This is a working overview of RP-HPLC, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-02-17 and is reviewed periodically as new material appears.
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.
Clinical reports describe use in ischaemic stroke, transient ischaemic attack, optic nerve conditions, and cognitive complaints, but most of these studies are small and were conducted in a single region. Systematic reviews have generally described the evidence base as limited in size and variable in methodological quality. Randomised controlled data suitable for international regulatory assessment are scarce. As a result, major treatment guidelines outside Russia do not include the peptide, and interest in it remains largely research-driven rather than routine clinical.
Lyophilised powder is normally kept at -20 °C in a desiccated container, with some suppliers recommending -80 °C for long-term archival storage. Repeated freeze-thaw cycles are the most common cause of avoidable loss, so aliquoting before freezing reduces variability between working sessions. Dissolved peptide is far less stable than the dry solid and is usually prepared fresh or held briefly at 4 °C. Aqueous solutions support both hydrolysis of the backbone and oxidation of the N-terminal methionine, and these two routes dominate degradation under ordinary laboratory conditions.
Identity and purity are confirmed with reversed-phase high-performance liquid chromatography, typically monitored at 214 nanometres where the peptide bond absorbs. Mass spectrometry, either electrospray or MALDI-TOF, verifies molecular mass against the theoretical value and detects truncation or adduct formation. Amino acid analysis and peptide mapping provide additional confirmation when required. The most frequently reported impurities are deletion sequences from incomplete coupling, methionine sulfoxide from oxidation, and dimeric species formed through non-covalent aggregation. Impurity profiles depend strongly on the synthesis and purification route chosen by the producer.
Published research has focused mainly on neurological and cognitive endpoints in animal models, with proposed mechanisms involving brain-derived neurotrophic factor and related signalling pathways. A substantial share of the human data originates from a limited number of research groups, and independent replication in other countries remains sparse. Regulatory status reflects that distribution: the peptide is registered as a medicine in Russia and appears in some neighbouring markets, while elsewhere it is handled as a research chemical without approved therapeutic labelling. Questions about dose-response relationships, long-term effects, and comparability across studies are still open.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C37H51N9O10S | Free acid form of the heptapeptide; depends on terminal groups |
| Molecular mass | About 813.9 g/mol | Average mass used for mass spectrometry confirmation |
| Appearance | White to off-white solid | Supplied as a lyophilised powder; hygroscopic |
| Solubility class | Freely soluble in aqueous media | Water, saline, and phosphate buffers; limited organic solubility |
| Typical storage temperature | -20 degrees Celsius | Long term and dry; short working periods may use 2 to 8 degrees Celsius |
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.
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 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.
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.
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.
Indium has greater solubility in liquid mercury than any other metal (more than 50 mass percent of indium at 0 °C). Indium displays a ductile viscoplastic response, found to be size-independent in tension and compression. However it does have a size effect in bending and indentation, associated to a length-scale of order 50–100 μm, significantly large when compared with other metals.
== Taxonomy == The species was originally described based on female morphology, being a member of Polyphaga, while the males were described as a separate species, Homœogamia sinensis. Further and re-examination resulted in Eupolyphaga sinensis being established. Historically males were confused with the species E. thibetana and E. yunnanensis, they are now recognized as separate species, having morphological differences that distinguish them. E. sinensis was the first member of the family Corydiidae (at the time referred to as Polyphagidae) to have its mitochondrial DNA sequenced.
As a sign of the expanding commercial ties between the two regions (and Han and Tibetan peoples in particular), a special exhibition was held in Chengdu, so that Sichuanese may see and come into contact with Xikang products. In order to levy taxes from the region, Liu also established a Finance Ministry. Historians and analysts have debated over the effectiveness of these measures. Yang Zhonghua, writing in 1941, praised them as a relatively proactive policy; however, it has been argued by Xie Benzao that Liu's plans, though ambitious on paper, were limited by the realities of war and mostly for the purpose of resource extraction. Another road-building project of Liu Wenhui, constructed in the late 1920s from Yazhou to Chengdu, was known by locals mainly for the ruthlessness of its methods. Despite these projects, Xikang was mostly seen as a rear location distant from the conflicts in Sichuan. Liu encouraged students from Sichuan to take part in "border construction" in Xikang. In September 1929, he set up a newsletter, Bianzheng (邊政), dedicated to frontier administration. The issues of the Bianzheng promoted Sun Yat-sen's Three Principles and advertised Xikang as an attractive region for Chinese settlement, teeming with resources but nonetheless coveted by British imperialists. Propaganda plays published in the newsletter, which can be seen as the official policy of Liu Wenhui's government, exhorted youths to settle and develop the Xikang frontier, despite hardships, and thwart the imperialist plans of Tibet and Britain.
Sources: en.wikipedia.org
=== Expansion west and into rural areas === Refrigerated transportation expanded markets for agricultural regions in the South and West by allowing producers to sell perishable goods farther from where they were grown. California became an important producer and shipper of fruits including grapes, peaches, pears, plums and apples, while other regions developed specialized production of crops such as peaches, strawberries, tomatoes and cantaloupes. In California, shipments using refrigerated rail cars increased from about 4,500 carloads in 1895 to between 8,000 and 10,000 carloads in 1905. By 1917, established fruit- and vegetable-producing regions nearer eastern markets faced increased competition from more distant specialized production centres. Refrigeration also expanded the geographic range of dairy production and distribution. By the early twentieth century, some large cities obtained dairy products from farms as far as 640 kilometres (400 mi) away. Refrigeration allowed western dairy producers located far from eastern markets to compete despite transportation costs. More broadly, refrigerated transportation reduced some of the disadvantages faced by productive agricultural areas located away from traditional transport routes and major population centres.
==== Freeze-drying ==== This method is the most expensive out of all dehydration methods but provides the advantage of long stable shelf life at room temperature and an excellent retention of soluble nutrients (nitrogen protein and other solids). The product undergoes quick freeze at 10 °C (50 °F) and is then dried at a moderate temperature inside a strong vacuum. Due to the expensive nature of the equipment, the final product price is higher than tempeh preserved through other methods.
1998 A record for the duration of life among males. The Danish-American Christian Mortensen lived 115 years and 252 days. 1998 Scientists managed to extend, in a laboratory environment, the life of normal human cells beyond the Hayflick limit using telomerase. 1999 Establishment of the Buck Institute for Research on Aging – the first institute originally established primarily to study intervention into the aging process. 1999 Sierra Sciences, a biotechnology company focused on aging research with the goal of curing human aging, was founded by William H. Andrews.
Sources: en.wikipedia.org
==== Current usage in medicine ==== Desmosine is currently used as a biomarker in the medical field. It is measured in order to monitor elastin breakdown. Since it is connected to the degradation of elastin, it can be used to identify COPD. Desmosine is one of the oldest biomarkers and was developed in the 1960s, but the first time it was correlated to lung elastin content was in the 80s through urinary excretion. Biomarkers are judged in 6 ways:
Barbara Walters Interview with General Schwarzkopf, Coalition commander in the Persian Gulf War (Video: ABC, 1991) Gulf War Discussion from the Dean Peter Krogh Foreign Affairs Digital Archives Historical Context from the Dean Peter Krogh Foreign Affairs Digital Archives CBC Digital Archives – The 1991 Gulf War Master Index of Desert Storm Oral History Interviews Archived 31 December 2010 at the Wayback Machine by the United States Army Center of Military History Bibliography of the Desert Shield and Desert Storm compiled by the United States Army Center of Military History (via Wayback Machine) Desert Shield/Desert Storm Photographs Archived 17 October 2015 at the Wayback Machine US Army Heritage and Education Center, Carlisle, Pennsylvania Persian Gulf War 20th Anniversary of Desert Storm in Photos Air Force and Air Defense of Iraq before the war (not translated) exact list of the technical details Liberating Kuwait United States Marine Corps Friendly-fire Incidents Archived 1 June 2013 at the Wayback Machine – www.gulflink.osd.mil Operations Desert Shield and Desert Storm: Valorous Unit Award Citations by the United States Army Center of Military History
=== Crystallization === The structure of β-Amanitin was determined using X-ray crystallography. The crystallization and analysis were performed by Edward C. Kostansek and William H. Lipscomb in 1978. They crystallized β-Amanitin by dissolving a purified sample in almost pure ethanol in a round bottom flask. The flask was left open overnight and crystals formed as the ethanol evaporated. This is considered to be an incredibly easy crystallization to perform.
Sources: en.wikipedia.org
It is described as a synthetic analogue of the ACTH(4–10) fragment, a short segment of adrenocorticotropic hormone. Its sequence differs from that fragment and includes two proline residues, which influence stability and behaviour in solution.
It appears in Russian pharmaceutical listings as a nasal formulation, but it is not an authorised medicine in the United States or the European Union. Outside those markets it is normally encountered as a research chemical rather than a prescription product.
Laboratory and animal work points to melanocortin signalling and changes in neurotrophic factor levels, especially brain-derived neurotrophic factor. The exact receptor targets and the degree to which these findings transfer to humans are still unresolved.
Reversed-phase HPLC gives the main purity figure, most often with UV detection near 214 nanometres. Mass spectrometry then confirms the molecular mass. Together the two methods distinguish a correct sequence from a closely related impurity.