If you have been reading about intranasal delivery and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-06-02. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
| 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 |
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.
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.
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.
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.
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.
Although sodium-dependent transporters for vitamin C exists, it is present mainly in specialized cells whereas the glucose transporters, most notably GLUT1, transport DHA in most cells, where recycling back to ascorbic acid generates the necessary enzyme cofactor and intracellular antioxidant, (see Transport to mitochondria). The structure shown here for DHA is the commonly shown textbook structure. This 1,2,3-tricarbonyl is too electrophilic to survive more than a few milliseconds in aqueous solution, however. The actual structure shown by spectroscopic studies is the result of rapid hemiketal formation between the 6-OH and the 3-carbonyl groups. Hydration of the 2-carbonyl is also observed. The lifetime of the stabilized species is commonly said to be about 6 minutes under biological conditions. Destruction results from irreversible hydrolysis of the lactone bond, with additional degradation reactions following. Crystallization of solutions of DHA gives a pentacyclic dimer structure of indefinite stability. Recycling of vitamin C via active transport of DHA into cells, followed by reduction and reuse, mitigates the inability of humans to synthesize it from glucose.
== Market operations == Nachash, former proprietor of Doxbin, wrote a guide in early 2015 entitled So, You Want To Be a Darknet Drug Lord ... Background research tasks included learning from past drug lords, researching legal matters, studying law enforcement agency tactics and obtaining legal representation. With regards to the prospective market's hosting, he recommends identifying a hosting country with gaps in their mutual legal assistance treaty with one's country of residence, avoiding overpriced bulletproof hosting and choosing a web host with Tor support that accepts suitably hard-to-trace payment. Patterns recommended to avoid include hiring hitmen like Dread Pirate Roberts, and sharing handles for software questions on sites like Stack Exchange. He advises on running a secured server operating system with a server-side transparent Tor proxy server, hardening web application configurations, Tor-based server administration, automated server configuration management rebuild and secure destruction with frequent server relocation rather than a darknet managed hosting service. To protect against guard node deanonymization he recommends obfuscating traffic by investing in Tor relays which the market site will exclusively use. For a local machine configuration, he recommends a computer purchased for cash running Linux, using a local Tor transparent proxy. For operations security he suggests avoiding storing conversation logs, varying writing styles, avoiding mobile phone-based tracking and leaking false personal details to further obfuscate one's identity.
=== Medical diagnostics and treatments === Magnetic nanoparticles have been examined for use in an experimental cancer treatment called magnetic hyperthermia in which an alternating magnetic field (AMF) is used to heat the nanoparticles. To achieve sufficient magnetic nanoparticle heating, the AMF typically has a frequency between 100–500 kHz, although significant research has been done at lower frequencies as well as frequencies as high as 10 MHz, with the amplitude of the field usually between 8-16kAm−1. Affinity ligands such as epidermal growth factor (EGF), folic acid, aptamers, lectins etc. can be attached to the magnetic nanoparticle surface with the use of various chemistries. This enables targeting of magnetic nanoparticles to specific tissues or cells. This strategy is used in cancer research to target and treat tumors in combination with magnetic hyperthermia or nanoparticle-delivered cancer drugs. Despite research efforts, however, the accumulation of nanoparticles inside of cancer tumors of all types is sub-optimal, even with affinity ligands. Willhelm et al. conducted a broad analysis of nanoparticle delivery to tumors and concluded that the median amount of injected dose reaching a solid tumor is only 0.7%. The challenge of accumulating large amounts of nanoparticles inside of tumors is arguably the biggest obstacle facing nanomedicine in general. While direct injection is used in some cases, intravenous injection is most often preferred to obtain a good distribution of particles throughout the tumor.
== Side effects == Side effects of etifoxine include slight drowsiness and headache. Rarely, etifoxine can cause benign skin eruptions or rashes and allergic reactions such as hives and angioedema. Etifoxine shows less adverse effects of anterograde amnesia, sedation, impaired psychomotor performance, and withdrawal syndromes than those of benzodiazepines. No cases of misuse or dependence with etifoxine were identified in a French pharmacovigilance survey, which is also in contrast to benzodiazepines. Etifoxine has been associated rarely with cases of severe dermal toxicity and liver toxicity. Skin and subcutaneous disorders are the most frequently reported, but these generally resolve after drug cessation. A 2012 review of etifoxine by the French National Pharmacovigilance Committee determined that etifoxine was safe and continued to provide a favorable alternative to benzodiazepine anxiolytics. The committee found (for a ten-year pharmacovigilance period) that safety concerns were rare or very rare and that the incidence of idiosyncratic hepatic (liver) problems were very rare.
Sources: en.wikipedia.org
=== Cardiac rhythm monitoring === An electrocardiogram is necessary to rule out abnormal heart rhythms, such as atrial fibrillation, that can predispose patients to clot formation and embolic events. Hospitalized patients should be placed on heart rhythm telemetry, which is a continuous form of monitoring that can detect abnormal heart rhythms. Prolonged heart rhythm monitoring (such as with a Holter monitor or implantable heart monitoring) can be considered to rule out arrhythmias like paroxysmal atrial fibrillation that may lead to clot formation and TIAs, however this should be considered if other causes of TIA have not been found.
=== Viscosity === If the evolent has high viscosity, it would produce a high backpressure. Consequently, low-viscosity evolents are preferred. IPA is strongly eluting, but also very viscuous, which results in high backpressures. ACN and MeOH are less viscous than IPA, although a mixture of 50:50 percent of MeOH:water is also very viscous. In general, as the ratio of organic solvent:water increases from 0:1 to 1:0, the viscosity increases, then decreases again. In general, backpressure increased when the flow rate is increased, the mobile phase temperature is lowered, or the stationary phase particle size is increased.
The first step in the reaction mechanism by which cysteine proteases catalyze the hydrolysis of peptide bonds is deprotonation of a thiol in the enzyme's active site by an adjacent amino acid with a basic side chain, usually a histidine residue. The next step is nucleophilic attack by the deprotonated cysteine's anionic sulfur on the substrate carbonyl carbon. In this step, a fragment of the substrate is released with an amine terminus, the histidine residue in the protease is restored to its deprotonated form, and a thioester intermediate linking the new carboxy-terminus of the substrate to the cysteine thiol is formed. Therefore, they are also sometimes referred to as thiol proteases. The thioester bond is subsequently hydrolyzed to generate a carboxylic acid moiety on the remaining substrate fragment, while regenerating the free enzyme.
Multivariate calibration: Used to develop models that correlate instrument responses (e.g., spectra) to analyte concentrations, essential in techniques like near-infrared spectroscopy. Pattern recognition: Employed to classify samples based on their analytical profile, with applications in food authenticity and medical diagnostics. Machine learning and artificial intelligence: These techniques are increasingly used for predictive modeling, optimizing analytical methods, and automating data interpretation.
== Prelude == In November 2024, a coalition of rebel groups spearheaded by HTS attacked Aleppo, quickly overrunning the demotivated and disorganized defenders. In response, Assad travelled to Russia to ask for military aid on 28 November; his request was denied. Upon returning home, however, he lied to his senior commanders and advisors, claiming that Russia would soon send aid. His wife Asma had already been in Moscow for cancer treatment for months, accompanied by their children. A few days later, the rebels captured Aleppo. Afterward, reports emerged of a coup led by Syrian State Security Director General Hossam Louka against the Assad government. The Syrian Army General Command as well as the Iranian ambassador to Syria, Hossein Akbari, both denied these reports. On 2 December, Assad met with Iranian Foreign Minister Abbas Araghchi to discuss the situation. He confided that the Syrian Armed Forces were too weak to offer effective resistance to the continuing rebel advance. Regardless, he did not request increased Iranian aid, probably due to concerns about an Israeli intervention. At this point, the Syrian president had possibly concluded that the war was already lost. Despite this, he continued to tell his inner circle that Russian support would be coming, imploring them to continue their work. After the fall of Hama on 5 December, the government began redeploying its troops from Eastern Ghouta, including Douma and Harasta, to the entrances and exits of Damascus.
Sources: en.wikipedia.org
Cocaine produced in Colombia and Bolivia has increasingly been shipped via West Africa (especially in Nigeria, Cape Verde, Guinea-Bissau, Cameroon, Mali, Benin, Togo, and Ghana). The money is often laundered in countries such as Nigeria, Ghana, and Senegal. According to the Africa Economic Institute, the value of illicit drug smuggling in Guinea-Bissau is almost twice the value of the country's GDP. Police officers are often bribed. A police officer's normal monthly wage of $106 is less than 2% of the value of 1 kilogram (2.2 lb) of cocaine (€7000 or $9978). The money can also be laundered using real estate. A house is built using illegal funds—and when the house is sold—legal money is earned. When drugs are sent over land, through the Sahara, the drug traders have been forced to cooperate with terrorist organizations, such as al-Qaeda in the Islamic Maghreb.
Ions in a quadrupole field experience restoring forces that drive them back toward the center of the trap. The motion of the ions in the field is described by solutions to the Mathieu equation. When written for ion motion in a trap, the equation is
In summing up the international ramifications of these events, Vladislav Zubok stated: 'The collapse of the Soviet empire was an event of epochal geopolitical, military, ideological, and economic significance.' After the dissolution of the Soviet Union, Russia drastically cut military spending, and restructuring the economy left millions unemployed. According to Western analysis, the neoliberal reforms in Russia culminated in a recession in the early 1990s more severe than the Great Depression as experienced by the United States and Germany. Western analysts suggest that in the 25 years following the end of the Cold War, only five or six of the post-communist states are on a path to joining the rich and capitalist world while most are falling behind, some to such an extent that it will take several decades to catch up to where they were before the collapse of communism.
=== Microfibrilated cellulose === Micro cellulose (MFC) is a type of nanocellulose that is more heterogeneous than cellulose nanofibers or nanocrystals as it contains a mixture of nano- and micro-scale particles. The term is sometimes misused to refer to cellulose nanofibers instead.
At the time of the Miller–Urey experiment, Harold Urey was a Professor of Chemistry at the University of Chicago who had a well-renowned career, including receiving the Nobel Prize in Chemistry in 1934 for his isolation of deuterium and leading efforts to use gaseous diffusion for uranium isotope enrichment in support of the Manhattan Project. In 1952, Urey postulated that the high temperatures and energies associated with large impacts in Earth's early history would have provided an atmosphere of methane (CH4), water (H2O), ammonia (NH3), and hydrogen (H2), creating the reducing environment necessary for the Oparin-Haldane "primordial soup" scenario. Stanley Miller arrived at the University of Chicago in 1951 to pursue a PhD under nuclear physicist Edward Teller, another prominent figure in the Manhattan Project. Miller began to work on how different chemical elements were formed in the early universe, but, after a year of minimal progress, Teller was to leave for California to establish Lawrence Livermore National Laboratory and further nuclear weapons research. Miller, having seen Urey lecture on his 1952 paper, approached him about the possibility of a prebiotic synthesis experiment. While Urey initially discouraged Miller, he agreed to allow Miller to try for a year. By February 1953, Miller had mailed a manuscript as sole author reporting the results of his experiment to Science.
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.
The most common approach combines reverse-phase liquid chromatography with mass spectrometry. Chromatography separates the components while mass spectrometry confirms the molecular mass. Peptide sequencing or tandem mass analysis can further verify the amino acid order.