Reversed-phase HPLC is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2025-10-23. Numbers and descriptions here follow the published literature rather than marketing material.
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 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。
Identity and purity of semax are established with reversed-phase high-performance liquid chromatography coupled to ultraviolet detection, usually at 214 nanometres. Mass spectrometry, most often electrospray ionisation in positive mode, confirms the molecular mass and reveals truncated sequences. Amino acid analysis and peptide mapping after enzymatic digestion provide additional structural confirmation. Laboratories typically report purity as the percentage area of the main peak, a figure that does not capture isomeric or oxidised variants unless the method resolves them.
The peptide is prone to several degradation pathways. Oxidation of the methionine residue produces a sulfoxide that elutes close to the parent peak in many chromatographic systems. Hydrolysis of peptide bonds and deamidation of susceptible residues in related sequences also reduce purity over time. Lyophilised material kept dry at minus twenty degrees Celsius and shielded from light is the most stable form commonly described in laboratory practice.
| Property | Value | Notes |
|---|---|---|
| 化学类别 | 合成七肽 | ACTH(4-10) 结构类似物 |
| 氨基酸序列 | Met-Glu-His-Phe-Pro-Gly-Pro | 单字母写作 MEHFPGP |
| 分子量 | 约 813.9 Da | 随确切形式和盐型略有变化 |
| 常见同义词 | ACTH(4-10) 类似物 | 俄语文献称 Семакс |
| 开发来源 | 俄罗斯 | 二十世纪八十年代 |
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。
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.
Later generations of the molecule include an N-acetylated form and an amidated form, both marketed online alongside the parent peptide. These variants differ in terminal chemistry and stability, and they are frequently discussed in the same breath even though they have not been compared in controlled trials. Supply outside formal healthcare systems comes largely from laboratories that synthesize peptides to order. Purity and identity of these materials vary widely, and no single body oversees the international trade.
Semax is a synthetic heptapeptide developed in the Soviet Union during the 1980s by researchers at the Institute of Molecular Genetics in Moscow. It was designed as a truncated analog of adrenocorticotropic hormone, retaining only the fragment spanning residues four through ten. Investigators sought a peptide that would preserve the cognitive effects associated with ACTH while eliminating the hormonal stimulation of the adrenal cortex. The compound entered clinical use in Russia during the following decade.
Russian regulatory authorities approved the peptide for nasal administration, and it remains listed in the national pharmacopoeia under several trade names. Documented indications include acute ischemic stroke, transient ischemic attacks, traumatic brain injury, and certain ophthalmological and neurological conditions. Physicians also prescribe it for cognitive complaints in older patients, although the evidence base for that use is thinner. Outside Russia and a few neighboring states, the substance is not an approved medicine and is sold instead as a research chemical.
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.
Identity and purity are established with standard peptide methods. Reversed-phase HPLC with ultraviolet detection near 214 nm resolves the parent peak from deletion and truncation byproducts, and reports typically quote a main-peak percentage. Mass spectrometry by electrospray or MALDI-TOF confirms the expected molecular mass, while amino acid analysis or peptide mapping can verify composition when the sequence itself is in question. A certificate of analysis that pairs a chromatogram with a mass spectrum is more informative than a purity figure alone. Counter-ion content and residual solvents are separate specifications and are frequently omitted.
Usually, a set of individually designed oligonucleotides is made on automated solid-phase synthesizers, purified and then connected by specific annealing and standard ligation or polymerase reactions. To improve specificity of oligonucleotide annealing, the synthesis step relies on a set of thermostable DNA ligase and polymerase enzymes. To date, several methods for gene synthesis have been described, such as the ligation of phosphorylated overlapping oligonucleotides, the Fok I method and a modified form of ligase chain reaction for gene synthesis. Additionally, several PCR assembly approaches have been described. They usually employ oligonucleotides of 40-50 nucleotides length that overlap each other. These oligonucleotides are designed to cover most of the sequence of both strands, and the full-length molecule is generated progressively by overlap extension (OE) PCR, thermodynamically balanced inside-out (TBIO) PCR or combined approaches. The most commonly synthesized genes range in size from 600 to 1,200 bp although much longer genes have been made by connecting previously assembled fragments of under 1,000 bp. In this size range it is necessary to test several candidate clones confirming the sequence of the cloned synthetic gene by automated sequencing methods.
Sendai virus (family Paramyxoviridae) has a linear, single-stranded, negative-sense, nonsegmented RNA genome. The viral RdRp consists of two virus-encoded subunits, a smaller one P and a larger one L. Testing different inactive RdRp mutants with defects throughout the length of the L subunit in pairwise combinations, restoration of viral RNA synthesis was observed in some combinations. This positive L–L interaction is referred to as intragenic complementation and indicates that the L protein is an oligomer in the viral RNA polymerase complex.
77. Tirzepatide. Farzam K(1), Patel P. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan–. 2026 Sep 14. Author information: (1)McMaster University Tirzepatide is a medication approved by the US Food and Drug Administration (FDA) for the treatment of type 2 diabetes, obesity, and obstructive sleep apnea. As a dual agonist of the glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide receptors, it improves glycemic control and reduces body weight in patients with type 2 diabetes. Administered once weekly via subcutaneous injection with incremental dose adjustments, tirzepatide is used as a second-line diabetes medication. Tirzepatide is not approved for the treatment of type 1 diabetes and has not been adequately studied in patients with pancreatitis. Common adverse effects are gastrointestinal, including nausea, vomiting, and diarrhea. This activity provides an overview of the indications, mechanism of action, administration, adverse effects, contraindications, drug interactions, and considerations for specific patient populations. The activity also enhances clinicians’ competence in administering tirzepatide, monitoring treatment response and adverse effects, and managing patients with type 2 diabetes to improve patient outcomes and safety. Copyright © 2026, StatPearls Publishing LLC.
Sources: en.wikipedia.org
== Early life and education == Vasquez was born on August 3, 1984, in El Paso, Texas. He was raised in the El Paso–Juárez–Las Cruces border region, spending much of his childhood in both the United States and Mexico. He grew up in Ciudad Juárez, Mexico, where he spent time in his grandfather's television repair shop. His grandfather Javier Bañuelos, originally from Zacatecas, Mexico, had transitioned from farming to working as a mailman before establishing his repair business. Vasquez later attended Montwood High School in El Paso and then enrolled at New Mexico State University (NMSU) in Las Cruces, where he earned a Bachelor of Arts degree in English and journalism in 2008. During college, he served as the news editor and later as editor-in-chief of The Round Up, NMSU's student-run newspaper.
Protein synthesis, as any other of the 20 proteinogenic amino acids Lipid synthesis, especially by cancer cells. Regulation of acid-base balance in the kidney by producing ammonium Cellular energy, as a source, next to glucose Nitrogen donation for many anabolic processes, including the synthesis of purines Carbon donation, as a source, refilling the citric acid cycle Nontoxic transporter of ammonia in the blood circulation.
Exosomes are vesicular structures containing genetic information. Recently, exosomes are being utilized as drug carriers. These systems are observed to be stable, specific, and safe. Moreover, delivery of exosomes shows less immunogenic affects. Further surface modifications and conjugation with liposomes enhances the therapeutic effects. Based on a previous study, intranasal delivery of exosomes loaded with a Stat3 inhibitor reduced brain inflammation and slowed brain tumor growth.
Sources: en.wikipedia.org
5 July – The Fields Medal in mathematics is awarded to Hugo Duminil-Copin, June Huh, James Maynard and Maryna Viazovska. 2 December – Winners of the Earthshot Prize are announced, established in 2021 and awarded for developments useful for international climate change mitigation and sustainability goals.
=== Niche uses === Triethylamine is commonly used in the production of anionic polyurethane dispersions (resins dispersed in water rather than solvents) as a neutralizing agent. Triethylamine is used to give salts of various carboxylic acid-containing pesticides, e.g. Triclopyr and 2,4-dichlorophenoxyacetic acid. Triethylamine is the active ingredient in FlyNap, a product for anesthetizing fruit flies. It is also used in mosquito and vector control labs to anesthetize mosquitoes. This is done to preserve any viral material that might be present during species identification. The bicarbonate salt of triethylamine (often abbreviated TEAB, triethylammonium bicarbonate [(CH3CH2)3NH]+HCO−3) is useful in reverse phase chromatography, often in a gradient to purify nucleotides and other biomolecules. Triethylamine was discovered by the Germans during the early 1940s to be hypergolic in combination with nitric acid, and was used as a component in the German Wasserfall rocket. The Soviet Scud missile used TG-02, a mixture of 50% xylidine and 50% triethylamine as a starting fluid to ignite its rocket engine.
== Physiology == A subunits of human factor XIII are made primarily by platelets and other cells of bone marrow origin. B subunits are secreted into blood by hepatocytes. A and B units combine within blood to form heterotetramers of two A units and two B units. Blood plasma concentration of the heterotetramers is 14–48 mg/L and half-life is 9–14 days. A clot that has not been stabilized by FXIIIa is soluble in 5 mol/L urea, while a stabilized clot is resistant to this phenomenon.
== Mechanism == The effects are caused by furanocoumarins (and, to a lesser extent, flavonoids) which are compounds produced by many plants including but not limited to grapefruit. These chemicals inhibit key drug metabolizing enzymes, such as cytochrome P450 3A4 (CYP3A4). CYP3A4 is a metabolizing enzyme for almost 50% of drugs, and is found in the liver and small intestinal epithelial cells. Organic derivatives of furanocoumarin interfere with liver and intestinal enzyme CYP3A4 and may be responsible for the effects of grapefruit on the enzyme. Cytochrome isoforms affected by grapefruit components include CYP1A2, CYP2C9, and CYP2D6, but CYP3A4 is the major CYP enzyme in the intestine. Inhibition of enzymes can have two different effects:
Sources: en.wikipedia.org
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。
Semax 被描述为 ACTH(4-10) 的结构类似物，两者共享部分序列特征。它保留了该片段的部分神经相关活性方向，但去除了完整片段带来的激素释放效应。二者并非同一物质，也不能互相替代。
加入的 Pro-Gly-Pro 三肽被普遍认为能提升分子对蛋白水解酶的稳定性。这种设计让短肽在体内维持时间更长。具体延长的程度以及不同组织中是否一致，文献中仍存在不同报告。
Reversed-phase high-performance liquid chromatography is the standard method, with detection in the ultraviolet range. Peak area percentage yields a purity figure for the main component. Mass spectrometry is normally run alongside to confirm molecular identity.