methionine sulfoxide 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 2025-08-15. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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。
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。
| Property | Value | Notes |
|---|---|---|
| Purity assay | RP-HPLC, UV 214 nm | Typical research grade 95 percent or higher |
| Mass confirmation | ESI-MS or MALDI-TOF | Compared with theoretical value |
| Main degradation route | Methionine oxidation | Sulfoxide formation in solution |
| Powder storage | -20 °C, desiccated | Amber vial, minimal headspace |
| Working solution | Sterile water or saline | Prepare fresh; avoid repeated thawing |
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.
Purity assessment relies mainly on reversed-phase high-performance liquid chromatography, which separates the target heptapeptide from truncated sequences, deletion analogues, and oxidised forms. Mass spectrometry, usually coupled to liquid chromatography, confirms identity through the expected molecular ion and reveals modifications such as methionine sulfoxide formation. Amino acid analysis can verify composition, and tandem mass spectrometry supports sequence confirmation. Ultraviolet detection near 254 to 280 nanometres is convenient because the phenylalanine and histidine residues absorb in that region. Nuclear magnetic resonance is rarely used for routine release testing.
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.
Published studies examine a fairly narrow set of endpoints. Rodent experiments commonly measure maze learning, infarct volume after induced ischemia, and tissue levels of neurotrophic factors. Clinical reports from Russian centres describe attention, memory and recovery scores in patients after stroke or transient ischemic attack. Most of those human studies are small and few have been repeated by independent groups. Outcome measures differ between studies, which limits direct comparison.
Circulation time for the peptide is short because peptidases cleave it readily. The Pro-Gly-Pro tail is thought to slow breakdown compared with the bare ACTH fragment, but the gain appears modest. Absorption after intranasal dosing is limited, and only a fraction of a dose is expected to reach the central nervous system. Laboratory concentrations therefore sit well above levels achieved systemically, a gap that complicates translation from bench findings to clinical claims.
The mechanisms attributed to semax are inferred from animal and cell studies rather than traced to one confirmed target. The most frequently cited pathway involves increased expression of brain-derived neurotrophic factor and nerve growth factor in hippocampal and cortical tissue. Some work points to engagement of melanocortin receptors, particularly MC4, which the parent ACTH fragment can activate. Effects on dopaminergic and serotonergic signalling have also been reported. No single account explains all observed results, and the relative weight of each pathway remains unsettled.
In organic chemistry, an active ester is an ester functional group that is highly susceptible toward nucleophilic attack. Activation can be imparted by modifications of the acyl or the alkoxy components of a normal ester, say ethyl acetate. Typical modifications call for electronegative substituents. Active esters are employed in both synthetic and biological chemistry.
There have been calls for tapentadol to be only marketed in countries where appropriate controls exist, but after performing a critical review, the United Nations Expert Committee on Drug Dependence in 2014 advised that tapentadol not be placed under international control but remain under surveillance. As mentioned, the enhanced potency of tapentadol makes it considerably more susceptible to abuse compared to other opioids. This increased potency is one of the key factors that contribute to its higher potential for misuse. Furthermore, tapentadol is water soluble, which allows for a variety of methods to ingest or administer the drug. It can be snorted, inhaled, or even delivered rectally, all of which significantly increase the risk of abuse and the potential for dangerous consequences. These factors combined make tapentadol a particularly risky substance when it comes to misuse, posing serious concerns for both individuals and public health. The FDA's Controlled Substance Staff (CSS) recognizes that tapentadol is available as an immediate-release formula, and that in the past there was no requirement of a medication guide for immediate-release opioids. However, tapentadol exhibits several distinctive properties that makes it highly abusable. According to them:
=== Motivational disorders === Selegiline has been found to produce pro-motivational effects and to reverse motivational deficits in rodents. In case reports and small clinical studies, selegiline has been reported to improve disorders of diminished motivation like apathy and abulia due to conditions such as traumatic brain injury. In accordance with the preceding findings, selegiline, along with other dopaminergic and activating agents, may be useful in the treatment of disorders of diminished motivation, including apathy, abulia, and akinetic mutism.
=== Discovery and initial characterization === Radioactivity was discovered in 1896 by Henri Becquerel in uranium, and subsequently observed by Marie and Pierre Curie in thorium and in the newly discovered elements polonium and radium. In 1899, Ernest Rutherford separated radioactive emissions into two types: alpha and beta (now beta minus), based on penetration of objects and ability to cause ionization. Alpha rays could be stopped by thin sheets of paper or aluminium, whereas beta rays could penetrate several millimetres of aluminium. In 1900, Paul Villard identified a still more penetrating type of radiation, which Rutherford termed gamma rays. In 1900, Becquerel measured the mass-to-charge ratio (m/e) for beta particles by the method of J.J. Thomson used to study cathode rays and identify the electron. He found that m/e for a beta particle is the same as for Thomson's electron, and therefore suggested that the beta particle is in fact an electron. In 1901, Rutherford and Frederick Soddy showed that alpha and beta radioactivity involves the transmutation of atoms into atoms of other chemical elements. In 1913, after the products of more radioactive decays were known, Soddy and Kazimierz Fajans independently proposed their radioactive displacement law, which states that beta (i.e., β−) emission from one element produces another element one place to the right in the periodic table, while alpha emission produces an element two places to the left.
== Concept == In 1975, Pizza Hut began testing concepts with Applegate's Landing. with restaurants that featured Colonial-style exteriors and eclectic interiors that included a truck with a salad bar in the bed. The chain offered much of the same pizza and pasta dishes, with some additions like hamburgers and bread pudding. Applegate's Landing went defunct in the mid-1980s except for one location in McPherson, Kansas, that closed in late 1995.
Sources: en.wikipedia.org
Florey was awarded the Cameron Prize for Therapeutics of the University of Edinburgh and the Lister Medal in 1945, for his contributions to surgical science. The corresponding Lister Oration, given at the Royal College of Surgeons of England later that year, was titled "Use of Micro-organisms for Therapeutic Purposes". He was awarded many honorary degrees from British and foreign universities, including University of São Paulo in Brazil. He won the Gold Medal of the Royal Society of Medicine in 1947. He became a commander of the French Legion of Honour in 1946 and was awarded the American Medal for Merit in 1948 and the James Smithson Medal in 1965. Florey was elected to the United States National Academy of Sciences and the American Philosophical Society in 1963, and was elected to the American Academy of Arts and Sciences the following year. He became an honorary Fellow of the Royal College of Surgeons in 1961. On 4 February 1965, Florey was created a life peer and became Baron Florey, of Adelaide in the Commonwealth of Australia and of Marston in the City of Oxford. This was a higher honour than the knighthood awarded to Sir Alexander Fleming, and it recognised the monumental work Florey had done in making penicillin available in sufficient quantities to save millions of lives. He was formally introduced to the House of Lords in April, sponsored by Lord Cottesloe, Margaret Jennings's brother, and Lord Adrian, one of Florey's predecessors as President of the Royal Society. On 15 July 1965 he was appointed a member of the Order of Merit.
The structure of the AG glycans consists of a backbone of β-1,3 linked galactose (Gal), with sidechains of β-1,6 linked Gal and have terminal residues of arabinose (Ara), rhamnose (Rha), Gal, fucose (Fuc), and glucuronic acid (GlcA). These AG glycan moieties are assembled by glycosyltransferases (GTs). O-glycosylation of AGPs is initiated by the action of Hyp-O-galactosyltransferases (Hyp-O-GalTs) that add the first Gal onto the protein. The complex glycan structures are then elaborated by a suite of glycosyltransferases, the majority of which are bio-chemically uncharacterized. The GT31 family is one of the families involved in AGP glycan backbone biosynthesis. Numerous members of the GT31 family have been identified with Hyp-O-GALT activity and the core β-(1,3)-galactan backbone is also likely to be synthesized by the GT31 family. Members of the GT14 family are implicated in adding β-(1,6)- and β-(1,3)-galactans to AGPs. In Arabidopsis, terminal sugars such as fucose are proposed to be added by AtFUT4 (a fucosyl transferase) and AtFUT6 in the GT37 family and the terminal GlcA incorporation can be catalysed by the GT14 family. A number of GTs remain to be identified, for example those responsible for terminal Rha.
MAAs are widespread in the microbial world and have been reported in many microorganisms including heterotrophic bacteria, cyanobacteria, microalgae, ascomycetous and basidiomycetous fungi, as well as some multicellular organisms such as macroalgae and marine animals. Most research done on MAAs is on their light absorbing and radiation protecting properties. The first thorough description of MAAs was done in cyanobacteria living in a high UV radiation environment. The major unifying characteristic among all MAAs is UV light absorption. All MAAs absorb UV light that can be destructive to biological molecules (DNA, proteins, etc.). Though most MAA research is done on their photo-protective capabilities, they are also considered to be multi-functional secondary metabolites that have many cellular functions. MAAs are effective antioxidant molecules and are able to stabilize free radicals within their ring structure. In addition to protecting cells from mutation via UV radiation and free radicals, MAAs are able to boost cellular tolerance to desiccation, salt stress, and heat stress.
A clinical data management system (CDMS) is a tool used in clinical research to manage the data of a clinical trial. The clinical trial data gathered at the investigator site in the case report form are stored in the CDMS. To reduce the possibility of errors due to human entry, the systems employ various means to verify the data. Systems for clinical data management can be self-contained or part of the functionality of a CTMS. A CTMS with clinical data management functionality can help with the validation of clinical data as well as helps the site employ for other important activities like building patient registries and assist in patient recruitment efforts. The CDMS can be broadly divided into paper-based and electronic data capture systems.
The tree was created by maximum likelihood analysis without bootstrap: consequently accuracy is traded off for size and many phylum level clades are not correctly resolved (such as the Firmicutes). (Eukaryotes not present in analysis). This phylogeny is a summary of the 16S rRNA based LTP_07_2026 and contains all type species with validly published names up to July 2026. Branching order of bacterial phyla (Woese, 1987) Branching order of bacterial phyla (Gupta, 2001) Branching order of bacterial phyla (Cavalier-Smith, 2002) Branching order of bacterial phyla (Rappe and Giovanoni, 2003) Branching order of bacterial phyla (Battistuzzi et al., 2004) Branching order of bacterial phyla (Ciccarelli et al., 2006) Branching order of bacterial phyla (Genome Taxonomy Database, 2018) Bacterial phyla List of Archaea genera List of bacteria genera List of bacterial orders LPSN, list of accepted bacterial and archaeal names http://www.arb-silva.de/projects/living-tree/
Sources: en.wikipedia.org
Reversed-phase HPLC gives the main purity figure, most often with UV detection near 214 nanometres. Mass spectrometry then confirms the molecular mass. Together the two methods distinguish a correct sequence from a closely related impurity.
The main chemical risks are methionine oxidation and backbone hydrolysis in solution. Moisture and repeated temperature cycling accelerate both processes. Dry powder held cold and desiccated is considerably more stable than any reconstituted preparation.
It holds a medicine registration in Russia, where it has been used clinically for decades. In most other countries it is treated as a research chemical. That split explains the uneven distribution of clinical literature.
不存在。它是依据 ACTH 的一段序列人工设计的分子，天然蛋白质中找不到与之完全相同的七肽。名称属于研究代号，而非天然物质名。