Intranasal route raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2025-08-30. Anything still debated is marked as such rather than presented as settled.
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.
Naming for this compound is not fully standardised in English sources. The spelling Selanc appears in some transliterations, and catalogue entries may instead list the peptide sequence itself as the identifier. Reference material sometimes groups it with other short synthetic peptides studied for behavioural effects, which can create confusion when citations are compared. Distinguishing the exact sequence from related tuftsin analogues is therefore a practical first step when reviewing any dataset or specification sheet.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, frequently abbreviated as TKPRPGP. It was designed as a structural analogue of tuftsin, a naturally occurring tetrapeptide released by enzymatic cleavage of the immunoglobulin heavy chain. The two additional proline residues at the C-terminal end extend the parent chain and change how the molecule behaves in solution. The free peptide has a calculated molecular mass of approximately 751.9 g/mol and is generally supplied as a lyophilised white to off-white powder.
| 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 |
Quality assessment of Selank samples typically combines purity determination with identity confirmation and counter-ion analysis. Purity is usually reported as a percentage by chromatographic area, with values above 95 percent often quoted for research-grade material. Water content and residual solvents are checked in lyophilized batches because they affect both stability and accurate mass determination. A reported purity figure does not by itself establish that a sample is the intended sequence, so orthogonal methods are needed to rule out sequence isomers or truncation products.
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.
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.
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
Pharmacokinetic data are limited. Like most short peptides, Selank is vulnerable to plasma and tissue peptidases, and its measured half-life in circulation is short, on a minutes scale. The Pro-Gly-Pro tail slows this degradation but does not eliminate it. Intranasal administration is the route described in most reports, with absorption through the nasal mucosa and a hypothesized path into the central nervous system that avoids the blood-brain barrier. Direct measurements of human brain exposure are unavailable, so distribution claims rest on inference from animal work.
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
== Toxicological experiments == During the 1980s the Philip Morris Tobacco Company carried out research on sidestream smoke at the Institut für Biologische Forschung, although this was not voluntarily published. This study found that sidestream smoke is nearly four times more toxic than mainstream smoke per metric gramme. They also found that sidestream condensate was nearly three times more toxic than mainstream smoke as well as 2–6 times more tumourigenic per gram than mainstream condensate when applied to the skin of a mouse; results also showed that sidestream smoke hinders an animal's ability to reach a weight that is considered normal. The research team concluded that the only way to protect oneself from sidestream smoke was to be in smoke-free public places and workspaces.
=== Sahrawi Arab Democratic Republic === The Castillo Administration recognized the Sahrawi Arab Democratic Republic, a partially-recognized state claimed by Morocco. Although the recognition came without forewarning, officially it was due to Castillo's push for a foreign policy based on self-determination and non-intervention. The Congressional opposition has opposed the recognition of the SADR, claiming that it creates geopolitical instability and risks Peru's relations with the Middle East.
== Pathology == It has been found that type 2 diabetics are not responsive to GIP and have lower levels of GIP secretion after a meal when compared to non-diabetics. In research involving knockout mice, it was found that absence of the GIP receptors correlates with resistance to obesity.
Occasionally a radiologic diagnosis of disc degeneration is made incidentally when a cervical X-ray, chest X-ray, or abdominal X-ray is taken for other reasons and the abnormalities of the vertebral column are recognized. The diagnosis of DDD is not a radiologic diagnosis, since the interpreting radiologist is not aware whether there are symptoms. Typical radiographic findings include disc space narrowing, displacement of vertebral bodies, fusion of adjacent vertebral bodies, and development of bone in adjacent soft tissue (osteophyte formation). An MRI is typically reserved for those with symptoms, signs, and X-ray findings suggesting a need for surgical intervention. Treatment may include physical therapy for pain relief, ROM (range of motion), and appropriate muscle/strength training, with emphasis on correcting abnormal posture, assisting the paravertebral (paraspinous) muscles in stabilizing the spine, and core muscle strengthening; stretching exercises; massage therapy; oral analgesia with non-steroidal anti-inflammatory agents (NSAIDS); and topical analgesia with lidocaine, ice, and heat. Immediate surgery may be indicated if the symptoms are severe or sudden in onset, or suddenly worsen. Elective surgery may be indicated after six months of conservative therapy with unsatisfactory relief of symptoms.
== Role in bone decomposition == Diagenesis alters the proportions of organic collagen and inorganic components (hydroxyapatite, calcium, magnesium) of bone exposed to environmental conditions, especially moisture. This is accomplished by the exchange of natural bone constituents, deposition in voids or defects, adsorption onto the bone surface and leaching from the bone.
Sources: en.wikipedia.org
Keene, Douglas R.; Sakai, Lynn Y.; Lunstrum, Gregory P.; Morris, Nicholas P.; Burgeson, Robert E. (1987). "Type VII collagen forms an extended network of anchoring fibrils". The Journal of Cell Biology. 104 (3): 611–21. doi:10.1083/jcb.104.3.611. PMC 2114566. PMID 3818794. McGrath, John A.; Ishida-Yamamoto, Akemi; O'Grady, Anthony; Leigh, Irene M.; Eady, Robin A. J. (1993). "Structural Variations in Anchoring Fibrils in Dystrophic Epidermolysis Bullosa: Correlation with Type VII Collagen Expression". Journal of Investigative Dermatology. 100 (4): 366–72. doi:10.1111/1523-1747.ep12471830. PMID 8454899.
RTG technology was first developed by Los Alamos National Laboratory during the 1960s and 1970s to provide radioisotope thermoelectric generator power for cardiac pacemakers. Of the 250 plutonium-powered pacemakers Medtronic manufactured, twenty-two were still in service more than twenty-five years later, a feat that no battery-powered pacemaker could achieve. This same RTG power technology has been used in spacecraft such as Pioneer 10 and 11, Voyager 1 and 2, Cassini–Huygens and New Horizons, and in other devices, such as the Mars Science Laboratory and Mars 2020 Perseverance Rover, for long-term nuclear power generation.
=== Effect on nutrients and sensory quality === Due to the low processing temperatures and the minimization of deterioration reactions, nutrients are retained and color is maintained. Freeze-dried fruit maintains its original shape and has a characteristic soft crispy texture.
In molecular biology, the amino acid kinase domain is a protein domain. It is found in protein kinases with various specificities, including the aspartate, glutamate and uridylate kinase families. In prokaryotes and plants the synthesis of the essential amino acids lysine and threonine is predominantly regulated by feed-back inhibition of aspartate kinase (AK) and dihydrodipicolinate synthase (DHPS). In Escherichia coli, thrA, metLM, and lysC encode aspartokinase isozymes that show feedback inhibition by threonine, methionine, and lysine, respectively. The lysine-sensitive isoenzyme of aspartate kinase from spinach leaves has a subunit composition of 4 large and 4 small subunits. In plants although the control of carbon fixation and nitrogen assimilation has been studied in detail, relatively little is known about the regulation of carbon and nitrogen flow into amino acids. The metabolic regulation of expression of an Arabidopsis thaliana aspartate kinase/homoserine dehydrogenase (AK/HSD) gene, which encodes two linked key enzymes in the biosynthetic pathway of aspartate family amino acids has been studied. The conversion of aspartate into either the storage amino acid asparagine or aspartate family amino acids may be subject to a coordinated, reciprocal metabolic control, and this biochemical branch point is a part of a larger, coordinated regulatory mechanism of nitrogen and carbon storage and utilization.
USS Windham Bay delivered Grumman F8F Bearcat fighter aircraft to Saigon on January 26, 1951. On March 2, 1951, the United States Navy transferred USS Agenor (LST 490) to the French Navy in Indochina in accordance with the MAAG-led MAP. Renamed RFS Vulcain (A-656), she was used in Operation Hirondelle in 1953. USS Sitkoh Bay carrier delivered Grumman F8F Bearcat aircraft to Saigon on March 26, 1951. During September 1953, USS Belleau Wood (renamed Bois Belleau) was lent to France and sent to French Indochina to replace the Arromanches. She was used to support delta defenders in the Hạ Long Bay operation in May 1954. In August she joined the Franco-American evacuation operation called "Passage to Freedom". The same month, the United States delivered additional aircraft, again using USS Windham Bay. On April 18, 1954, during the siege of Dien Bien Phu, USS Saipan delivered 25 Korean War AU-1 Corsair aircraft for use by the French Aeronavale in supporting the besieged garrison.
Sources: en.wikipedia.org
The two substrates of this enzyme are L-lysine and oxidised nicotinamide adenine dinucleotide (NAD+). Its products are (2S)-2,3,4,5-tetrahydropyridine-2-carboxylic acid (1), ammonia, reduced NADH, and a proton. The enzyme is highly specific for L-lysine as substrate, although S-(2-aminoethyl)-L-cysteine can act as a substrate, but more slowly.
Its quadrupole moment causes line broadening. Used in metabolic and biochemical studies of chemical equilibria. 19F, spin-1/2, relatively commonly measured. Sensitive, yields sharp signals, has a wide chemical shift range. 31P, spin-1/2, 100% of natural phosphorus. Medium sensitivity, wide chemical shift range, yields sharp lines. Spectra tend to have a moderate level of noise. Used in biochemical studies and in coordination chemistry with phosphorus-containing ligands. 35Cl and 37Cl, spin-3/2, broad signal. 35Cl is significantly more sensitive, preferred over 37Cl despite its slightly broader signal. Organic chlorides yield very broad signals. Its use is limited to inorganic and ionic chlorides and very small organic molecules. 43Ca, spin-7/2, relatively small quadrupole moment, moderately sensitive, very low natural abundance. Used in biochemistry to study calcium binding to DNA, proteins, etc. 195Pt, used in studies of catalysts and complexes. Other nuclei (usually used in the studies of their complexes and chemical bonding, or to detect presence of the element):
=== Prokaryotic === Although sterol biosynthesis is rare in prokaryotes, certain bacteria, including Methylococcus capsulatus, specific methanotrophs, myxobacteria, and the planctomycete Gemmata obscuriglobus, are capable of producing sterols. In G. obscuriglobus, sterols are essential for cell viability, but their roles in other bacteria remain poorly understood. Prokaryotic sterol synthesis involves the tetracyclic steroid framework, as found in myxobacteria, as well as hopanoids, pentacyclic lipids that regulate bacterial membrane functions. These sterol biosynthetic pathways may have originated in bacteria or been transferred from eukaryotes. Sterol synthesis depends on two key enzymes: squalene monooxygenase and oxidosqualene cyclase. Phylogenetic analyses of oxidosqualene cyclase (Osc) suggest that some bacterial Osc genes may have been acquired via horizontal gene transfer from eukaryotes, as certain bacterial Osc proteins closely resemble their eukaryotic homologs.
Along with Blount and McClung, those who purchased lots in the city included merchants Hugh Dunlap, Thomas Humes, and Nathaniel and Samuel Cowan, newspaper publisher George Roulstone, the Reverend Samuel Carrick, frontiersman John Adair (who had built a fort just to the north in what is now Fountain City), and tavern keeper John Chisholm.
Nutrition science (theoretical focus) and dietetics (practical focus) is the study of the relationship of food and drink to health and disease, especially in determining an optimal diet. Medical nutrition therapy is done by dietitians and is prescribed for diabetes, cardiovascular diseases, weight and eating disorders, allergies, malnutrition, and neoplastic diseases. Pathology as a science is the study of disease – the causes, course, progression and resolution thereof. Pharmacology is the study of drugs and their actions. Photobiology is the study of the interactions between non-ionizing radiation and living organisms. Physiology is the study of the normal functioning of the body and the underlying regulatory mechanisms. Radiobiology is the study of the interactions between ionizing radiation and living organisms. Toxicology is the study of hazardous effects of drugs and poisons.
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.
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, commonly written as TKPRPGP. It shares the first four residues with tuftsin and carries three prolines in the chain. The proline-rich tail is the main structural feature that separates it from the parent tetrapeptide.