HPLC comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2026-08-01. Numbers and descriptions here follow the published literature rather than marketing material.
Development took place at the Institute of Molecular Genetics of the Russian Academy of Sciences, where a series of short peptides were designed in the 1980s and 1990s. Selank was selected from variants of tuftsin that showed resistance to plasma peptidases. Russian regulatory approval covers it as an anxiolytic agent given intranasally. Outside that market the compound is normally handled as a research chemical rather than a medicine, and no widely recognised international pharmacopoeial monograph exists. The name Selank is a coined trade designation rather than a systematic chemical name.
Enzymatic stability motivates the extra three residues at the carboxyl end. Native tuftsin is cleaved quickly by circulating aminopeptidases and carboxypeptidases, which limits its duration of action and its usefulness as a tool compound. Extending the chain with proline-rich segments is a common design tactic because proline constrains the backbone and slows proteolysis. The same Pro-Gly-Pro motif appears in other Russian-developed peptides of the era. Whether the full seven-residue chain is required for activity, or whether it acts mainly as a prodrug releasing tuftsin, remains unresolved.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. Its four N-terminal residues reproduce tuftsin, a tetrapeptide fragment of the immunoglobulin heavy chain, while the C-terminal Pro-Gly-Pro extension is a synthetic addition. The peptide has a molecular mass near 752 daltons and carries a net positive charge at physiological pH because of the arginine and lysine side chains. Published indexes list it under the name Selank and the sequence abbreviation TKPRPGP. Solid-phase peptide synthesis is the standard production route for research quantities.
Published clinical evidence is limited. Most controlled trials were conducted in Russia, enrolled modest numbers of participants, and appeared in Russian-language journals, which restricts independent verification. Reported outcomes include lower anxiety scores, improved attention and memory measures, and changes in fatigue ratings. Reviews written in English note methodological limitations such as small samples and inconsistent endpoints. Whether the compound produces clinically meaningful benefit relative to established anxiolytics is therefore an open question rather than an established finding.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue with a C-terminal Pro-Gly-Pro tail |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Abbreviated TKPRPGP in most catalogues |
| Molecular mass | About 752 Da | Value for the free peptide |
| Solubility | Freely soluble in water | Aqueous solutions are kept cold and used promptly |
| Typical storage | -20 °C, dry, protected from light | Applies to the lyophilised powder before reconstitution |
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
Handling follows standard practice for research peptides. Material is weighed in a low-humidity environment because the powder absorbs atmospheric moisture. Purity is reported as the percentage area of the main peak in a chromatogram, with specifications commonly set at 95 percent or higher; values below that threshold indicate the presence of truncated or modified species. Residual trifluoroacetate from purification is often present and may affect mass balance. Certificates of analysis should state the analytical method, the column and gradient used, and the lot-specific retention time so that results can be compared across suppliers.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
Peptide bonds in selank are susceptible to hydrolysis under strongly acidic or basic conditions, and the terminal proline residues are vulnerable to exopeptidase activity in biological samples. Lyophilized powder stored dry at -20 °C typically remains stable for extended periods, whereas aqueous solutions degrade faster and may lose measurable purity within days to weeks depending on pH, temperature, and microbial load. Repeated freeze-thaw cycles promote aggregation and adsorption to container surfaces. For analytical work, solutions are usually prepared fresh, kept cold, and used within a single working day.
The compound was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences during the 1980s and 1990s. The stated design goal was to retain the immunomodulatory and central nervous system activity attributed to tuftsin while improving resistance to enzymatic breakdown. Adding a proline-rich tail to the short parent peptide was a deliberate strategy, because proline residues restrict the conformations available to many peptidases. The same laboratory produced Semax, an ACTH fragment analog, and both compounds were developed in parallel as short, enzymatically stabilized peptides intended for intranasal use.
Selank is not a naturally occurring peptide and has no known endogenous counterpart in human physiology. Russian-language sources frequently call it TP-7, while English-language sources use the name Selank almost exclusively. Database indexing is uneven, partly because early reports appeared in regional journals that are not widely cataloged. Some summaries describe the material as a tuftsin analog and others as a synthetic heptapeptide; the labels overlap rather than conflict. Citing the primary sequence resolves ambiguity more reliably than the research or trade name alone.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter notation. Its structure consists of the immunomodulatory tetrapeptide tuftsin, Thr-Lys-Pro-Arg, extended at the carboxyl terminus by a Pro-Gly-Pro segment. The molecular formula is commonly given as C33H57N11O9, corresponding to a monoisotopic mass near 751.4 Da and an average molecular mass near 751.9 Da. All seven residues are proteinogenic amino acids, and the molecule carries no modified side chains or non-natural linkages.
1962 Waksman Merck postdoc fellowship, USA. 1967 Humboldt assistant professorship stipend at the Max-Planck Institute, Munich, Germany. 1970 visiting professorship at the Weizmann Institute of Science, Rehovot, Israel. 1973 guest professorship in Dallas, Texas, USA. 1978 guest professorship (Japan Society for the Promotion of Science) in Japan. 1982–1986 Full Professor (Ordinarius) in biotechnology at The Federal Institute of technology, ETH Zurich, Switzerland. 1993 honorary visiting professorship in biochemistry at the University of Bath, UK. 1995 honorary visiting professorship in biochemistry at the Université Catholique de Louvain, Louvain-la-Neuve, Belgium. During these stays he collaborated with Nobel Prize winners Lynen, Waksman as well as with Professors Estabrook and Srere, Katchalski-Katzir and Wilchek, Fukui, Chibata, Suzuki, Rees and Creighton respectively.
Notch family members play a role in a variety of developmental processes by controlling cell fate decisions. The Notch signaling network is an evolutionarily conserved intercellular signaling pathway that regulates interactions between physically adjacent cells. In Drosophila, notch interaction with its cell-bound ligands (delta, serrate) establishes an intercellular signaling pathway that plays a key role in development. This protein functions as a receptor for membrane bound ligands, and may play multiple roles during development. A deficiency can be associated with bicuspid aortic valve. There is evidence that activated Notch 1 and Notch 3 promote differentiation of progenitor cells into astroglia. Notch 1, then activated before birth, induces radial glia differentiation, but postnatally induces the differentiation into astrocytes. One study shows that Notch-1 cascade is activated by Reelin in an unidentified way. Reelin and Notch1 cooperate in the development of the dentate gyrus, according to another.
freezing point Also crystallization point. The temperature at which a substance changes state from a liquid to a solid. Because freezing is the reverse of melting, the freezing point of a substance is identical to its melting point, but by convention only the melting point is referred to as a characteristic property of a substance.
=== July === 1 July SpudCells, a type of artificial cell, are publicly announced. A study published in Nature reports that GPNMB-targeted CAR-T cells can target both glioblastoma cells and tumour-associated macrophages, eliminating detectable tumours and producing long-term disease control in preclinical models. Astronomers report the discovery of Gaia23bra b, the first gravitationally bound exoplanet detected by the Transiting Exoplanet Survey Satellite using gravitational microlensing. The planet is a super-Jupiter orbiting a K dwarf about 40,000 light-years from Earth. 6 July – A study presented at the Federation of European Neuroscience Societies Forum finds that multilingualism is associated with a younger estimated brain age, with people speaking four languages showing brain-connectivity patterns corresponding to about 13 years younger than monolingual people. 13 July – Astronomers announce the detection of erythrulose molecules inside a cloud of gas and dust near the centre of the Milky Way, marking the first evidence of sugar in interstellar space. 16 July – Astronomers report the first observationally confirmed atmosphere around a rocky exoplanet within its star's habitable zone, after detecting helium escaping from the upper atmosphere of LHS 1140 b, a super-Earth approximately 49 light-years from Earth. 29 July – Researchers report a previously unrecognised pathological structure in Alzheimer's disease, termed a "mitochondrial plaque": an accumulation of damaged mitochondria within neuronal processes, associated with impaired mitophagy and lysosomal function.
The American Society for Clinical Pathology (ASCP), formerly known as the American Society of Clinical Pathologists, is a professional association based in Chicago, Illinois, encompassing 130,000 pathologists and laboratory professionals. Founded in 1922, the ASCP provides programs in education, certification and advocacy on behalf of patients, pathologists and lab professionals. In addition, the ASCP publishes numerous textbooks, newsletters and other manuals, and publishes two industry journals: American Journal of Clinical Pathology (AJCP) and LabMedicine. On August 10, 2026, Dr. Alexandra Brown, MD, FASCP, was named CEO.
Sources: en.wikipedia.org
Pindolol, sold under the brand name Visken among others, is a non-selective beta blocker which is used in the treatment of hypertension. It is also an antagonist of the serotonin 5-HT1A receptor, preferentially blocking inhibitory 5-HT1A autoreceptors, and has been researched as an add-on therapy to various antidepressants, such as clomipramine and the selective serotonin reuptake inhibitors (SSRIs), in the treatment of depression and obsessive–compulsive disorder (OCD).
In May 2016, a study published in the journal Nature determined that HNK, specifically (2S,6S;2R,6R)-HNK, is responsible for the antidepressant-like effects of ketamine in mice; administration of (2R,6R)-HNK demonstrated ketamine-type antidepressant-like effects, and preventing the metabolic conversion of ketamine into HNK blocked the antidepressant-like effects of the parent compound. As (2R,6R)-HNK, unlike ketamine, does not antagonize the NMDA receptor to a clinically relevant degree, and produces no dissociative or euphoric effects, it has consequently been concluded that the antidepressant effects of ketamine may in fact not be mediated via the NMDA receptor. This is tentative, as confirmation that the findings translate to humans is still needed, but it is notable that published human data show a positive association between the antidepressant responses of ketamine and plasma (2S,6S;2R,6R)-HNK levels. In accordance with the notion that the NMDA receptor is not responsible for the antidepressant effects of ketamine, dizocilpine (MK-801), which binds to and blocks the same site on the NMDA receptor that ketamine does, lacks antidepressant-like effects. Moreover, the findings would explain why other NMDA receptor antagonists such as memantine, lanicemine, and traxoprodil have thus far failed to demonstrate ketamine-like antidepressant effects in human clinical trials. Instead of acting via blockade of the NMDA receptor, (2R,6R)-HNK increases activation of the AMPA receptor via a currently unknown/uncertain mechanism.
== Corporate Social Responsibility == As part of their Corporate Social Responsibility commitment, Hetero Group founded Sindhu Hospitals, a not-for-profit yet premium healthcare facility dedicated to providing world class healthcare underserved communities.
Mercury is commonly used in small scale gold mining. To do this, large amounts of mercury are usually mixed with gold-containing materials to create a gold-mercury alloy called amalgam. To separate the gold, the amalgam is heated in a furnace causing the mercury to vaporize. During this process, miners are directly exposed to mercury vapors, and surrounding communities may be indirectly exposed through contaminated air, water, and soil. Continuous high levels of mercury vapor inhalation can cause a variety of health effects. Inhalation may result in tremors, mood swings, muscle weakness, memory loss, or headaches. Prolonged exposure can lead to kidney damage, respiratory failure, and even death. Ingestion of mercury through contaminated water, food, or soil pose great risk to pregnant women and their developing fetuses. When born, this can impair the infants' cognitive functions, memory, language development, and fine motor skills. Despite its widespread use across countries, mercury exposure in artisanal small-scale gold mining is preventable. Mercury-free techniques like direct smelting result in gold recovery without the need of mercury resulting in the elimination of mercury. In this method, borax is used to decrease the viscosity and melting temperature of non-gold minerals so they can be easily separated from the gold. This not only results in improved worker and community health but also lower in cost and eco-friendly.
== Resistance genes == Resistance to blasticidin S can be conferred by either of two deaminases: BSD, originally isolated from Aspergillus terreus or bsr, isolated from Bacillus cereus. Both deaminases work by modifying blasticidin S directly, replacing the amine on the cytosine ring with a hydroxyl group, resulting in the inactive deaminohydroxy-blasticin S. bsr and BSD are the most commonly used resistance genes. The proteins produced from these genes enable the cells carrying them to produce proteins in the presence of blasticidin.
Sources: en.wikipedia.org
=== Bromine halides === The halogens form many binary, diamagnetic interhalogen compounds with stoichiometries XY, XY3, XY5, and XY7 (where X is heavier than Y), and bromine is no exception. Bromine forms a monofluoride and monochloride, as well as a trifluoride and pentafluoride. Some cationic and anionic derivatives are also characterised, such as BrF2−, BrCl2−, BrF2+, BrF4+, and BrF6+. Apart from these, some pseudohalides are also known, such as cyanogen bromide (BrCN), bromine thiocyanate (BrSCN), and bromine azide (BrN3). The pale-brown bromine monofluoride (BrF) is unstable at room temperature, disproportionating quickly and irreversibly into bromine, bromine trifluoride, and bromine pentafluoride. It thus cannot be obtained pure. It may be synthesised by the direct reaction of the elements, or by the comproportionation of bromine and bromine trifluoride at high temperatures. Bromine monochloride (BrCl), a red-brown gas, quite readily dissociates reversibly into bromine and chlorine at room temperature and thus also cannot be obtained pure, though it can be made by the reversible direct reaction of its elements in the gas phase or in carbon tetrachloride. Bromine monofluoride in ethanol readily leads to the monobromination of the aromatic compounds PhX (para-bromination occurs for X = Me, But, OMe, Br; meta-bromination occurs for the deactivating X = -CO2Et, –CHO, -NO2); this is due to heterolytic fission of the Br–F bond, leading to rapid electrophilic bromination by Br+. At room temperature, bromine trifluoride (BrF3) is a straw-coloured liquid.
There are many formats of BsAbs, but the two main categories are IgG-like and non-IgG-like. The main types of manufacturing methods are quadromas, chemical conjugation, and genetic recombination, and each method results in a unique format.
=== Gases === The solubility of gases in water is usually thought to decrease with temperature, but this only occurs to a certain temperature, before increasing again. For nitrogen, this minimum is 74 °C and for oxygen it is 94 °C Gases are soluble in superheated water at elevated pressures. Above the critical temperature, water is completely miscible with all gases. The increasing solubility of oxygen in particular allows superheated water to be used for wet oxidation processes.
In January 2016, fellow El Mencho brother-in-law Elvis González Valencia was arrested as well, though he was later released in December 2016. In 2018, two more El Mencho brother-in-laws, Arnulfo and Ulises Gonzalez Valencia, was arrested as well. In May 2019, the U.S. government acknowledged that Ulises Gonzalez Valencia, a key CJNG leader who had been issued new Office of Foreign Assets Control sanctions, had in fact been arrested in 2018. In July 2018, Mexican authorities arrested José Guadalupe Rodríguez Castillo (alias 'El 15'), a local leader of the cartel. His arrest is related to the disappearance of three Italian businessmen in the Southern Jalisco town of Tecalitlán in January 2018. In March 2019, a senior CJNG leader, who chose to remain anonymous and was only identified as "El 20", was arrested by Mexican authorities. "El 20", who remained anonymous, was second-in-command to the CJNG. More than 80 elements of 41 Military Zone, as well as the Navy, and the Federal Police, as well as four CJNG members who also remained anonymous, were also arrested with "El 20." In April 2019, Adrián Alonso Guerrero Covarrubias, known as "El 8" or "El M", was arrested for drug trafficking and kidnapping. Guerrero served as head of the cartel's operations in the Ciénega and northern Los Altos regions in Jalisco and all of southeastern Guanajuato, and is the godson to cartel leader Nemesio Oseguera Cervantes. In February 2020, El Mencho's daughter Jessica Johana, 33, known as "La Negra" was arrested in Washington D.C.
== History and etymology == Proline was first isolated in 1900 by Richard Willstätter who obtained the amino acid while studying N-methylproline, and synthesized proline by the reaction of sodium salt of diethyl malonate with 1,3-dibromopropane. The next year, Emil Fischer isolated proline from casein and the decomposition products of γ-phthalimido-propylmalonic ester, and published the synthesis of proline from phthalimide propylmalonic ester. The name proline comes from pyrrolidine, one of its constituents.
Sources: en.wikipedia.org
Selank is a seven-amino-acid peptide built from the tuftsin sequence plus a Pro-Gly-Pro tail. It is produced by chemical synthesis rather than extracted from a natural source. The free peptide is usually supplied as a lyophilised powder or in an aqueous formulation.
Tuftsin is a natural tetrapeptide derived from the Fc portion of immunoglobulin G. Selank retains that tetrapeptide at its N-terminus and adds three residues to improve resistance to enzymatic breakdown. The relationship is structural, and the two molecules are not interchangeable in experimental work.
It holds a product registration in Russia for intranasal use as an anxiolytic. Registrations of that kind are not automatically accepted by regulators elsewhere. In most other countries it is treated as an unapproved substance or a research material.
It is a seven-amino-acid peptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro, produced by chemical synthesis rather than extracted from biological tissue. Its design is based on tuftsin, a natural immunomodulatory tetrapeptide. The C-terminal Pro-Gly-Pro segment is a common stabilising motif in short regulatory peptides.