This is a working overview of pharmacokinetics, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-09-09 and is reviewed periodically as new material appears.
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.
Development work on the compound began in the 1980s and 1990s at the Institute of Molecular Genetics in Moscow, within the same research programme that produced the peptide Semax. Early investigators sought a tuftsin derivative with improved resistance to enzymatic breakdown and with activity in the central nervous system after peripheral administration. Most of the primary literature from this period was published in Russian, a factor that still shapes how easily the findings can be checked by outside groups.
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 |
|---|---|---|
| Typical purity report | 95% or higher by HPLC | Area percentage at 214 nm |
| Identity confirmation | Mass spectrometry | Electrospray or MALDI |
| Powder storage | -20 C, desiccated | Protect from light |
| Solution storage | 2-8 C short term | Freeze aliquots for longer |
| Quality document | Certificate of analysis | States method and value |
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.
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.
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.
Pharmacokinetic data are sparse and largely derived from animal work. After intranasal administration the peptide appears in plasma within minutes, and reported half-lives are short, on the order of minutes to tens of minutes. Degradation proceeds through ordinary proteolytic cleavage into constituent amino acids and smaller fragments. Direct evidence that intact Selank reaches brain tissue in meaningful amounts is limited, and the extent of blood-brain barrier penetration is debated. Some authors argue that fragments, not the parent peptide, carry much of the observed activity.
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.
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.
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.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter notation. Its structure consists of the immunomodulatory tetrapeptide tuftsin, Thr-Lys-Pro-Arg, extended at the carboxyl terminus by a Pro-Gly-Pro segment. The molecular formula is commonly given as C33H57N11O9, corresponding to a monoisotopic mass near 751.4 Da and an average molecular mass near 751.9 Da. All seven residues are proteinogenic amino acids, and the molecule carries no modified side chains or non-natural linkages.
The compound was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences during the 1980s and 1990s. The stated design goal was to retain the immunomodulatory and central nervous system activity attributed to tuftsin while improving resistance to enzymatic breakdown. Adding a proline-rich tail to the short parent peptide was a deliberate strategy, because proline residues restrict the conformations available to many peptidases. The same laboratory produced Semax, an ACTH fragment analog, and both compounds were developed in parallel as short, enzymatically stabilized peptides intended for intranasal use.
Selank is not a naturally occurring peptide and has no known endogenous counterpart in human physiology. Russian-language sources frequently call it TP-7, while English-language sources use the name Selank almost exclusively. Database indexing is uneven, partly because early reports appeared in regional journals that are not widely cataloged. Some summaries describe the material as a tuftsin analog and others as a synthetic heptapeptide; the labels overlap rather than conflict. Citing the primary sequence resolves ambiguity more reliably than the research or trade name alone.
== Toxicity == Carbonyl sulfide has the "rotten egg" odor characteristic of sulfides, although some sources suggest that the associated odor is due to impurities, and not present in the pure compound. The detectability threshold is estimated at 135μg/m
Kynureninase or L-Kynurenine hydrolase (KYNU) (EC 3.7.1.3) is a pyridoxal-phosphate dependent enzyme that catalyses the cleavage of kynurenine into anthranilic acid. It can also act on 3-hydroxykynurenine (to produce 3-hydroxyanthranilate) and some other (3-arylcarbonyl)-alanines. Humans express one kynureninase enzyme that is encoded by the KYNU gene located on chromosome 2. KYNU is part of the pathway for the catabolism of tryptophan and the biosynthesis of nicotinamide adenine dinucleotide (NAD) cofactors from tryptophan (Trp). This reaction produces anthranilic acid and L-alanine:
== Plasma-based techniques == Plasma-based ambient ionization is based on an electrical discharge in a flowing gas that produces metastable atoms and molecules and reactive ions. Heat is often used to assist in the desorption of volatile species from the sample. Ions are formed by chemical ionization in the gas phase. One proposed mechanism involves Penning ionization of ambient water clusters in a helium discharge:
UAE Brigadier General Musallam Al Rashidi responded to the accusations by stating that Al Qaeda cannot be reasoned with and citing that they killed many of his soldiers. The UAE military stated that accusations of allowing AQAP to leave with cash contradict their primary objective of depriving AQAP of its financial strength. The notion of the coalition recruiting or paying AQAP has been thoroughly denied by the United States Pentagon, with spokesperson Robert Manning calling the news source "patently false". The governor of Hadramut Faraj al-Bahsani, dismissed the accusations that Al Qaeda has joined with the coalition ranks, explaining that if they did there would be sleeper cells and that he would be "the first one to be killed". According to The Independent, AQAP activity on social media as well as the number of terror attacks conducted by them has decreased since the Emirati intervention. On 13 July 2020, the UK Ministry of Defence logged more than 500 Saudi air raids in possible breach of international law in Yemen. These figures were revealed a few days after the UK government decided to resume arms sales to Saudi Arabia, which could be used in the Yemen war, just over a year after the court of appeal ruled them unlawful. It justified resuming arms sales stating that only isolated incidents without any pattern have occurred. In March 2019, the United States Congress voted to end US support to the Saudi war effort; however, US President Donald Trump vetoed it.
Sources: en.wikipedia.org
Acarbose (INN) is an anti-diabetic drug used to treat diabetes mellitus type 2 and (in some countries), prediabetes. It is sold in Europe and China as Glucobay (Bayer AG), in North America as Precose (Bayer Pharmaceuticals), and in Canada as Prandase (Bayer AG). Acarbose is a starch blocker that works by inhibiting alpha glucosidase, an intestinal enzyme that releases glucose from larger carbohydrates such as starch and sucrose. It is composed of an acarviosin moiety with a maltose at the reducing terminus. It can be degraded by gut bacteria. Acarbose is inexpensive and popular in China, but not in the U.S. One physician explains that U.S. use is limited, because it is not potent enough to offset side effects of diarrhea and flatulence. However, a large 2013 study reported that "acarbose is effective, safe and well tolerated in a large cohort of Asian patients with type 2 diabetes." One possible explanation for the differing claims is that acarbose is significantly more effective in patients eating a relatively high-starch, Eastern diet.
=== 2009 === A report prepared for the British House of Lords comes to the conclusion that "The precise circumstances surrounding the August 2008 outbreak of the conflict are not yet clear but responsibility for the conflict was shared, in differing measures, by all the parties. There is evidence of a Russian military build-up prior to the August war." On 17 February 2009, the commanding General of the United States Army Europe Carter Ham commented on the training of Georgian military that the United States had trained the Georgian military for Iraq in the previous years, not for the defense of the homeland against Russia. In May 2009, anonymous European diplomat told The New York Times that NATO officials were told in April 2008 by Russia's defense chief that Georgia would be invaded later that year. In July 2009, Alexander Bastrykin, Chairman of the Investigative Committee of the Prosecutor General's Office, told journalists that the investigation of the war was almost complete. However, the guilt of Georgian president Mikheil Saakashvili in instigating the conflict in South Ossetia could not be proven. In September 2009, first president of the Czech Republic Václav Havel, Otto von Habsburg and other European politicians and thinkers wrote: "First, a big power will always find or engineer a pretext to invade a neighbour whose independence it resents. We should remember that Hitler accused the Poles of commencing hostilities in 1939, just as Stalin pinned the blame on the Finns when he invaded their country in 1940.
=== Validation === Validation is intended to ensure a product, service, or system (or portion thereof, or set thereof) results in a product, service, or system (or portion thereof, or set thereof) that meets the operational needs of the user. For a new development flow or verification flow, validation procedures may involve modeling either flow and using simulations to predict faults or gaps that might lead to invalid or incomplete verification or development of a product, service, or system (or portion thereof, or set thereof). A set of validation requirements (as defined by the user), specifications, and regulations may then be used as a basis for qualifying a development flow or verification flow for a product, service, or system (or portion thereof, or set thereof). Additional validation procedures also include those that are designed specifically to ensure that modifications made to an existing qualified development flow or verification flow will have the effect of producing a product, service, or system (or portion thereof, or set thereof) that meets the initial design requirements, specifications, and regulations; these validations help to keep the flow qualified. It is a process of establishing evidence that provides a high degree of assurance that a product, service, or system accomplishes its intended requirements. This often involves acceptance of fitness for purpose with end users and other product stakeholders. This is often an external process.
Sources: en.wikipedia.org
Monosaccharides are also called "simple sugars", the most important being glucose. Most monosaccharides have a formula that conforms to CnH2nOn with n between 3 and 7 (deoxyribose being an exception). Glucose has the molecular formula C6H12O6. The names of typical sugars end with -ose, as in "glucose" and "fructose". Such labels may also refer to any types of these compounds. Fructose, galactose and glucose are all simple sugars, monosaccharides, with the general formula C6H12O6. They have five hydroxyl groups (−OH) and a carbonyl group (C=O) and are cyclic when dissolved in water. They each exist as several isomers with dextro- and laevo-rotatory forms that cause polarised light to diverge to the right or the left.
Very severe hypothyroidism and myxedema coma are rare, with it estimated to occur in 0.22 per million people a year. The majority of cases occur in women over 60 years of age, although it may happen in all age groups. Most hypothyroidism is primary in nature. Central/secondary hypothyroidism affects 1:20,000 to 1:80,000 of the population or about one out of every thousand people with hypothyroidism.
The "Cave with the Ring-Bearing Doves" (Cave 123) had a type of "central pillar" structure, with niche and circumambulating corridor, but with a very uncharacteristic cubic main cella crowned by a magnificent dome decorated with divinities. The main cella forms a square vestibule or main hall (3.42 x 3.42 meters; 12 x 12 feet) in front of the pillar forming the back wall, the vestibule being surmounted by a decorated dome. The prototype for the dome decorated with standing Buddhist deities is to be found in Group C of the caves at Bamiyan. It can also be seen in some other caves in the region, such as in Kumtura. The cave is named after a pattern of "flying geese holding a wreath" (or ring). This pattern is also known from Cave 69, which is dated to 625–647 CE because of the depiction and inscription of a historically identified king. Because of this marker, Cave 123 may be dated to the same period. Two monumental Buddha images occupy the sides of the main cella. They have full-body "mandorla" halos filled with a multitude of sitting or standing Buddhas. These monumental images represent the second Great Miracle of the Sakyamuni Buddha at Shravasti. The myriads of Buddhas emanating from him, each standing on a lotus, are a result of his deep meditation at Shravasti, as recounted in the Divyavadana. This understanding of the Great Miracle is most prominent among the Sarvastivadin and the Mulasarvastivadin. The two monumental Buddhas are surrounded by attendants, some light-skinned and some dark-skinned, and a Vajrapani.
Sources: en.wikipedia.org
Purity is usually reported as an HPLC area percentage, most often measured at 214 nm. Identity is confirmed separately by mass spectrometry. A certificate of analysis should state both the method and the observed value.
Dry powder is kept frozen, desiccated, and shielded from light. Dissolved material is aliquoted and frozen to limit freeze-thaw cycles. Short-term refrigerated storage is common for working solutions.
Russia registers it as a prescription nasal product. Most other markets classify it as a research chemical with no approved medical use. Oversight of purity and labeling is consequently minimal in those markets.
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.