melanocortin signalling 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 2026-06-15 and is reviewed periodically as new material appears.
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.
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.
Identity and purity are established with standard peptide methods. Reversed-phase HPLC with ultraviolet detection near 214 nm resolves the parent peak from deletion and truncation byproducts, and reports typically quote a main-peak percentage. Mass spectrometry by electrospray or MALDI-TOF confirms the expected molecular mass, while amino acid analysis or peptide mapping can verify composition when the sequence itself is in question. A certificate of analysis that pairs a chromatogram with a mass spectrum is more informative than a purity figure alone. Counter-ion content and residual solvents are separate specifications and are frequently omitted.
| Property | Value | Notes |
|---|---|---|
| Sequence | Met-Glu-His-Phe-Pro-Gly-Pro | Heptapeptide; ACTH(4-10) analog extended at C-terminus |
| Molecular mass | ~813.9 Da | Free peptide, unmodified |
| Appearance | White to off-white powder | Typical lyophilized solid |
| Solubility | Soluble in water and saline | Also soluble in common aqueous buffers |
| Storage (solid) | -20 °C, desiccated | Protect from moisture and repeated thawing |
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.
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。
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.
Routine characterization relies on reversed-phase high-performance liquid chromatography to establish purity and on mass spectrometry to confirm molecular identity. Electrospray ionization and matrix-assisted laser desorption ionization are both used for mass verification. Amino acid analysis and peptide mapping can detect sequence errors. Common impurities include truncated sequences, methionine sulfoxide formed by oxidation, and deamidated products. Chromatograms are usually recorded near 214 nm, where the peptide backbone absorbs, and purity is reported as the percentage area of the principal peak.
Verification of a supplied batch generally combines a certificate of analysis with independent testing, because certificates are self-reported documents. A typical package includes a chromatographic trace, a mass spectrum, and a stated water or counter-ion content. Batch-to-batch consistency matters more than a single purity figure when results are compared across experiments. No single mandatory standard governs research-grade peptide release, so laboratories are expected to define their own acceptance criteria. Residual trifluoroacetate from purification is a frequently overlooked counter-ion.
=== Legal status in weapons === In 1996, the International Court of Justice (ICJ) gave an advisory opinion on the "legality of the threat or use of nuclear weapons". This made it clear, in paragraphs 54–56, that international law on poisonous weapons—the Second Hague Declaration of 29 July 1899, Hague Convention IV of 18 October 1907 and the Geneva Protocol of 17 June 1925—did not cover nuclear weapons, because their prime or exclusive use was not to poison or asphyxiate. This ICJ opinion was about nuclear weapons, but the sentence "The terms have been understood, in the practice of States, in their ordinary sense as covering weapons whose prime, or even exclusive, effect is to poison or asphyxiate," also removes depleted uranium weaponry from coverage by the same treaties as their primary use is not to poison or asphyxiate, but to destroy materiel and kill soldiers through kinetic energy. The Sub-Commission on Prevention of Discrimination and Protection of Minorities of the United Nations Human Rights Commission, passed two motions—the first in 1996 and the second in 1997. They listed weapons of mass destruction, or weapons with indiscriminate effect, or of a nature to cause superfluous injury or unnecessary suffering and urged all states to curb the production and the spread of such weapons. Included in the list was weaponry containing depleted uranium. The committee authorized a working paper, in the context of human rights and humanitarian norms, of the weapons. The requested UN working paper was delivered in 2002 by Y. K. J.
==== Addictiveness and dependence ==== Frequent use of GHB or GBL, even when taken long-term and in moderate doses, does not appear to cause significant physical dependency in the majority of its users. In many people, quitting or temporarily abstaining from use of the drugs is achieved with minimal or no difficulty. However, when consumed in excessive amounts with a high frequency of dosing, physical and psychological dependence can develop. Management of GBL dependence involves considering the person's age, comorbidity and the pharmacological pathways of GBL. GHB and GBL users can adopt a '24/7' dosing regime. This is where the user has become tolerant to the effects of the drug, increasing the dosage and frequency of dosage simply to avoid withdrawal symptoms. For those users who do report withdrawal symptoms upon quitting the use of GHB or GBL, symptoms seem to depend on the dosage and the length of time the drug was used. Light to moderate users often experience insomnia and sleep-related problems, whereas heavy, prolonged use can cause severe withdrawal symptoms similar to Benzodiazepine withdrawal syndrome (BWS).
== Avoidance == In theory, avoidance is simply a matter of preventing hyperinsulinemia. In practice, the difficulty for a diabetic person to aggressively dose insulin to keep blood sugars levels close to normal — while adjusting the insulin regimen to the demands of exercise, stress, and wellness — can practically assure occasional hyperinsulinemia. The pharmacokinetic imperfections of all insulin replacement regimens is a severe limitation. Some practical behaviors which are useful in avoiding chronic Somogyi rebound are:
The epiphyseal arteries and osteogenic cells invade the epiphysis, depositing osteoclasts and osteoblasts which erode the cartilage and build bone, respectively. This occurs at both ends of long bones but only one end of digits and ribs.
Sources: en.wikipedia.org
=== Comparing PAM and BLOSUM === Although the PAM log-odds matrices were the first scoring matrices used with BLAST, the PAM matrices have largely been replaced by the BLOSUM matrices. Although both matrices produce similar scoring outcomes they were generated using differing methodologies. The BLOSUM matrices were generated directly from the amino acid differences in aligned blocks that have diverged to varying degrees the PAM matrices reflect the extrapolation of evolutionary information based on closely related sequences to longer timescales. Since scoring information for the PAM and BLOSUM matrices were generated in very different ways the numbers associated with the matrices have fundamentally different meanings; the numbers for PAM matrices increase for comparisons among more divergent proteins whereas the numbers for the BLOSUM matrices decrease. However, all amino acid substitution matrices can be compared in an information theoretic framework using their relative entropy.
which is 50 times bigger than the force on the left piston. The difference between force and pressure is important: the additional pressure is exerted against the entire area of the larger piston. Since there is 50 times the area, 50 times as much force is exerted on the larger piston. Thus, the larger piston will support a 50 N load – fifty times the load on the smaller piston. Forces can be multiplied using such a device. One newton input produces 50 newtons output. By further increasing the area of the larger piston (or reducing the area of the smaller piston), forces can be multiplied, in principle, by any amount. Pascal's principle underlies the operation of the hydraulic press. The hydraulic press does not violate energy conservation, because a decrease in distance moved compensates for the increase in force. When the small piston is moved downward 100 centimeters, the large piston will be raised only one-fiftieth of this, or 2 centimeters. The input force multiplied by the distance moved by the smaller piston is equal to the output force multiplied by the distance moved by the larger piston; this is one more example of a simple machine operating on the same principle as a mechanical lever. A typical application of Pascal's principle for gases and liquids is the automobile lift seen in many service stations (the hydraulic jack). Increased air pressure produced by an air compressor is transmitted through the air to the surface of oil in an underground reservoir. The oil, in turn, transmits the pressure to a piston, which lifts the automobile.
Gamma delta T cells (γδ T cells) represent a small subset of T cells which possess a γδ TCR rather than the αβ TCR on the cell surface. The majority of T cells express αβ TCR chains. This group of T cells is much less common in humans and mice (about 2% of total T cells) and are found mostly in the gut mucosa, within a population of intraepithelial lymphocytes. In rabbits, sheep, and chickens, the number of γδ T cells can be as high as 60% of total T cells. The antigenic molecules that activate γδ T cells are still mostly unknown. However, γδ T cells are not MHC-restricted and seem to be able to recognize whole proteins rather than requiring peptides to be presented by MHC molecules on APCs. Some murine γδ T cells recognize MHC class IB molecules. Human γδ T cells that use the Vγ9 and Vδ2 gene fragments constitute the major γδ T cell population in peripheral blood. These cells are unique in that they specifically and rapidly respond to a set of nonpeptidic phosphorylated isoprenoid precursors, collectively named phosphoantigens, which are produced by virtually all living cells. The most common phosphoantigens from animal and human cells (including cancer cells) are isopentenyl pyrophosphate (IPP) and its isomer dimethylallyl pyrophosphate (DMPP). Many microbes produce the active compound hydroxy-DMAPP (HMB-PP) and corresponding mononucleotide conjugates, in addition to IPP and DMAPP. Plant cells produce both types of phosphoantigens. Drugs activating human Vγ9/Vδ2 T cells comprise synthetic phosphoantigens and aminobisphosphonates, which upregulate endogenous IPP/DMAPP.
=== Poison warning and variable content === In 2022, the Tennessee Poison Center warned that use of yohimbine supplements may have fatal effects due to the possibility for high, unregulated amounts of yohimbine in over-the-counter (OTC) supplement products. Due to inaccurate product labeling and the potential for serious adverse effects, yohimbine supplements have been banned in many countries. Use of such products has been associated with cardiovascular problems and seizures. The European Food Safety Authority Panel on Food Additives determined that it was not possible to conclude about the safety or to establish a health-based guidance value for yohimbine in supplement products. They wrote:
== Medical uses == Patiromer is used for the treatment of hyperkalemia, but not as an emergency treatment for life-threatening hyperkalemia, as it acts relatively slowly. Such a condition needs other kinds of treatment, for example calcium infusions, insulin plus glucose infusions, salbutamol inhalation, and hemodialysis. Typical reasons for hyperkalemia are chronic kidney disease and application of drugs that inhibit the renin–angiotensin–aldosterone system (RAAS) – e.g. ACE inhibitors, angiotensin II receptor antagonists, or potassium-sparing diuretics – or that interfere with kidney function in general, such as nonsteroidal anti-inflammatory drugs (NSAIDs).
Sources: en.wikipedia.org
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.
Its sequence corresponds to the 4-10 region of corticotropin extended by three residues. This fragment lacks the region responsible for adrenal steroid release, so it is explored for neural rather than hormonal effects. The relationship explains the compound's classification among ACTH-derived peptides.
It holds approval in Russia for several neurological indications as a nasal spray or drop formulation. Regulatory agencies in the United States and the European Union have not approved it. Products sold elsewhere are generally labeled for research use only.
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.