The short version of Pro-Gly-Pro fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-01-17 and is reviewed periodically as new material appears.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Route studied | Intranasal | Predominant route in published reports |
| Circulation stability | Short, minutes scale | Peptidases cleave it; the tail slows the process |
| Analytical method | RP-HPLC with mass spectrometry | Used for identity and purity assessment |
| Reported outcome domains | Anxiety and cognitive measures | Derived from small, mostly regional trials |
| Regulatory status | Marketed in Russia | Availability outside that market is limited |
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.
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
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.
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.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
== Properties == Glyoxalase I requires bound metal ions for catalysis. The human enzyme and its counterparts in yeast (Saccharomyces cerevisiae) and Pseudomonas putida use divalent zinc, Zn2+. By contrast, the prokaryotic versions often use a nickel ion. The glyoxalase I found in eukaryotic trypanosomal parasites such as Leishmania major and Trypanosoma cruzi can also use nickel for activity, possibly reflecting an acquisition of their GLO1 gene by horizontal gene transfer. A property of glyoxalase I is its lack of specificity for the catalytic metal ion. Most enzymes bind one particular type of metal, and their catalytic activity depends on having bound that metal. For example, oxidoreductases often use a specific metal ion such as iron, manganese or copper and will fail to function if their preferred metal ion is replaced, due to differences in the redox potential; thus, the ferrous superoxide dismutase cannot function if its catalytic iron is replaced by manganese, and vice versa. By contrast, although human glyoxalase I prefers to use divalent zinc, it is able to function with many other divalent metals, including magnesium, manganese, cobalt, nickel and even calcium; however, the enzyme is inactive with the ferrous cation. Similarly, although the prokaryotic glyoxalase I prefers nickel, it is able to function with cobalt, manganese and cadmium; however, the enzyme is inert with bound zinc, due to a change in coordination geometry from octahedral to trigonal bipyramidal.
Hypnotica was a class of somniferous drugs and substances tested in medicine of the 1890s and later. These include urethan, acetal, methylal, sulfonal, paraldehyde, amylenhydrate, hypnon, chloralurethan, ohloralamid, or chloralimid. Research about using medications to treat insomnia evolved throughout the last half of the 20th century. Treatment for insomnia in psychiatry dates back to 1869, when chloral hydrate was first used as a soporific. Barbiturates emerged as the first class of drugs in the early 1900s, after which chemical substitution allowed derivative compounds. Although they were the best drug family at the time (with less toxicity and fewer side effects), they were dangerous in overdose and tended to cause physical and psychological dependence. During the 1970s, quinazolinones and benzodiazepines were introduced as safer alternatives to replace barbiturates; by the late 1970s, benzodiazepines emerged as the safer drug. Benzodiazepines are not without their drawbacks; substance dependence is possible, and deaths from overdoses sometimes occur, especially in combination with alcohol or other depressants. Questions have been raised as to whether they disturb sleep architecture. Nonbenzodiazepines or Z-drugs like zolpidem were introduced in the 1980s and 1990s. Although it is clear that they are less toxic than barbiturates, their predecessors, comparative efficacy over benzodiazepines has not been established. Such efficacy is hard to determine without longitudinal studies.
Specific glycosylation has been shown to occur after the formation of the heptpeptide aglycone. Three separate glycosyl transferases are required for the glycosylation of the teicoplanin aglycone. Tei10* catalyses the addition of GlcNAc to residue 4, followed by deacetylation by Tei2*. The acyl chain (produced by the action of Tei30* and Tei13*) is then added by Tei11*. Tei1 then adds a second GlcNAc to the β-hydroxyl group of residue 6, followed by mannosylation of residue 7 catalysed by Tei3*.
Sources: en.wikipedia.org
==== Democratic reaction ==== The narrow passage of OBBBA led to internal backlash and division in the Democratic Party. Three elderly Democratic representatives (Raúl Grijalva of Arizona, age 77; Sylvester Turner of Texas, age 70; and Gerry Connolly of Virginia, age 75) died in the first five months of 2025. If any of the three had been alive when the vote was taken, the result of the vote could have been different. The vote "quickly reignited an intraparty debate about gerontocracy and aging politicians clinging to power".
==== Llanos and tropical ecology ==== In February 1800, Humboldt and Bonpland departed the Caribbean coast, setting their sights on the Orinoco River. This important northern neighbor of the Amazon promised a gateway into the equatorial jungles, famed for their extraordinary biodiversity and dense tropical vegetation. For Humboldt, the journey offered a long-awaited opportunity to conduct magnetic measurements at latitudes where Earth’s magnetism would differ significantly from what he had found in Europe. The expedition also carried the excitement of possibly confirming the rumored connection between the Orinoco and Amazon or Rio Negro river systems—a geographical mystery that had fascinated explorers for years. The most direct route from Caracas to the Orinoco would have been to cross the southern mountain chain between Baruta and Salamanca, traverse the savannahs of Ocumare, and embark at Cabruta near the Rio Guarico’s mouth. However, this shortcut would have denied the travelers the chance to survey the most fertile and cultivated regions of the province—the valleys of Aragua—along with valuable opportunities to measure the elevation of the coastal mountain chain by barometer and to descend the Rio Apure to its meeting point with the Orinoco. From Puerto Cabello, Humboldt and Bonpland made their way across the coastal ranges and llanos towards Lake Valencia. The heat was so intense that they often rode at night to avoid the sun’s punishing rays.
=== Volatile acidity === While volatile acidity (VA) is usually measured in terms of acetic acid content, its sensory perception is a combination of acetic (vinegary aromas) and ethyl acetate (nail polish remover and model airplane glue aromas). High levels of VA can inhibit wine yeast and may lead to a sluggish or stuck fermentation. Several microbes can be a source for VA, including Acetobacter, Brettanomyces, and film yeast such as Candida, as well as LAB. However, while LAB usually only produce acetic acid, these other microbes often produce ethyl acetate, as well as acetic acid. Most wine-producing countries have laws regulating the amount volatile acidity permitted for wine available for sale and consumption. In the United States, the legal limit is 0.9 g/L for foreign wine exported to the United States, 1.2 g/L for white table wine, 1.4 g/L for red wine, 1.5 g/L for white dessert wine, and 1.7 g/L for red dessert wine. European Union wine regulations limit VA to 1.08 g/L for white table wines and 1.20 g/L for red table wines. Heterofermenting species of Oenococcus and Lactobacillus have the potential to produce high levels of acetic acid through the metabolism of glucose, though with most strains of O. oeni, the amount is usually only 0.1 to 0.2 g/L. Several species of Pediococcus can also produce acetic acid through other pathways. Wines starting out with a high pH levels (above 3.5) stand the greatest risk of excessive acetic acid production due to the more favorable conditions for Lactobacillus and Pediococcus species. L.
Sources: en.wikipedia.org
Mycosporine–like amino acids are rather small molecules (<400 Da). The structures of over 30 MAAs have been resolved and all contain a central cyclohexenone or cyclohexenimine ring and a wide variety of substitutions. The ring structure is thought to absorb UV light and accommodate free radicals. All MAAs absorb ultraviolet wavelengths, typically between 310 and 362 nm. They are considered to be amongst the strongest natural absorbers of UV radiation. It is this light absorbing property that allows MAAs to protect cells from the harmful UV-B and UV-A components of sunlight. Biosynthetic pathways of MAAs depend on the specific MAA molecule and the organism that is producing it. These biosynthetic pathways often share common enzymes and metabolic intermediates with pathways of the primary metabolism. An example is the shikimate pathway that is classically used to produce the aromatic amino acids (phenylalanine, tyrosine and tryptophan); with many intermediates and enzymes from this pathway utilized in MAA biosynthesis.
In 2004, Maheshwari joined the University of Alabama at Birmingham, Alabama as an assistant professor. He studied innate immunity and the pathogenesis of gut mucosal and systemic inflammation in newborn infants, with a particular focus on a disease called necrotizing enterocolitis (NEC). In this disease, the intestines of a premature or critically ill infant become inflamed and lose viability. His research was supported by the American Gastroenterological Association and the National Institutes of Health. In 2010, he moved to the University of Illinois College of Medicine at Chicago, Illinois as the Head of Neonatology. In 2014, he was recruited to the University of South Florida as the Pamela and Leslie Muma Professor, Head of Neonatology, and Assistant Dean for Medical Education. He administered the academic and the clinical programs at the neonatal intensive care unit at Tampa General Hospital. In his laboratory, he investigated the role of intestinal macrophages and platelets in intestinal inflammation. In 2018, he relocated to the Johns Hopkins University School of Medicine, Baltimore, Maryland as the Josephine S. Sutland Professor of Newborn Medicine, Head of Neonatology, and vice-chairman of the Department of Pediatrics.
There are over 200 Clostridium species in the world that live in mundane places such as soil, water, dust, and even our digestive tracts. Some of these species produce harmful toxins such as botulinum toxin and tetanus toxin among others. Most Clostridium species that do have toxins typically have AB toxins with part of the toxin involved in cellular entry and the other element delivering a toxic cargo, that is often an enzyme into the cell. Clostridial toxins are widespread and are common causes of disease in humans and other organisms. Clostridioides difficile Toxin A and Toxin B are the two major toxins produced by Clostridioides difficile. Toxin A and toxin B are glucosyltransferases that cause the antibiotic-associated pseudomembranous colitis and severe diarrhea that characterize disease presentation of Clostridioides difficile infections. The binary toxin toxin CDT is also produced by some strains of C. difficile.
"Standard weapon grade plutonium requires a 240Pu content of no more than 6.5%." which is 65,000 ppm, and the analogous 238Pu was produced in levels of 0.5% (5,000 ppm) or less). Gun-type fission weapons additionally need low levels (1 ppm range) of light impurities, to keep the neutron generation low. The production of "clean" 233U, low in 232U, requires a few factors: 1) obtaining a relatively pure 232Th source, low in 230Th (which also transmutes to 232U), 2) moderating the incident neutrons to have an energy not higher that 6 MeV (too-high energy neutrons cause the 232Th (n,2n) → 231Th reaction) and 3) removing the thorium sample from neutron flux before the 233U concentration builds up to a too high level, in order to avoid fissioning the 233U itself (which would produce energetic neutrons). The Molten-Salt Reactor Experiment (MSRE) used 233U that contained 222 ppm 232U.
Sources: en.wikipedia.org
Reports describe effects on GABA-A receptor expression, monoamine turnover, and neurotrophic factor levels. These are proposed mechanisms drawn mainly from animal models. No single molecular target has been established.
Intranasal delivery is the route described in most published work. It is used because the peptide is degraded quickly once it reaches circulation. Direct evidence of brain penetration in humans is lacking.
Most trials are small, regionally concentrated, and often lack rigorous blinding or placebo control. Independent replication is limited. Reviews in English generally rate the evidence as preliminary.
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.