A practical reference on Reversed-phase HPLC: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2025-09-09 and is reviewed periodically as new material appears.
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.
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.
Lyophilized material is chemically stable for extended periods when kept dry, cold, and protected from light. The powder is hygroscopic, so vials should be warmed to room temperature before opening to reduce condensation on the contents. Once dissolved, the peptide is far less stable because peptide bonds are susceptible to hydrolysis and the methionine residue can oxidize. Solutions are typically aliquoted and held at 2-8 °C for short intervals or frozen for longer ones, and repeated freeze-thaw cycles should be avoided.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic heptapeptide | Analog of an ACTH fragment |
| Amino acid length | Seven residues | Met-Glu-His-Phe-Pro-Gly-Pro |
| Origin | Moscow, 1980s | Institute of Molecular Genetics |
| Approved regions | Russia and some neighboring states | Not cleared in Western markets |
| Common trade names | Multiple national brands | Sold as a nasal formulation |
Semax is a synthetic heptapeptide whose sequence is Met-Glu-His-Phe-Pro-Gly-Pro. The first four residues correspond to the ACTH(4-10) fragment, while the terminal Pro-Gly-Pro extension was added to improve metabolic stability. Its molecular formula is C37H51N9O10S and its monoisotopic mass is approximately 813.9 Da. The compound is classified as a peptide research chemical and as a registered pharmaceutical product in Russia, but it does not hold marketing approval in the European Union or the United States. Naming conventions vary across supplier catalogs.
Development of the compound took place in the Soviet Union during the 1980s, largely through peptide research groups affiliated with the Shemyakin-Ovchinnikov Institute and Moscow State University. Investigators screened fragments of adrenocorticotropic hormone for activity on the central nervous system while attempting to separate cognitive effects from hormonal ones. The shortened sequence was selected because it retained behavioral activity in animal models without stimulating corticosteroid release. Early publications described the molecule as an ACTH(4-10) analog.
Stability depends heavily on physical state. Lyophilized powder held dry, cold and dark retains its content over long periods, whereas dissolved peptide begins to change within days at room temperature. The most cited degradation route is oxidation of the methionine residue, which converts the peptide to a sulfoxide form that elutes differently on chromatography. Hydrolysis of amide bonds and adsorption onto container walls contribute smaller losses. Buffers that exclude oxygen from the headspace slow the oxidation pathway, but no single condition prevents all change indefinitely.
Practical handling follows from those properties. Bulk material is best divided into single-use portions soon after receipt, because each thaw exposes the whole container to moisture and temperature cycling. Vials should be allowed to reach room temperature before opening to prevent condensation on the powder. Low-binding plasticware reduces loss of dilute solutions, and sterile filtration is used when a preparation must remain free of microbial growth. Records of batch number, reconstitution date and storage history are what allow a later analytical result to be interpreted meaningfully.
Datura arenicola Gentry ex Bye & Luna Datura ceratocaula Ortega Datura discolor Bernh. Datura ferox L. Datura innoxia Mill. Datura kymatocarpa Barclay Datura lanosa A.S.Barclay ex Bye Datura leichhardtii Benth. Datura metel L. Datura pruinosa Greenm. Datura quercifolia Kunth Datura reburra Barclay Datura stramonium L. Datura wrightii Regel Of the above, D. leichhardtii is close enough to D. pruinosa to merit demotion to a subspecies and likewise D. ferox and D. quercifolia are close enough in morphology to merit being subsumed in a single species. Furthermore, the Australian provenance of D. leichhardtii, the Chinese provenance of D. ferox, and the Afro-Asiatic provenance of D. metel have been cast into serious doubt, with the three species being almost certainly post-Columbian introductions to the regions to which they were originally thought native. The case of D. metel is unique in that not only is the plant not a true species at all, but an assemblage of ancient pre-Columbian cultivars created from D. innoxia in the Greater Antilles, but evidence is mounting that it was introduced to the Indian subcontinent no later than the second century CE—whether by natural or human agency is, as yet, unknown—making it one of the most ancient plant introductions (if not the most ancient) from the New World to the Old World (see Columbian Exchange). D. arenicola is a recently discovered species, described first in 2013, of very restricted range, and so distinctive as to have merited the creation for it of the new section Discola [not to be confused with the species name D.
== Contraindications == Modafinil is contraindicated (should not be used) during pregnancy and 2 months before getting pregnant. Women who take modafinil should not become pregnant, and, additionally, should be aware that modafinil reduces effectiveness of hormonal contraceptives, increasing chances of getting pregnant. Modafinil therapy during pregnancy increases the risk of birth defects, such as with congenital torticollis (twisted neck), hypospadias (a urethral abnormality), and congenital heart defects. Modafinil is contraindicated for individuals with known hypersensitivity (allergic reaction) to either modafinil or armodafinil. Modafinil is also contraindicated in certain cardiac conditions, including uncontrolled moderate to severe hypertension, arrhythmia, cor pulmonale, and in cases with signs of CNS stimulant-induced mitral valve prolapse or left ventricular hypertrophy. These contraindications arise because modafinil elicits sympathomedullary activation, producing notable increases in heart rate and blood pressure that can worsen pre-existing cardiovascular conditions. Modafinil is also contraindicated in people with galactose intolerance, lactase deficiency, or glucose-galactose malabsorption (inherited conditions affecting the digestion of certain sugars, relevant because modafinil tablets contain lactose monohydrate as an inactive ingredient).
It is noteworthy that the genetic code for all organisms is basically the same, so that all living beings use the same 'genetic language'. In general, the introduction of new functional unnatural amino acids into proteins of living cells breaks the universality of the genetic language, which ideally leads to alternative life forms. Proteins are produced thanks to the translational system molecules, which decode the RNA messages into a string of amino acids. The translation of genetic information contained in messenger RNA (mRNA) into a protein is catalysed by ribosomes. Transfer RNAs (tRNA) are used as keys to decode the mRNA into its encoded polypeptide. The tRNA recognizes a specific three nucleotide codon in the mRNA with a complementary sequence called the anticodon on one of its loops. Each three-nucleotide codon is translated into one of twenty naturally occurring amino acids. There is at least one tRNA for any codon, and sometimes multiple codons code for the same amino acid. Many tRNAs are compatible with several codons. An enzyme called an aminoacyl tRNA synthetase covalently attaches the amino acid to the appropriate tRNA. Most cells have a different synthetase for each amino acid (20 or more synthetases). On the other hand, some bacteria have fewer than 20 aminoacyl tRNA synthetases, and introduce the "missing" amino acid(s) by modification of a structurally related amino acid by an aminotransferase enzyme.
Sources: en.wikipedia.org
== Lineage == Constituted 5 July 1942 in the Army of the United States as the 2d Company, 1st Battalion, First Regiment, 1st Special Service Force, a combined Canadian-American organization Activated on 9 July 1942 at Fort William Henry Harrison, Montana Disbanded on 6 January 1945 in France Reconstituted on 15 April 1960 in the Regular Army; concurrently consolidated with Company B, 1st Ranger Infantry Battalion (activated 19 June 1942), and consolidated unit redesignated as Headquarters and Headquarters Company, 1st Special Forces Group, 1st Special Forces Consolidated on 30 September 1960 with Headquarters and Headquarters Company, 1st Special Forces Group (constituted 14 June 1957 in the Regular Army and activated 24 June 1957 in Japan), and the consolidated unit was designated as Headquarters and Headquarters Company, 1st Special Forces Group, 1st Special Forces (organic units concurrently constituted and activated 4 October 1960) Group inactivated 30 June 1974 at Fort Bragg, North Carolina Activated 1 September 1984 at Fort Lewis, Washington (Former Company B, 1st Ranger Infantry Battalion, withdrawn 3 February 1986, consolidated with Company N, 75th Infantry, and consolidated unit redesignated as Company N, 75th Ranger Regiment – hereafter separate lineage) Redesignated 1 October 2005 as the 1st Special Forces Group, 1st Special Forces Regiment
A Drugscope survey of drug workers at the end of 2012 reported that mephedrone use was still widespread in the UK and that there were increasing reports of problematic users. It was being taken as not only a "poor man's cocaine" but also amongst users of heroin and crack cocaine. Cases of intravenous use were also reported to be on the increase.
Weak affinity chromatography (WAC) is an affinity chromatography technique for affinity screening in drug development. WAC is an affinity-based liquid chromatographic technique that separates chemical compounds based on their different weak affinities to an immobilized target. The higher affinity a compound has towards the target, the longer it remains in the separation unit, and this will be expressed as a longer retention time. The affinity measure and ranking of affinity can be achieved by processing the obtained retention times of analyzed compounds. Affinity chromatography is part of a larger suite of techniques used in chemoproteomics based drug target identification. The WAC technology is demonstrated against a number of different protein targets – proteases, kinases, chaperones and protein–protein interaction (PPI) targets. WAC has been shown to be more effective than established methods for fragment based screening. Affinity chromatography was conceived and first developed by Pedro Cuatrecasas and Meir Wilchek.
Sources: en.wikipedia.org
==== Unstructured ==== An unstructured repository may simply be a stack of tapes, DVD-Rs or external HDDs with minimal information about what was backed up and when. This method is the easiest to implement, but unlikely to achieve a high level of recoverability as it lacks automation.
=== Coolant additive === Graphene's high thermal conductivity suggests that it could be used as an additive in coolants. Preliminary research work showed that 5% graphene by volume can enhance the thermal conductivity of a base fluid by 86%. Another application due to graphene's enhanced thermal conductivity was found in PCR.
Pancreatic secretory trypsin inhibitor (PSTI) also known as serine protease inhibitor Kazal-type 1 (SPINK1) or tumor-associated trypsin inhibitor (TATI) is a protein that in humans is encoded by the SPINK1 gene. In the context of rat biology, it is also sometimes called monitor peptide.
[A] self-reproducing and self-reinforcing process, driven on by competitive and combative struggles in the media and political fields and giving rise to more and more scandals which increasingly become the focus of mediated forms of public debate, marginalizing or displacing other issues and producing on occasion a climate of political crisis which can debilitate or even paralyse a government.
Sources: en.wikipedia.org
It originated at the Institute of Molecular Genetics in Moscow during the 1980s. The work was carried out by a Russian research group that specialized in peptide neuropharmacology.
It is registered as a medicine in Russia and has been used clinically there for decades. No regulatory agency in Western Europe or North America has approved it for any indication.
Semax corresponds to the four-to-ten fragment of adrenocorticotropic hormone. Because it omits the first three residues, it lacks the adrenal-stimulating action of the full hormone.
Dry powder is normally held at -20 °C or lower, away from light and moisture. Sealed vials can also be kept at 2-8 °C for shorter intervals. Warming to room temperature before opening prevents condensation.