intranasal delivery raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2025-07-31 and is reviewed periodically as new material appears.
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.
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.
Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
The compound has a calculated molecular weight near 751.9 daltons and carries a net positive charge at physiological pH because of its arginine residue. It dissolves freely in water and in common aqueous buffers, and typically appears as a white or off-white lyophilized powder. The amide backbone makes the molecule susceptible to peptidases, which limits oral use and favors intranasal or parenteral routes. Nomenclature in the literature varies: the substance is also described by the sequence abbreviation TP-7 and by a Russian trade designation.
| Property | Value | Notes |
|---|---|---|
| Peptide sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Seven residues; tuftsin plus a Pro-Gly-Pro tail |
| Molecular formula | C33H57N11O9 | Commonly reported value for the free peptide |
| Monoisotopic mass | Roughly 751.4 Da | Average molecular mass near 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as a lyophilized solid |
| Solubility class | Freely soluble in water | Also dissolves in saline and other polar solvents |
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.
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.
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.
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.
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.
== Safety and regulation == Active packaging is designed to interact with the packaged product or the surrounding environment. The active function does not remove the requirement for the underlying packaging to comply with applicable food-contact, pharmaceutical, transport, environmental, and product-safety rules. In the European Union, Commission Regulation (EC) No 450/2009 establishes specific requirements for active and intelligent materials intended to come into contact with food. It defines active materials as materials designed to deliberately release or absorb substances in order to extend shelf life or maintain or improve food condition. Substances intended to migrate into food may also be subject to food-additive and labelling requirements. Components positioned behind a functional barrier must remain within applicable migration limits. Intelligent packaging must not provide misleading information about the condition or safety of a product. An indicator that makes spoiled food appear acceptable could create a safety risk. Safety assessment may include:
Preparation begins with the heating of stones over a fire, and the meat is then placed on top. The fire is covered with grass and earth, and the resulting oven is opened up after around two hours. Typically, a large quantity of meat is cooked, perhaps a whole sheep, to serve several people.
==== MeSH D08.811.739 – recombinases ==== MeSH D08.811.739.250 – holliday junction resolvases MeSH D08.811.739.500 – integrases MeSH D08.811.739.500.667 – transposases MeSH D08.811.739.500.667.500 – hiv integrase MeSH D08.811.739.650 – rec a recombinases MeSH D08.811.739.650.500 – rad51 recombinase MeSH D08.811.739.800 – transposon resolvases MeSH D08.811.739.900 – vdj recombinases
Sources: en.wikipedia.org
The advance voting on 1 February saw many complaints of issues with the election process. One reported issue, which was also seen in the previous election, was that election officials wrote wrong codes on ballot envelopes, raising concerns that the ballots might end up in a different district and therefore be counted for the wrong candidate. Voters also reported missing or incorrect on information boards at some polling stations. This included cases where a candidate's information was entirely missing from the information board. In some of these cases, it was reported that polling station officials initially claimed that the missing candidates had been disqualified and only later rectified the mistake. Those affected included candidates from the People's Party, Pheu Thai Party, and Democrat Party.
The iron-containing co-factor is found tightly associated with the protein. It can be released upon denaturation with 2-mercaptoethanol or guanidine hydrochloride. Expression of the Hmd gene in E. coli without the co-factor results in an inactive holoenzyme. However, hydrogenase activity can be rescued by the addition of the iron-containing cofactor taken from denatured active enzyme. As mentioned, irradiation of the cofactor with UV light results in the loss of CO and Fe. In addition the 542 Da compound can be further degraded by a phosphodiesterase (which specifically cleaves phosphate bonds). Hydrolysis of the phosphate bonds generates the ribonucleotide guanosine monophosphate and a modified 2-pyridone. On the basis of spectroscopic characterization, Shima et al. have proposed a structure for this organic cofactor (minus the iron atom and CO molecules) as shown:
This synthesis reaction was used by Fermi and his collaborators in their design of the reactors located at the Hanford Site, which produced significant amounts of plutonium-239 for the nuclear weapons of the Manhattan Project and the United States' post-war nuclear arsenal. Actinides with the highest mass numbers are synthesized by bombarding uranium, plutonium, curium and californium with ions of nitrogen, oxygen, carbon, neon or boron in a particle accelerator. Thus nobelium was produced by bombarding uranium-238 with neon-22 as
Sources: en.wikipedia.org
=== Verification === Verification is intended to check that a product, service, or system meets a set of design specifications. In the development phase, verification procedures involve performing special tests to model or simulate a portion, or the entirety, of a product, service, or system, then performing a review or analysis of the modeling results. In the post-development phase, verification procedures involve regularly repeating tests devised specifically to ensure that the product, service, or system continues to meet the initial design requirements, specifications, and regulations as time progresses. It is a process that is used to evaluate whether a product, service, or system complies with regulations, specifications, or conditions imposed at the start of a development phase. Verification can be in development, scale-up, or production. This is often an internal process.
== Applications of peptide microarrays == Peptide microarrays can be used to study different kinds of protein-protein interactions, specially those involving modular protein substructures called peptide recognition modules or, most commonly, protein interaction domains. The reason for this is that such protein substructures recognize short linear motifs often exposed in natively unstructured regions of the binding partner, such that the interaction can be modelled in vitro by peptides as probes and the peptide recognition module as analyte. Most publications can be found in the context of immune monitoring and enzyme profiling.
=== Azapirones === Buspirone can be useful in GAD but not particularly effective in treating phobias, panic disorder or social anxiety disorders. It is a safer option for long-term use as it does not cause dependence like benzodiazepines.
The official language of Brazil is Portuguese (Article 13 of the Constitution of the Federal Republic of Brazil), which almost all of the population speaks and is virtually the only language used in newspapers, radio, television, and for business and administrative purposes. Brazil is the only Portuguese-speaking nation in the Americas, making the language an important part of Brazilian national identity and giving it a national culture distinct from those of its Spanish-speaking neighbors. Brazilian Portuguese has had its own development, mostly similar to 16th-century Central and Southern dialects of European Portuguese (despite a very substantial number of Portuguese colonial settlers, and more recent immigrants, coming from Northern regions, and in minor degree Portuguese Macaronesia), with a few influences from the Amerindian and African languages, especially West African and Bantu restricted to the vocabulary only. As a result, the language is somewhat different, mostly in phonology, from the language of Portugal and other Portuguese-speaking countries (the dialects of the other countries, partly because of the more recent end of Portuguese colonialism in these regions, have a closer connection to contemporary European Portuguese). These differences are comparable to those between American and British English.
Sources: en.wikipedia.org
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter code. It combines the tetrapeptide tuftsin with a carboxyl-terminal Pro-Gly-Pro extension. This full sequence identifies the molecule more precisely than the research name.
No peptide with this exact sequence has been identified as an endogenous substance. It is a laboratory-designed analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The Pro-Gly-Pro extension has no known natural source.
Proline introduces conformational constraints that make a peptide less accessible to common peptidases. This is a standard stabilization strategy in peptide design. The added residues also increase the distance between the active tuftsin portion and typical cleavage sites.
Selank is a synthetic seven-amino-acid peptide modeled on tuftsin, a fragment of the immunoglobulin G heavy chain. It was designed in Russia to combine anxiolytic and immunomodulatory properties in one molecule.