Semax raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2025-09-27. Anything still debated is marked as such rather than presented as settled.
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.
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.
| 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 |
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.
The primary structure of Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro, corresponding to the molecular formula C33H57N11O9 and a monoisotopic mass of roughly 751.9 daltons. The N-terminal threonine and the arginine residue in the fourth position are shared with tuftsin, which carries the sequence Thr-Lys-Pro-Arg. The three additional residues at the C-terminus, Pro-Gly-Pro, extend the chain and are associated with greater resistance to enzymatic degradation. This extension also separates Selank from the shorter parent peptide.
Naming conventions place Selank in the same research family as Semax, another Russian-developed peptide investigated for cognitive effects. The two compounds share a lineage but differ in sequence and in the biological systems proposed as their targets. Semax descends from ACTH fragments, whereas Selank descends from tuftsin. Publications sometimes identify Selank by its full peptide sequence or by laboratory codes rather than one uniform trade name. Because replication outside Russia is limited, reports on its properties are best read alongside the study design and the purity of the material tested.
Selank is a synthetic heptapeptide developed in Russia during the 1990s. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences designed it as a stabilized analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The compound has been studied primarily for its reported anxiolytic and nootropic effects. It remains largely unknown in Western pharmacology and is not approved as a medicine by major regulators such as the FDA or the EMA.
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.
He merged as many as fourteen neighboring municipalities and suburbs to the city on the Strait.although four, by government decree of 26 January 1933, broke away to form Villa San Giovanni (Campo Calabro and Fiumara again became autonomous after the war). The urban population thus exceeded 100,000. The reasons for this restructuring included a desire to speed up earthquake reconstruction, to make trade and communication by sea easier, and to entice emigration from small mountain towns into an urban center. During the 1920s and 1930s Reggio Calabria modernized, building new neighborhoods. Social housing districts sprang up and public facilities such as the Reggio di Calabria Centrale railway station, the National Museum of Magna Graecia and the Francesco Cilea Municipal Theater were built. Other cities benefited from the Fascist building policy. Minister of Public Works Luigi Razza built a new municipal palace for his hometown of Monteleone di Calabria (renamed Vibo Valentia). Vibo Valentia named its military airport, stadium, a square and a street in the historic center after Razza. As with the rest of Italy, Calabria's maximum support for fascism came with the Second Italo-Ethiopian War of 1935–1936, in which many Calabrians participated, momentarily relieving the region's prevailing misery with soldier's remittances. Many members of the Calabrian clergy supported the war. This marked the pinnacle of collaboration between Church and State following the Lateran Pacts of 1929.
=== SPAC merger, public listing, and acquisitions (2020–2023) === In October 2020, Hims announced an agreement to become a publicly traded company through a merger with Oaktree Acquisition Corp., a special-purpose acquisition company led by Oaktree Capital Management co-chairman Howard Marks. The transaction closed on January 20, 2021 at a valuation of $1.6 billion, and shares began trading the following day on the New York Stock Exchange. The deal provided the company with about $280 million in proceeds, including $75 million from private placement investors such as Franklin Templeton Investments. In June 2021, Hims & Hers acquired London-based Honest Health Limited, marking its first international acquisition and expanding its United Kingdom operations. The following month, the company acquired the teledermatology platform Apostrophe (YoDerm, Inc.) for potential consideration of up to $200 million. Apostrophe was shut down in 2025.
=== Chemical reactions === Diallyl disulfide can be readily oxidized to allicin with hydrogen peroxide or peracetic acid. Allicin in turn can hydrolyze giving diallyl disulfide and trisulfide. Reaction of diallyl disulfide with liquid sulfur gives a mixture containing diallyl polysulfides with as many as 22 sulfur atoms in a continuous chain identified. When diallyl disulfide is heated it decomposes giving a complex mixture. The carbon-sulfur bond of diallyl disulfide is 16 kcal mol−1 weaker than the sulfur-sulfur bond (46 kcal mol−1 versus 62 kcal mol−1, respectively), with the consequence that on heating diallyl disulfide gives the allyldithio radical (AllSS•), which through addition to the double bonds in diallyl disulfide followed by fragmentation and subsequent reactions generates numerous organosulfur compounds, many of which are found in trace amounts in distilled garlic oil. In the presence of a catalyst, diallyl disulfide can combine with alkyl halides forming 1-alkylthio-3-allylthio-1-propene and 1,3-di(alkylthio)propene.
=== Detergents, cosmetics, etc. === Sulfation is widely used in the production of consumer products such as detergents, shampoos, and cosmetics. Since the sulfate group is highly polar, its conjugation to a lipophilic "tail" gives surfacant-like properties. Well known sulfates are sodium lauryl sulfate and sodium laureth sulfate. Alkylsulfate are produced from alcohols by reaction with chlorosulfuric acid:
As (R)-MDMA is less neurotoxic than (S)-MDMA and MDMA or even non-neurotoxic, it may allow for greater clinical viability and prolonged regimens of drug-assisted psychotherapy. (R)-MDMA and (S)-MDMA have shown equivalent effects in terms of inducing prosocial behavior in monkeys. However, (S)-MDMA shows higher potency, whereas (R)-MDMA shows greater maximal effects. Conversely, (S)-MDMA does not increase prosocial behavior in mice, whereas both MDMA and (R)-MDMA do so. MDMA and (S)-MDMA increase locomotor activity, a measure of psychostimulant-like effect, in rodents, whereas (R)-MDMA does not do so. (R)-MDMA likewise showed fewer reinforcing effects than (S)-MDMA in non-human primates. These findings further add to (R)-MDMA showing reduced psychostimulant-like and addictive effects compared to MDMA and (S)-MDMA.
Sources: en.wikipedia.org
=== Non-IgG-like === There are other BsAbs that lack an Fc region entirely, and thus leads to relatively simple design strategies. These include chemically linked Fabs, consisting of only the Fab regions, and various types of bivalent and trivalent single-chain variable fragments (ScFvs). There are also fusion proteins mimicking the variable domains of two antibodies. The furthest developed of these newer formats are the bi-specific T-cell engagers (BiTEs), which uses the G4S linker to connect two ScFvs-one CD3 antibody ScFv and one tumor-associated antigen (TAA) or tumor-specific ScFv-to redirect T cells to cancer cells for target killing. Other platforms include tetravalent antiparallel structure (TandAbs) and VH only (Bi-Nanobody). The TandAb platform is formed by a tetravalent antibody molecule containing two binding sites for each of two antigens. In this platform, the reverse pairing of two peptide chains forms a homodimer molecule. As an example, AFM11 is based on the TandAbs platform and targets both CD3 and CD19 to achieve therapeutic effects. AFM11 showed dose-dependent inhibition of Raji tumors in vivo. The Bi-Nanobody platform forms multi-specific binding through the connection between the VH regions of two or more antibody molecules. The products that are designed based on this platform are small molecules and these small molecules have high stability and better tissue permeability in vivo. Even though non-IgG-like BsAbs have low molecular weight and thus high tumor tissue permeability, their half-life is relatively short and they require multiple doses.
=== Androgen-independent === Minoxidil dilates small blood vessels; it is not clear how this causes hair to grow. Other treatments include tretinoin combined with minoxidil, ketoconazole shampoo, dermarolling (Collagen induction therapy), spironolactone, alfatradiol, topilutamide (fluridil), topical melatonin, and intradermal and intramuscular botulinum toxin injections to the scalp. The drug suvomipic (PP405; JXL069) is a potential treatment which works by stimulating follicular mitochondria. It is currently in Phase II human clinical trials.
The People's Liberation Army (PLA) is the military wing of the Chinese Communist Party (CCP) and the primary armed forces of the People's Republic of China (PRC). It consists of four services—Ground Force, Navy, Air Force, and Rocket Force—and four arms—Aerospace Force, Cyberspace Force, Information Support Force, and Joint Logistics Support Force. It operates under the CCP's absolute control and is led by the Central Military Commission (CMC) with its chairman as commander-in-chief. Alongside the paramilitary People's Armed Police (PAP) and the Militia, the PLA forms the bulk of the country's armed forces. The PLA can trace its origins during the Republican era to the left-wing units of the National Revolutionary Army (NRA) of the Kuomintang (KMT), when they broke away in 1927 in an uprising against the nationalist government as the Chinese Red Army before being reintegrated into the NRA as units of New Fourth Army and Eighth Route Army during the Second Sino-Japanese War. The two NRA communist units were reconstituted as the PLA in 1947. Since 1949, the PLA has used nine different military strategies, which it calls "strategic guidelines". The most important came in 1956, 1980, and 1993. Politically, the PLA and the PAP have the largest delegation in the National People's Congress (NPC); the joint delegation currently has 281 deputies—over 9% of the total—all of whom are CCP members. The PLA is the armed wing of the CCP and controlled by the party, not by the state. The PLA's primary mission is the defense of the party and its interests.
== In drug discovery == Identification of active sites is crucial in the process of drug discovery. The 3-D structure of the enzyme is analysed to identify active site residues and design drugs which can fit into them. Proteolytic enzymes are targets for some drugs, such as protease inhibitors, which include drugs against AIDS and hypertension. These protease inhibitors bind to an enzyme's active site and block interaction with natural substrates. An important factor in drug design is the strength of binding between the active site and an enzyme inhibitor. If the enzyme found in bacteria is significantly different from the human enzyme then an inhibitor can be designed against that particular bacterium without harming the human enzyme. If one kind of enzyme is only present in one kind of organism, its inhibitor can be used to specifically wipe them out. Active sites can be mapped to aid the design of new drugs such as enzyme inhibitors. This involves the description of the size of an active site and the number and properties of sub-sites, such as details of the binding interaction. Modern database technology called CPASS (Comparison of Protein Active Site Structures) however allows the comparison of active sites in more detail and the finding of structural similarity using software.
==== Housekeeping and waste disposal ==== When performing cleaning and decontaminating the work area where antineoplastic drugs are used, one should make sure that there is sufficient ventilation to prevent the buildup of airborne drug concentrations. When cleaning the work surface, hospital workers should use deactivation and cleaning agents before and after each activity as well as at the end of their shifts. Cleaning should always be done using double protective gloves and disposable gowns. After employees finish up cleaning, they should dispose of the items used in the activity in a yellow chemotherapy waste container while still wearing protective gloves. After removing the gloves, they should thoroughly wash their hands with soap and water. Anything that comes into contact or has a trace of the antineoplastic drugs, such as needles, empty vials, syringes, gowns, and gloves, should be put in the chemotherapy waste container.
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.
Reports describe modulation of GABA signalling, changes in monoamine turnover and effects on neurotrophic factor expression. These observations come mainly from animal and cell studies. A single unifying mechanism has not been demonstrated.