Semax comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-03-19. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Calculated for the free peptide |
| Molecular weight | About 751.9 g/mol | Derived from the sequence |
| Appearance | White to off-white powder | Typical lyophilised form |
Reported activity for Selank centers on anxiolytic and nootropic effects. Russian clinical reports describe use in anxiety and in cognitive or attention-related complaints. Most of this evidence comes from studies conducted by the same research groups that developed the peptide. Independent replication in other countries remains limited, and no major Western regulatory agency has approved the compound for any indication. The gap between local reports and external verification is a recurring point in discussions of the peptide.
Tuftsin, the parent structure, is a naturally occurring immunomodulatory tetrapeptide released from the Fc region of immunoglobulin G by spleen enzymes. Selank extends this four-residue sequence with three additional amino acids. The stated rationale is that the added tail slows enzymatic breakdown and may influence receptor interactions. How the full heptapeptide behaves at the molecular level is not firmly established, and proposed mechanisms often involve indirect modulation of neurotransmitter or immune signaling rather than a single defined target.
Selank is a synthetic heptapeptide developed in Russia. Its sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, a seven-residue chain built around the natural tetrapeptide tuftsin. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences first described the compound in the mid-1990s. The design combined the tuftsin core with an added Pro-Gly-Pro tail, a modification intended to extend the molecule's stability in biological fluids. Published work on the peptide has appeared mainly in Russian-language journals.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
Lyophilized Selank, the dry powder form, is generally stored frozen at minus 20 degrees Celsius or colder for long-term keeping. The solid is hygroscopic and should stay sealed, dry, and protected from light. Once dissolved, the peptide is less stable and is usually held refrigerated at 2 to 8 degrees Celsius for short periods. Repeated freezing and thawing is avoided because it can promote aggregation and loss of activity. Buffers and pH choice also affect how long a solution remains usable.
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
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.
=== Selenoproteins === Selenocysteine has a lower reduction potential than cysteine. These properties make it very suitable in proteins that are involved in antioxidant activity. Although it is found in the three domains of life, it is not universal in all organisms. Unlike other amino acids present in biological proteins, selenocysteine is not coded for directly in the genetic code. Instead, it is encoded in a special way by a UGA codon, which is normally the "opal" stop codon. Such a mechanism is called translational recoding and its efficiency depends on the selenoprotein being synthesized and on translation initiation factors. When cells are grown in the absence of selenium, translation of selenoproteins terminates at the UGA codon, resulting in a truncated, nonfunctional enzyme. The UGA codon is made to encode selenocysteine by the presence of a selenocysteine insertion sequence (SECIS) in the mRNA. The SECIS element is defined by characteristic nucleotide sequences and secondary structure base-pairing patterns. In bacteria, the SECIS element is typically located immediately following the UGA codon within the reading frame for the selenoprotein. In Archaea and in eukaryotes, the SECIS element is in the 3′ untranslated region (3′ UTR) of the mRNA and can direct multiple UGA codons to encode selenocysteine residues. As of 2021, 136 human proteins (in 37 families) are known to contain selenocysteine (selenoproteins).
=== Elastase-like === Elastase-like proteases have a much smaller S1 cleft than either trypsin- or chymotrypsin-like proteases. Consequently, residues such as alanine, glycine and valine tend to be preferred.
=== "Last dictators" advertisement === In 2011, Nando's launched a "Last dictators" advert in South Africa. The 60-second commercial shows a sad Robert Mugabe dining alone at Christmas in a large mansion while he reminisces about "happier times" with former dictators, such as playing water tag with Muammar Gaddafi, singing karaoke with Mao Zedong, making snow angels in the sand with Saddam Hussein, pushing P. W. Botha on a swing set, and riding a Covenanter cruiser tank with Idi Amin in a similar fashion to Leonardo DiCaprio and Kate Winslet embracing each other from the film Titanic, while the music from "Those Were the Days" is played. Musekiwa Kumbula, holder of the Nando's franchise in Zimbabwe, said his group "strongly feels the advertisement is insensitive and in poor taste." The advert also offended Chipangano, a Zimbabwean youth militia loyal to Mugabe, who then demanded an apology from Nando's, threatened to boycott the South Africa-based chain, and demanded the advert be withdrawn or the restaurant face retribution. Nando's South Africa subsequently withdrew the advert citing threats to its staff in Zimbabwe from a youth group.
Sources: en.wikipedia.org
The first step of transcription for some negative, single-stranded RNA viruses is cap snatching, in which the first 10 to 20 residues of a host cell RNA are removed (snatched) and used as the 5′ cap and primer to initiate the synthesis of the nascent viral mRNA. The viral RNA-dependent RNA polymerase (RdRp) can then proceed to transcribe positive-sense viral mRNA using the negative-sense viral RNA as a template. Cap-snatching also explains why some viral mRNA have 5' terminal extensions of 10-20 nucleotides that are not encoded for in the genome. Examples of viruses that engage in cap-snatching include influenza viruses (Orthomyxoviridae), Lassa virus (Arenaviridae), hantaan virus (Hantaviridae) and rift valley fever virus (Phenuiviridae). Most viruses snatch 15-20 nucleotides except for the families Arenaviridae and Nairoviridae and the genus Thogotovirus (Orthomyxoviridae) which use a shorter strand. In the influenza virus, cap snatching occurs in the nucleus of the cell. The cap snatching endonuclease function is contained in the PA subunit of the RNA polymerase. In Arenaviridae and Bunyavirales, cap-snatching takes place in the cytoplasm.
=== Cancer research === For hundreds of years, S. mutilans was used in traditional Chinese medicine for cancer treatment and other curative effects. Arthropod medicines were found to have a high level of antitumour effect in modern studies, and centipede is one of the major constituents of such medication. Extraction from these centipedes was found to be effective in controlling the proliferation of HepG2 cells (liver cancer). The mechanism by which the centipede extract alleviates liver cancer is related to the regulation of PI3/AKT, STA3, and MAPK signalling pathways. Water extracts from the dried whole body of this species were reported to have antitumour properties, and would lead to enhanced immune responses. SPPC is a polysaccharide-protein complex that can be extracted from the centipede by pouring hot water over the powdered, dried body of the organism. In mice clinical trials, SPPC was found to effectively suppress the growth of S180 cancer cell in mice by promoting both specific and nonspecific immune responses. H22-bearing mice were found to have extended survival time with the administration of SPPC.
==== Nonreversible couples ==== Many redox processes observed by CV are quasi-reversible or non-reversible. In such cases the thermodynamic potential E01/2 is often deduced by simulation. The irreversibility is indicated by ipa/ipc ≠ 1. Deviations from unity are attributable to a subsequent chemical reaction that is triggered by the electron transfer. Such EC processes can be complex, involving isomerization, dissociation, association, etc.
By the 1880s, Knoxville had a murder rate that was higher than Los Angeles's murder rate in the 1990s. Journalist Jack Neely points out that "saloons, whorehouses, cocaine parlors, gambling dens, and poolrooms" lined Central Street from the railroad tracks to the river. High-profile shootouts were not uncommon, the most well-known being the Mabry-O'Connor shootout on Gay Street, which left banker Thomas O'Connor, businessman Joseph Mabry, and Mabry's son, dead in 1882. In 1901, Kid Curry, a member of Butch Cassidy's Wild Bunch, shot and killed two police officers at Ike Jones's Bar on Central. The Kid Curry shooting helped fuel calls for citywide prohibition, which was enacted in 1907. After World War I, the United States suffered a major economic recession, and Knoxville, like many other cities, experienced an influx of migrants moving to the city in search of work. Racial tensions heightened as poor whites and blacks competed for the few available jobs, and both the Ku Klux Klan and the National Association for the Advancement of Colored People (NAACP) opened chapters in the city. On August 30, 1919, these tensions erupted in the so-called Riot of 1919, the city's worst race riot, which shattered the city's vision of itself as a racially tolerant Southern town.
Sources: en.wikipedia.org
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.
Selank is a synthetic analogue built on the tuftsin tetrapeptide Thr-Lys-Pro-Arg. Extra proline residues were added to the C-terminus during design work. That modification is intended to make the peptide less vulnerable to rapid enzymatic degradation.
Transliteration from Russian produces variant spellings such as Selanc. Many suppliers avoid the trade-style name entirely and list the peptide sequence. Comparing sequences rather than names is the reliable way to confirm two entries describe the same molecule.
Most published work uses intranasal application, either as drops or as a nasal spray. Injection routes appear in a smaller set of animal experiments. Oral use is uncommon in the literature because peptide breakdown and poor absorption limit this route.