lyophilised powder 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 2025-08-23. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
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.
| 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 |
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
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.
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
==== Differential mobility spectrometry (DMS) ==== Also known as field asymmetric-waveform ion mobility spectrometry (FAIMS) or RF-DC ion mobility spectrometry is a technique in which ions are separated by the application of a high-voltage asymmetric waveform at radio frequency (RF) combined with a static (DC) waveform applied between two electrodes. Depending on the ratio of the high-field and low-field mobility of the ion, it will migrate toward one or the other electrode. Only ions with specific mobility will pass through the device. It is well known that the high RF field distort the conformation of the ions, FAIMS thus is a separation technique without preserving the structure of the ions and the CCSs of the ions cannot be measured. Because FAIMS is a mass selector (other ions are excluded), the sensitivity in the scan mode is much lower than that of the drift tube ion mobility (all the ions are analyzed). Therefore, FAIMS is usually coupled with triple quadrupole mass spectrometer which is also ion selection type instrument.
=== Pharmacodynamics === NM-2-AI acts as a highly selective norepinephrine reuptake inhibitor and releasing agent in vitro and does not release serotonin or dopamine even at very high concentrations (100 μM). NM-2AI has high affinity (2.4 μM IC50) as a norepinephrine reuptake inhibitor but also has affinity as a TAAR1 receptor agonist (3.3 μM EC50), an Alpha-2A adrenergic receptor agonist (0.49 μM Ki) and as a binding agent at the 5-HT1A (3.6 μM Ki) and 5-HT2A (5.4 μM Ki) receptors.
Carbon dioxide occupies a different binding site on the hemoglobin. At tissues, where carbon dioxide concentration is higher, carbon dioxide binds to allosteric site of hemoglobin, facilitating unloading of oxygen from hemoglobin and ultimately its removal from the body after the oxygen has been released to tissues undergoing metabolism. This increased affinity for carbon dioxide by the venous blood is known as the Bohr effect. Through the enzyme carbonic anhydrase, carbon dioxide reacts with water to give carbonic acid, which decomposes into bicarbonate and protons:
== Prognosis == The use of DMARDs in the management of JIA have made disease-free remission achievable for the majority of children with JIA. Clinical remission can be defined as the absence of signs and symptoms of inflammatory disease activity, including extra-articular manifestations of the disease. Differentiating subtypes of JIA helps to target treatment and leads to more positive outcomes, however subtype is not the only predictor of JIA outcome. Poor prognostic factors include arthritis of the hip, cervical spine, ankles or wrists; prolonged elevation of inflammatory markers; and radiographic evidence of joint damage including erosions or joint space narrowing. Patients with RF-positive polyarthritis often have worse outcomes associated with more aggressive disease. Despite this, the probability of this subgroup achieving inactive disease at least once within five years was shown to be 90% in a large Canadian study. Research is currently being undertaken into clinical prediction models to allow earlier identification of children who are likely to have a worse prognosis. Compliance with therapy, especially medications, has a positive correlation with disease outcome. Disease recurrence after medical therapy discontinuation is high, with 30-100% of children having clinical relapse of disease after treatment discontinuation. It has been previously suggested that children with JIA are at an increased risk of malignancies when being treated with anti-TNF therapy.
Sources: en.wikipedia.org
== Aftermath == The recapture of Constantinople signalled the restoration of the Byzantine Empire, and on 15 August, the day of the Dormition of the Theotokos, Emperor Michael VIII entered the city in triumph and was crowned at the Hagia Sophia. The rights of the legitimate emperor, John IV Laskaris, for whom Palaiologos had been ostensibly ruling as a guardian, were brushed aside, and the boy subsequently was blinded and imprisoned.
In its simplest form, nutrient-enriched water is pumped into containers with plants in a growing medium such as Expanded clay aggregate At regular intervals, a simple timer causes a pump to fill the containers with nutrient solution, after which the solution drains back down into the reservoir. This keeps the medium regularly flushed with nutrients and air.
The word "parsley" is a merger of Old English petersilie (which is identical to the contemporary German word for parsley: Petersilie) and the Old French peresil. Both of these names are derived from Medieval Latin petrosilium, from Latin petroselinum, which is the latinization of the Greek πετροσέλινον, petroselinon, 'rock-celery', from πέτρα, petra, 'rock, stone' and σέλινον, selinon, 'celery'. Mycenaean Greek se-ri-no, in Linear B, is the earliest attested form of the word selinon.
== Uses == The useful physiological properties of yeast have led to their use in the field of biotechnology. Fermentation of sugars by yeast is the oldest and largest application of this technology. Many types of yeasts are used for making many foods: baker's yeast in bread production, brewer's yeast in beer fermentation, and yeast in wine fermentation and for xylitol production. So-called red rice yeast is actually a mold, Monascus purpureus. Yeasts include some of the most widely used model organisms for genetics and cell biology.
Penicillium expansum is a psychrophilic blue mold that is common throughout the world in soil. It causes Blue Mold of apples, one of the most prevalent and economically damaging post-harvest diseases of apples. Though primarily known as a disease of apples, this plant pathogen can infect a wide range of hosts, including pears, strawberries, tomatoes, corn, and rice. Penicillium expansum produces the carcinogenic metabolite patulin, a neurotoxin that is harmful when consumed. Patulin is produced by the fungus as a virulence factor as it infects the host. Patulin levels in foods are regulated by the governments of many developed countries. Patulin is a particular health concern for young children, who are often heavy consumers of apple products. The fungus can also produce the mycotoxin citrinin.
Sources: en.wikipedia.org
== Structure == The MT-TD gene is located on the p arm of the mitochondrial DNA at position 12 and it spans 67 base pairs. The structure of a tRNA molecule is a distinctive folded structure which contains three hairpin loops and resembles a three-leafed clover.
While the Commission has a monopoly on initiating legislation, the European Parliament and the Council of the European Union have powers of amendment and veto during the legislative process. According to the Treaty on European Union articles 9 and 10, the EU observes "the principle of equality of its citizens" and is meant to be founded on "representative democracy". In practice, equality and democracy are still in development because the elected representatives in the Parliament cannot initiate legislation against the commission's wishes, citizens of smallest countries have greater voting weight in Parliament than citizens of the largest countries, and "qualified majorities" or consensus of the council are required to legislate. This "democratic deficit" has encouraged numerous proposals for reform, and is usually perceived as a hangover from earlier days of integration led by member states. Over time, the Parliament gradually assumed more voice: from being an unelected assembly, to its first direct elections in 1979, to having increasingly more rights in the legislative process. Citizens' rights are therefore limited compared to the democratic polities within all European member states: under TEU article 11, citizens and associations have the right to publicise their views and the right to submit an initiative that must be considered by the Commission if it has received at least one million signatures. TFEU article 227 contains a further right for citizens to petition the Parliament on issues which affect them.
== Symptoms == The main symptoms of chronic kidney disease in cats are lack of appetite (anorexia), increased drinking (polydipsia), increased urine output (polyuria), fatigue (apathy), vomiting and weight loss. In addition, diarrhea, inflammation of the oral mucosa (stomatitis) with the formation of ulcers (ulcera), increased salivation (hypersalivation) and bad breath may occur as a result of uremia. Increased blood pressure (arterial hypertension) with damage to the eye (fundus hypertonicus, hypertensive retinopathy), anemia (anemia), itching, dehydration, soft tissue calcifications, bleedings and accumulation of water in the tissues (oedemas) are also more frequent accompanying symptoms. In the case of severe uremia, neurological neurology manifestations such as apathy, seizures, delirium, coma, abnormal movements and muscle disorders (myopathies). Typically, the symptoms—in contrast to acute renal failure—occur gradually over weeks, months or even years, and the general condition is poor. In addition, acute kidney failure is initially characterized by reduced urine production. However, an existing mild or moderate chronic kidney disease is often suddenly worsened by an acute event ("exacerbation") and thus becomes conspicuous to the cat owner.
== Discovery == In 1994, Mollereau et al. cloned a receptor that was highly homologous to the classical opioid receptors (OPs) μ-OR (MOP), κ-OR (KOP), and δ-OR (DOP) that came to be known as the Nociceptin Opioid Peptide receptor (NOP). As these “classical” opioid receptors were identified 30 years earlier in the mid-1960s, the physiological and pharmacological characterization of NOP as well as therapeutic development targeting this receptor remain decades behind. Although research on NOP has blossomed into its own sub-field, the lack of widespread knowledge of NOP's existence means that it is commonly omitted from studies that investigate the OP family, despite its promising role as a therapeutic target.
== Location == They can exist either presynaptically or postsynaptically depending upon cell types. The μ-opioid receptors exist mostly presynaptically in the periaqueductal gray region, and in the superficial dorsal horn of the spinal cord (specifically the substantia gelatinosa of Rolando). Other areas where they have been located include the external plexiform layer of the olfactory bulb, the nucleus accumbens, in several layers of the cerebral cortex, and in some of the nuclei of the amygdala, as well as the nucleus of the solitary tract. Some MORs are also found in the intestinal tract. Activation of these receptors inhibits peristaltic action which causes constipation, a major side effect of μ agonists.
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.
Selank is a synthetic heptapeptide designed as a stabilized analog of the natural tetrapeptide tuftsin. It has been investigated mainly for anxiolytic and cognitive effects. It is not an approved pharmaceutical in most countries.