both traditional and modern production, with a gradual shift toward modern industrial techniques. Somalia has the largest population of camels in the world. According to the Central Bank of Somalia, about 80% of the population are nomadic or semi-nomadic pastoralists, who keep goats, sheep, camels and cattle. The nomads also gather resins and gums to supplement their income.
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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.
Suppliers normally quote a percentage of total chromatographic peak area, most often from reversed-phase HPLC. That figure says nothing about what the remaining percentage contains, and it depends on the detection wavelength used. A mass spectrometry result is a separate and stronger check on identity.