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 2025-10-31. Where a claim depends on a specific study, the study is described rather than over-claimed.
Selank is a hydrophilic peptide and dissolves readily in water and in aqueous buffers. The lyophilised powder is typically a white to off-white solid. Because short peptides are prone to hydrolysis and oxidation, handling benefits from limiting exposure to heat, moisture and strong light. Working solutions are commonly prepared in sterile water or saline, and repeated freeze-thaw cycles are avoided to reduce aggregation and loss of activity. These practices reflect general laboratory convention rather than published stability specifications.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilised solid form |
| Solubility class | Freely soluble in water | Hydrophilic heptapeptide |
| Dry storage temperature | -20 degrees Celsius or lower | Sealed, desiccated, protected from light |
| Solution storage | 2 to 8 degrees Celsius short term | Avoid repeated freeze-thaw cycles |
| Common identification method | Reversed-phase HPLC with mass spectrometry | Confirms purity and molecular mass |
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade material.
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.
=== Transplant === While dietary therapy has been shown to be effective to normalize the very-long chain fatty acid concentrations in the plasma of individuals with ALD, allogeneic hematopoietic stem cell transplants is the only treatment that can stop demyelination that is the hallmark of the cerebral forms of the disease. In order to be effective, the transplant must be done at an early stage of the disease; if the demyelination has progressed, transplant can worsen the outcome, and increase the rate of decline. While transplants have been shown to be effective at halting the demyelination process in those presenting with the childhood cerebral form of ALD, follow-up of these patients has shown that it does not improve adrenal function.
=== Hot melt extrusion === Hot melt extrusion is utilized in pharmaceutical solid oral dose processing to enable delivery of drugs with poor solubility and bioavailability. Hot melt extrusion has been shown to molecularly disperse poorly soluble drugs in a polymer carrier increasing dissolution rates and bioavailability. The process involves the application of heat, pressure and agitation to mix materials together and 'extrude' them through a die. Twin-screw high shear extruders blend materials and simultaneously break up particles. The resulting particles can be blended and compressed into tablets or filled into capsules.
== Chemical properties == At physiological pH, the ε-amino group (–NH2) of the lysine residue exists almost entirely in its protonated form (–NH3+), whereas the carboxyl group (–COOH) of the malonyl group exists almost entirely in its deprotonated form (–COO-). Through the covalent attachment of a malonyl group to the ε-amino group, the lysine residue loses its positive charge and assumes the negative charge of the malonyl group, resulting in a charge shift from +1 to −1. This complete reversal of charge is thought to disrupt ionic interactions both within the protein itself and with negatively charged components of nucleotides, proteins and small molecules. Such alterations can occur at multiple lysine residues within a single protein, although their overall frequency varies considerably across the proteome. In mouse liver, for example, about half of all malonylated proteins contain a single site, while the frequency decreases sharply beyond four sites and only a few are extensively modified, the most heavily modified enzyme being carbamoyl‑phosphate synthetase 1 (CPS1) of the urea cycle with 31 sites. In the context of other lysine acylations, malonylation can be positioned as follows: While acetylation neutralizes lysine's positive charge, malonylation introduces a negative one, placing it among the acidic acylations alongside methylmalonylation, succinylation, glutarylation, 3‑hydroxy‑3‑methylglutarylation, 3‑methylglutaconylation, and 3‑methylglutarylation.
Sources: en.wikipedia.org
=== May === 1 May – 2025 United Kingdom local elections 2 May – Reform UK wins 677 of around 1,600 seats contested in the English local elections, making gains mostly at the expense of the Conservatives. Reform also wins the Runcorn and Helsby by-election and the Lincolnshire mayoral election. The Liberal Democrats gain an extra 160 seats, and control of Oxfordshire County Council, Shropshire County Council and Cambridgeshire County Council. 4 May – Conservative Party leader Kemi Badenoch tells the BBC it would be wrong to think a change of leader would "fix everything" following the party's heavy local election losses, and that the Conservatives will "come out fighting". 5 May – Reform UK is forced to clarify that it will continue to fly county standards from council buildings in councils it controls following controversy after chairman Zia Yusuf said the only flags permitted to fly would be the Union Flag and St George's Flag. Donna Edmunds, elected for Reform UK in Shropshire on 1 May, resigns from the party after she was suspended for tweeting that she intended to defect to another party. 6 May – The UK government says it has no plans to reverse cuts to winter fuel payments despite growing calls from within the Labour Party for it to do so. 8 May – 42 Labour MPs sign a letter calling for changes to proposed cuts to disability benefits. John Swinney says he will not support assisted suicide in Scotland. Carla Denyer says she will not be a candidate in the 2025 Green Party of England and Wales leadership election.
==== 2000-2009 ==== In 2000, Teva acquired Canada-based Novopharm. In October 2003, Teva announced its intentions to acquire Sicor Inc. for $3.4 billion. Following the announcement, the acquisition was completed on January 22, 2004, which marked Teva's entry into biosimilars' market. In 2005, Teva opened a new, state-of-the-art pharmaceutical manufacturing plant in Har Hotzvim, a technology park in Jerusalem. The plant received FDA approval in early 2007. Teva entered the Japanese market in 2005 and in 2008 established a generics joint venture with Kowa. In January 2006, Teva acquired its U.S. rival Ivax Corporation for $7.4 billion. In 2008, sales totalled $11.08 billion, $13.9 billion in 2009, and in 2010 total sales rose to $16.1 billion, of which a major portion was in Europe and North America. In July 2008, Teva announced it completed the acquisition of Bentley Pharmaceuticals for its generic pharmaceutical operations in Spain for $360 million in cash. On December 23, 2008, Teva acquired Barr Pharmaceuticals for $7.5 billion, making Barr and Pliva (which Barr bought earlier) part of Teva.
=== Other uses === Fumaric acid is used in the manufacture of polyester resins and polyhydric alcohols and as a mordant for dyes. Fumaric acid can be used to make 6-methylcoumarin. When fumaric acid is added to their feed, lambs produce up to 70% less methane during digestion.
Sources: en.wikipedia.org
These genes can be placed in three categories: genes that increase the risk of migraine in general, those that specifically increase risk for migraine with aura, and those that specifically increase risk for migraine without aura. Three of these genes, CALCA, CALCB, and HTR1F, are already targets for migraine specific treatments. Five genes are specific to risk of migraine with aura, PALMD, ABO, LRRK2, CACNA1A and PRRT2, and 13 genes are specific to risk of migraine without aura. Using the accumulated genetic risk of common variations to calculate a so-called polygenetic risk score, it is possible to assess, for example, the treatment response to triptans.
==== Structure ==== Like other eukaryotic cells, animal cells are made up of a cell membrane containing a gel like cytoplasm. In this cytoplasm are a variety of membrane organelles, including all the shared eukaryotic organelles: the cell nucleus, the endoplasmic reticulum, ribosomes, the Golgi apparatus, mitochondria, peroxisomes, endosomes, vacuoles and vesicles, and vaults; as well and centrosomes, which are unique to animal cells.
If the branched and complex structures seen in cpDNA experiments are real and not artifacts of concatenated circular DNA or broken circles, then a D-loop mechanism of replication is insufficient to explain how those structures would replicate. At the same time, homologous recombination does not expand the multiple A --> G gradients seen in plastomes. Because of the failure to explain the deamination gradient as well as the numerous plant species that have been shown to have circular cpDNA, the predominant theory continues to hold that most cpDNA is circular and most likely replicates via a D loop mechanism.
== Adverse effects == Urea can be irritating to skin, eyes, and the respiratory tract. Repeated or prolonged contact with urea in fertilizer form on the skin may cause dermatitis. High concentrations in the blood can be damaging. Ingestion of low concentrations of urea, such as are found in typical human urine, are not dangerous with additional water ingestion within a reasonable time-frame. Many animals (e.g. camels, rodents or dogs) have a much more concentrated urine which may contain a higher urea amount than normal human urine. Urea can cause algal blooms to produce toxins, and its presence in the runoff from fertilized land may play a role in the increase of toxic blooms. The substance decomposes on heating above melting point, producing toxic gases, and reacts violently with strong oxidants, nitrites, inorganic chlorides, chlorites and perchlorates, causing fire and explosion.
Sources: en.wikipedia.org
Dry powder is normally held at -20 degrees Celsius or below in a sealed, light-protected container with desiccant. Brief room-temperature handling during weighing is generally tolerated. Storage instructions vary between suppliers, so the accompanying certificate of analysis should be followed.
Reversed-phase HPLC establishes purity, while mass spectrometry confirms the expected molecular mass. Sequence confirmation may use tandem mass spectrometry or peptide mapping. A certificate of analysis typically reports these results alongside the analytical method applied.
In Russia it is a registered medicine available by prescription. In many other countries it is not approved for human use and is supplied only as a research chemical. Import and possession rules differ by jurisdiction, and buyers are responsible for checking local requirements.
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.