The short version of pharmacokinetics fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-05-23 and is reviewed periodically as new material appears.
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.
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.
Dry powder is normally held at -20 degrees Celsius or lower, in a sealed container with desiccant and protection from light. Reconstituted solutions are usually kept at 2 to 8 degrees Celsius for short periods and frozen for longer ones. Proline residues at several positions are generally associated with some resistance to peptidase attack, but chemical stability still declines at neutral to alkaline pH and at elevated temperature. Exact shelf-life figures are product-specific and are not standardised across suppliers.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C33H57N11O9 | Free peptide form |
| Molecular mass | About 751.9 Da | Calculated average mass |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form TKPRPGP |
| Structural basis | Tuftsin analogue | Extended version of a natural tetrapeptide |
| Development origin | Russian Academy of Sciences | Work carried out from the 1980s onward |
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 work is concentrated in Russian-language journals and generally involves small samples without independent replication. Systematic reviews in English note the shortage of randomised, placebo-controlled trials and the difficulty of verifying methods from translated reports. Outcome measures vary between studies, which complicates pooling of results. Interest in the compound as a cognitive or anxiolytic agent therefore rests on a thinner evidence base than the volume of citations suggests. Replication in well-powered trials with preregistered endpoints would be needed before firm conclusions about efficacy can be drawn.
Proposed mechanisms centre on the GABAergic system. Animal and tissue studies report changes in GABA-A receptor expression and reduced activity of GABA transaminase, the enzyme that degrades GABA. Effects on monoamine turnover, including serotonin and dopamine pathways, are also described, and a separate line of work links the peptide to increased expression of brain-derived neurotrophic factor in hippocampal tissue. Most of these findings come from rodent models and cell preparations. How the individual observations combine into a single coherent mode of action is not settled.
Most published work on selank originates from a small number of research groups in the Russian Federation. A large share of that record appears in Russian-language journals, which limits access for readers who rely on English-indexed databases. Independent replication by laboratories outside the original research network is sparse in publicly available sources. This concentration of origin and language is a frequently noted feature when the compound is summarized in broader reviews of synthetic peptides.
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.
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.
== Theory == There are just 230 different ways of arranging objects in regular three-dimensional arrays. In molecular crystallography, these arrangements are called 'space groups'. However, only 65 of these arrangements are accessible to chiral objects or chiral molecules. The remaining 165 space groups contain either a center of symmetry or a mirror plane and are thus not accessible to natural globular proteins, which are chiral molecules. Wukowitz and Yeates developed a mathematical theory to explain the preference of globular proteins to crystallize in certain space groups. They suggested the preferred space group was determined by the number of degrees of freedom (D) or dimensionality as a measure of the ease with which a given symmetry can be formed. They analyzed the number of degrees of freedom for both chiral and achiral space groups where it was found that the space group P1(bar) with D=8 is theoretically the most dominant space group. Since the achiral space group had a higher degree of freedom compared to the chiral space groups, they predicted that racemic mixtures of protein enantiomers would crystallize more readily compared to the natural L-proteins alone by forming achiral {L-protein plus D-protein} pairs. While space group P1(bar) is most preferred, P21/c and C2/c are also highly preferred, whereas the other achiral space groups are expected to appear less frequently. Hence, P1(bar), P21/c, and C2/c are considered common centrosymmetric space groups in racemic mixtures.
Chromatography software is called also Chromatography Data System. It is located in the data station of modern liquid, gas or supercritical fluid chromatographic systems. This is a dedicated software connected to a hardware interface within the chromatographic system, which serves as a central hub for collecting, analyzing, and managing the data generated during the chromatographic analysis. The data station is connected to the entire instrument in modern systems, especially the detectors, allowing real-time monitoring of the runs, exhibiting them as chromatograms. A chromatogram is a graphical representation of the results obtained from the chromatographic system. In a chromatogram, each component of the mixture appears as a peak or band at a specific retention time, which is related to its characteristics, such as molecular weight, polarity, and affinity for the stationary phase. The height, width, and area of the peaks in a chromatogram provide information about the amount and purity of the components in the sample. Analyzing a chromatogram helps identify and quantify the substances present in the mixture being analyzed.
== History == The first IUD was developed in 1909 by the German physician Richard Richter of Waldenburg. Unlike modern intrauterine devices, early interuterine (from Latin inter-, meaning "between", as opposed to intra-) devices crossed both the vagina and the uterus, causing a high rate of pelvic inflammatory disease. Ernst Gräfenberg, another German physician (after whom the G-spot is named), created the first Ring IUD, Gräfenberg's ring, made of silver filaments. His work was suppressed during the Nazi regime, when contraception was considered a threat to Aryan women. In 1935, Gräfenberg, who was Jewish, was in jail in Berlin and Margaret Sanger paid a ransom to have him released. He moved to the United States and opened a private practice in New York, New York. His colleagues H. Hall and M. Stone took up his work after his death and created the stainless steel Hall-Stone Ring. Dr. Jack Lippes helped begin the increase of IUD use in the United States in the late 1950s. In this time, thermoplastics, which can bend for insertion and retain their original shape, became the material used for first-generation IUDs. Lippes also devised the addition of the nylon string to facilitate IUD removal. Lippes and his friend Paul Bronnenkant, a plastics developer, crafted the first Lippes Loop in Bronnenkant's kitchen, heating and molding the plastic on cookie sheets in the oven. His trapezoid-shaped Lippes Loop IUD became one of the most popular first-generation IUDs. In the following years, many different-shaped plastic IUDs were invented and marketed.
2024 United Kingdom riots: Two 12-year-old boys become the youngest people to be convicted following their involvement in the disorder. Figures show that 125 migrants crossed the English Channel in small boats. 13 August Banknotes featuring King Charles, with a face value of £78,430 and low serial numbers, are auctioned for £914,127 to raise money for charity. An inquest is held into the death of former England cricketer Graham Thorpe, who died from suicide after being struck by a train at a railway station. Data from the Office for National Statistics shows UK unemployment fell to 4.2% in the three months to June, down from 4.4% during the previous quarter. Ofgem approves a £3.4bn project for a subsea cable allowing renewable energy to be transported from Scotland to England more easily. 14 August Inflation is reported to have risen from 2% to 2.2%, the first increase during 2024. The predicted increase is largely a result of a smaller fall in gas and electricity prices in July when compared to July 2023. 2024 United Kingdom riots: A 53-year-old woman from Cheshire is sentenced to 15 months in prison after admitting sending a communication threatening death or serious harm over a Facebook post in which she suggested a mosque should "be blown up with the adults inside". Two men found in a burned-out car in Malmö, Sweden, are confirmed as two British men, Farooq Abdulrazak, 37, and Juan Cifuentes, 33, who went missing in July. Train drivers' union ASLEF is to ballot its members on a revised pay offer following negotiations with the Department for Transport.
In 2010, the Ghent nosology was revised, and new diagnostic criteria superseded the previous agreement made in 1996. The seven new criteria can lead to a diagnosis: In the absence of a family history of MFS:
Sources: en.wikipedia.org
An FA disciplinary commission found Wenger guilty; he received a 12-match touchline ban and a fine of four weeks' salary. He successfully appealed the ban, but was reprimanded and fined £10,000 for his actions. Following the 2007 Football League Cup Final, he called a linesman a liar, for stating Emmanuel Adebayor aimed a punch at Chelsea's Frank Lampard. This led to an investigation by the FA, a fine of £2,500 and a warning. In March 2011, Wenger was charged with improper conduct by UEFA, over comments made to referee Massimo Busacca, after his team's defeat to Barcelona. He was fined €10,000 and suspended for one UEFA club competition match; however, the ban was later extended to a further two games, after Wenger was found guilty of communicating with Arsenal's bench while serving a touchline ban against Udinese. A year later, Wenger was charged for post-match comments made about referee Damir Skomina, in Arsenal's defeat to Milan in the Champions League. He was fined £33,000 and handed a three-match touchline ban in the competition.
== History == The earliest human activity in Ningxia can be traced back to 30,000 years ago, with remains of the Shuidonggou culture found in Lingwu. As a frontier zone between nomadic pastoralists and sedentary farmers, Ningxia was a frequent seat of war and incursions by non-Chinese tribes. Ningxia and its surrounding areas were incorporated into the Qin as the Beidi Commandery as early as the 3rd century BC. To pacify the region, the imperial government established military colonies to reclaim land. In addition, horse pasturages were founded under the Imperial Stud to safeguard the supply of army horses, as early as the Western Han dynasty (206 BC – AD 9). Throughout the Han dynasty and the Tang dynasty there were several large cities established in the region. The Liang Province rebellion at the end of the Han dynasty affected Ningxia. By the 11th century the Tangut people had established the Western Xia dynasty on the outskirts of the then-Song dynasty. Jews also lived in Ningxia, as evidenced by the fact that in 1489, after a major flood destroyed Torah scrolls in Kaifeng, a replacement set was sent to the Kaifeng Jews by the Ningbo and Ningxia Jewish communities. It then came under Mongol domination after Genghis Khan conquered Yinchuan in the early 13th century. Muslims from Central Asia also began moving into Ningxia from the west. By the late 17th century, Ningxia had become a weaving centre, producing many early Chinese carpets. The Muslim Dungan Revolt of the 19th century affected Ningxia. In 1914, Ningxia was merged with the province of Gansu.
1942: Native American aerospace engineer Mary Golda Ross became employed at Lockheed Aircraft Corporation, where she provided troubleshooting for military aircraft. She went on to work for NASA, developing operational requirements, flight plans, and a Planetary Flight Handbook for spacecraft missions such as the Apollo program. 1943: British geologist Eileen Guppy was promoted to the rank of assistant geologist, therefore becoming the first female geology graduate appointed to the scientific staff of the British Geological Survey. 1943: American geologist and crystallographer Elizabeth A. Wood became the first female to be hired as a member of the technical staff (MTS) at Bell Telephone Laboratories in Murray Hill, New Jersey. 1944: Indian chemist Asima Chatterjee became the first Indian woman to receive a doctorate of science, completing her studies at the University of Calcutta. She went on to establish the Department of Chemistry at Lady Brabourne College. 1945: American physicists and mathematicians Frances Spence, Ruth Teitelbaum, Marlyn Meltzer, Betty Holberton, Jean Bartik and Kathleen Antonelli programmed the electronic general-purpose computer ENIAC, becoming some of the world's first computer programmers.
Adoniram Judson was the first American missionary to go abroad. On June 17, 1812, the Judsons arrived in Calcutta. When the War of 1812 became known, British officials forced him to leave and he went to Burma in 1813, where he spent four decades as a missionay. Charlotte White (1782-1863) was the first American woman appointed as a missionary and sent to a foreign country. Sponsored by the Baptist Board of Foreign Missions. she embarked for Calcutta, India, in December 1815. Other American missionaries to India during the pre-British Raj era include: Lyman Jewett, Samuel B. Fairbank, Nathan Brown, John Welsh Dulles, Luther Rice, Samuel Newell, David Oliver Allen, Cynthia Farrar, Henry Richard Hoisington, Samuel Nott, Harriet Newell, George Warren Wood, Miron Winslow, Gordon Hall, Azubah Caroline Condit, Levi Spaulding, George Bowen, Ann Hasseltine Judson, George Boardman, Jeremiah Phillips, and William Arthur Stanton.
Sources: en.wikipedia.org
=== Antigen recognition === Garcia's earliest research as a graduate student at Johns Hopkins University focused on understanding how anti-idiotyopic antibodies recognize peptide antigens. As a postdoctoral scholar at The Scripps Research Institute, Garcia conducted a groundbreaking study that revealed how T cells of the immune system survey peptides presented by major histocompatibility complex proteins (MHC), thus allowing them to distinguish between "self" and "non-self". Garcia's research led to the first visualization of a T cell receptor (TCR) bound to a peptide-MHC (pMHC) complex and was published in the journal Science in 1996. Garcia's 1996 article on the TCR-MHC interaction has had broad impact in the fields of immunology and immunotherapy. At Stanford University, the Garcia Laboratory reported the structure of the pre-B cell receptor (pre-BCR) in 2007, which revealed how pre-BCRs oligomerize to signal in the absence of antigen. Garcia's group has also authored several additional landmark articles exploring various aspects of TCR-pMHC interactions, including the first structure of a γδ TCR-pMHC complex, the molecular basis for dual recognition of "self" and "foreign" MHCs by TCRs, insights into the germline basis of TCR/MHC interactions, the extent of cross-reactivity in the TCR repertoire, and elucidation of the structural trigger for TCR signaling. In Garcia's most recent work, his lab developed a peptide-MHC library technology that has enabled the discovery of antigens for orphan T cell receptors, such as those resident in tumors.
=== Occurrence in fungi === Many fungi produce hydrogen cyanide from glycine. These include representatives of the genera funnel mushrooms (Clitocybe), dwindlers (Marasmius), stem porcini (Polyporus), and Ritterlinge (Tricholoma). The epurpurins are a group of yellow phenolic pigments, each bearing two nitrile groups, occurring in Emericella purpurea. Diatretin II occurs in Fleshy Fungus (Clitocybe diatreta) and in the purple reddish bolete. In the clove dwarf mushroom, the cyanohydrin of glyoxylic acid is present; it is formed from two glycine molecules and releases hydrocyanic acid upon tissue damage.
Once this was finished, the riggers carefully made their way across the hanging cables, tying the foot-ropes together and connecting the handrails and the foot-ropes with the remainder of the thin grass ropes. Not all rope bridges were exactly alike in terms of design and build. Some riggers also wove pieces of wood into the foot-ropes. Modern-day rope bridge builders in Huinchiri, Peru make offerings to Pacha Mama, otherwise known as "Mother Earth," throughout their building process to ensure that the bridge will be strong and safe. This may have been a practice used by the Inca people since they too were religious. If all went smoothly and if tasks were performed in a timely fashion, a bridge had the potential of being constructed in three days.
Applications of this method include the analysis of fragile molecules and guest-host interactions that cannot be studied using regular electrospray ionization. Electrospray ionization has also been achieved at pressures as low as 25 torr and termed subambient pressure ionization with nanoelectrospray (SPIN) based upon a two-stage ion funnel interface developed by Richard D. Smith and coworkers. The SPIN implementation provided increased sensitivity due to the use of ion funnels that helped confine and transfer ions to the lower pressure region of the mass spectrometer. Nanoelectrospray emitter is made out of a fine capillary with a small aperture about 1–3 micrometer. For sufficient conductivity this capillary is usually sputter-coated with conductive material, e.g. gold. Nanoelectrospray ionization consumes only a few microliters of a sample and forms smaller droplets. Operation at low pressure was particularly effective for low flow rates where the smaller electrospray droplet size allowed effective desolvation and ion formation to be achieved. As a result, the researchers were later able to demonstrate achieving an excess of 50% overall ionization utilization efficiency for transfer of ions from the liquid phase, into the gas phase as ions, and through the dual ion funnel interface to the mass spectrometer.
These cells generate action potentials that propagate down axons to the nerve endings in the pituitary; the endings contain large numbers of oxytocin-containing vesicles, which are released by exocytosis when the nerve terminals are depolarised.
Sources: en.wikipedia.org
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.
The core four residues correspond to tuftsin, which occurs naturally as part of immunoglobulin G. The full seven-residue sequence, however, is not a known endogenous peptide. It is a laboratory-designed analogue intended to combine tuftsin-like activity with greater resistance to breakdown.
No single receptor has been confirmed as the primary target. Reports describe involvement of the GABAergic system, interference with enkephalin degradation, and shifts in neurotrophic factor expression. Because these observations come from different models and assays, they have not yet been integrated into one accepted mechanism.
Dry powder is normally held at -20 degrees Celsius or below in a sealed, light-protected container with desiccant. Brief room-temperature handling during weighing is generally tolerated. Storage instructions vary between suppliers, so the accompanying certificate of analysis should be followed.