If you have been reading about HPLC and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2025-11-20. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic heptapeptide | Stabilized analog of tuftsin |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Monoisotopic mass about 751.9 Da |
| Appearance | White to off-white powder | Typically supplied as lyophilized solid |
| Solubility | Freely soluble in water | Also soluble in common polar solvents |
Measuring peptide exposure inside the brain is technically difficult. Selank is degraded rapidly in plasma, and assays must separate intact peptide from fragments, which favors targeted mass spectrometry over immunoassays alone. Reported half-lives are short, on the order of minutes, so effects observed hours later are attributed to downstream signaling rather than to the parent compound. Blood-brain barrier permeability is debated and rarely quantified directly. Gaps include absent dose-response characterization, inconsistent reporting of purity, and almost no pharmacokinetic data from human participants.
Selank is studied chiefly as an animal-model anxiolytic with proposed secondary effects on memory and immune signaling. Reported mechanisms include modulation of the GABA-A receptor complex, inhibition of enkephalin-degrading enzymes, and shifts in monoamine turnover within limbic structures. Some experiments describe increased expression of brain-derived neurotrophic factor in the hippocampus after repeated dosing. No single molecular target has been confirmed, and the peptide does not bind any receptor with the selectivity typical of a conventional small-molecule drug. Mechanism therefore remains a set of hypotheses rather than an established pathway.
Laboratory work relies on standard behavioral paradigms. Rodents are tested in the elevated plus maze, open field, and passive avoidance tasks, with outcomes compared against diazepam or vehicle controls. Intranasal dosing is used most often because it bypasses first-pass metabolism, though intraperitoneal and intravenous routes also appear in published protocols. Biochemical endpoints include tissue BDNF concentrations, cytokine levels, and monoamine metabolites. Human data are limited to small Russian trials reporting reduced anxiety scores; most were not prospectively registered, and few employed independent outcome assessment.
Dry powder is normally held at -20 degrees Celsius or lower, in a sealed container with desiccant and protection from light. Reconstituted solutions are usually kept at 2 to 8 degrees Celsius for short periods and frozen for longer ones. Proline residues at several positions are generally associated with some resistance to peptidase attack, but chemical stability still declines at neutral to alkaline pH and at elevated temperature. Exact shelf-life figures are product-specific and are not standardised across suppliers.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, with mass spectrometry used to confirm molecular mass and sequence information. Amino acid analysis and peptide mapping may supplement these methods. Certified reference standards are scarce, and many commercial lots are sold as research chemicals without a pharmacopoeial monograph. Regulatory treatment differs by country: Selank is a registered prescription medicine in Russia, while in the European Union and the United States it is not an approved drug and may fall under research-chemical or unapproved-product frameworks.
The dugite (Pseudonaja affinis) is a highly venomous Australian brown snake species. The venom of this species contains highly potent presynaptic and postsynaptic neurotoxins and procoagulants. The murine LD50 is 0.66 mg/kg SC. The average venom yield per bite is 18 mg (dry weight of milked venom) according to Meier and White (1995). Rate of envenomation is 20–40% and the untreated mortality rate is 10–20% by cardiac arrest, kidney failure, or cerebral hemorrhage.
In November 2023, reports indicated that medical care at Al-Rantisi and Al-Nasr children's hospitals has nearly come to a halt. Only a small generator provided power to the intensive care and neonatal intensive care units. Al-Rantisi Hospital faced intense attacks and hostilities. Furthermore, Al-Nasr Children's Hospital has once again suffered damage, including vital equipment. Another children's hospital in the northern region has ceased operations due to both damage and a shortage of fuel. Additionally, a specialized maternity hospital is in dire need of fuel to continue functioning. On 15 February 2024, the United Nations reported that Israel had destroyed its clinic for visually impaired children, stating the "centre was available to all visually impaired children across the Gaza Strip and provided braille machines, canes, [and] visual aids."
The ultrasound examination allows morphological changes in the kidneys in more detail. In addition to changes in size and shape, renal cysts, localized (focal) organ damage, water sac kidneys and urinary retention as well as tumors can also be visualized. Hardly defined (diffuse) organ changes are accompanied by changes in echogenicity, but can only rarely be assigned to defined diseases. Pulsed Wave Doppler" can also be used to detect circulatory disorders. Calcification (nephrocalcinosis) is also common in chronic kidney disease and can also be detected sonographically. Renal biopsy is not routinely used, but may be indicated in certain preliminary reports—for example, young Abyssinian cats with symptoms of kidney disease for the detection of amyloidosis. Although computed tomography and magnetic resonance imaging have very good detail recognition, they only play a subordinate role in veterinary medicine due to their high costs and limited availability.
== Receptors == The anuran BB4 receptor homologue is termed frog BB4 (fBB4). Iwabuchi et al. 2003 discovered a chicken (Gallus domesticus) receptor which is homologous to both the mammalian BB3 and fBB4 and so they named it chBRS-3.5.
Sources: en.wikipedia.org
== Alternative Structural Classification == Many phosphatases are promiscuous with respect to substrate type, or can evolve quickly to change substrate. An alternative structural classification notes that 20 distinct protein folds have phosphatase activity, and 10 of these contain protein phosphatases.
== Structural studies == Several structures are available of this enzyme, which is part of the respiratory chain. It is a multi-subunit enzyme in which this activity is located in the hydrophilic domain. The subunits of the membrane-embedded domain are responsible for proton translocation.
==== Knight Commander of the Order of the British Empire (KBE) ==== Military Division Vice Admiral Michael Antony Claes Moore, . Civil Division The Right Honourable Baron Thomas Alexander Fermor Hesketh. For political service.
=== Heart failure === Although loop diuretics help to treat acute symptoms of heart failure, mineralocorticoid receptor antagonist diuretics (such as spironolactone) can be used long-term to reduce mortality and morbidity associated with certain types of chronic heart failure. A randomized controlled trial in 1999 found that spironolactone reduced death from any cause by 30%, as well as cardiac death and heart failure hospitalisations, in patients with HFrEF on standard therapy. A 2011 randomized controlled trial found similar benefits with eplerenone in HFrEF, supporting the use of mineralocorticoid receptor antagonists in HFrEF when added to contemporary heart failure therapy. Current recommendations from the American Heart Association are to use spironolactone in patients with NYHA Class II-IV heart failure who have a left ventricular ejection fraction of less than 35%. Spironolactone improves left ventricular diastolic function in patients with heart failure with preserved ejection fraction, but it has no effect on mortality and hospitalization. Due to its antiandrogenic properties, spironolactone can cause effects associated with low androgen levels and hypogonadism in males. For this reason, men are typically not prescribed spironolactone for any longer than a short period of time, e.g., for an acute exacerbation of heart failure. A newer medication, eplerenone, has been approved by the US Food and Drug Administration (FDA) for the treatment of heart failure, and lacks the antiandrogenic effects of spironolactone.
=== 19 May === The Ukrainian military said it had repelled another Russian air attack in the morning, destroying 19 drones and three Kalibr missiles out of a total of 28 launched. An elderly woman was seriously injured during airstrikes on Kryvyi Rih. The Pentagon announced that it had made an accounting error in relation to the aid supplied to Ukraine. The error was made when the Pentagon overestimated to Congress, by at least $3 billion, the cost of weapons sent to Ukraine. This error meant that these funds were effectively a surplus that could be spent on more weapons for Ukraine. President Biden said he would support a joint effort with allies to train Ukrainian pilots on fourth generation aircraft, including F-16s fighter jets. Shortly afterwards, Denmark said it would provide direct help in training. No date was announced for such training to commence. Once it does it could take six to nine months to properly train Ukrainian pilots and crews to use the F-16. A US official told CNN that the United States was prepared to help train Ukrainian pilots on the F-16. The training would take place in Europe in the "coming weeks", along with European allies, while a decision on the number of aircraft would be made at a later date. During the 49th G7 summit in Hiroshima, Japan, UK Prime Minister Rishi Sunak announced that the government was introducing new sanctions against Russian exports, particularly on diamonds, nickel, copper and aluminum.
Sources: en.wikipedia.org
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.
It was developed in Russia, at the Institute of Molecular Genetics of the Russian Academy of Sciences, during the 1990s. Most published research originates from Russian institutions. Independent international replication remains limited.
Tuftsin is a natural tetrapeptide with the sequence Thr-Lys-Pro-Arg that participates in immune signaling. Selank extends that sequence with Pro-Gly-Pro at the C-terminus. The added residues are linked to greater resistance to enzymatic breakdown.
Reverse-phase HPLC is the usual method and gives a percentage purity value. Mass spectrometry then confirms the molecular mass. Together they provide a basic identity and purity profile for a lot.