A practical reference on semax: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-02-01. Anything still debated is marked as such rather than presented as settled.
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 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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilised solid |
| Solubility class | Freely soluble in water | Also dissolves in aqueous buffers |
| Typical storage temperature | -20 °C | Dry, desiccated, protected from light |
| Typical analytical method | RP-HPLC with UV detection | Often paired with LC-MS |
| Water content | Reported as Karl Fischer value | Freeze-dried material is hygroscopic |
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.
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。
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。
=== 6 March === Sudan filed a case in the International Court of Justice (ICJ) against the United Arab Emirates, accusing it of complicity in genocide by providing weapons to the RSF. Canada imposed sanctions on al-Burhan and Hemedti, citing in part "an unwillingness on the part of the leaders to negotiate an end to the war".
== See also == Attending physician Fellowship (medicine) International medical graduate Internship (medicine) Medical resident work hours William Osler Post graduate year annotation (PGY) Physician training Dermatology Postdoctoral researcher Validation of foreign studies and degrees
=== Halogenation === Direct difluoromethylation via Zn(SO2CF2H)2 N–X Anomeric Amides as Electrophilic Halogenation Reagents (2023) Guanidine-based chlorinating reagent, CBMG or "Palau'chlor" (2014) Regioselective bromination of N-oxides (2013)
Sources: en.wikipedia.org
Indian childhood cirrhosis is a form of neonatal cholestasis characterized by deposition of copper in the liver Alpha-1 antitrypsin deficiency is an autosomal co-dominant disorder of low levels of the enzyme alpha-1 antitrypsin Cardiac cirrhosis is due to chronic right-sided heart failure, which leads to liver congestion Galactosemia Glycogen storage disease type IV Cystic fibrosis Hepatotoxic drugs or toxins, such as acetaminophen (paracetamol), methotrexate, or amiodarone
Thaumatin (also known as talin) is a low-calorie sweetener and taste modifier. The protein is often used primarily for its flavor-modifying properties and not exclusively as a sweetener. The thaumatins were first found as a mixture of proteins isolated from the katemfe fruit (Thaumatococcus daniellii) (Marantaceae) of West Africa. Although very sweet, thaumatin's taste is markedly different from sugar's. The sweetness of thaumatin builds very slowly. Perception lasts a long time, leaving a liquorice-like aftertaste at high concentrations. Thaumatin is highly water soluble, stable to heating, and stable under acidic conditions.
Tertiary structure may give way to the formation of quaternary structure in some proteins, which usually involves the "assembly" or "coassembly" of subunits that have already folded; in other words, multiple polypeptide chains could interact to form a fully functional quaternary protein.
7-Eleven has been established in Norway since 13 September 1986, when the first store opened in Oslo. In 2004, Reitan Convenience, a branch of the Norwegian Reitan Group bought the rights to use the 7-Eleven brand in Norway, Sweden and Denmark and since then has massively grown the number of operating shops in Scandinavia.
Sources: en.wikipedia.org
== History == This cone was described by Sir Geoffrey Ingram Taylor in 1964 before electrospray was "discovered". This work followed on the work of Zeleny who photographed a cone-jet of glycerine in a strong electric field and the work of several others: Wilson and Taylor (1925), Nolan (1926) and Macky (1931). Taylor was primarily interested in the behavior of water droplets in strong electric fields, such as in thunderstorms.
== 3D structure == The overall fold of Rieske proteins, comprising two subdomains, is dominated by antiparallel β-structure and contains variable numbers of α-helices. The smaller "cluster-binding" subdomains in mitochondrial and chloroplast proteins are virtually identical, whereas the large subdomains are substantially different in spite of a common folding topology. The [Fe2S2] cluster-binding subdomains have the topology of an incomplete antiparallel β-barrel. One iron atom of the Rieske [Fe2S2] cluster in the domain is coordinated by two cysteine residues and the other is coordinated by two histidine residues through the Nδ atoms. The ligands coordinating the cluster originate from two loops; each loop contributes one Cys and one His.
== Recreational use == In 1979, the first case of xylazine toxicity was reported in a 34-year-old male who had self-medicated for insomnia with an injection of 1g of xylazine. In the US, Xylazine is not regulated as a controlled substance under the Controlled Substances Act. It is sold online through distributors often without requiring proof of a veterinary license. The cost to purchase Xylazine from overseas suppliers is around $6–20 per kilogram. This low price makes it attractive for dealers looking for a cheap additive that is addictive and not treatable with opiate withdrawal medications. The withdrawal can last for two weeks and has a quicker onset than fentanyl. As an adulterant, xylazine is most commonly ingested with fentanyl. Xylazine has also been reported in combination with medetomidine, another potent α2-adrenergic receptor agonist. It is unknown if drug users are ingesting it knowingly. As of 2024, Seattle police report that some users wrongly believe they are consuming higher-quality fentanyl. Xylazine's street name in Puerto Rico is anestesia de caballo, which translates to "horse anesthetic". From 2002 to 2008, its use was associated with a high number of inmate deaths at the Guerrero Correctional Institution in Aguadilla, Puerto Rico. Xylazine's street name in the United States, particularly when it is mixed with fentanyl, is "tranq", "tranq dope" and "zombie drug". As of 2012, xylazine users in Puerto Rico were more likely to be male, under age 30, living in a rural area, and injecting rather than inhaling xylazine.
=== As an antibiotic target === The sortases are thought to be good targets for new antibiotics as they are important proteins for pathogenic bacteria and some limited commercial interest has been noted by at least one company.
The most recently named elements – nihonium (113), moscovium (115), tennessine (117), and oganesson (118) – completed the seventh row of the periodic table. Future elements would have to begin an eighth row. These elements may be referred to either by their atomic numbers (e.g. "element 164"), or by the IUPAC systematic element names adopted in 1978, which directly relate to the atomic numbers (e.g. "unhexquadium" for element 164, derived from Latin unus "one", Greek hexa "six", Latin quadra "four", and the traditional -ium suffix for metallic elements). All attempts to synthesize such elements have failed so far. Attempts to make element 119 have been ongoing since 2018 at the Riken research institute in Japan and since 2026 at the JINR in Russia, and an attempt to make element 120 has been ongoing since 2025 at the LBNL in the United States. The Heavy Ion Research Facility in Lanzhou (HIRFL) in China also plans to make its own attempts at synthesizing the first few period 8 elements. If the eighth period followed the pattern set by the earlier periods, then it would contain fifty elements, filling the 8s, 5g, 6f, 7d, and finally 8p subshells in that order. But by this point, relativistic effects should result in significant deviations from the Madelung rule. Various different models have been suggested for the configurations of eighth-period elements, as well as how to show the results in a periodic table. All agree that the eighth period should begin like the previous ones with two 8s elements, 119 and 120.
Sources: en.wikipedia.org
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.
Dry lyophilised powder is generally kept at minus twenty degrees Celsius, protected from light and moisture. Repeated freeze-thaw cycles are avoided because they encourage aggregation and moisture uptake. Solutions are less stable than the solid form and degrade faster at room temperature.
A certificate documents what the supplier measured, not what an independent party confirmed. Methods, instruments and acceptance criteria can differ between suppliers. Third-party testing is the usual way to resolve discrepancies.
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.