methionine sulfoxide raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-05-05 and is reviewed periodically as new material appears.
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。
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.
Common degradation pathways include oxidation of the methionine side chain, hydrolysis of the peptide backbone, and aggregation under unfavourable pH or concentration. Stability studies typically monitor the main peak by chromatography and report total related substances as a percentage. Because no official monograph exists, acceptance criteria vary between laboratories, and reported purity values are not directly comparable across suppliers. Analysts therefore document the method, column, and detection wavelength alongside each result, and open questions remain about how much biological activity the oxidised forms retain.
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.
| Property | Value | Notes |
|---|---|---|
| 化学类别 | 合成七肽 | ACTH(4-10) 结构类似物 |
| 氨基酸序列 | Met-Glu-His-Phe-Pro-Gly-Pro | 单字母写作 MEHFPGP |
| 分子量 | 约 813.9 Da | 随确切形式和盐型略有变化 |
| 常见同义词 | ACTH(4-10) 类似物 | 俄语文献称 Семакс |
| 开发来源 | 俄罗斯 | 二十世纪八十年代 |
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.
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.
This leads to a condition called anorexia cachexia syndrome (ACS) and additional nutrition or supplementation is unlikely to help. Symptoms of weight loss from ACS include severe weight loss from muscle rather than body fat, loss of appetite and feeling full after eating small amounts, nausea, anemia, weakness and fatigue. Serious weight loss may reduce quality of life, impair treatment effectiveness or recovery, worsen disease processes and be a risk factor for high mortality rates. Malnutrition can affect every function of the human body, from the cells to the most complex body functions, including:
=== Cytochrome P450 inhibitors and inducers === Trazodone is metabolized by several liver enzymes, including CYP3A4, CYP2D6, and CYP1A2. Its active metabolite meta-chlorophenylpiperazine (mCPP) is known to be formed by CYP3A4 and metabolized by CYP2D6. Inhibition or induction of the aforementioned enzymes by various other substances may alter the metabolism of trazodone or mCPP, leading to increased or decreased blood concentrations. The enzymes in question are known to be inhibited and induced by many medications, herbs, and foods, and as such, trazodone may interact with these substances. Potent CYP3A4 inhibitors such as clarithromycin, erythromycin, fluvoxamine, grapefruit juice, ketoconazole, and ritonavir may lead to increased concentrations of trazodone and decreased concentrations of mCPP, while CYP3A4 inducers like carbamazepine, enzalutamide, phenytoin, phenobarbital, and St. John's wort may result in decreased trazodone concentrations and increased mCPP concentrations. CYP2D6 inhibitors may result in increased concentrations of both trazodone and mCPP, while CYP2D6 inducers may decrease their concentrations. Examples of potent CYP2D6 inhibitors include bupropion, cannabidiol, duloxetine, fluoxetine, paroxetine, quinidine, and ritonavir, while CYP2D6 inducers include dexamethasone, glutethimide, and haloperidol. CYP1A2 inhibitors may increase trazodone concentrations, while CYP1A2 inducers may decrease trazodone concentrations.
A strike on 2 November killed three, a strike on 6 November killed three, and a strike on 10 November killed four. A 13 February 2026 strike on a Designated Terrorist Organization vessel killed three. A 23 February strike killed three. A 25 March strike killed four. By June 2026 an estimated 210 people had been killed in U.S. military boat strikes.
Sources: en.wikipedia.org
14 November Archaeologists report the oldest likely evidence (via heated fish teeth from a deep cave) of controlled use of fire to cook food by archaic humans ~780,000 years ago. After being linked to risks for obesity, mental disorders, and potentially other health issues, a study finds a likely association between (contemporary types of) outdoor artificial light at night and diabetes. 15 November A scientific review finds that human sperm counts fell by 62% in the last 50 years and are decreasing at an accelerating rate, likely a result of factors such as poor diets, endocrine disruptors in prevalent products, unhealthy lifestyles and toxic forever chemicals in air and water. A study using neuroimaging identifies rapid GABA boosting as a major potential explanation-component for why learning is often more efficient in children. Scientists report leprosy-causing bacteria viably regenerate and rejuvenate the liver in its armadillos hosts, which may enable novel human therapies. 16 November NASA conducts the first uncrewed flight of its Space Launch System (SLS), the largest rocket in history. The onboard Orion capsule will orbit the Moon before returning to Earth, as a demonstration of planned human missions. A satellite-free GPS-alternative higher-resolution positioning system using existing telecommunications networks is demonstrated, SuperGPS.
== External links == A comprehensive NIH factsheet on iron and nutrition Iron Disorders Institute: A nonprofit group concerned with iron disorders; site has helpful links and information on iron-related medical disorders. An interactive medical learning portal on iron metabolism Information about iron outside the body
21 October Metropolitan Police officer Martyn Blake is cleared of the murder of Chris Kaba, who was shot in Streatham in September 2022. BBC News reports that the Serious Fraud Office is investigating the construction of a hotel and conference centre owned by the Unite union. The UK government announces plans to make more medical records, test results and letters from doctors available on the NHS App. A man dies and 15 people treated in hospital following a low-speed crash between two trains near the village of Llanbrynmair in Powys. 22 October Reporting restrictions are lifted on the background of Chris Kaba, who it is revealed was a suspect in a shooting at a nightclub days before his death, and was also a rapper who belonged to the infamous 67 gang, a UK drill group and criminal gang. Figures show that government borrowing rose by £16.6bn in September 2024, the third highest September on record since records began in 1993. The International Monetary Fund increases its growth forecast for the UK from 0.7% (in July) to 1.1%, and says the UK economy is set to "accelerate". The UK government begins a second tranche of early prisoner releases involving 1,100 inmates in order to alleviate prison overcrowding in England and Wales. 23 October The National Institute of Health and Care Excellence (NICE) announces that the Alzheimer's drug Donanemab will not be made available on the NHS in England because of its cost and relatively minor benefit to patients.
Sources: en.wikipedia.org
=== Non-medical use === Vosilasarm and other SARMs are sold on the black market on the Internet. Aside from vosilasarm, the other most commonly used SARMs include enobosarm (ostarine; GTx-024, S-22), LGD-4033 (VK5211; "ligandrol"), and andarine (GTx-007; S-4). Social media has played an important role in facilitating the widespread non-medical use of SARMs.
A technetium-99m generator, or colloquially a technetium cow or moly cow, is a device used to extract the metastable isotope 99mTc of technetium from a decaying sample of molybdenum-99. 99Mo has a half-life of 66 hours and can be easily transported over long distances to hospitals where its decay product technetium-99m (with a half-life of only 6 hours, inconvenient for transport) is extracted and used for a variety of nuclear medicine diagnostic procedures, where its short half-life is very useful.
== External links == "FDA revises label of diabetes drug canagliflozin". U.S. Food and Drug Administration (FDA). 15 January 2016. Archived from the original on 13 December 2019. "FDA Drug Safety Communication: FDA confirms increased risk of leg and foot amputations with the diabetes medicine canagliflozin (Invokana, Invokamet, Invokamet XR)". U.S. Food and Drug Administration (FDA). 18 May 2016. "FDA Drug Safety Communication: Interim clinical trial results find increased risk of leg and foot amputations, mostly affecting the toes, with the diabetes medicine canagliflozin (Invokana, Invokamet); FDA to investigate". U.S. Food and Drug Administration (FDA). 9 May 2017. Archived from the original on 1 October 2019. "Warning use metformin in certain patients with reduced kidney function". U.S. Food and Drug Administration (FDA). 14 November 2017. Archived from the original on 1 October 2019. "Warning: infection of genital area with SGLT2 inhibitors for diabetes". U.S. Food and Drug Administration (FDA). 7 September 2018.
== Production == Produced mainly in parts of the world where pineapples are grown, such as Thailand or Malaysia, bromelain is extracted from the peel, stem, leaves or waste of the pineapple plant after processing the fruit for juice or other purposes. The starting material is blended and pressed through a filter to obtain a supernatant liquid containing the soluble bromelain enzyme. Further processing includes purification and concentration of the enzyme.
Sources: en.wikipedia.org
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。
Semax 被描述为 ACTH(4-10) 的结构类似物，两者共享部分序列特征。它保留了该片段的部分神经相关活性方向，但去除了完整片段带来的激素释放效应。二者并非同一物质，也不能互相替代。
加入的 Pro-Gly-Pro 三肽被普遍认为能提升分子对蛋白水解酶的稳定性。这种设计让短肽在体内维持时间更长。具体延长的程度以及不同组织中是否一致，文献中仍存在不同报告。
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.