A practical reference on intranasal delivery: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-04-15. Anything still debated is marked as such rather than presented as settled.
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.
Peptide bonds in selank are susceptible to hydrolysis under strongly acidic or basic conditions, and the terminal proline residues are vulnerable to exopeptidase activity in biological samples. Lyophilized powder stored dry at -20 °C typically remains stable for extended periods, whereas aqueous solutions degrade faster and may lose measurable purity within days to weeks depending on pH, temperature, and microbial load. Repeated freeze-thaw cycles promote aggregation and adsorption to container surfaces. For analytical work, solutions are usually prepared fresh, kept cold, and used within a single working day.
Handling follows standard practice for research peptides. Material is weighed in a low-humidity environment because the powder absorbs atmospheric moisture. Purity is reported as the percentage area of the main peak in a chromatogram, with specifications commonly set at 95 percent or higher; values below that threshold indicate the presence of truncated or modified species. Residual trifluoroacetate from purification is often present and may affect mass balance. Certificates of analysis should state the analytical method, the column and gradient used, and the lot-specific retention time so that results can be compared across suppliers.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Analog of the tetrapeptide tuftsin |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Reported consistently across pharmacopoeial descriptions |
| Appearance | White to off-white lyophilized powder | Typical form of research-grade material |
| Solubility | Freely soluble in water | Aqueous buffers; poor in nonpolar solvents |
| Typical storage temperature | -20 degrees Celsius | Lyophilized powder; protect from moisture |
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.
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.
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.
=== Reducing agent compatible (RAC) BSA assay === This type of BCA assay includes a proprietary thiol covalent blocking "Compatibility Reagent" a.k.a. a Reducing Agent Compatibility Agent (RACA). Although this allows greater compatibility with reducing agents, the assay has a different interference profile from other non-protein components.
A time-dependent recoverable component – this causes the development of microcracks, which can lead to fracturing and, ultimately, a breakthrough; A time-dependent irrecoverable component – this is commonly referred to as creep, which is related with the mechanisms responsible for glacier flow (long term) and plays a negligible role in the response of an ice road to loading. Thus, an ice cover may be able to safely support a vehicle, but if it remains on the ice for too long, deformation will continue via microcracking, leading to the collapse of the ice cover below the vehicle. Recommendations vary as to how this can be avoided. Some sources prescribe a maximum of two hours for a stationary load, which is also what Gold recommended. Others advise to use the freeboard of the ice as an indicator, which can be done by drilling a hole in it and monitoring the distance between the water in the hole and the ice surface. The vehicle should be removed before the water reaches the surface in that hole. Another reason why the amount of freeboard matters is that if the water makes its way onto the ice surface (through cracks and fissures), the ice cover's bearing capacity diminishes rapidly, which can accelerate breakthrough. For long-term loads, a professional engineer may have to be consulted.
In the brain, zinc is stored in specific synaptic vesicles by glutamatergic neurons and can modulate neuronal excitability. It plays a key role in synaptic plasticity and so in learning. Zinc homeostasis also plays a critical role in the functional regulation of the central nervous system. Dysregulation of zinc homeostasis in the central nervous system that results in excessive synaptic zinc concentrations is believed to induce neurotoxicity through mitochondrial oxidative stress (e.g., by disrupting certain enzymes involved in the electron transport chain, including complex I, complex III, and α-ketoglutarate dehydrogenase), the dysregulation of calcium homeostasis, glutamatergic neuronal excitotoxicity, and interference with intraneuronal signal transduction. L- and D-histidine facilitate brain zinc uptake. SLC30A3 is the primary zinc transporter involved in cerebral zinc homeostasis.
After tracing the adaptation strategy of the party, he found confirming evidence for five of the factors contributing to its electoral success, already mentioned in the theoretical literature on former Marxist–Leninist parties, namely the economic situation, the weakness of the opponents, the electoral laws, the fragmentation of the political spectrum and the legacy of the old regime. However, Marandici identified seven additional explanatory factors at work in the Moldovan case, namely the foreign support for certain political parties, separatism, the appeal to the ethnic minorities, the alliance-building capacity, the reliance on the Soviet notion of the Moldovan identity, the state-building process and the control over a significant portion of the media. It is due to these seven additional factors that the party managed to consolidate and expand its constituency. In the post-Soviet states, the Party of Communists are the only ones who have been in power for so long and did not change the name of the party. In Asia, a number of Marxist–Leninist regimes and movements continue to exist. The People's Republic of China has continued the agenda of Deng Xiaoping's 1980s reforms by initiating significant privatisation of the national economy. At the same time, no corresponding political liberalisation has occurred as happened in previous years to Eastern European countries.
Sources: en.wikipedia.org
Marxism–Leninism develops the New Soviet man, an educated and cultured citizen possessed of a proletarian class consciousness who is oriented towards the social cohesion necessary for developing a communist society as opposed to the antithetic bourgeois individualist associated with social atomisation.
== Catalytic mechanism == The accepted catalytic mechanism, called the “ping-pong mechanism,” consists of four major stages. The first stage is the oxidation of the substrate by the double-redox center. After the hydroxyl group of substrate alcohol occupies the solvent coordination site, the hydroxyl group is deprotonated by Tyr495, followed by the release of Tyr495. This step makes the alcohol more prone to oxidation. The proton on the carbon to which the hydroxyl group used to be attached is then transferred to Tyr272 (serving as the hydrogen acceptor), coupled with the oxidation of the substrate. One electron goes to the radical ligand, the other electron goes to the copper(II) center, which is then reduced to copper(I) as a result. Meanwhile, Tyr272 radical is also reduced. The proton subtraction step is rate determining and stereospecific since only the pro-S hydrogen on the alcohol carbon is removed (supported by studies of its kinetic isotope effect). The overall result of stage 1 is the removal of two hydrogen atoms and the removal two electrons from the substrate, of which the order is unclear, however. The second stage is the release of oxidized substrate (aldehyde in this case) and the coordination of dioxygen at the substrate coordination site. In the third stage, dioxygen is rapidly reduced by copper(I) to form superoxide. The superoxide is a reactive species that subtracts the proton and an electron from the Tyr272 and re-forms the tyrosine radical. In the fourth stage, the hydroperoxide deprotonates Tyr496 and is released as H2O2.
== Treatment == Silicosis is a permanent disease with no cure. Treatment options currently available focus on alleviating the symptoms and preventing any further progress of the condition. These include:
=== By individual compound === This list includes notable compounds representative of most of the structural variations that have been explored in this series, but is by no means exhaustive. Many derivatives invented for scientific study into the structure-activity relationships of 5-HT2 receptor agonists have never appeared as designer drugs, while conversely some derivatives that have appeared as designer drugs are structurally novel and of unknown pharmacological activity (e.g. C30-NBOMe, 5-APB-NBOMe).
== See also == Other diamond-like compounds: Boron nitride Abiogenic petroleum origin Nanorobot “Diamonoids” were claimed as an airburst proxy, but may have been a misspelling of diamondoid in a now-retracted paper.
Sources: en.wikipedia.org
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.
The first four residues of Selank reproduce the tuftsin sequence Thr-Lys-Pro-Arg. A Pro-Gly-Pro extension at the C-terminus was added to slow enzymatic breakdown and extend residence time.
It holds marketing authorization in Russia, where nasal drop formulations are sold. No equivalent approval exists in the European Union, the United States, or most other countries.
Identity is confirmed by matching the retention time in reversed-phase chromatography against a reference standard and by measuring the molecular mass with mass spectrometry. Tandem mass spectrometry or amino acid analysis can verify the sequence of the seven residues. Because the peptide contains no aromatic amino acids, detection at 280 nm is not useful.