HPLC 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 2026-03-18. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
Characterization of Selank in laboratory settings relies on standard peptide analytical techniques. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities and degradation products, while mass spectrometry confirms molecular identity through accurate mass measurement. Amino acid analysis and peptide sequencing verify the primary structure when reference material is unavailable. Because Selank is a short chain, fragmentation-based analysis produces a diagnostic ion pattern that supports confident identification.
| 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 |
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.
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.
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.
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.
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.
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.
== Reactions == Ammonium sulfate decomposes upon heating above 250 °C (482 °F), first forming ammonium bisulfate. Heating at higher temperatures results in decomposition into ammonia, nitrogen, sulfur dioxide, and water. As a salt of a strong acid (H2SO4) and weak base (NH3), its solution is acidic; the pH of 0.1 M solution is 5.5. In aqueous solution the reactions are those of [NH4]+ and SO2−4 ions. For example, addition of barium chloride, precipitates out barium sulfate. The filtrate on evaporation yields ammonium chloride (NH4Cl). Ammonium sulfate forms many double salts (ammonium metal sulfates) when its solution is mixed with equimolar solutions of metal sulfates and the solution is slowly evaporated. With trivalent metal ions, alums such as ferric ammonium sulfate (NH4Fe(SO4)2·12H2O) are formed. Double metal sulfates include ammonium cobaltous sulfate, ferrous diammonium sulfate ((NH4)2SO4·Fe(SO4)·6H2O), ammonium nickel sulfate which are known as Tutton's salts (M2M′(SO4)2(H2O)6) and ammonium ceric sulfate ((NH4)4Ce(SO4)4·2H2O). Anhydrous double sulfates of ammonium also occur in the Langbeinites family. Airborne particles of evaporated ammonium sulfate comprise approximately 30% of fine particulate pollution worldwide. It reacts with additional sulfuric acid to give triammonium hydrogen disulphate, (NH4)3H(SO4)2.
Formic acid, which has a pungent, penetrating odor, is found naturally in insects, weeds, fruits and vegetables, and forest emissions. It appears in most ants and in stingless bees of the genus Oxytrigona. Wood ants from the genus Formica can spray formic acid on their prey or to defend the nest. The puss moth caterpillar (Cerura vinula) sprays it as well when threatened by predators. It is also found in the trichomes of stinging nettle (Urtica dioica). Apart from that, this acid is incorporated in many fruits such as pineapple (0.21 mg per 100 g), apple (2 mg per 100 g) and kiwi (1 mg per 100 g), and in many vegetables, namely onion (45 mg per 100 g), eggplant (1.34 mg per 100 g), and in extremely low concentrations, cucumber (0.11 mg per 100 g). Formic acid is a naturally occurring component of the atmosphere primarily due to forest emissions.
== Interactions == Plasmin has been shown to interact with Thrombospondin 1, Alpha 2-antiplasmin and IGFBP3. Moreover, plasmin induces the generation of bradykinin in mice and humans through high-molecular-weight kininogen cleavage. Plasmin has also been implicated to play a role in mammalian reproduction noting its important in fertilization and the oocyte-sperm interaction. Studies have shown that plasmin inhibition hindered oocyte maturation and embryo development. It can also inhibit cleavage rates and blastocyst formation as well as play a key role in sperm adhesion to the oocyte.
Flicker noise is electronic noise with a 1/ƒ frequency spectrum; as f increases, the noise decreases. Flicker noise arises from a variety of sources, such as impurities in a conductive channel, generation, and recombination noise in a transistor due to base current, and so on. This noise can be avoided by modulation of the signal at a higher frequency, for example, through the use of a lock-in amplifier.
doi:10.1016/j.forsciint.2020.110199 Ottone NE (2020). Micro-Plastination. Technique for Obtaining Slices below 250 μm for the Visualization of Microanatomy in Morphological and Pathological Morphology Protocols. International Journal of Morphology, 38( 2 ): 389–91. doi:10.4067/S0717-95022020000200389
Sources: en.wikipedia.org
The aim of the partnership is to combine both technologies in a bio-artificial pancreas device, which releases insulin in response to blood glucose levels, to bring to clinical trial stages. The San Diego, California based biotech company ViaCyte has also developed a product aiming to provide a solution for type 1 diabetes which uses an encapsulation device made of a semi-permeable immune reaction-protective membrane. The device contains pancreatic progenitor cells that have been differentiated from embryonic stem cells. After surgical implantation in an outpatient procedure, the cells mature into endocrine cells which arrange in islet-like clusters and mimic the function of the pancreas, producing insulin and glucagon. The technology advanced from pre-clinical studies to FDA approval for phase 1 clinical trials in 2014, and presented two-year data from the trial in June 2018. They reported that their product, called PEC-Encap, has so far been safe and well tolerated in patients at a dose below therapeutic levels. The encapsulated cells were able to survive and mature after implantation, and immune system rejection was decreased due to the protective membrane. The second phase of the trial will evaluate the efficacy of the product. ViaCyte has also been receiving financial support from JDRF on this project.
=== Colonial and Revolutionary eras === True Asian tea (Camellia Sinensis) was first brought to North America by Dutch traders in the 17th century. In the Dutch colony of New Amsterdam, now known as New York, tea was served with the best silver strainers, the finest porcelain cups and pots, and wooden tea caddies. Regular shipments of tea to the American colonies began in the 1720s. Legally, American colonists were only supposed to buy British tea, but in reality, smuggling was widespread, and Dutch, French, and other teas were widely available. Asian tea soon became a very popular drink in the American colonies, and tea parties were common among all classes. The first tea vendors in Boston were Benjamin Harris and Daniel Vernon, who received licenses to sell tea in 1690. In Salem, Massachusetts, tea leaves were boiled to create a bitter brew, then served as a vegetable side dish with butter. By the time of the American Revolution, tea was drunk everywhere from the backwoods to the cities. The view of tea in American culture began to shift when the British government introduced the Townshend Acts in 1767. Tea was taxed as part of these laws which made it less affordable for the colonial population. However, cheaper tea was still smuggled into America. Later in 1773 the Tea Act was put into place which allowed the East India Company (EIC) to gain a monopoly on tea sales in America by being able to sell tea at prices that were cheaper than both the colonial tea importers and smugglers.
== Medical uses == The original indication of chloramphenicol was in the treatment of typhoid, but the presence of multiple drug-resistant Salmonella typhi has meant it is seldom used for this indication except when the organism is known to be sensitive. In low-income countries, the WHO no longer recommends only chloramphenicol as first-line to treat meningitis, but recognises it may be used with caution if there are no available alternatives. During the last decade chloramphenicol has been re-evaluated as an old agent with potential against systemic infections due to multidrug-resistant gram positive microorganisms (including vancomycin resistant enterococci). In vitro data have shown an activity against the majority (> 80%) of vancomycin resistant E. faecium strains. In the context of preventing endophthalmitis, a complication of cataract surgery, a 2017 systematic review found moderate evidence that using chloramphenicol eye drops in addition to an antibiotic injection (cefuroxime or penicillin) will likely lower the risk of endophthalmitis, compared to eye drops or antibiotic injections alone.
== Aftermath == In the aftermath of the incident, security protocols at the facility were strengthened, including tighter restrictions on tool access. The North Carolina prison system also improved safety by equipping guards with body armor and providing supervisors with tasers. On October 12, 2022—the fifth anniversary of the failed escape—staff at Pasquotank held a moment of silence and released balloons in remembrance.
Sources: en.wikipedia.org
=== Awards === Counter-Strike earned numerous accolades on its release. In 2000, it was recognized by many gaming magazines and websites as Game of the Year, Action Game of the Year, or Online Game of the Year. The game also won 2 reader polls for Game of the Year from GameSpot US and VoodooExtreme readers. At the Game Developer 2001 Spotlight Awards, Counter-Strike was named Best Multiplayer Game and received a Special Achievement in Gaming. In 2003, Counter-Strike was inducted into GameSpot's greatest games of all-time list.
Two of the most significant differences between puberty in females and puberty in males are the age at which it begins, and the major sex steroids involved, the androgens and the estrogens. Although there is a wide range of normal ages, females typically begin the process of puberty around age 10½; males at ages 11½–12. Puberty generally ends between 15–17 for females and 16–17 for males. Females attain reproductive maturity about four years after the first physical changes of puberty appear. In contrast, males accelerate more slowly but continue to grow for about six years after the first visible pubertal changes. For males, the androgen testosterone is the principal sex hormone; while testosterone is produced, all males' changes are characterized as virilization. A substantial product of testosterone metabolism in males is the estrogen estradiol. The conversion of testosterone to estradiol depends on the amount of body fat and estradiol levels in males are typically much lower than in females. The male "growth spurt" also begins later, accelerates more slowly, and lasts longer before the epiphyses fuse. Although males are on average 2 centimetres (0.8 in) shorter than females before puberty begins, adult men are on average about 13 centimetres (5.1 in) taller than women. Most of this sex difference in adult heights is attributable to a later onset of the growth spurt and a slower progression to completion, a direct result of the later rise and lower adult male levels of estradiol. The hormonal maturation of females is considerably more complicated than in males.
==== Endogenous ==== Endogenous pyrogens are cytokines released from monocytes (which are part of the immune system). In general, they stimulate chemical responses, often in the presence of an antigen, leading to a fever. Whilst they can be a product of external factors like exogenous pyrogens, they can also be induced by internal factors like damage associated molecular patterns such as cases like rheumatoid arthritis or lupus. Major endogenous pyrogens are interleukin 1 (α and β) and interleukin 6 (IL-6). Minor endogenous pyrogens include interleukin-8, tumor necrosis factor-β, macrophage inflammatory protein-α and macrophage inflammatory protein-β as well as interferon-α, interferon-β, and interferon-γ. Tumor necrosis factor-α (TNF) also acts as a pyrogen, mediated by interleukin 1 (IL-1) release. These cytokine factors are released into general circulation, where they migrate to the brain's circumventricular organs where they are more easily absorbed than in areas protected by the blood–brain barrier. The cytokines then bind to endothelial receptors on vessel walls to receptors on microglial cells, resulting in activation of the arachidonic acid pathway. Of these, IL-1β, TNF, and IL-6 are able to raise the temperature setpoint of an organism and cause fever. These proteins produce a cyclooxygenase which induces the hypothalamic production of PGE2 which then stimulates the release of neurotransmitters such as cyclic adenosine monophosphate and increases body temperature.
=== Australia === As of July 2019, beak trimming is only banned in the Australian Capital Territory by means of the Animal Welfare Act 1992 (ACT) s 9C. It is currently debated in parliament whether debeaking should be banned in Victoria and New South Wales. A 2019 Voiceless report recommended the NSW Parliament to prohibit debeaking and instead '[introduce] enriched environmental conditions, such as litter and suitable range areas [to] encourage interaction and mental stimulation for hens. Better nutrition, lighting and parasite management may also help reduce injurious pecking.' In a 2015 survey conducted by the Humane Society International Australia, 91% of respondents stated that free range egg boxes should display whether the hens had undergone beak trimming.
In 1991, Japanese scientists created the first milk-based ACE inhibitor, in the form of a fermented milk drink, using specific cultures to liberate the tripeptide isoleucine-proline-proline (IPP) from the dairy protein. Valine-proline-proline (VPP) is also liberated in this process—another milk tripeptide with a very similar chemical structure to IPP. Together, these peptides are now often referred to as lactotripeptides. In 1996, the first human study confirmed the blood pressure-lowering effect of IPP in fermented milk. Although twice the amount of VPP is needed to achieve the same ACE-inhibiting activity as the originally discovered IPP, VPP also is assumed to add to the total blood pressure lowering effect. Since the first lactotripeptides discovery, more than 20 human clinical trials have been conducted in many different countries.
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.
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.