This is a working overview of heptapeptide, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-07-31 and is reviewed periodically as new material appears.
多数实验室与市售的 Semax 以冻干粉形式提供。冻干粉通常建议保存在 -20 °C 或更低温度下，同时避免光照与反复升温。短期运输有时采用冷藏条件，但长期保存仍以冷冻为主。分包操作应尽量减少开盖次数，以降低吸湿和微生物污染的风险。开封后若未一次用完，建议在干燥环境中密封并尽快放回低温储存。
溶液状态的稳定性明显低于冻干粉。肽类在水溶液中可能经历水解、氧化与聚集，其中甲硫氨酸和天冬酰胺等残基常是敏感位点。Semax 含有甲硫氨酸，因此氧化风险相对突出。工作液一般主张现配现用，或冷藏并在数日内用尽。缓冲液种类、pH 和离子强度都会影响降解速率，而关于最佳条件的公开数据并不统一。
常规纯度与身份确认依赖反相高效液相色谱，并辅以质谱测定分子量。氨基酸组成分析可用于验证序列构成，肽图分析则能进一步定位修饰或降解产物。杂质谱通常关注缺失序列肽、截短片段和氧化产物。不同方法的检出限并不相同，因此各实验室报告的纯度数值不宜直接横向比较。
Clinical evidence consists largely of small trials with modest sample sizes, often without independent replication. Reported endpoints include cognitive scores, recovery after stroke, and visual function, but study designs vary widely and few trials meet contemporary reporting standards. Systematic reviewers have noted a high risk of bias in several of these reports. No large multicenter trial conducted outside Russia has been published. The compound is therefore best described as investigational in most jurisdictions, with its clinical role still unresolved.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. Its chain combines the first seven residues of corticotropin with a C-terminal proline-glycine-proline extension, a modification intended to slow enzymatic breakdown. The free peptide has a molecular mass near 813.9 daltons. It belongs to the class of ACTH-derived fragments studied for central nervous system activity rather than for adrenal steroid stimulation. This structural relationship to a natural hormone fragment is the usual starting point for describing the compound in the literature.
Development took place during the 1980s at institutes of the Russian Academy of Sciences, where peptide fragments of ACTH were screened for cognitive and neuroprotective effects. The compound received regulatory approval in Russia as a nasal preparation, marketed for conditions such as ischemic stroke, transient ischemic attacks, and optic nerve disorders. Registration in other countries has not followed. Most published clinical reports originate from a small number of Russian research groups, and independent replication outside that setting remains limited. The regulatory status therefore differs sharply between Russia and the rest of the world.
| Property | Value | Notes |
|---|---|---|
| 外观 | 白色至类白色粉末 | 常见于冻干制剂 |
| 溶解度 | 易溶于水 | 在极性溶剂中一般也可溶 |
| 建议储存温度 | -20 °C | 冻干粉，避光密封 |
| 常见分析手段 | 反相高效液相色谱 | 常与质谱联用 |
| 主要降解路径 | 水解与氧化 | 溶液状态更显著 |
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.
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.
The compound was developed during the 1980s at the Institute of Molecular Genetics in Moscow as part of research on fragments of adrenocorticotropic hormone. Early work examined short ACTH-derived sequences that retained neurotrophic effects while lacking the endocrine activity of the full hormone. Semax entered clinical use in Russia during the 1990s, where it received registration for several neurological indications. Outside that region it remained primarily a laboratory research material rather than an approved therapeutic. English-language literature on it grew more slowly and frequently cited the original Russian studies.
Terminology around the compound varies by source. It appears in catalogues and papers as Semax, as the heptapeptide ACTH(4-7)-Pro-Gly-Pro, and under various alphanumeric laboratory codes used by individual suppliers. These names refer to the same sequence but may imply different salt forms, purity grades, or counter-ions. Peptide databases usually list the free base mass, while product descriptions sometimes report acetate or trifluoroacetate salts with a different formula weight. Because naming conventions for research peptides are not standardised across vendors, checking the declared sequence and measured mass is more reliable than relying on a trade name alone.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. Its design combines the ACTH(4-7) core fragment with a C-terminal Pro-Gly-Pro extension, a modification intended to improve stability and prolong activity. The molecule is hydrophilic, carries no lipid chains or glycosylation, and has a theoretical mass just over 810 daltons in its free form. All seven residues are proteinogenic amino acids, so no non-natural building blocks appear in the backbone. A free N-terminal methionine and C-terminal proline define the unmodified parent peptide.
Anti-citrullinated protein antibodies (ACPAs) are autoantibodies (antibodies to an individual's own proteins) that are directed against peptides and proteins that are citrullinated. They are present in the majority of patients with rheumatoid arthritis. Clinically, cyclic citrullinated peptides (CCP) are frequently used to detect these antibodies in patient serum or plasma (then referred to as anti–citrullinated peptide antibodies). During inflammation, arginine amino acid residues can be enzymatically converted into citrulline residues in proteins such as vimentin, by a process called citrullination. If their shapes are significantly altered, the proteins may be seen as antigens by the immune system, thereby generating an immune response. ACPAs have proved to be powerful biomarkers that allow the diagnosis of rheumatoid arthritis (RA) to be made at a very early stage. In July 2010, the 2010 ACR/EULAR Rheumatoid Arthritis Classification Criteria were introduced. These new classification criteria include ACPA testing, and overruled the "old" ACR criteria of 1987 and are adapted for early RA diagnosis.
All other European Union nations voted in favour or abstained: the Netherlands, which voted against a resolution in 2007, voted in favour, as did Finland and Norway, both of which had abstained in 2007, while the Czech Republic, which voted against the resolution in 2007, abstained. The two other states that voted against the resolution were Israel and the United States (both of which voted against in 2007), while as before China was absent for the vote, and Russia abstained. In June 2009, Belgium became the first country in the world to ban: "inert ammunition and armour that contains depleted uranium or any other industrially manufactured uranium." The move followed a unanimous parliamentary vote on the issue on 22 March 2007. The text of the 2007 law allowed for two years to pass until it came into force. In April 2009, the Belgian Senate voted unanimously to restrict investments by Belgian banks into the manufacturers of depleted uranium weapons. In September 2009, the Latin American Parliament passed a resolution calling for a regional moratorium on the use, production and procurement of uranium weapons. It also called on the Parlatino's members to work towards an international uranium weapons treaty. In November 2010 the Irish Senate passed a bill seeking to outlaw depleted uranium weapons, but it lapsed before approval by the Dáil.
Empagliflozin, sold under the brand name Jardiance ( JAR-dee-əns), among others, is an antidiabetic medication used to improve glucose control in people with type 2 diabetes and/or for patients with established heart failure with reduced ejection fraction (HFrEF). Studies have shown great benefits for heart failure (HF) outcomes and decreased hospitalisations. It is taken by mouth. Common side effects of empagliflozin include genital yeast infections and hypotension, particularly in patients with volume depletion. Other symptoms such as nausea and vomiting may occur and seem more pronounced in combination with metformin. Rare but serious adverse events, such as euglycemic diabetic ketoacidosis (DKA) which may present with hyperventilation, lethargy, or mental status changes have been reported but are infrequent in trials. Other serious but rare serious adverse events include Fournier's gangrene, a severe skin infection of the groin, and diabetic ketoacidosis that may occur even with normal blood glucose levels. Use during pregnancy or breastfeeding is not recommended. Empagliflozin is a SGLT2 inhibitor: a reversible inhibitor of the sodium glucose co-transporter-2 (SGLT-2). It reduces the kidney's glucose reabsorption and excretes the excess glucose through the urine, thus its place in the treatment of type two diabetes. It is dependent on blood glucose concentrations and the glomerular filtration rate of the kidney.
It can be difficult to tell whether a trait has been lost and then re-evolved convergently, or whether a gene has simply been switched off and then re-enabled later. Such a re-emerged trait is called an atavism. From a mathematical standpoint, an unused gene (selectively neutral) has a steadily decreasing probability of retaining potential functionality over time. The time scale of this process varies greatly in different phylogenies; in mammals and birds, there is a reasonable probability of a gene's remaining in the genome in a potentially functional state for around 6 million years.
Sources: en.wikipedia.org
== Treatment == Treatment of diving barotrauma depends on the symptoms, which depend on the affected tissues. Lung over-pressure injury may require a chest drain to remove air from the pleura or mediastinum. Recompression with hyperbaric oxygen therapy is the definitive treatment for arterial gas embolism, as the raised pressure reduces bubble size, the reduced blood inert gas concentration may accelerate inert gas solution, and high oxygen partial pressure helps oxygenate tissues compromised by the emboli. Care must be taken when recompressing to avoid a tension pneumothorax. Barotraumas that do not involve gas in the tissues are generally treated according to severity and symptoms for similar trauma from other causes.
=== Polycythemia in adults === Different diseases or conditions can cause polycythemia in adults. These processes are discussed in more detail in their respective sections below. Relative polycythemia, also known as pseudopolycythemia, is not a true increase in the number of red blood cells or hemoglobin in the blood, but rather an elevated laboratory finding caused by reduced blood plasma (hypovolemia, cf. dehydration). Relative polycythemia is often caused by loss of body fluids, such as through burns, dehydration, and stress. A specific type of relative polycythemia is Gaisböck syndrome; in this syndrome, primarily occurring in obese men, hypertension causes a reduction in plasma volume, resulting in (amongst other changes) a relative increase in red blood cell count. If relative polycythemia is deemed unlikely because the patient has no other signs of hemoconcentration and has sustained polycythemia without clear loss of body fluids, the patient likely has absolute or true polycythemia. Absolute or true polycythemia (also erythrocytosis) can be split into two categories:
==== Refeeding syndrome ==== When a malnourished person is refed too quickly, they may develop refeeding syndrome (RFS), which can be life-threatening. Factors associated with increased risk for RFS include:
Sources: en.wikipedia.org
一般不建议常温长期保存。多数说明指向 -20 °C 冷冻避光。常温运输通常被视为短期可接受，但会加快降解风险。
公开资料对此没有统一答案。普遍建议现配现用，或冷藏并在数日内用完。含甲硫氨酸的序列更易氧化，放置时间越长风险越高。
反相高效液相色谱是最常用的手段，配合质谱确认分子量。氨基酸组成分析和肽图分析可补充序列层面的验证。
Semax is a synthetic seven-amino-acid peptide derived from a fragment of corticotropin. It is used in Russia as a nasal preparation, while elsewhere it is studied as a research compound. It is not approved as a medicine in most countries.