Research chemical 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.
Last reviewed on 2025-11-02. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
Regulatory status differs sharply by region. Selank holds a Russian marketing authorization, where it is supplied mainly as nasal drops, while authorities elsewhere have not approved it for medical use. Material sold internationally is therefore usually labeled as a research chemical rather than a medicine. Peer-reviewed publications come predominantly from Russian laboratories, and sample sizes are generally small. Whether the compound produces comparable effects under independent, well-controlled replication remains an open question that the broader literature has not settled.
Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
| Property | Value | Notes |
|---|---|---|
| Common route | Intranasal | Also injected in some animal work |
| Solubility class | Freely soluble in water | Solid form is hygroscopic |
| Typical storage | About -20 degrees Celsius | Keep desiccated and dark |
| Purity method | Reverse-phase HPLC | Reported as area percent |
| Confirmatory method | Mass spectrometry | Verifies expected molecular mass |
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, with mass spectrometry used to confirm molecular mass and sequence information. Amino acid analysis and peptide mapping may supplement these methods. Certified reference standards are scarce, and many commercial lots are sold as research chemicals without a pharmacopoeial monograph. Regulatory treatment differs by country: Selank is a registered prescription medicine in Russia, while in the European Union and the United States it is not an approved drug and may fall under research-chemical or unapproved-product frameworks.
Selank is a hydrophilic peptide and dissolves readily in water and in aqueous buffers. The lyophilised powder is typically a white to off-white solid. Because short peptides are prone to hydrolysis and oxidation, handling benefits from limiting exposure to heat, moisture and strong light. Working solutions are commonly prepared in sterile water or saline, and repeated freeze-thaw cycles are avoided to reduce aggregation and loss of activity. These practices reflect general laboratory convention rather than published stability specifications.
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.
Naming conventions place Selank in the same research family as Semax, another Russian-developed peptide investigated for cognitive effects. The two compounds share a lineage but differ in sequence and in the biological systems proposed as their targets. Semax descends from ACTH fragments, whereas Selank descends from tuftsin. Publications sometimes identify Selank by its full peptide sequence or by laboratory codes rather than one uniform trade name. Because replication outside Russia is limited, reports on its properties are best read alongside the study design and the purity of the material tested.
Selank is a synthetic heptapeptide developed in Russia during the 1990s. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences designed it as a stabilized analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The compound has been studied primarily for its reported anxiolytic and nootropic effects. It remains largely unknown in Western pharmacology and is not approved as a medicine by major regulators such as the FDA or the EMA.
The primary structure of Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro, corresponding to the molecular formula C33H57N11O9 and a monoisotopic mass of roughly 751.9 daltons. The N-terminal threonine and the arginine residue in the fourth position are shared with tuftsin, which carries the sequence Thr-Lys-Pro-Arg. The three additional residues at the C-terminus, Pro-Gly-Pro, extend the chain and are associated with greater resistance to enzymatic degradation. This extension also separates Selank from the shorter parent peptide.
White sharks are estimated to swim 2.88–4.86 km/h (1.79–3.02 mph) but can sprint up to 24.12 km/h (14.99 mph). One individual was recorded cruising at a sustained speed of 4.7 km/h (2.9 mph) while migrating, which is fast for a shark and more similar to fast-swimming tuna. White sharks display various surface behaviors. These include spyhopping (poking head out of the surface) to observe an object above the water, as well as 'repetitive aerial gaping' where a spyhopping shark repeatedly gapes its mouth while belly-up, possibly as a sign of frustration after missing a bait. How they sleep is not well understood. At night, one individual was recorded swimming slowly in one direction along a current with its mouth open. The white shark is generally considered to be a solitary species, though aggregations do occur. A 2016 study of sharks around Mossel Bay, South Africa, concluded that white shark associations are generally random with few social interactions. By contrast, a 2019 study found that sharks around Neptune Islands gathered in non-random aggregations. Similarly, a 2022 study of white sharks at Guadalupe Island suggested that individuals may associate so that they can learn from others where to find prey or carcasses to scavenge. White shark aggregations can consist of individuals of a specific age and sex. At Neptune Islands, sightings of subadult females peak during April and May, subadult males in February and again in September, adult females in June, and adult males in September.
=== Presence in livestock species during gestation === Bovine/Ovine RBP, identical to that found in plasma has been identified in the placental tissues of both the ovine and the bovine, suggesting that RBP may be highly involved in retinol transport and metabolism during pregnancy. However, exact timing of expression had been yet to be identified. An antiserum specific for bovine conceptus RBP and immunohistochemistry has been utilized to identify the presence of RBP at different stages of early pregnancy. Strong immunostaining and hybridization were observed in the trophectoderm of tubular, but not spherical blastocysts at day 13. RBP mRNA was localized to epithelial cells of the chorion, allantois, and amnion at day 45 of pregnancy. Lastly, RBP mRNA was detected in the cotyledons, the fetal contribution to the placenta and the site of attachment to the uterine epithelium for fetal/maternal exchange. Expression of RBP in developing conceptuses, extraembryonic membranes, and at the fetal-maternal interface indicate that there may be some regulation of retinol transport and metabolism that occurs due to RBP by the extraembryonic membranes. Within the uterus of pregnant bovines, it has been found that RBP synthesis in the luminal and glandular epithelium is quite similar to that of a cyclic animal's; however upon reaching day 17 of the estrous cycle, levels of RBP remain constant and continue to gradually rise throughout gestation. It has also been suggested that ovarian steroids may play a role in regulating uterine RBP expression.
=== San Antonio Nathan Shock Center === The San Antonio Nathan Shock Center (NSC) is one of only eight National Institute on Aging (NIA)-funded Nathan Shock Centers of Excellence in the Basic Biology of Aging in the United States. Since its establishment in 1995, the Center has served as an internationally recognized resource dedicated to advancing the fundamental biology of aging and accelerating the development of interventions that promote healthy aging and extend healthspan. The overarching mission of the Center is to identify the molecular, cellular, and physiological mechanisms that drive the aging process and translate these discoveries into strategies that delay or prevent age-associated diseases and functional decline. The San Antonio Nathan Shock Center provides investigators with an integrated, "one-stop-shop" research infrastructure that supports every stage of aging research—from experimental design and animal model development to functional phenotyping, pathology, metabolism, pharmacology, and data interpretation. This comprehensive approach enables investigators to conduct rigorous, multidisciplinary studies that examine lifespan, healthspan, and the biological mechanisms underlying aging. By integrating specialized expertise and state-of-the-art technologies within a single research environment, the Center accelerates scientific discovery while promoting collaboration among investigators locally, nationally, and internationally. The Center is organized around six highly integrated research cores that provide specialized services and scientific expertise.
=== Gas chromatography === GC is a method involving the separation of different analytes within a sample of mixed gases. The separated gases can be detected multiple ways, but one of the most powerful detection methods for gas chromatography is mass spectrometry. After the gases separate, they enter the mass spectrometer and are analyzed. This combination not only separates the analytes, but gives structural information about each one. The GC sample must be volatile, or able to enter the gas phase, while also being thermally stable so that it does not break down as it is heated to enter the gas phase. Mass spectrometry ionization techniques requiring the sample to be in the gas phase have similar concerns. Electron ionization (EI) in mass spectrometry requires samples that are small molecules, volatile, and thermally stable, similar to that of gas chromatography. This ensures that as long as GC is performed on the sample before entering the mass spectrometer, the sample will be prepared for ionization by EI. Chemical ionization (CI) is another method that requires samples to be in the gas phase. This is so that the sample can react with a reagent gas to form an ion that can be analyzed by the mass spectrometer. CI has many of the same requirements in sample preparation as EI, such as volatility and thermal stability of the sample. GC is useful for sample preparation for this technique as well. One advantage of CI is that larger molecules separated by GC can be analyzed by this ionization method.
Ribosomal ribonucleic acid (rRNA) is a type of non-coding RNA which is the primary component of ribosomes, essential to all cells. rRNA is a ribozyme which carries out protein synthesis in ribosomes. Ribosomal RNA is transcribed from ribosomal DNA (rDNA) and then bound to ribosomal proteins to form small and large ribosome subunits. rRNA is the physical and mechanical factor of the ribosome that forces transfer RNA (tRNA) and messenger RNA (mRNA) to process and translate the latter into proteins. Ribosomal RNA is the predominant form of RNA found in most cells; it makes up about 80% of cellular RNA despite never being translated into proteins itself. Ribosomes are composed of approximately 60% rRNA and 40% ribosomal proteins, though this ratio differs between prokaryotes and eukaryotes.
Sources: en.wikipedia.org
TMA-2's affinity (Ki) for the serotonin 5-HT2A receptor has been found to be 1,300 nM. Its EC50Tooltip half-maximal effective concentration at the receptor was 190 nM and its EmaxTooltip maximal efficacy was 84%. The drug was also active at the serotonin 5-HT2B receptor and, to a much lesser extent, at the serotonin 5-HT2C receptor. In an earlier study, its affinities (Ki) were 1,650 nM at the serotonin 5-HT2 receptor and 46,400 nM at the serotonin 5-HT1 receptor. TMA-2 is inactive at the monoamine transporters. It was inactive at the mouse trace amine-associated receptor 1 (TAAR1), whereas it bound to the rat TAAR1 with an affinity (Ki) of 3,100 nM and was not assessed at the human TAAR1.
== Development history == The original concept of BsAbs was proposed by Nisonoff and his collaborators in the 1960s, including the first idea of antibody architecture and other findings. In 1975, the problem of producing pure antibodies was solved by the creation of hybridoma technology, and the new era of monoclonal antibodies (MAbs) came. In 1983, Milstein and Cuello created hybrid-hybridoma (quadroma) technology. In 1988, the single-chain variable fragment (scFv) was invented by the Huston team to minimize the refolding problems, which contains the incorrect domain pairing or aggregation of two-chain species. In 1996, the BsAbs became more developed when the knobs-into-holes technology emerged.
=== Arrays === Lectin and antibody arrays provide high-throughput screening of many samples containing glycans. This method uses either naturally occurring lectins or artificial monoclonal antibodies, where both are immobilized on a certain chip and incubated with a fluorescent glycoprotein sample. Glycan arrays, like that offered by the Consortium for Functional Glycomics and Z Biotech LLC, contain carbohydrate compounds that can be screened with lectins or antibodies to define carbohydrate specificity and identify ligands.
In addition, they claim that the Matazetas are "prohibited to extort, kidnap, steal, abuse, or do anything that will affect the national patrimony", and that they are the "armed wing of the Mexican people." On 6 October 2011 in Boca del Río, Veracruz, 36 bodies were found by the Mexican authorities in three different houses. The Navy first discovered 20 bodies inside a house in a residential neighborhood. While searching at another house they found 11 more bodies. The third and final house contained one body. Four other bodies were confirmed separately by the state government of Veracruz. A day later, Reynaldo Escobar Pérez, the State Justice Attorney General, stepped down and resigned due to the drug-violence. And a day after his resignation, 10 more bodies were found throughout the city of Veracruz. The CJNG was also responsible for 67 killings in Veracruz on 7 October 2011. By 9 October 2011, in only eighteen days, the state of Veracruz reported 100 killings.
Binding of CNP to NPR-B catalyzes the synthesis of cGMP, which is responsible for mediating the anti-fibrotic effects of CNP. Fibrotic heart tissue is associated with an increase risk of ventricular dysfunction which can ultimately lead to heart failure. Thus, anti-fibrotic strategies are a promising approach in the prevention and treatment of heart failure.
Sources: en.wikipedia.org
=== Bipolar disorder === In a small clinical study, pentazocine, a KOR agonist, rapidly reduced acute manic symptoms in bipolar disorder patients. The therapeutic mechanism is postulated to involve KOR agonist-mediated suppression of excessive dopaminergic signaling in reward pathways and striatal circuits that drive manic hyperactivity and impulsivity. Complete desensitization of KOR renders the receptor unable to gate dopaminergic signaling, thereby lifting the inhibitory constraint and disinhibiting phasic dopamine and norepinephrine release. Temporary KOR sensitization during acute mania may reverse this disinhibition.
=== Other names === GAR-936 Tygacil Tigeplug (marketed by Biocon, India) Tigilyn (Marketed by Real Value therapy pharmaceuticals company in Myanmar, Manufactured by Lyka) TIGILITE (marketed in INDIA, Scutonix Lifesciences, Bombay)
When allowed to react with superacids, sulfuric acid can act as a base and can be protonated, forming the [H3SO4]+ ion. Salts of [H3SO4]+ have been prepared (e.g. trihydroxyoxosulfonium hexafluoroantimonate(V) [H3SO4]+[SbF6]−) using the following reaction in liquid HF:
Among prokaryotes, five major groups of bacteria have evolved the ability to photosynthesize, including heliobacteria, green sulfur and nonsulfur bacteria and proteobacteria. However, the only lineage where oxygenic photosynthesis has evolved is in the cyanobacteria, often known as blue-green algae for their blue-green (cyan) coloration. They are classified as the phylum Cyanobacteriota or Cyanophyta. However, this phylum also includes two classes of non-photosynthetic bacteria: Melainabacteria (also called Vampirovibrionia or Vampirovibrionophyceae) and Sericytochromatia (also known as Blackallbacteria). A third class contains the photosynthetic ones, known as Cyanophyceae (also called Cyanobacteriia or Oxyphotobacteria). As bacteria, their cells lack membrane-bound organelles, with the exception of thylakoids. Like other algae, cyanobacteria have chlorophyll a as their primary photosynthetic pigment. Their accessory pigments include phycobilins (phycoerythrobilin and phycocyanobilin), carotenoids and, in some cases, b, d, or f chlorophylls, generally distributed in phycobilisomes found in the surface of thylakoids. They display a variety of body forms, such as single cells, colonies, and unbranched or branched filaments. Their cells are commonly covered in a sheath of mucilage, and they also have a typical gram-negative bacterial cell wall composed largely of peptidoglycan. They have various storage particles, including cyanophycin as aminoacid and nitrogen reserves, "cyanophycean starch" (similar to plant amylose) for carbohydrates, and lipid droplets.
== Terminology == In 1901, Jōkichi Takamine patented a purified extract from the adrenal glands, which was trademarked by Parke, Davis & Co in the US. The British Approved Name and European Pharmacopoeia term for this drug is hence adrenaline (from Latin ad, "on", and rēnālis, "of the kidney", from ren, "kidney"). However, the pharmacologist John Abel had already prepared an extract from adrenal glands as early as 1897, and he coined the name epinephrine to describe it (from Ancient Greek ἐπῐ́ (epí), "upon", and νεφρός (nephrós), "kidney"). As the term Adrenaline was a registered trademark in the US, and in the belief that Abel's extract was the same as Takamine's (a belief since disputed), epinephrine instead became the generic name used in the US and remains the pharmaceutical's United States Adopted Name and International Nonproprietary Name (though the name adrenaline is frequently used). The terminology is now one of the few differences between the INN and BAN systems of names. Although European health professionals and scientists preferentially use the term adrenaline, the converse is true among American health professionals and scientists. Nevertheless, even among the latter, receptors for this substance are called adrenergic receptors or adrenoceptors, and pharmaceuticals that mimic its effects are often called adrenergics. The history of adrenaline and epinephrine is reviewed by Rao.
Sources: en.wikipedia.org
Most published work uses intranasal application, either as drops or as a nasal spray. Injection routes appear in a smaller set of animal experiments. Oral use is uncommon in the literature because peptide breakdown and poor absorption limit this route.
Reported human trials are few, brief and originate mainly from one country. They describe effects on anxiety-related measures, but sample sizes are small and reporting is limited. The results are widely regarded as preliminary rather than confirmed.
Reverse-phase liquid chromatography is used to assess purity and separation of related impurities. Mass spectrometry confirms that the observed molecular mass matches the expected peptide. A certificate of analysis from the supplier is the usual document of record.
Selank is a synthetic seven-amino-acid peptide modeled on tuftsin, a fragment of the immunoglobulin G heavy chain. It was designed in Russia to combine anxiolytic and immunomodulatory properties in one molecule.