The short version of anxiolytic fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-05-15. Anything still debated is marked as such rather than presented as settled.
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
Published clinical evidence is limited. Most controlled trials were conducted in Russia, enrolled modest numbers of participants, and appeared in Russian-language journals, which restricts independent verification. Reported outcomes include lower anxiety scores, improved attention and memory measures, and changes in fatigue ratings. Reviews written in English note methodological limitations such as small samples and inconsistent endpoints. Whether the compound produces clinically meaningful benefit relative to established anxiolytics is therefore an open question rather than an established finding.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C33H57N11O9 | Free peptide form |
| Molecular mass | About 751.9 Da | Calculated average mass |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form TKPRPGP |
| Structural basis | Tuftsin analogue | Extended version of a natural tetrapeptide |
| Development origin | Russian Academy of Sciences | Work carried out from the 1980s onward |
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.
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.
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.
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.
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.
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.
In organic chemistry, thioesters are organosulfur compounds with the molecular structure R−C(=O)−S−R'. They are analogous to carboxylate esters (R−C(=O)−O−R') with the sulfur in the thioester replacing oxygen in the carboxylate ester, as implied by the thio- prefix. They are the product of esterification of a carboxylic acid (R−C(=O)−O−H) with a thiol (R'−S−H). In biochemistry, the best-known thioesters are derivatives of coenzyme A, e.g., acetyl-CoA. The R and R' represent organyl groups, or H in the case of R.
R6890, sometimes known as spirochlorphine, is an orphine opioid analgesic and a member of the spiropiperidine family of agents. The first known mention of this compound was in 1977. Other examples of agents from this class are Ro64-6198 and Ro65-6570. Brorphine also has a similar structure. It has been sold as a designer drug, and was proposed for placement on the Schedule 1 list in the USA on 1 July 2026. A precursor chemical used in the synthesis of R6890 is 1-phenyl-1,3,8-triazaspiro(4,5)decan-4-one (also known as spirodecanone), which is used in the synthesis of other drugs including spirilene, fluspirilene, spiramide, spiperone, RP-23618, spiroxatrine, L008716 and R5260.
== History == Mitomycin was discovered in 1955 by Japanese scientists in cultures of the microorganism Streptomyces caespitosus. Mitomycin C was isolated as purple crystals by Wakaki and his coworkers from Kyowa Hakko Kogyo in 1956. It was approved based on the results of the OLYMPUS (NCT02793128) multicenter trial involving 71 subjects with low-grade upper urinary tract urothelial cancer (UTUC). These subjects had never undergone treatment (treatment-naïve) or had recurrent low-grade non-invasive UTUC with at least one measurable papillary tumor (a tumor shaped like a small mushroom with its stem attached to the inner lining of an organ) located above the ureteropelvic junction. Subjects received mitomycin gel once a week (mitomycin gel 4 mg per mL instillations via ureteral catheter or nephrostomy tube) for six weeks and, if assessed as a complete response (complete disappearance of the papillary tumor), monthly for up to eleven additional months. Efficacy of mitomycin gel was evaluated using urine cytology (a test to look for abnormal cells in a subjects's urine), ureteroscopy (an examination of the upper urinary tract) and biopsy (if warranted) three months following the initiation of therapy. The primary endpoint was complete response at three months following initiation of therapy. A complete response was found in 41 of the 71 subjects (58%) following six treatments of mitomycin gel administered weekly.
Sources: en.wikipedia.org
Lactobacillales (order) as the most abundant; primarily upstream of pnuC, and sometimes pncB or pnuC–nadR operons. Notable organisms include species of Fructobacillus and many other lactic acid bacteria. Planctomycetota (phylum), commonly upstream of nadA. Pseudomonadota, found in Pseudomonas laurylsulfatiphila and related species, upstream of an annotated nucleoside transporter. Actinobacteriota, in isolated instances from metagenome-assembled genomes. The prevalence of mini-NAD⁺-II riboswitches in lactic acid bacteria is thought to be functionally significant, as these organisms rely on various anaerobic fermentation strategies (e.g., lactic acid or ethanol production) to maintain a balanced NAD⁺/NADH ratio. The prevalence of mini-NAD⁺-II riboswitches in lactic acid bacteria is thought to be functionally significant, as these organisms rely on various anaerobic fermentation strategies (e.g., lactic acid or ethanol production) to maintain a balanced NAD⁺/NADH ratio.
=== Research applications === Ribosomal proteins: For the studies of individual ribosomal proteins, the use of proteins that are produced and purified from recombinant sources has largely replaced those that are obtained through isolation. However, isolation is still required for the studies of the whole ribosome. Lysosomal proteins: Lysosomal proteins are difficult to produce recombinantly due to the number and type of post-translational modifications that they have (e.g. glycosylation). As a result, recombinant lysosomal proteins are usually produced in mammalian cells. Plant cell culture was used to produce FDA-approved glycosylated lysosomal protein-drug, and additional drug candidates. Recent studies have shown that it may be possible to produce recombinant lysosomal proteins with microorganisms such as Escherichia coli and Saccharomyces cerevisiae. Recombinant lysosomal proteins are used for both research and medical applications, such as enzyme replacement therapy.
=== Use with time-of-flight mass spectrometry === The electron ionization time of flight mass spectroscopy (EI-TOF MS) is well suited for analytical and basic chemical physics studies. EI-TOF MS is used to find ionization potentials of molecules and radicals, as well as bond dissociation energies for ions and neutral molecules. Another use of this method is to study about negative ion chemistry and physics. Autodetachment lifetimes, metastable dissociation, Rydberg electron transfer reactions and field detachment, SF6 scavenger method for detecting temporary negative ion states, and many others have all been discovered using this technique. In this method the field free ionization region allows for high precision in the electron energy and also high electron energy resolution. Measuring the electric fields down the ion flight tube determines autodetachment and metastable decomposition as well as field detachment of weakly bound negative ions. The first description of an electron ionization orthogonal-acceleration TOF MS (EI oa-TOFMS) was in 1989. By using "orthogonal-acceleration" with the EI ion source the resolving power and sensitivity was increased. One of the key advantage of oa-TOFMS with EI sources is for deployment with gas chromatographic (GC) inlet systems, which allows chromatographic separation of volatile organic compounds to proceed at high speed.
In January 2026, First Secretary of the Communist Party of Cuba Miguel Díaz-Canel strongly condemned strikes in Venezuela and the subsequent capture of President Nicolás Maduro, labeling the actions as "state terrorism". On 15 January 2026, he was present, alongside 94-year-old former Cuban leader Raúl Castro, in a ceremony in Havana to pay tribute to 32 Cuban soldiers killed in the United States intervention in Venezuela.
Sources: en.wikipedia.org
Platelet-Poor Plasma (PPP) is blood plasma with very low number of platelets (< 10 X 103/μL). Traditionally, PPP was recommended for use in platelet aggregation studies to both adjust the platelet-rich plasma concentration, and to serve as a control. PPP may have elevated levels of fibrinogen, which has the ability to form a fibrin-rich clot once activated. Wound healing requires cell migration and attachment, which is facilitated by this fibrin clot.
Former Labour MP Jared O'Mara, who submitted fake expense claims to fund his cocaine habit, is convicted of fraud. The following day, he is sentenced to four years in prison. Royal Mail unveils a new stamp design that will be available from 4 April, featuring an image of the unadorned head of King Charles III. 9 February The UK commits additional funding to help the victims of the earthquake in Turkey and Syria. 2023 West Lancashire by-election: Labour hold the seat with a large vote share of 62.3%, an increase of 10.3%. Ashley Dalton is the new MP. In a radio interview before his appointment as Deputy Chairman of the Conservative Party, Lee Anderson says he will support the return of capital punishment where the perpetrators are clearly identifiable. Prime Minister Rishi Sunak says neither he nor the government shares Anderson's stance. 10 February Chancellor Jeremy Hunt tells the BBC households are unlikely to receive extra help with their energy bills from April 2023, as he does not think the government has the "headroom to make a major new initiative to help people". Data released by the Office for National Statistics indicates the UK narrowly avoided a recession at the end of 2022 following zero per cent growth during October to December. This is also despite a fall in output of 0.5% during December due to strike action being staged prior to Christmas. Coronation of Charles III and Camilla Buckingham Palace unveils the official Coronation logo, designed by Sir Jony Ive. A ballot offering 10,000 free tickets to the Coronation concert at Windsor Castle on 7 May opens.
Neuromodulation is "the alteration of nerve activity through targeted delivery of a stimulus, such as electrical stimulation or chemical agents, to specific neurological sites in the body". It is carried out to normalize – or modulate – nervous tissue function. Neuromodulation is an evolving therapy that can involve a range of electromagnetic stimuli, such as a magnetic field (rTMS), an electric current, or a drug delivered directly into the subdural space (intrathecal drug delivery). Emerging applications involve targeted introduction of genes or gene regulators and light (optogenetics), and by 2014, these had been at minimum demonstrated in mammalian models, or first-in-human data had been acquired. The most clinical experience has been with electrical stimulation. Neurotherapy, in modern use, is a synonym for neuromodulation. While neurotherapy may have a broader meaning, its modern definition focuses exclusively on technological methods that exert an energy-based effect on the development of a balanced nervous system in order to address symptom control and cure several conditions. Neurotherapy is a medical treatment that implements systemic targeted delivery of an energy stimulus or chemical agents to a specific neurological zone in the body to alter neuronal activity and stimulate neuroplasticity in a way that develops (or balances) a nervous system in order to treat different diseases, restore and/or to improve patients' physical strength, cognitive functions, and overall health.
Sources: en.wikipedia.org
It is a seven-amino-acid peptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro, produced by chemical synthesis rather than extracted from biological tissue. Its design is based on tuftsin, a natural immunomodulatory tetrapeptide. The C-terminal Pro-Gly-Pro segment is a common stabilising motif in short regulatory peptides.
The core four residues correspond to tuftsin, which occurs naturally as part of immunoglobulin G. The full seven-residue sequence, however, is not a known endogenous peptide. It is a laboratory-designed analogue intended to combine tuftsin-like activity with greater resistance to breakdown.
No single receptor has been confirmed as the primary target. Reports describe involvement of the GABAergic system, interference with enkephalin degradation, and shifts in neurotrophic factor expression. Because these observations come from different models and assays, they have not yet been integrated into one accepted mechanism.
Dry powder is best kept sealed, protected from light, and held at minus 20 degrees Celsius or below. Desiccant packaging helps limit moisture uptake because the material is hygroscopic. A sealed vial should be allowed to equilibrate to room temperature before opening to reduce condensation.