If you have been reading about neuropeptide and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-08-01. Numbers and descriptions here follow the published literature rather than marketing material.
Pharmacokinetic accounts emphasize rapid breakdown. After intravenous dosing the intact peptide disappears from blood within minutes, and nasal delivery produces low but measurable concentrations. Metabolites rather than the parent molecule may account for part of the observed activity, although the relative contribution is unresolved. Dosing in the literature varies widely and no optimal schedule has been agreed. These gaps are regularly cited as a reason the findings have not produced broad clinical adoption beyond the original research setting.
Proposed mechanisms center on neurotrophic signaling rather than on classical melanocortin receptor activation. Rodent experiments have reported shifts in the expression of brain-derived neurotrophic factor and nerve growth factor after administration, together with changes in the associated receptor systems. Several authors argue that the peptide acts largely through its degradation products and their interaction with peptidergic pathways, but this remains a hypothesis rather than a settled finding. No single molecular target has been identified in a way that the field broadly accepts.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Primary research models | Rodent studies | Largest share of published data |
| Reported markers | BDNF and NGF expression | Measured mainly in animal tissue |
| Common administration | Intranasal | Matches the registered formulation |
| Blood residence time | Minutes | Rapid enzymatic degradation |
| Evidence quality | Small trials, limited replication | Noted repeatedly in reviews |
Material sold for laboratory use varies widely in stated purity and documentation. A certificate of analysis should list the analytical method, the column and detector used, and the observed purity value. Independent verification by an outside laboratory is the practical way to confirm identity when documentation is absent or internally inconsistent. Regulatory status differs by country, and a product legal in one jurisdiction may be unapproved or controlled in another.
Identity and purity of semax are established with reversed-phase high-performance liquid chromatography coupled to ultraviolet detection, usually at 214 nanometres. Mass spectrometry, most often electrospray ionisation in positive mode, confirms the molecular mass and reveals truncated sequences. Amino acid analysis and peptide mapping after enzymatic digestion provide additional structural confirmation. Laboratories typically report purity as the percentage area of the main peak, a figure that does not capture isomeric or oxidised variants unless the method resolves them.
The peptide is prone to several degradation pathways. Oxidation of the methionine residue produces a sulfoxide that elutes close to the parent peak in many chromatographic systems. Hydrolysis of peptide bonds and deamidation of susceptible residues in related sequences also reduce purity over time. Lyophilised material kept dry at minus twenty degrees Celsius and shielded from light is the most stable form commonly described in laboratory practice.
Reported pharmacological work centers on neurotrophic signaling, including changes in BDNF and NGF expression in hippocampal tissue in animal models. Human data come largely from studies conducted in Russia, and how well those results generalize to other populations remains an open question. Regulatory status differs sharply by jurisdiction: Semax is a registered prescription medicine in Russia, while it holds no approved marketing status in the United States or the European Union. Outside such jurisdictions it is generally handled as a research chemical, which affects both documentation and quality expectations.
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.
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。
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。
=== Microwave-assisted oxidation === In 2012, microwave energy was reported to directly synthesize graphene in one step. This approach avoids use of potassium permanganate in the reaction mixture. It was also reported that by microwave radiation assistance, graphene oxide with or without holes can be synthesized by controlling microwave time. Microwave heating can dramatically shorten the reaction time from days to seconds. Graphene can also be made by microwave assisted hydrothermal pyrolysis.
Macroamylasemia is the presence of macroamylase in the blood. Macroamylase is a complex of the enzyme amylase bound to other proteins forming a larger molecule. Macroamylase is typically composed of immunoglobulin A (IgA, 70%) and less often of immunoglobulin G (IgG, 30%). The association of amylase with some drugs has also been reported.
== Nucleotide level features == In vertebrates, the region of the mRNA that codes for the signal peptide (i.e. the signal sequence coding region, or SSCR) can function as an RNA element with specific activities. SSCRs promote nuclear mRNA export and the proper localization to the surface of the endoplasmic reticulum. In addition SSCRs have specific sequence features: they have low adenine-content, are enriched in certain motifs, and tend to be present in the first exon at a frequency that is higher than expected.
=== Other indications === Sertraline is approved for the treatment of post-traumatic stress disorder (PTSD). The UK's National Institute for Clinical Excellence recommends it for patients who prefer drug treatment to a psychological one. Other guidelines also suggest sertraline as a first-line option for pharmacological therapy. When necessary, long-term pharmacotherapy can be beneficial. There are both negative and positive clinical trial results for sertraline, which may be explained by the types of psychological traumas, symptoms, and comorbidities included in the various studies. Positive results were obtained in trials that included predominantly women (75%) with a majority (60%) having physical or sexual assault as the traumatic event. Somewhat contrary to the above suggestions, a meta-analysis of sertraline clinical trials for PTSD found it to be statistically superior to placebo in the reduction of PTSD symptoms but the effect size was small. Another meta-analysis relegated sertraline to the second line, proposing trauma focused psychotherapy as a first-line intervention. The authors noted that Pfizer had declined to submit the results of a negative trial for inclusion in the meta-analysis, making the results unreliable. Sertraline, when taken daily, can be useful for the treatment of premature ejaculation. A disadvantage of sertraline is that it requires continuous daily treatment to delay ejaculation significantly.
A zoster vaccine is a vaccine that reduces the incidence of herpes zoster (a.k.a. shingles), a disease caused by reactivation of the varicella zoster virus, which is also responsible for chickenpox. Shingles provokes a painful rash with blisters and can be followed by chronic pain (postherpetic neuralgia) and other complications. Older people are more often affected, as are people with weakened immune systems (immunosuppression). Both shingles and postherpetic neuralgia can be prevented by vaccination. Two zoster vaccines have been approved for use in people over 50 years old. Shingrix (GSK) is a recombinant subunit vaccine that has been used in many countries since 2017. Zostavax (Merck), in use since 2006, is an attenuated vaccine which consists of a larger-than-normal dose of varicella vaccine. Unlike Shingrix, Zostavax is not suitable for people with immunosuppression or diseases that affect the immune system. Zostavax was discontinued in the United States in November 2020. Shingrix appears to prevent more cases of shingles than Zostavax, although side effects seem to be more frequent. Varicella vaccine is used to prevent diseases caused by the same virus.
Sources: en.wikipedia.org
== Methods and practices == The term optical activity is derived from the interaction of chiral materials with polarized light. In a solution, the (−)-form, or levorotatory form, of an optical isomer rotates the plane of a beam of linearly polarized light counterclockwise. The (+)-form, or dextrorotatory form, of an optical isomer does the opposite. The rotation of light is measured using a polarimeter and is expressed as the optical rotation. The magnitudes of the optical rotations of both of the enantiomers are equal (but in opposite directions). Enantiomers can be separated by chiral resolution. This often involves forming crystals of a salt composed of one of the enantiomers and an acid or base from the so-called chiral pool of naturally occurring chiral compounds, such as malic acid or the amine brucine. Some racemic mixtures spontaneously crystallize into right-handed and left-handed crystals that can be separated by hand. Louis Pasteur used this method to separate left-handed and right-handed sodium ammonium tartrate crystals in 1849. Sometimes it is possible to seed a racemic solution with a right-handed and a left-handed crystal so that each will grow into a large crystal. Liquid chromatography (HPLC and TLC) may also be used as an analytical method for the direct separation of enantiomers and the control of enantiomeric purity, e.g. active pharmaceutical ingredients (APIs) which are chiral.
The +5 state is less stable than the +3, but relatively easier to attain than with arsenic. This is explained by the poor shielding afforded the arsenic nucleus by its 3d10 electrons. In comparison, the tendency of antimony (being a heavier atom) to oxidize more easily partially offsets the effect of its 4d10 shell. Tripositive antimony is amphoteric; pentapositive antimony is (predominately) acidic. Consistent with an increase in metallic character down group 15, antimony forms salts including an acetate Sb(CH3CO2)3, phosphate SbPO4, sulfate Sb2(SO4)3 and perchlorate Sb(ClO4)3. The otherwise acidic pentoxide Sb2O5 shows some basic (metallic) behaviour in that it can be dissolved in very acidic solutions, with the formation of the oxycation SbO+2. The oxide Sb2O3 is polymeric, amphoteric, and a glass former. Antimony has an extensive organometallic chemistry (see Organoantimony chemistry).
== Early life == Hird is the son of Allan and Margaret Hird. He was born in Canberra, where his father worked in the public service and his mother was a teacher, although they had met in Melbourne. Hird has two younger sisters. After first living in the Canberra suburb of Ainslie, his family moved to Latham. When Hird was in high school, the family moved to the suburb of Reid. Hird participated in rugby league, ballet, and soccer in his youth. He played for the Ainslie Football Club in the ACTAFL, and in June 1990, at the age of 17, he was a member of the league's senior representative team in a match against the Victorian Football Association.
=== Non-surgical === Indicated for people with exposed bone with symptoms of infection. This treatment modality may also be utilised for patients with other co-morbidities which precludes invasive surgical methods. This approach requires antimicrobial mouthwashes, systemic antibiotics and antifungal medication and analgesics.
Strikes in the 1970s led to a loss of reliability and punctuality, both of which are important for fish transportation. In 1986, the last refrigerated cars were replaced by reefer containers. Most Japanese reefer cars were four-wheeled due to small traffic demands. There were very few bogie wagons in late years. The total number of Japanese reefers numbered approximately 8,100. At their peak, about 5,000 refrigerated cars operated in the late 1960s. Mechanical refrigerators were tested, but did not see widespread use. There were no privately owned reefers in Japan. This is because national policies protected fish transportation, kept rates low, and made refrigerated car ownership unprofitable.
Sources: en.wikipedia.org
At low temperatures, the dominance of the T1.5 thermal conductivity contribution of the out-of-plane mode supersedes the T2 dependence of the linear modes. Some graphene phonon bands exhibit negative Grüneisen parameters, resulting in negative thermal expansion coefficient at low temperatures. The lowest negative Grüneisen parameters correspond to the lowest transverse acoustic ZA modes, whose frequencies increase with in-plane lattice parameter, akin to a stretched string with higher frequency vibrations.
=== Obstructive sleep apnea === C-reactive protein (CRP), a marker of systemic inflammation, is also increased in obstructive sleep apnea (OSA). CRP and interleukin-6 (IL-6) levels were significantly higher in patients with OSA compared to obese control subjects. Patients with OSA have higher plasma CRP concentrations that increased corresponding to the severity of their apnea-hypopnea index score. Treatment of OSA with CPAP (continuous positive airway pressure) significantly alleviated the effect of OSA on CRP and IL-6 levels.
Typically, synthetic oligonucleotides are single-stranded DNA or RNA molecules around 15–25 bases in length. Oligonucleotides find a variety of applications in molecular biology and medicine. They are most commonly used as antisense oligonucleotides, small interfering RNA, primers for DNA sequencing and amplification, probes for detecting complementary DNA or RNA via molecular hybridization, tools for the targeted introduction of mutations and restriction sites, and for the synthesis of artificial genes. An emerging application of Oligonucleotide synthesis is the re-creation of viruses from sequence alone — either harmless, such as Phi X 174, or dangerous such as the 1917 influenza virus or SARS-CoV-2.
== Tissue distribution == COL21A1 is expressed in a broad range of tissues, including skin, trachea, testis, uterus, placenta, lymph node, stomach and the walls of blood vessels, generally overlapping the distribution of type I collagen. Among these, relative expression is highest in lymph node, jejunum, pancreas, stomach, trachea, testis, uterus and placenta; moderate levels are found in brain, colon, lung, prostate, spinal cord, salivary gland and vascular smooth-muscle cells; and expression is weak in heart, liver, kidney, bone marrow, spleen and thymus. COL21A1 expression is developmentally regulated, being higher at fetal stages than in the corresponding adult tissues. In a comparison of matched human tissues, COL21A1 transcripts were approximately 2.7-, 22- and 30-fold more abundant in fetal brain, heart and liver, respectively, than in their adult counterparts, suggesting a role in developmental processes. In cultured aortic smooth-muscle cells, expression of COL21A1 is stimulated by platelet-derived growth factor (PDGF). Its presence in the walls of blood vessels, where it is produced by smooth-muscle cells, was noted in the original characterization of the gene. Type XXI collagen is also expressed in human skin, where it is a low-abundance component of the dermal extracellular matrix, as detected by quantitative proteomics of healthy skin. In a time-resolved proteomic atlas of the developing skin dermis, type XXI collagen was among the fibril-associated collagens whose abundance declined progressively with age over the human lifespan.
Collagen α-1 (XXIII) chain is a protein encoded by COL23A1 gene, which is located on chromosome 5q35 in humans, and on chromosome 11B1+2 in mice. The location of this gene was discovered by genomic sequence analysis. Collagen XXIII is a type II transmembrane protein and the fourth in the subfamily of non-fibrillar transmembranous collagens. This kind of collagens have a single pass hydrophobic transmembrane domain. The molecule of collagen XXIII can be found either in membrane-bond form or in shed form. Type XXIII collagen is expressed in both adult tissues and developing organs. It can be found in the epidermis and other epithelia such as those in tongue, gut and lung, but also in the brain, the kidney and the cornea. It has been shown that in prostate collagen XXIII expression is associated with tumor progression. The functions of collagen XXIII are still unknown, although it is believed that they could be similar to other transmembrane proteins, such as collagen XIII.
Sources: en.wikipedia.org
The main proposal is modulation of neurotrophic factors such as brain-derived neurotrophic factor, supported largely by animal experiments. Receptor-level targets have not been firmly established. Most reviews describe the mechanism as only partially characterized.
The compound is registered as a medicine in Russia, so clinical work has concentrated there. Trials elsewhere are few and generally small. This geographic concentration is a recognized limitation in evidence reviews.
Some fraction may reach the central nervous system through olfactory pathways, and this is often cited as the rationale for the nasal route. The size of that fraction in humans is not well quantified. Blood concentrations after nasal dosing are low, which complicates measurement.
It is a synthetic seven-amino-acid peptide built from the ACTH(4-7) sequence plus a Pro-Gly-Pro tail. It belongs to the family of short ACTH fragments studied for nervous-system effects. Its backbone contains only standard amino acids.