This is a working overview of ACTH fragment, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-12-03 and is reviewed periodically as new material appears.
从分子层面看，Semax 是线性七肽，没有二硫键、糖基或脂链修饰，N 端为游离氨基，C 端为游离羧基。分子含组氨酸与谷氨酸侧链，因此在水和甲醇等极性溶剂中溶解良好，在非极性溶剂中溶解有限。计算分子量约为 814 Da，与其质子化离子的质荷比吻合，可用于质谱确认。
稳定性主要由水解与氧化两条路径支配。肽键在中性或弱酸性条件下相对稳定，遇到强碱或长时间高温则明显断裂；甲硫氨酸侧链容易被氧化成亚砜，使主峰前移并拉低实际含量。金属离子、光照和反复冻融会进一步促进降解或聚集。冻干粉在低温避光条件下可存放较长时间，配制后的水溶液通常需要冷藏并尽快用完。
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。
| Property | Value | Notes |
|---|---|---|
| 分子式 | C37H51N9O10S | 游离碱形式 |
| 等电点 | 约 6.5 | 估算值，随缓冲体系变化 |
| 主要降解途径 | 水解与氧化 | 侧链氧化最为常见 |
| 溶液储存 | 2 至 8 摄氏度避光 | 避免反复冻融 |
| 常规分析手段 | 反相色谱与质谱联用 | 氨基酸分析辅助核对 |
Lyophilised powder is normally kept at -20 °C in a desiccated container, with some suppliers recommending -80 °C for long-term archival storage. Repeated freeze-thaw cycles are the most common cause of avoidable loss, so aliquoting before freezing reduces variability between working sessions. Dissolved peptide is far less stable than the dry solid and is usually prepared fresh or held briefly at 4 °C. Aqueous solutions support both hydrolysis of the backbone and oxidation of the N-terminal methionine, and these two routes dominate degradation under ordinary laboratory conditions.
Identity and purity are confirmed with reversed-phase high-performance liquid chromatography, typically monitored at 214 nanometres where the peptide bond absorbs. Mass spectrometry, either electrospray or MALDI-TOF, verifies molecular mass against the theoretical value and detects truncation or adduct formation. Amino acid analysis and peptide mapping provide additional confirmation when required. The most frequently reported impurities are deletion sequences from incomplete coupling, methionine sulfoxide from oxidation, and dimeric species formed through non-covalent aggregation. Impurity profiles depend strongly on the synthesis and purification route chosen by the producer.
Published research has focused mainly on neurological and cognitive endpoints in animal models, with proposed mechanisms involving brain-derived neurotrophic factor and related signalling pathways. A substantial share of the human data originates from a limited number of research groups, and independent replication in other countries remains sparse. Regulatory status reflects that distribution: the peptide is registered as a medicine in Russia and appears in some neighbouring markets, while elsewhere it is handled as a research chemical without approved therapeutic labelling. Questions about dose-response relationships, long-term effects, and comparability across studies are still open.
Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. The first four residues correspond to the ACTH(4-10) fragment, while the terminal Pro-Gly-Pro extension was added to improve metabolic stability. Its molecular formula is C37H51N9O10S and its monoisotopic mass is approximately 813.9 Da. The compound is classified as a peptide research chemical and as a registered pharmaceutical product in Russia, but it does not hold marketing approval in the European Union or the United States. Naming conventions vary across supplier catalogs.
Development of the compound took place in the Soviet Union during the 1980s, largely through peptide research groups affiliated with the Shemyakin-Ovchinnikov Institute and Moscow State University. Investigators screened fragments of adrenocorticotropic hormone for activity on the central nervous system while attempting to separate cognitive effects from hormonal ones. The shortened sequence was selected because it retained behavioral activity in animal models without stimulating corticosteroid release. Early publications described the molecule as an ACTH(4-10) analog.
Published research on this peptide originates mainly from Russian laboratories, and the wider international literature is comparatively thin. Studies have used rodent models of stroke, hypoxia, and memory tasks, with a smaller number of human trials reported. Reported outcomes include changes in attention and memory measures, along with effects on neurotrophic factor expression in some experiments. Small sample sizes, inconsistent dosing protocols, and limited independent replication are widely noted limitations, so the strength of the clinical evidence remains an open question.
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.
The parent fragment ACTH(4-10) carries the sequence Met-Glu-His-Phe-Arg-Trp-Gly. Semax replaces the arginine and tryptophan positions with a proline-glycine-proline tail, giving Met-Glu-His-Phe-Pro-Gly-Pro. That change removes residues associated with adrenal stimulation, so the peptide does not drive cortisol release the way full ACTH does. This distinction shapes how the compound is grouped in the literature, where it sits with neuropeptides and peptide neuromodulators rather than with corticosteroids.
Regulatory status varies sharply by country. Semax is registered for medical use in Russia, where it appears in formularies as a nasal solution, and it also holds registration in a small number of neighbouring states. It has no approval from the United States Food and Drug Administration or the European Medicines Agency, and it is not a scheduled controlled substance in most jurisdictions. Elsewhere it circulates mainly as laboratory material, so purity documentation comes from suppliers rather than from a national pharmacopoeia.
Between the summer of 2009 and March 2010, the use of mephedrone grew rapidly in the UK, with it becoming readily available at music festivals, head shops and on the internet. A survey of Mixmag readers in 2009, found it was the fourth most popular street drug in the United Kingdom, behind cannabis, cocaine, and ecstasy. The drug was used by a diverse range of social groups. Whilst the evidence was anecdotal, researchers, charity workers, teachers and users reported widespread and increasing use of the drug in 2009. The drug's rapid growth in popularity was believed to be related to both its availability and legality. In a book about drugs David Nutt reports the re-popularization story of mephedrone in a way that can be cross referenced with a report by Chemistry World in an article. Fiona Measham, a criminologist at the University of Lancaster, thought the emergence of mephedrone was also related to the decreasing purity of ecstasy and cocaine on sale in the UK, a view reinforced in a report by the National Treatment Agency for Substance Misuse. The average cocaine purity fell from 60% in 1999 to 22% in 2009 and about half of ecstasy pills seized in 2009 contained no MDMA, and by June 2010 almost all ecstasy pills seized in the UK contained no MDMA. A similar pattern was observed in the Netherlands, with the number of ecstasy tablets containing no MDMA rising from 10% in mid-2008 to 60% by mid-2009, with mephedrone being detected in 20% of ecstasy tablets by mid-2009.
John Arnold Cranston (working with Frederick Soddy and Ada Hitchins) is also credited with discovering the most stable isotope in 1915, but he delayed his announcement due to being called for service in the First World War. The longest-lived and most abundant (nearly 100%) naturally occurring isotope of protactinium, 231Pa, has a half-life of 32,760 years and occurs in the decay chain of uranium-235. Much smaller trace amounts of the short-lived 234Pa and its nuclear isomer 234mPa occur in the decay chain of uranium-238. 233Pa occurs as a result of the decay of thorium-233 as part of the chain of events necessary to produce uranium-233 by neutron irradiation of 232Th. It is an undesired intermediate product in thorium-based nuclear reactors, and is therefore removed from the active zone of the reactor during the breeding process. Ocean science uses the element to understand the ancient ocean's geography: analysis of the relative concentrations of various uranium, thorium, and protactinium isotopes in water and minerals is used in radiometric dating of sediments up to 175,000 years old, and in modeling of various geological processes. Protactinium is unusual among non-primordial elements in that its natural isotopic composition is extremely uniform across typical terrestrial samples, because essentially all naturally occurring protactinium is 231Pa, produced solely along a single pathway (namely, from the decay of primordial 235U).
Lisdexamfetamine (Vyvanse, others) is an amphetamine-type medication, sold for use in treating ADHD. Its effects typically last around 14 hours. Lisdexamfetamine is inactive on its own and is metabolized into dextroamphetamine in the body. Consequently, it has a lower abuse potential (i.e., reduced effects from parenteral administration).
1932) journalist-op-ed column writer for The Guardian, New Statesman, Financial Times, Time; Labour Party politician and former Member of Parliament; appointed Labour life peer with the title of Baron Dubs, of Battersea in the London Borough of Wandsworth; was chair of Broadcasting Standards Commission (Ofcom) and deputy chair of Independent Television Commission; chair of Liberty, trustee of Action Aid, trustee of the Immigration Advisory Service; vice president of Fabian Society; patron of Humanists UK, a patron of Refugee Support Group; treasurer of the All-Party Parliamentary Humanist Group. Matthew Engel (born 11 June 1951); writer, author of over ten books, editor, journalist for The Jewish Chronicle, The Guardian, Daily Mail, The Independent, The Telegraph, 1843, Financial Times, New Statesman, The Times Literary Supplement; of Polish Jewish ancestry. Richard Ferrer; journalist and editor of Jewish News; sub-editor at the Daily Mirror; written for the Daily Telegraph, The Times, Algemeiner, The Times of Israel and the Independent; regular contributor to programmes on BBC Radio 4. Lord Baron Daniel Finkelstein,(born 30 August 1962); journalist and politician; writes for Jewish Chronicle; former executive editor of The Times.; former chairman of Policy Exchange; chair of the think tank Onward; made a member of the House of Lords in August 2013, sitting as a Conservative.
Sources: en.wikipedia.org
=== Regulation by CRISPRi === Recent genome-wide CRISPR interference (CRISPRi) screens have identified genes whose selective inhibition modulates specific components of the SASP during inflammation-induced senescence, such as that triggered by interleukin-6 (IL-6). These approaches have helped distinguish molecular regulators of replicative senescence from those involved in inflammatory senescence, providing new targets for studying aging-related pathways. SASP has been reduced through inhibition of p38 mitogen-activated protein kinases and janus kinase. The protein hnRNP A1 (heterogeneous nuclear ribonucleoprotein A1) antagonizes cellular senescence and induction of the SASP by stabilizing Oct-4 and sirtuin 1 mRNAs.
=== May === 1 May Coronation of Charles III and Camilla: The Royal Collection Trust confirms that Charles III will use a recycled throne chair from the coronation of George VI for his own coronation in a bid to make the event more sustainable. Camilla will use a chair from the same coronation that was used by Queen Elizabeth the Queen Mother. The 2023 World Snooker Championship concludes, with Belgium's Luca Brecel defeating England's Mark Selby 18–15 in the final to win his first world title. Brecel becomes the first player from Mainland Europe to win a World Championship. 2 May The 5% pay increase for one million NHS staff in England is signed off at a meeting between the UK government and representatives from 14 trade unions; all NHS employees but doctors and dentists are represented at the meeting. A man is arrested outside Buckingham Palace after throwing shotgun cartridges into the grounds. A controlled explosion is also carried out by police. 3 May – Coronation of Charles III and Camilla: As the Metropolitan Police release details of security measures in place, Security Minister Tom Tugendhat says that anti-monarchy groups will be allowed to protest at the coronation. 4 May 2023 United Kingdom local elections: The Conservatives incur significant losses, while Labour and the Lib Dems gain control of a number of councils from the Conservatives. The Green Party also make record gains, with over 200 councillors, and win majority control of Mid Suffolk District Council, the party's first ever council majority.
In chromatography, endcapping refers to the replacement of accessible silanol groups in a bonded stationary phase by trimethylsilyl groups. End-capped columns have much lower residual silanol group activity compared to non-endcapped columns. Endcapped columns show decreased retention for hydrogen bond acceptors, such as ionized bases, and increased retention for protonated bases.
Sources: en.wikipedia.org
The synthetic opioid ketazocine and terpenoid natural product salvinorin A are potent and selective KOR agonists. The KOR also mediates the dysphoria and hallucinations seen with opioids such as pentazocine.
6,14-Endoethenotetrahydrooripavine is the central nucleus, or backbone, of a class of morphinan opioids known as the Bentley compounds and may be considered their "privileged scaffold". These include but are not limited to etorphine and buprenorphine. They usually have thebaine or oripavine as their precursor in their syntheses (and are thus termed "thevinols" and "orvinols", respectively).
=== Research === With a scholarship from the University of Birmingham, he pursued research in physics following the discovery of X-rays and radioactivity in the mid-1890s. Aston studied the current through a gas-filled tube. The research, conducted with self-made discharge tubes, led him to investigate the volume of the Aston dark space. After the death of his father, and a trip around the world in 1908, he was appointed lecturer at the University of Birmingham in 1909 but moved to the Cavendish Laboratory in Cambridge on the invitation of J. J. Thomson in 1910. Birmingham University awarded him a BSc in Applied/Pure Science in 1910 and a DSc in Applied/Pure Science in 1914. Joseph John Thomson revealed the nature of the cathode ray and then discovered the electron and he was now doing research on the positively charged "Kanalstrahlen" discovered by Eugen Goldstein in 1886. The method of deflecting particles in the "Kanalstrahlen" by magnetic fields was discovered by Wilhelm Wien in 1908; combining magnetic and electric fields allowed the separation of different ions by their ratio of charge and mass. Ions of a particular charge/mass ratio would leave a characteristic parabolic trace on a photographic plate, demonstrating for the first time that atoms of a single element could have different masses. The first sector field mass spectrometer was the result of these experiments.
Sources: en.wikipedia.org
电喷雾或基质辅助激光解吸电离质谱是常用手段，测得的质子化离子质荷比可换算为分子量。结果与理论值落在合理误差内，才支持结构一致的判断。
甲硫氨酸侧链含硫醚，在氧气、光照或金属离子存在时容易被氧化。氧化产物极性略增，常在色谱图上表现为主峰之前的肩峰或前伸峰。
通常建议冷藏避光，并在较短时间内使用。不存在适用于所有配方的统一期限，具体取决于浓度、缓冲体系与容器材质。
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。