This is a working overview of Methionine oxidation, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-06-08. Anything still debated is marked as such rather than presented as settled.
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。
Semax is normally supplied as a lyophilized powder, and that form is the most stable. Suppliers commonly recommend storage at -20 °C in a desiccated container protected from light, with short-term handling at room temperature limited to weighing and transfer. Powder that has absorbed moisture degrades faster, so vials should be warmed to ambient temperature before opening to prevent condensation on the contents. Hygroscopic behavior is typical of short hydrophilic peptides, and humidity control matters more than temperature alone for long-term retention.
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.
| Property | Value | Notes |
|---|---|---|
| 结构类别 | 线性合成七肽 | 无环化结构，不含二硫键 |
| 氨基酸序列 | Met-Glu-His-Phe-Pro-Gly-Pro | N 端为甲硫氨酸 |
| 分子量 | 约 814 Da | 游离碱形式的计算值 |
| 外观 | 白色至类白色粉末 | 具吸湿性 |
| 溶解性 | 易溶于水 | 亦可溶于甲醇等极性溶剂 |
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。
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。
Identity and purity of Semax are established mainly by reversed-phase high-performance liquid chromatography coupled with mass spectrometry. The chromatographic trace gives a purity estimate as a percentage of total peak area, while electrospray or matrix-assisted laser desorption ionization confirms the molecular mass against the calculated value. Amino acid analysis and sequence-specific fragmentation provide further confirmation when a supplier's chain of custody is unclear. Vendors frequently quote a purity figure without stating the detection wavelength or the integration method, which limits how far one number can be compared with another.
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.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It is described in the literature as an analogue of the ACTH(4–10) fragment, a short N-terminal portion of adrenocorticotropic hormone that retains some neurotropic activity without the full hormonal effects of the parent peptide. The molecule carries a methionine residue at the N-terminus and two proline residues near the C-terminus, features that shape both its interactions with receptor systems and its chemical stability. The free peptide corresponds to the formula C37H51N9O10S and a molecular mass near 813.9 Da.
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.
==== Limitations ==== Studying the exact functions mediated by KOR is limited by the non-selectivity and signaling biases of the compounds used in the research and naturally occurring in the human body. Dynorphin peptides, endogenous agonists of KOR, especially big dynorphin, are direct complex modulators of the NMDA receptor. Certain dynorphin peptides also have affinity for the MOR and DOR and influence other pathways that are not directly coupled to KOR. KOR activation in the context of in vivo stress responses could be biased for β-arrestin2 and other pathways related to dysphoria due to the presence of corticotropin-releasing hormone (CRF). Salvinorin A as well as other KOR agonists have been found to possess properties such as dopamine D2 receptor agonism with lower, but non-negligible affinity and potency. Salvinorin A is a balanced G protein and β-arrestin2 agonist.
Apiin (apigenin 7-O-apioglucoside), isolated from parsley and celery Apigetrin (apigenin 7-glucoside), found in dandelion coffee Vitexin (apigenin 8-C-glucoside) Isovitexin (apigenin 6-C-glucoside) Rhoifolin (apigenin 7-O-neohesperidoside) Schaftoside (apigenin 6-C-glucoside 8-C-arabinoside)
==== Subcultural model ==== Historically, addiction has been viewed from the etic perspective, defining users through the pathology of their condition. As reports of drug use rapidly increased, the cultural model found application in anthropological research exploring western drug subculture practices. The approach evolved from the ethnographic exploration into the lived experiences and subjectivities of 1960s and 70s drug subcultures. The publication "Taking care of business", by Edward Preble and John J. Casey, documented the daily lives of New York street-based intravenous heroin users in detail, providing insight into the dynamic social worlds and activities that surrounded their drug use. Singer writes that this work reframed substance use as a social phenomenon rather than a matter of immorality or deviance. The prevailing culture can influence drug-taking behaviors, along with the physical and psychological effects of the drug. To marginalized individuals, drug subcultures can provide social connection, symbolic meaning, and socially constructed purpose that they may feel is unattainable through conventional means. On this account, a biosocial approach is required for a holistic understanding of addiction.
Sources: en.wikipedia.org
==== Indigenous ==== Black bears feature prominently in the stories of some of North America's indigenous peoples. One tale tells of how the black bear was a creation of the Great Spirit, while the grizzly bear was created by the Evil Spirit. In the mythology of the Haida, Tlingit and Tsimshian people of the northwest coast, mankind first learned to respect bears when a girl married the son of a black bear chieftain. In Kwakwa̱ka̱ʼwakw mythology, black and brown bears became enemies when Grizzly Bear Woman killed Black Bear Woman for being lazy. Black Bear Woman's children, in turn, killed Grizzly Bear Woman's children. The Navajo believed that the Big Black Bear was chief among the bears of the four directions surrounding Sun's house and would pray to it in order to be granted its protection during raids. Sleeping Bear Dunes in Michigan is named after a Native American legend, where a female bear and her two cubs swam across Lake Michigan to escape a fire on the Wisconsin shore. The mother bear reached the shore and waited for her cubs, but they did not make it across. Two islands mark where the cubs drowned, while the dune marks the spot where the mother bear waited.
Research into the clinical use of a recombinant form of human Activated Protein C (rhAPC) known as Drotrecogin alfa-activated, branded Xigris by Eli Lilly and Company, has been surrounded by controversy. Eli Lilly ran an aggressive marketing campaign to promote its use for people with severe sepsis and septic shock and sponsored the 2004 Surviving Sepsis Campaign Guidelines. However, a 2012 Cochrane review found that its use cannot be recommended since it does not improve survival and increases bleeding risk. In October 2011, Xigris was withdrawn from the market by Eli Lilly due to a higher mortality in a trial among adults.
Rabson–Mendenhall syndrome is a rare autosomal recessive disorder characterized by severe insulin resistance. The disorder is caused by mutations in the insulin receptor gene. Symptoms include growth abnormalities of the head, face and nails, along with the development of acanthosis nigricans. Treatment involves controlling blood glucose levels by using insulin and incorporating a strategically planned, controlled diet. Also, direct actions against other symptoms may be taken (such as surgery for facial abnormalities). Only about 50 cases have been reported and affected patients usually die during adolescence.
Sources: en.wikipedia.org
== Definitions of molar mass average == Different average values can be defined, depending on the statistical method applied. In practice, four averages are used, representing the weighted mean taken with the mole fraction, the weight fraction, and two other functions which can be related to measured quantities:
=== Generic names === Estradiol cypionate is the generic name of the drug and its INNTooltip International Nonproprietary Name and USANTooltip United States Adopted Name. It is also known as estradiol cyclopentylpropionate (ECP).
== Production == 60Co does not occur naturally on Earth in significant amounts, so 60Co is synthesized by bombarding a 59Co target with a thermal neutron source - in a commercial or industrial context, that means a nuclear reactor. The CANDU reactors can be used to activate 59Co, by substituting the control rods with cobalt rods. In the United States, as of 2010, it is being produced in a boiling water reactor at Hope Creek Nuclear Generating Station. The cobalt targets are substituted here for a small number of fuel assemblies. Still, over 40% of all single-use medical devices are sterilized using 60Co from Bruce nuclear generating station. The reaction in all cases is
Sources: en.wikipedia.org
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。
Semax 对应 ACTH 第 4 至第 10 位的片段，并在两端做了替换与延长，使其不再具备促肾上腺皮质激素的典型内分泌活性。这一改动同时改变了它在体内的稳定性与分布特征。
俄罗斯将其列为处方药物，需要医生开具处方。多数其他国家把它当作研究化合物，不能作为药品销售或宣称疗效。具体合法性取决于当地法规。
Each freeze-thaw cycle can degrade a fraction of the peptide and promote aggregation. Dividing a stock solution into single-use volumes removes repeated cycling as a variable. It also limits the time a thawed solution spends at room temperature.