counter-ion is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-07-09. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
Development is attributed to researchers at the Institute of Molecular Genetics in Moscow during the early 1980s, building on earlier Soviet work with ACTH fragments. Russian regulatory approval followed for intranasal use, and the compound has remained commercially available there for decades. Most published human data originate from Russian and, later, some Eastern European clinical reports, which are not always accessible in English translation. Outside that region the material is generally handled as a research chemical rather than a licensed medicine.
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.
| Property | Value | Notes |
|---|---|---|
| Solid storage temperature | -20 °C or below | Desiccated and protected from light |
| Solution storage temperature | -80 °C as single-use aliquots | Avoid repeated freeze-thaw cycles |
| Purity assessment method | RP-HPLC, around 214 nm | Reported as main-peak area percent |
| Identity confirmation method | ESI-MS or MALDI-TOF | Measured mass compared with calculated mass |
| Common synonyms | ACTH(4-10) analog; Met-Glu-His-Phe-Pro-Gly-Pro | Also written as Semaxum in some sources |
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.
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.
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.
The compound is registered in Russia as a pharmaceutical product, most commonly formulated as a nasal solution, and has been used in that setting since the 1990s. Outside that jurisdiction it is generally handled as a research chemical rather than an approved medicine. Regulatory status therefore differs sharply between countries, and material sold internationally may not correspond to the Russian pharmaceutical formulation. Documentation with commercial samples is typically limited to a certificate of analysis covering purity and identity, not clinical status or local legal classification.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It corresponds to the ACTH(4-7) fragment extended at the C-terminus by a Pro-Gly-Pro tripeptide, an addition intended to slow enzymatic breakdown. The molecular formula is C37H51N9O10S and the molecular mass is approximately 814 daltons. In the literature it is often described as an ACTH(4-10) analog, although that label reflects a naming convention as much as a precise structural relationship. The compound was developed in Russia and remains most closely associated with that research tradition.
As a result, work done by the heart will decrease and will allow the heart to contract less strongly. Weaker contractions will lead to more blood flow in the coronary arteries, which will help the ischemic cardiac myocytes.
Orthologous sequences provide useful information in taxonomic classification and phylogenetic studies of organisms. The pattern of genetic divergence can be used to trace the relatedness of organisms. Two organisms that are very closely related are likely to display very similar DNA sequences between two orthologs. Conversely, an organism that is further removed evolutionarily from another organism is likely to display a greater divergence in the sequence of the orthologs being studied.
=== Protein tyrosine phosphatases === Protein Tyrosine Phosphatase (PTPs) are a group of enzymes that possess a catalytic domain with phosphotyrosine-specific phosphohydrolase activity. PTPs are capable of modifying the activity of receptor tyrosine kinases in both a positive and negative manner. PTPs can dephosphorylate the activated phosphorylated tyrosine residues on the RTKs which virtually leads to termination of the signal. Studies involving PTP1B, a widely known PTP involved in the regulation of the cell cycle and cytokine receptor signaling, has shown to dephosphorylate the epidermal growth factor receptor and the insulin receptor. Some PTPs, on the other hand, are cell surface receptors that play a positive role in cell signaling proliferation. Cd45, a cell surface glycoprotein, plays a critical role in antigen-stimulated dephosphorylation of specific phosphotyrosines that inhibit the Src pathway.
Sources: en.wikipedia.org
In September 2015, the FDA issued a warning related to canagliflozin (Invokana) and canagliflozin/metformin (Invokamet) due to decreased bone mineral density and therefore increased risk of bone fractures. Using gliflozins in combination therapy with metformin can lower the risk of hypoglycemia compared to other type 2 diabetes treatments such as sulfonylureas and insulin. Increased risk of lower limb amputation is associated with canagliflozin, but further data is needed to confirm this risk associated with different gliflozins. A European Medicines Agency review concluded that there is a potential increased risk of lower limb amputation (mostly affecting the toes) in people taking canagliflozin, dapagliflozin and empagliflozin. In August 2018, the FDA issued a warning of an increased risk of Fournier gangrene in patients using SGLT2 inhibitors. The absolute risk is considered very low. In the FDA Adverse Event Reporting System an increase was reported in events of acute kidney injury associated with SGLT2 inhibitors, though data from clinical trials actually showed a reduction in such events with SGLT-2 treatment.
=== Indirect unknown mechanism === Two of the primary active constituents of the medicinal herb Hypericum perforatum (St. John's Wort) are hyperforin and adhyperforin. Hyperforin and adhyperforin are wide-spectrum inhibitors of the reuptake of serotonin, norepinephrine, dopamine, glutamate, GABA, glycine, and choline, and they exert these effects by binding to and activating the transient receptor potential cation channel TRPC6. Activation of TRPC6 induces the entry of calcium (Ca2+) and sodium (Na+) into the cell, which causes the effect through unknown mechanism.
In coordination chemistry, EDTA4− is a member of the aminopolycarboxylic acid family of ligands. EDTA4− usually binds to a metal cation through its two amines and four carboxylates, i.e., it is a hexadentate ("six-toothed") chelating agent. Many of the resulting coordination compounds adopt octahedral geometry. Although of little consequence for its applications, these octahedral complexes are chiral. The cobalt(III) anion [Co(EDTA)]− has been resolved into enantiomers. Many complexes of EDTA4− adopt more complex structures due to either the formation of an additional bond to water, i.e. seven-coordinate complexes, or the displacement of one carboxylate arm by water. The iron(III) complex of EDTA is seven-coordinate. Early work on the development of EDTA was undertaken by Gerold Schwarzenbach in the 1940s. EDTA forms especially strong complexes with Mn(II), Cu(II), Fe(III), Pb(II) and Co(III). Several features of EDTA's complexes are relevant to its applications. First, because of its high denticity, this ligand has a high affinity for metal cations:
Gastrin–cholecystokinin family: gastrin and cholecystokinin Secretin family: secretin, glucagon, vasoactive intestinal peptide and gastric inhibitory peptide Somatostatin family Motilin family Substance P. Ghrelin is a peptide hormone released from the stomach and liver and is often referred to as the "hunger hormone" since high levels of it are found in individuals that are fasting. Ghrelin agonistic treatments can be used to treat illnesses such as anorexia and loss of appetites in cancer patients. Ghrelin treatments for obesity are still under intense scrutiny and no conclusive evidence has been reached. This hormone stimulates growth hormone release. Amylin controls glucose homeostasis and gastric motility Glucose-dependent insulinotropic polypeptide possesses an acute influence on food intake through its effects on adipocytes Oxyntomodulin plays a role in controlling acid secretion and satiation
Sources: en.wikipedia.org
{\displaystyle {\begin{aligned}m_{\text{u}}&={\frac {m_{\text{e}}}{A_{\text{r}}({\text{e}})}}={\frac {2R_{\infty }h}{A_{\text{r}}({\text{e}})c\alpha ^{2}}}={\frac {M_{\text{u}}}{N_{\text{A}}}},\\[1ex]N_{\text{A}}&={\frac {M_{\text{u}}A_{\text{r}}({\text{e}})}{m_{\text{e}}}}={\frac {M_{\text{u}}A_{\text{r}}({\text{e}})c\alpha ^{2}}{2R_{\infty }h}},\end{aligned}}}
== Contraindications == Carvedilol should not be used in patients with bronchial asthma or bronchospastic conditions due to increased risk of bronchoconstriction. It should not be used in people with second- or third-degree atrioventricular block, sick sinus syndrome, severe bradycardia (unless a permanent pacemaker is in place), or a decompensated heart condition. People with severe hepatic impairment should use carvedilol with caution.
=== Scalding === In making Cheddar (or many other hard cheeses) the curd is cut into small cubes and the temperature is raised to approximately 39 °C (102 °F) to 'scald' the curd particles. Syneresis occurs and cheese whey is expressed from the particles. The Cheddar curds and whey are often transferred from the cheese vat to a cooling table which contains screens that allow the whey to drain, but which trap the curd. The curd is cut using long, blunt knives and 'blocked' (stacked, cut and turned) by the cheesemaker to promote the release of cheese whey in a process known as 'cheddaring'. During this process the acidity of the curd increases to a desired level. The curd is then milled into ribbon shaped pieces and salt is mixed into it to arrest acid development. The salted green cheese curd is put into cheese moulds lined with cheesecloths and pressed overnight to allow the curd particles to bind together. The pressed blocks of cheese are then removed from the cheese moulds and are either bound with muslin-like cloth, or waxed or vacuum packed in plastic bags to be stored for maturation. Vacuum packing removes oxygen and prevents mould (fungal) growth during maturation, which, depending on the wanted final product, may or may not be a desirable characteristic.
Flow focusing is a usually passive formation method that involves the dispersed phase flowing to meet the continuous phase typically at an angle (nonparallel streams) then undergoing a constraint that creates a droplet. This constraint is generally a narrowing in the channel to create the droplet though symmetric shearing, followed by a channel of equal or greater width. As with cross-flowing, the continuous phase flow rate is typically higher than the dispersed phase flow rate. Decreasing the flow of the continuous phase can increase the size of the droplets. Flow focusing can also be an active method with the constraint point being adjustable using pneumatic side chambers controlled by compressed air. The movable chambers act to pinch the flow, deforming the stream and creating a droplet with a changeable driving frequency. Droplet size is usually around several hundred nanometers with a CV of less than 3% and a rate of up to several hundred Hz to tens of kHz.
GABAA receptor: positive allosteric modulator (primarily of δ subunit-containing receptors) NMDA receptor: negative allosteric modulator AMPA receptor: negative allosteric modulator Kainate receptor: negative allosteric modulator Glycine receptor: positive allosteric modulator Serotonin 5-HT3 receptor: positive allosteric modulator Opioid receptor: endogenous positive allosteric modulator Muscarinic acetylcholine receptor: positive allosteric modulator. Nicotinic acetylcholine receptor: positive allosteric modulator Glycine reuptake inhibitor Adenosine reuptake inhibitor L-type calcium channel: channel blocker GIRK: channel opener Voltage-gated calcium channel Dihydropyridine-sensitive L-type Ca2+ channels BK channel modulation G-protein-activated inwardly rectifying K+ channels Brain medulla: Decreased levels of nitric oxide Mesolimbic pathway: Increased levels of dopamine and endogenous opioids, secondary to other actions Many of these actions have been found to occur only at very high concentrations that may not be pharmacologically significant at recreational doses of ethanol, and it is unclear how or to what extent each of the individual actions is involved in the effects of ethanol. Some of the actions of ethanol on ligand-gated ion channels, specifically the nicotinic acetylcholine receptors and the glycine receptor, are dose-dependent, with potentiation or inhibition occurring dependent on ethanol concentration. This seems to be because the effects of ethanol on these channels are a summation of positive and negative allosteric modulatory actions.
Sources: en.wikipedia.org
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.
A high main-peak percentage says little about identity, counter-ion content, or residual solvents. It also does not distinguish an isomer or a closely eluting analog. Mass confirmation and the accompanying documentation cover those gaps.
Salt form changes mass, solubility, and hygroscopicity, and acetate and trifluoroacetate salts behave differently in solution. Storage guidance still centers on -20 °C for powder and lower temperatures for solutions. The certificate should state which salt is present.
It is a short synthetic peptide built from seven amino acids: methionine, glutamic acid, histidine, phenylalanine and three prolines. The sequence derives from the 4-10 fragment of adrenocorticotropic hormone with an added proline-glycine-proline tail. No plant or animal extract is involved; the material is produced by solid-phase peptide synthesis.