RP-HPLC raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2025-12-18. Anything still debated is marked as such rather than presented as settled.
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.
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.
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.
Laboratory work points toward modulation of neurotrophic signaling, particularly expression of brain-derived neurotrophic factor and nerve growth factor in hippocampal tissue. Studies also describe effects on monoamine turnover, inflammatory mediators, and oxidative markers. These observations come mainly from animal models and cultured cells, so the causal chain in humans is not firmly established. Whether the reported molecular changes translate into measurable clinical benefit is an open question. Reviews generally present the mechanism as plausible rather than demonstrated.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilised solid |
| Solubility class | Freely soluble in water | Also dissolves in aqueous buffers |
| Typical storage temperature | -20 °C | Dry, desiccated, protected from light |
| Typical analytical method | RP-HPLC with UV detection | Often paired with LC-MS |
| Water content | Reported as Karl Fischer value | Freeze-dried material is hygroscopic |
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.
Later generations of the molecule include an N-acetylated form and an amidated form, both marketed online alongside the parent peptide. These variants differ in terminal chemistry and stability, and they are frequently discussed in the same breath even though they have not been compared in controlled trials. Supply outside formal healthcare systems comes largely from laboratories that synthesize peptides to order. Purity and identity of these materials vary widely, and no single body oversees the international trade.
Semax is a synthetic heptapeptide developed in the Soviet Union during the 1980s by researchers at the Institute of Molecular Genetics in Moscow. It was designed as a truncated analog of adrenocorticotropic hormone, retaining only the fragment spanning residues four through ten. Investigators sought a peptide that would preserve the cognitive effects associated with ACTH while eliminating the hormonal stimulation of the adrenal cortex. The compound entered clinical use in Russia during the following decade.
Russian regulatory authorities approved the peptide for nasal administration, and it remains listed in the national pharmacopoeia under several trade names. Documented indications include acute ischemic stroke, transient ischemic attacks, traumatic brain injury, and certain ophthalmological and neurological conditions. Physicians also prescribe it for cognitive complaints in older patients, although the evidence base for that use is thinner. Outside Russia and a few neighboring states, the substance is not an approved medicine and is sold instead as a research chemical.
== History == 1996 - Institut für Bioanalytik GmbH was founded by Herbert Stadler, IBA introduces Strep-tag products 1998 - Acquisition of NAPS Göttingen GmbH (Nucleic Acid Products Supply) 1999 - Biologics joint venture with GBF Braunschweig 2001 - Institut für Bioanalytik GmbH was renamed to IBA GmbH 2003 - IBA introduces Streptamer cell isolation technology 2004 - Operations segmented into Protein, Gene and Cell TAGnology business units 2007 - IBA introduces StarGate cloning system 2008 - Innovation Award for StarGate 2010 - IBA introduces Fab-Streptamer technology 2011 - Innovation Award for Streptamer cell isolation technology 2012 - IBA introduces Fab-TACS (Formerly known as T-CATCH) column based cell purification 2014 - IBA earned its ISO 9001:2008 certification for Quality Management Standard, IBA introduces Strep-Tactin XT products 2015 - 6th foreign Trade Award of Lower Saxony (Germany), IBA launches MEXi mammalian expression system 2016 - IBA introduces cell selection device FABian
Liquid metals have several properties that are useful in sensing and actuation, particularly their electrical conductivity and ability to transmit forces (incompressibility). As freely flowing substances, liquid metals retain these bulk properties even under extreme deformation. For this reason, they have been proposed for use in soft robots and wearable healthcare devices, which must be able to operate under repeated deformation. The metal gallium is considered to be a promising candidate for these applications as it is a liquid near room temperature, has low toxicity, and evaporates slowly.
Certain serpins spontaneously undergo the S to R transition without having been cleaved by a protease, to form a conformation termed the latent state. Latent serpins are unable to interact with proteases and so are no longer protease inhibitors. The conformational change to latency is not exactly the same as the S to R transition of a cleaved serpin. Since the RCL is still intact, the first strand of the C-sheet has to peel off to allow full RCL insertion. Regulation of the latency transition can act as a control mechanism in some serpins, such as PAI-1. Although PAI-1 is produced in the inhibitory S conformation, it "auto-inactivates" by changing to the latent state unless it is bound to the cofactor vitronectin. Similarly, antithrombin can also spontaneously convert to the latent state, as an additional modulation mechanism to its allosteric activation by heparin. Finally, the N-terminus of tengpin, a serpin from Thermoanaerobacter tengcongensis, is required to lock the molecule in the native inhibitory state. Disruption of interactions made by the N-terminal region results in spontaneous conformational change of this serpin to the latent conformation.
Sources: en.wikipedia.org
Electron transfer dissociation takes place in an ion trap mass spectrometer with an electrospray ionization source. The first ETD experiments at the University of Virginia utilized a radio frequency quadrupole linear ion trap (LQT) modified with a chemical ionization (CI) source at the back side of the instrument (see diagram at right). Because a spectrum can be obtained in about 300 milliseconds, liquid chromatography is often coupled with the ETD MS/MS. The disadvantage of using LQT is that the mass resolving power is less than that of other mass spectrometers. Subsequent studies have tried other instrumentation to improve mass resolution. Having a negative CI source at the back of the instrument interfered with the high-resolution analyzer in LQT-Orbitrap and quadrupole time-of-flight (QTOF), so alternate ionization methods for the radical anions have been introduced. In 2006 a group at Purdue University led by Scott McLuckey used a quadrupole/time-of-flight (QqTOF) tandem mass spectrometer with pulsed nano-ESI/atmospheric pressure chemical ionization (APCI) dual ionization source using radical anions of 1,3-dinitrobenzene as the electron donor. Later a lab at the University of Wisconsin adapted a hybrid quadrupole linear ion trap-orbitrap mass spectrometer to use ETD. This method also used a front-end ionization method for the radical anions of 9-anthracenecarboxylic acid via pulsed dual ESI sources.
== Research career == Mary Osborn carried out postdoctoral research from 1967 to 1969 in the laboratory of James Watson at Harvard University. Then she conducted research at the Laboratory of Molecular Biology, Cambridge, UK (1969–72) before moving to the Cold Spring Harbor Laboratory (1972-75.) Osborn had married her husband, Klaus Weber, on 14 July 1972. Weber and Osborn moved to the Göttingen Max Planck Institute for Biophysical Chemistry where Weber was Director and Osborn received a staff appointment in 1975. in 1989, she was appointed an honorary professor at University of Göttingen.
However, insulin therapy may be conducted without CGM and although there is not yet an automated insulin-regulation feedback mechanism between measure and infusion to control the amount and timing of insulin, this is clearly a future objective. Any change in basal or bolus is patient-driven by programming the pump using the Bolus Wizard. The latest model pumps are the MiniMed Paradigm 522 and 722, which differ in reservoir size, 176 versus 300 units, respectively. In 2007 the FDA approved a pediatric model for patients 7 to 17 years old.
In November 1965 the government of the British colony of Southern Rhodesia issued an illegal Unilateral Declaration of Independence. This government represented the country's small white minority and was led by Prime Minister Ian Smith. The black majority of the population had little influence on the government, which sought to continue white racial privileges. At the time of independence the Rhodesian Security Forces were relatively large and well trained and equipped. Two groups with armed elements emerged as the opposition to the white Rhodesian regime. These were the Zimbabwe African National Union (ZANU), whose military wing was the Zimbabwe African National Liberation Army (ZANLA), and the Zimbabwe African People's Union (ZAPU) and its armed wing the Zimbabwe People's Revolutionary Army (ZIPRA). Both groups were initially based in Zambia, and from the late 1960s began dispatching insurgents into Rhodesia who used guerrilla tactics. These attacks initially proved ineffective and the Rhodesian military, which had been bolstered by forces from South Africa, was able to effectively counter them. Rhodesia's security situation began to deteriorate from late 1972, when the guerrilla armies began making more effective attacks in the north-east of the country. The collapse of the Portuguese Empire in 1975 that led to the independence of Mozambique led to a further increase to the challenges facing the Rhodesian regime, with the guerrillas using that country as well as Botswana as bases.
Sources: en.wikipedia.org
Reversed-phase high-performance liquid chromatography is the standard method, with detection in the ultraviolet range. Peak area percentage yields a purity figure for the main component. Mass spectrometry is normally run alongside to confirm molecular identity.
Dry lyophilised powder is generally kept at minus twenty degrees Celsius, protected from light and moisture. Repeated freeze-thaw cycles are avoided because they encourage aggregation and moisture uptake. Solutions are less stable than the solid form and degrade faster at room temperature.
A certificate documents what the supplier measured, not what an independent party confirmed. Methods, instruments and acceptance criteria can differ between suppliers. Third-party testing is the usual way to resolve discrepancies.
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.