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 2026-02-05 and is reviewed periodically as new material appears.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular weight | ~813.9 Da (free heptapeptide) | N-acetylated form is about 42 Da heavier |
| Residue count | 7 (heptapeptide) | Four residues from ACTH(4-10), three added |
| Appearance | White to off-white powder | Usually supplied lyophilized |
| Solubility class | Freely soluble in water | Also dissolves in DMSO and polar organic solvents |
| Related parent fragment | ACTH(4-10) | Parent motif is Met-Glu-His-Phe |
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。
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.
Safrole is listed as a Table I precursor under the United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances. Due to their role in the manufacture of MDMA, safrole, isosafrole, and piperonal are Category I precursors under regulation no. 273/2004 of the European Community. In the United States, safrole is currently a List I chemical. The root bark of American sassafras contains a low percentage of steam-volatile oil, which is typically 75% safrole. Attempts to refine safrole from sassafras bark in mass quantities are generally not economically viable due to low yield and high effort. However, smaller quantities can be extracted quite easily via steam distillation (about 10% of dry sassafras root bark by mass, or about 2% of fresh bark). Demand for safrole is causing rapid and illicit harvesting of the Cinnamomum parthenoxylon tree in Southeast Asia, in particular the Cardamom Mountains in Cambodia. However, it is not clear what proportion of illicitly harvested safrole is going toward MDMA production, as over 90% of the global safrole supply (about 2,000 tonnes or 2,200 short tons per year) is used to manufacture pesticides, fragrances, and other chemicals. Sustainable harvesting of safrole is possible from leaves and stems of certain plants, including the roots of camphor seedlings.
The 2026 FIFA World Cup was the 23rd FIFA World Cup, the quadrennial international men's soccer championship contested by the national teams of the member associations of FIFA. The tournament began on June 11, 2026, and concluded on July 19 with Spain winning the championship for the second time. It was jointly hosted by 16 cities—11 in the United States, 3 in Mexico, and 2 in Canada. The tournament was the first FIFA World Cup to be hosted by three countries and the first to include 48 teams, an expansion from the previous 32-team format. The 2026 tournament was the second World Cup to be hosted by multiple nations, after the 2002 edition. Mexico became the first country to host the World Cup three times, having hosted the 1970 and 1986 tournaments. The United States previously hosted the World Cup in 1994, while it was Canada's first time hosting the tournament. The event returned to its traditional June–July schedule after the 2022 World Cup in Qatar, which was uniquely held in November and December to avoid Qatar's extreme summer heat. Canada, Mexico, and the United States qualified automatically as hosts, while Cape Verde, Curaçao, Jordan, and Uzbekistan made their World Cup debuts. For the first time in the tournament's history, the top four teams from the FIFA Men's World Ranking at the time of the contest (Argentina, Spain, France, and England) advanced to the semifinals. Spain won the final against defending champion Argentina 1–0 after extra time, winning its second title and first since 2010.
Physical organic chemistry, a term coined by Louis Hammett in 1940, refers to a discipline of organic chemistry that focuses on the relationship between chemical structures and reactivity, in particular, applying experimental tools of physical chemistry to the study of organic molecules. Specific focal points of study include the rates of organic reactions, the relative chemical stabilities of the starting materials, reactive intermediates, transition states, and products of chemical reactions, and non-covalent aspects of solvation and molecular interactions that influence chemical reactivity. Such studies provide theoretical and practical frameworks to understand how changes in structure in solution or solid-state contexts impact reaction mechanism and rate for each organic reaction of interest.
== Medical uses == Penbutolol is used to treat mild to moderate high blood pressure. Like other beta blockers it is not a first line treatment for this indication. It should not be used or only used with caution in people with heart failure and people with asthma. It may mask signs of low blood sugar in people with diabetes and it may mask signs of hyperthyroidism. Animal studies showed some signs of potential trouble for women who are pregnant, and it has not been tested in women who are pregnant. It is not known if penbutolol is secreted in breast milk.
The United in Science 2022 report is published by the WMO, summarizing latest climate science-related updates and assessing recent climate change mitigation progress as "going in the wrong direction". 14 September A new deep learning technique enables year-round measurements of sea ice thickness in the Arctic. A research report by NewsGuard indicates there is a high level of online misinformation delivered – to a mainly young user base – with TikTok, whose usage is increasing. The WHO joins health associations and scientists in calling for a global fossil fuel non-proliferation treaty to protect lives of current and future generations.
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Liquid chromatography is a method of physical separation in which the components of a liquid mixture are distributed between two immiscible phases, called the stationary and mobile phases. The practice of LC can be divided into five categories: adsorption chromatography, partition chromatography, ion-exchange chromatography, size-exclusion chromatography, and affinity chromatography. Among these, the most widely used variant is the reverse-phase (RP) mode of the partition chromatography technique, which makes use of a nonpolar (hydrophobic) stationary phase and a polar mobile phase. In common applications, the mobile phase is a mixture of water and other polar solvents (such as methanol, isopropanol, and acetonitrile), and the stationary matrix is prepared by attaching long-chain alkyl groups (such as n-octadecyl or C18) to the external and internal surfaces of irregularly or spherically shaped, 5 μm diameter, porous silica particles. In HPLC, typically 20 μl of the sample of interest are injected into the mobile phase stream delivered by a high pressure pump. The mobile phase containing the analytes permeates through the stationary phase bed in a definite direction. The components of the mixture are separated depending on their chemical affinity with the mobile and stationary phases. The separation occurs after repeated sorption and desorption steps occurring when the liquid interacts with the stationary bed. The liquid solvent (mobile phase) is delivered under high pressure (up to 400 bar or 5800 psi) into a packed column containing the stationary phase.
=== Career and polymer science === Flory's earliest work in polymer science was in the area of polymerization kinetics at the DuPont Experimental Station. In condensation polymerization, he challenged the assumption that the reactivity of the end group decreased as the macromolecule grew, and by arguing that the reactivity was independent of the size, he was able to derive the result that the number of chains present decreased with size exponentially. In addition polymerization, he introduced the important concept of chain transfer to improve the kinetic equations and remove difficulties in understanding the polymer size distribution. In 1938, after Carothers' death, Flory moved to the Basic Science Research Laboratory at the University of Cincinnati. There he developed a mathematical theory for the polymerization of compounds with more than two functional groups and the theory of polymer networks or gels. This led to the Flory-Stockmayer theory of gelation, which was equivalent to percolation on the Bethe lattice and represents the first paper in the percolation field. In 1940 he joined the Linden, NJ laboratory of the Standard Oil Development Company where he developed a statistical mechanical theory for polymer mixtures. In 1943 he left to join the research laboratories of Goodyear as head of a group on polymer fundamentals. In the Spring of 1948 Peter Debye, then chairman of the chemistry department at Cornell University, invited Flory to give the annual Baker Lectures. He then was offered a position with the faculty in the Fall of the same year.
Ion exchange chromatography can be used to separate proteins because they contain charged functional groups. The ions of interest (in this case charged proteins) are exchanged for another ions (usually H+) on a charged solid support. The solutes are most commonly in a liquid phase, which tends to be water. Take for example proteins in water, which would be a liquid phase that is passed through a column. The column is commonly known as the solid phase since it is filled with porous synthetic particles that are of a particular charge. These porous particles are also referred to as beads, may be aminated (containing amino groups) or have metal ions in order to have a charge. The column can be prepared using porous polymers, for macromolecules of a mass of over 100 000 Da, the optimum size of the porous particle is about 1 μm2. This is because slow diffusion of the solutes within the pores does not restrict the separation quality. The beads containing positively charged groups, which attract the negatively charged proteins, are commonly referred to as anion exchange resins. The amino acids that have negatively charged side chains at pH 7 (pH of water) are glutamate and aspartate. The beads that are negatively charged are called cation exchange resins, as positively charged proteins will be attracted. The amino acids that have positively charged side chains at pH 7 are lysine, histidine and arginine. The isoelectric point is the pH at which a compound—in this case a protein—has no net charge.
=== Made by Nacho === In April 2021, Flay, with Elly Truesdell and Katja Lang, launched Made by Nacho, a premium cat food company named for his Maine Coon, Nacho Flay. The brand sells wet cat food, dry kibble, and freeze-dried protein treats. Made by Nacho sells cat food from their website and in PetSmart in addition to offering a subscription service. Flay has also founded the Made By Nacho Charitable Fund as part of The New York Community Trust.
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The sequence is Met-Glu-His-Phe-Pro-Gly-Pro, a seven-residue peptide. The first four residues correspond to the ACTH(4-10) fragment, and Pro-Gly-Pro is added at the C-terminus. N-acetylated versions also appear in the literature and differ in mass.
Semax is a synthetic analog of the ACTH(4-10) fragment rather than a copy of the full hormone. Truncation plus the added tail removes the steroidogenic portion of ACTH. That distinction explains why it is studied for nervous-system effects instead of adrenal stimulation.
It is registered as a prescription product in Russia and has been used there clinically, chiefly by the intranasal route. No approval exists in the United States or the European Union. Availability elsewhere typically falls under research-chemical distribution, with varying purity documentation.
Dry powder is usually kept at about -20 degrees Celsius for long-term storage and at 2 to 8 degrees Celsius for short working periods. Containers should stay sealed and protected from light and moisture to limit degradation.