The short version of batch purity fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-10-12 and is reviewed periodically as new material appears.
Reported pharmacological effects center on reduced anxiety-like behavior in animal models and on measures of memory and learning. Proposed contributing mechanisms include modulation of GABAergic signaling, shifts in monoamine turnover, and changes in the activity of enzymes that degrade neuropeptides. Effects on the expression of genes linked to neuroplasticity have also been described. No single molecular target is widely accepted, and whether the behavioral findings arise from one pathway or several remains an open question.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed as a stabilized analogue of tuftsin, a naturally occurring tetrapeptide fragment derived from the immunoglobulin heavy chain. The additional Pro-Gly-Pro segment at the carboxyl terminus is intended to slow enzymatic cleavage. The compound is usually described in the literature as a synthetic peptide with anxiolytic and cognitive-related activity, a label that reflects a research context rather than an approved therapeutic category.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C33H57N11O9 | Derived from the seven-residue sequence |
| Molecular weight | About 751.9 g/mol | Average mass; the monoisotopic value is slightly lower |
| Residue count | Seven amino acids | Thr-Lys-Pro-Arg-Pro-Gly-Pro |
| Parent compound | Tuftsin (Thr-Lys-Pro-Arg) | Selank extends tuftsin at the C-terminus |
| Compound class | Synthetic short peptide | Studied in a research setting; not a licensed drug in most markets |
Characterization of Selank in laboratory settings relies on standard peptide analytical techniques. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities and degradation products, while mass spectrometry confirms molecular identity through accurate mass measurement. Amino acid analysis and peptide sequencing verify the primary structure when reference material is unavailable. Because Selank is a short chain, fragmentation-based analysis produces a diagnostic ion pattern that supports confident identification.
Peptide stability depends strongly on temperature, moisture, and pH. Lyophilized Selank is generally most stable when stored cold and dry, with freezer temperatures commonly used for long-term storage. In solution, the compound is susceptible to hydrolysis and to microbial growth if it is not handled aseptically. The C-terminal proline-rich extension appears to slow enzymatic cleavage relative to tuftsin, though quantitative degradation rates vary with the matrix and the conditions tested. Published stability data specific to Selank remain sparse.
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade material.
Regulatory treatment varies by jurisdiction. In Russia the compound is a registered prescription product, while in the European Union and the United States it is generally handled as a research chemical without a marketing authorization. Suppliers therefore operate outside pharmaceutical oversight, and buyers rely on supplier documentation for purity and identity claims. Chain of custody and third-party testing are the main verification tools. Analysts note that the absence of a pharmacopoeial monograph for research-grade material limits standardization across vendors.
Purity assessment relies mainly on reverse-phase high-performance liquid chromatography with ultraviolet detection. Because the peptide lacks a strong chromophore, detection often uses backbone absorbance near 214 nm. Identity is confirmed by mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, comparing the measured mass against the expected value. Amino acid analysis can verify composition after acid hydrolysis. Diastereomer content and residual counterions are reported less often, although both can influence biological assays.
Lyophilized material is generally stable for extended periods when kept dry at or below minus twenty degrees Celsius. Working solutions are less stable, and common practice is to aliquot and freeze them so that repeated freeze-thaw cycles are avoided. Aqueous solutions are sensitive to pH extremes and to microbial growth, so short-term storage at refrigerator temperature is typical. Oxidation and hydrolysis are the principal degradation routes. Reconstitution with sterile water or a mild buffer is standard, and solutions should be protected from light.
==== HEp-2 ==== Until around 1975, when HEp-2 cells were introduced, animal tissue was used as the standard substrate for immunofluorescence. HEp-2 cells are currently one of the most common substrates for ANA detection by immunofluorescence. Originally started a laryngeal carcinoma strain, the cell line was contaminated and displaced by HeLa cells, and has now been identified as actually HeLa cells. They are superior to the previously used animal tissues because of their large size and the high rate of mitosis (cell division) in the cell line. This allows the detection of antibodies to mitosis-specific antigens, such as centromere antibodies. They also allow identification of anti-Ro antibodies, because acetone is used for fixation of the cells (other fixatives can wash the antigen away). There are many nuclear staining patterns seen on HEp-2 cells: homogeneous, speckled, nucleolar, nuclear membranous, centromeric, nuclear dot and pleomorphic. The homogeneous pattern is seen when the condensed chromosomes and interphase chromatin stain. This pattern is associated with anti-dsDNA antibodies, antibodies to nucleosomal components, and anti-histone antibodies. There are two speckled patterns: fine and coarse. The fine speckled pattern has fine nuclear staining with unstained metaphase chromatin, which is associated with anti-Ro and anti-La antibodies. The coarse staining pattern has coarse granular nuclear staining, caused by anti-U1-RNP and anti-Sm antibodies.
==== Lipid metabolism ==== The liver plays several roles in lipid metabolism: it performs cholesterol synthesis, lipogenesis, and the production of triglycerides, and a bulk of the body's lipoproteins are synthesized in the liver. The liver plays a key role in digestion, as it produces and excretes bile (a yellowish liquid) required for emulsifying fats and helps the absorption of vitamin K from the diet. Some of the bile drains directly into the duodenum, and some is stored in the gallbladder. The liver produces insulin-like growth factor 1, a polypeptide protein hormone that plays an important role in childhood growth and continues to have anabolic effects in adults.
isomers Ions or molecules with identical chemical formulas but distinct structures or spatial arrangements. Isomers do not necessarily share similar properties. The two main types of isomers are structural isomers and stereoisomers.
Voltage – Regulated by the difference in voltage across the membrane Stress – Regulated by physical pressure on the transporter (as in the cochlea of the ear) Ligand – Regulated by the binding of a ligand to either the intracellular or extracellular side of the cell Uniporters are found in mitochondria, plasma membranes and neurons.The uniporter in the mitochondria is responsible for calcium uptake. The calcium channels are used for cell signaling and triggering apoptosis. The calcium uniporter transports calcium across the inner mitochondrial membrane and is activated when calcium rises above a certain concentration. The amino acid transporters function in transporting neutral amino acids for neurotransmitter production in brain cells. Voltage-gated potassium channels are also uniporters found in neurons and are essential for action potentials. This channel is activated by a voltage gradient created by sodium-potassium pumps. When the membrane reaches a certain voltage, the channels open, which depolarizes the membrane, leading to an action potential being sent down the membrane. Glucose transporters are found in the plasma membrane and play a role in transporting glucose. They help to bring glucose from the blood or extracellular space into cells usually to be utilized for metabolic processes in generating energy. Uniporters are essential for certain physiological processes in cells, such as nutrient uptake, waste removal, and maintenance of ionic balance.
Sources: en.wikipedia.org
=== Biochemistry === Iron acquisition poses a problem for aerobic organisms because ferric iron is poorly soluble near neutral pH. Thus, these organisms have developed means to absorb iron as complexes, sometimes taking up ferrous iron before oxidising it back to ferric iron. In particular, bacteria have evolved very high-affinity sequestering agents called siderophores. After uptake in human cells, iron storage is precisely regulated. A major component of this regulation is the protein transferrin, which binds iron ions absorbed from the duodenum and carries it in the blood to cells. Transferrin contains Fe3+ in the middle of a distorted octahedron, bonded to one nitrogen, three oxygens and a chelating carbonate anion that traps the Fe3+ ion: it has such a high stability constant that it is very effective at taking up Fe3+ ions even from the most stable complexes. At the bone marrow, transferrin is reduced from Fe3+ to Fe2+ and stored as ferritin to be incorporated into hemoglobin. The most commonly known and studied bioinorganic iron compounds (biological iron molecules) are the heme proteins: examples are hemoglobin, myoglobin, and cytochrome P450. These compounds participate in transporting gases, building enzymes, and transferring electrons. Metalloproteins are a group of proteins with metal ion cofactors. Some examples of iron metalloproteins are ferritin and rubredoxin. Many enzymes vital to life contain iron, such as catalase, lipoxygenases, and IRE-BP.
=== EC 1.14.18 With another compound as one donor, and incorporation of one atom of oxygen into the other donor === EC 1.14.18.1: tyrosinase EC 1.14.18.2: CMP-N-acetylneuraminate monooxygenase EC 1.14.18.3: methane monooxygenase (particulate) EC 1.14.18.4: phosphatidylcholine 12-monooxygenase EC 1.14.18.5: sphingolipid C4-monooxygenase EC 1.14.18.6: 4-hydroxysphinganine ceramide fatty acyl 2-hydroxylase EC 1.14.18.7: dihydroceramide fatty acyl 2-hydroxylase EC 1.14.18.8: Now included with EC 1.14.14.139, 5β-cholestane-3α,7α-diol 12α-hydroxylase EC 1.14.18.9: 4α-methylsterol monooxygenase EC 1.14.18.10: plant 4,4-dimethylsterol C-4α-methyl-monooxygenase EC 1.14.18.11: plant 4α-monomethylsterol monooxygenase EC 1.14.18.12: 2-hydroxy fatty acid dioxygenase
A serous membrane lines the pericardial cavity of the heart, and reflects back to cover the heart, much like an under-inflated balloon would form two layers surrounding a fist. Called the pericardium, this serous membrane is a two-layered sac that surrounds the entire heart except where blood vessels emerge on the heart's superior side; The pleura is the serous membrane that surrounds the lungs in the pleural cavity; The peritoneum is the serous membrane that surrounds several organs in the abdominopelvic cavity. The tunica vaginalis is the serous membrane, which surrounds the male gonad, the testis. The two layers of serous membranes are named parietal and visceral. Between the two layers is a thin fluid filled space. The fluid is produced by the serous membranes and stays between the two layers to reduce friction between the walls of the cavities and the internal organs when they move with respect to one another, such as when the lungs inflate or the heart beats. Such movement could otherwise lead to inflammation of the organs.
Sources: en.wikipedia.org
The sequencing platform to be used is chosen depending on different factors such as laboratory's research objectives, personal experience and skill levels. So far, the Illumina MiSeq system has proven to be the most commonly used platform for infectious disease research, pathogen surveillance, and pathogen discovery in research and public health. The instrument is compact enough to fit on a laboratory bench, has a fast runtime as compared to other similar platforms, and has a strong user support community. However, with further improvements of this technology and with additional error reduction and software stabilization, the MinION may be an excellent addition to the arsenal of current sequencing technologies for routine surveillance, especially in smaller laboratories with limited resources. For instance, the MinION was successfully used in the ZiBRA project for real-time Zika virus surveillance of mosquitoes and humans in Brazil, and in Guinea to perform real-time surveillance during the ongoing Ebola outbreak. In general, for limited resources IlluminaMiSeq, iSeq, Ion Torrent PGM, Oxford Nanopore, MinION are used. While for substantial resources Illumina NextSeq, NovaSeq, PacBio Sequel, Oxford Nanopore and PromethION are preferred.
In MCCs, there is no deconvolution required to determine which compounds are biologically active, because each synthesis in an array has only a single product, thus the identity of the compound should be unequivocally known.
== Ingestion == There are a few ways to consume Salvia divinorum. In traditional Mazatec ritual, shamans use only fresh Salvia divinorum leaves. Modern methods have been developed to more effectively absorb the active principle, salvinorin A. If enough salvinorin A is absorbed, an altered state of consciousness can occur. The duration of experience varies with the method of ingestion and the amount of salvinorin A absorbed.
== Cellular immunotherapy == Immune cell-based therapies for solid tumors may be limited by tumor-antigen heterogeneity, restricted immune-cell trafficking, an immunosuppressive tumor microenvironment, limited cell persistence, treatment-related toxicities, and complex manufacturing requirements.
Sources: en.wikipedia.org
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, designed as a metabolically stabilized analogue of the endogenous tetrapeptide tuftsin. It has been studied mainly against anxiety-related and cognitive endpoints rather than as an approved medicine in most jurisdictions.
Tuftsin contains four residues, while selank carries an additional Pro-Gly-Pro segment at the carboxyl end. That extension is intended to reduce enzymatic cleavage. Comparative pharmacokinetic data in humans remain limited.
No single receptor target is widely accepted as the definitive mediator of the reported effects. Proposed contributors include GABAergic modulation, shifts in monoamine turnover, and altered neuropeptide degradation. The mechanism is treated in the literature as unresolved.
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.