lyophilization is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2026-08-01. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Dry storage temperature | -20 C or below | Sealed, desiccated, protected from light |
| Solution stability | Hours to days at 2-8 C | Depends on buffer and microbial load |
| Preferred pH range | Near neutral to slightly acidic | Alkaline pH accelerates hydrolysis |
| Main degradation routes | Hydrolysis and deamidation | No cysteine or methionine in sequence |
| Identity confirmation | Electrospray mass spectrometry | Observed mass compared with 751.9 Da |
Development work on the compound began in the 1980s and 1990s at the Institute of Molecular Genetics in Moscow, within the same research programme that produced the peptide Semax. Early investigators sought a tuftsin derivative with improved resistance to enzymatic breakdown and with activity in the central nervous system after peripheral administration. Most of the primary literature from this period was published in Russian, a factor that still shapes how easily the findings can be checked by outside groups.
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.
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.
Regulatory treatment varies by jurisdiction. In Russia the compound is a registered prescription product, while in the European Union and the United States it is generally handled as a research chemical without a marketing authorization. Suppliers therefore operate outside pharmaceutical oversight, and buyers rely on supplier documentation for purity and identity claims. Chain of custody and third-party testing are the main verification tools. Analysts note that the absence of a pharmacopoeial monograph for research-grade material limits standardization across vendors.
Purity assessment relies mainly on reverse-phase high-performance liquid chromatography with ultraviolet detection. Because the peptide lacks a strong chromophore, detection often uses backbone absorbance near 214 nm. Identity is confirmed by mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, comparing the measured mass against the expected value. Amino acid analysis can verify composition after acid hydrolysis. Diastereomer content and residual counterions are reported less often, although both can influence biological assays.
=== NOP cellular signalling partners === Like most G-protein coupled receptors, NOP signals through canonical G proteins upon activation. G proteins are heterotrimeric complexes consisting of α, β, and γ subunits. NOP signals through a variety of Gα subtypes that trigger diverse downstream signaling cascades. NOP coupling to Gαi or Gαo subunits leads to an inhibition of adenylyl cyclase (AC) causing an intracellular decrease in cyclic adenosine monophosphate(cAMP) levels, an important second messenger for many signal transduction pathways. NOP acting through Gαi/o pathways has also been shown to activate Phospholipase A2 (PLA2), thereby initiating Mitogen-activated protein kinase (MAPK) signaling cascades. In contrast to classical OPs, NOP also couples to Pertussis toxin (PTX)-insensitive subtypes Gαz, Gα14, and Gα16, as well as potentially to Gα12 and Gαs. Activation of NOP's canonical β-arrestin pathway causes receptor phosphorylation, internalization, and eventual downregulation and recycling. NOP activation also causes indirect inhibition of opioid receptors MOP and KOP, resulting in anti-opioid activity in certain tissues. Additionally, NOP activation leads to the activation of potassium channels and inhibition of calcium channels which collectively inhibit neuronal firing.
Chemical crystallography before X-rays describes how chemical crystallography developed as a science up to the discovery of X-rays by Wilhelm Conrad Röntgen in 1895. In the period before X-rays, crystallography can be divided into three broad areas: geometrical crystallography culminating in the discovery of the 230 space groups in 1891–1894, physical crystallography and chemical crystallography. Up until 1800 neither crystallography nor chemistry were established sciences in the modern sense; as the 19th century progressed both sciences developed in parallel. In the 18th century chemistry was in a transitional period as it moved from the mystical and philosophical approach of the alchemists, to the experimental and logical approach of the scientific chemists such as Antoine Lavoisier, Humphry Davy and John Dalton. Before X-rays, chemical crystallographic research involved observation using a goniometer, a microscope, and reference to crystal classes, tables of crystal angles, axial ratios, and the ratio between molecular weight and density (M/ρ). In this period crystallography was a science supported by empirical laws (law of constancy of interfacial angles, law of rational indices, law of symmetry) based on observations rather than theory. The history of chemical crystallography covers a broad range of topics including isomorphism, polymorphism, molecular chirality and the interaction with mineralogy, structural chemistry and solid-state physics.
=== 10 January === Ukrainian steel production was reduced by about 70% in 2022 as a result of the conflict. US and Ukrainian officials stated that Russian artillery fire had declined nearly 75% in some places. The UK said most of Soledar was under Russian control, whereas Wagner claimed all.
Etymology The term poultice comes from the Latin puls or pultēs, meaning "porridge" or "thick pap," through Middle English pultes. This reflects the traditional preparation of poultices as soft, moist masses resembling porridge. Ancient use Poultices have been documented in many ancient medical traditions, including Egypt, Mesopotamia, India, Greece, and Rome. They were usually made from plants, animal products, or minerals, and applied directly to the skin to reduce pain, inflammation, or infection.
== Adverse effects == Application to large areas or to severe burns may lead to systemic absorption and lead to adverse effects similar to those of other sulfonamides. About 0.1 to 1.0% of people show hypersensitivity reactions such as rashes or erythema multiforme. This reaction is known from other sulfonamides including antibacterials, thiazide diuretics, and sulfonylurea antidiabetics; but data on the likelihood of cross-allergies are inconsistent. Incorporation of the silver ions can lead to local argyria (discoloration of the skin), especially if the treated area is exposed to ultraviolet light. Generalised argyria with silver accumulation in kidneys, liver, and retina has only been found in association with excessive long-term use, or repeated use on severe and heavily inflamed burns. Possible consequences of generalised argyria include interstitial nephritis and anemia.
Sources: en.wikipedia.org
5 August – The 18th century Crooked House, once known as "Britain's wonkiest pub", is gutted by a fire. The pub is demolished two days later. Police subsequently confirm they are treating the fire as arson. 6 August – The Mirror reports that former Lostprophets singer Ian Watkins, who is serving a 29-year sentence for child sex offences, was stabbed during an attack at Wakefield Prison the previous day. 7 August – Data published by Halifax Bank indicates house prices have fallen by their fastest rate in South East England over the past year, with a 3.9% fall, an average of around £15,500. Consultants in England belonging to the British Medical Association announce a two-day strike on 19 and 20 September. 9 August – Nine arrests are made in London's Oxford Street and 34 dispersal orders issued after youths descend on the area prompted by online videos urging them to turn up and cause disruption. 10 August – NHS hospital waiting lists in England reached 7.5 million at the end of June 2023, up around 100,000 from the previous month, and three times higher than they were at the start of the COVID-19 pandemic. A murder investigation is launched following the discovery of a 10-year-old girl's body at an address in Woking, Surrey. The girl is subsequently named as Sara Sharif, while an international manhunt is launched after it emerges that three people known to her bought one way tickets to Pakistan and left the UK before her body was discovered.
=== Protein-type CSP === Proteins are complex, high-molecular weight biopolymers. They are inherently chiral being composed of L-amino acids and possess ordered 3D-structure. They are known to bind/interact stereoselectively with small molecules reversibly, making them extremely versatile CSPs for chiral separation of drug molecules. Hermansson made use of this property to develop number of CSPs by immobilizing proteins on to silica surface. They operate under reverse phase mode (phosphate buffer and organic modifiers). Protein polymer remains in twisted form because of the different intramolecular bonding. These bonding create different type of chiral loops/grooves present in the protein molecule. Separation mechanism of proteins depends on unique combination of hydrophobic and polar interactions by which the analytes are oriented to chiral surfaces. H-bonding and charge transfer may also contribute to enantioselectivity. The mechanism of chiral distinction by proteins is mostly not well established due to their complex nature. Several proteins based CSP have been employed for chiral drug analysis including α-acid glycoprotein (enantiopac; chiral-AGP), ovomucoid protein (Ultron ES DVM), human serum albumin (HSA). α-AGP CSP (chiral AGP), has been employed for the quantification of atenolol enantiomers in biological matrices, for pharmacokinetic investigation of racemic metoprolol. The major weakness of protein based CSPs include low loading capacity, protein phases are expensive, extremely fragile, delicate to handle, very low column efficiency, cannot invert elution order.
Lithium fluoride had already been proposed in the USA in 1950 by Farrington Daniels (1889-1972), Charles A. Boyd and Donald F. Saunders (1924-2013) for solid-state dosimetry using thermoluminescent dosimeters. The intensity of the thermoluminescent light is proportional to the amount of radiation previously absorbed. This type of dosimetry has been used since 1953 in the treatment of cancer patients and wherever people are occupationally exposed to radiation. The thermoluminescence dosimeter was followed by OSL dosimetry, which is not based on heat but on optically stimulated luminescence and was developed by Zenobia Jacobs and Richard Roberts at the University of Wollongong (Australia). The detector emits the stored energy as light. The light output, measured with photomultipliers, is then a measure of the dose.
Undecaprenyl phosphate will attack the UDP-MurNAc penta, creating a PP-MurNac penta, which is now a lipid (lipid I). EC 2.7.8.13 by MraY. UDP-GlcNAc is then transported to MurNAc, creating Lipid-PP-MurNAc penta-GlcNAc (lipid II), a disaccharide, also a precursor to peptidoglycan. EC 2.4.1.227 by MurG. Lipid II is transported across the membrane by flippase (MurJ), a discovery made in 2014 after decades of searching. Once it is there, it is added to the growing glycan chain by the enzyme peptidoglycan glycosyltransferase (GTase, EC 2.4.1.129). This reaction is known as transglycosylation. In the reaction, the hydroxyl group of the GlcNAc will attach to the MurNAc in the glycan, which will displace the lipid-PP from the glycan chain. In a final step, the DD-transpeptidase (TPase, EC 3.4.16.4) crosslinks individual glycan chains. This protein is also known as the penicillin-binding protein. Some versions of the enzyme also performs the glycosyltransferase function, while others leave the job to a separate enzyme.
Sources: en.wikipedia.org
Piritramide (R-3365, trade names Dipidolor, Piridolan, Pirium and others) is a synthetic opioid analgesic (narcotic painkiller) that is marketed in certain European countries including: Austria, Belgium, Czech Republic, Slovenia, Germany and the Netherlands. It comes in free form, is about 0.75x times as potent as morphine and is given parenterally (by injection) for the treatment of severe pain. Nausea, vomiting, respiratory depression and constipation are believed to be less frequent with piritramide than with morphine (the gold standard opioid against which other opioids are compared and contrasted), and it produces more rapid-onset analgesia (pain relief) when compared to morphine and pethidine. After intravenous administration the onset of analgesia is as little as 1–2 minutes, which may be related to its great lipophilicity. The analgesic and sedative effects of piritramide are believed to be potentiated with phenothiazines and its emetic (nausea/vomiting-inducing) effects are suppressed. The volume of distribution is 0.7-1 L/kg after a single dose, 4.7-6 L/kg after steady-state concentrations are achieved and up to 11.1 L/kg after prolonged dosing. Piritramide was developed and patented in Belgium, at Janssen, in 1960. It is part of an eponymous two-member class of opioids in clinical use with the other being bezitramide (Burgodin). The closest chemical and structural relatives of piritramide in clinical use include the diphenoxylate family, fentanyl (both Janssen discoveries) and somewhat more distantly alphaprodine.
=== Biophysical limitations === The tree of the African locust bean requires "between 0-300 metres of altitude, a mean annual rainfall of between 400-700 millimetres and a mean annual temperature of about 24-28°C." It prefers well-drained, thick clay soils but can also be found on shallow, thin sandy soils.
This album cover... I like to refer to it as "revenge". The song 'Dirt' was written to a certain person who basically buried my ass, so the woman on the album cover is kinda the portrayal of that person being sucked down into the dirt (laughs), instead of me. The picture is the spitting image of her, and that wasn't even planned. Actually, I was pretty angry about it when I first saw it – she's not happy about it either (laughs). It was real eerie. The cover was referenced on the music video for Alice in Chains' 2009 single "A Looking in View". At the 6:55 mark of the video, a woman (played by Sacha Senisch) is seen lying on a cracked desert floor similarly to Dirt's cover. "A Looking in View" was featured on Alice in Chains' fourth studio album, Black Gives Way to Blue, released exactly 17 years after Dirt, on September 29, 2009.
== Venom == The venom of the Wagler's pit viper contains four novel peptides (Waglerins 1-4). The Waglerins produce fatal respiratory paralysis of adult mice. An initial study indicated that micromolar concentrations of Waglerin 1 act both pre- and postsynaptically to inhibit transmission across rat neuromuscular junctions. However, Waglerin-1 is a more potent inhibitor of transmission across the mouse neuromuscular junction. A subsequent study demonstrated that Waglerin-1 inhibited the adult mouse endplate response to acetylcholine with an IC50 of 50 nanomolar. In striking contrast, transmission across neuromuscular junctions of neonatal or transgenic mice lacking the adult acetylcholine receptor was not altered by micromolar concentrations of Waglerin-1. Biochemical studies demonstrated that the exquisite selectivity of Waglerin-1 for the adult mouse acetylcholine receptor relies upon several amino acid residues unique to the epsilon subunit of the adult mouse acetylcholine receptor. Waglerin-1's selectivity for the epsilon-subunit containing acetylcholine receptor of adult mice is complemented by selectivity of small peptide toxins purified from the venom of Conus geographus and Conus pergrandis for the gamma-subunit containing acetylcholine receptor of neonatal skeletal muscle. The Waglerins and complementary conotoxins are useful tools to discover the contribution of acetylcholine receptor subunits to synaptogenesis. In addition, study of the Waglerins and related toxic peptides may lead to the discovery of novel molecular targets for drug development.
== Industrial production == Four large pharmaceutical companies, Monsanto, American Cyanamid, Eli Lilly, and Upjohn, developed commercial rBST products and submitted them to the US Food and Drug Administration (FDA) for approval. Monsanto was the first firm to receive approval; it has been sold in the USA since February 3, 1994. Other countries (Mexico, Brazil, India, Russia, and at least ten others) also approved rBST for commercial use. Monsanto licensed Genentech's patent and marketed their product as "Posilac". In October 2008, Monsanto sold this business, in full, to Eli Lilly and Company for $300 million plus additional consideration.
Sources: en.wikipedia.org
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.
Hydrolysis of peptide bonds and deamidation of arginine and proline residues are the main degradation routes. Alkaline pH and higher temperatures accelerate both processes. Buffered, near-neutral solutions stored cold generally degrade more slowly than unbuffered ones.
Reverse-phase chromatography gives the clearest single view of related impurities and truncated sequences. Mass spectrometry then confirms that the main peak carries the expected mass. Neither test detects enantiomeric impurities, which require a separate chiral assay.
Selank is a synthetic peptide made of seven amino acids. It is modeled on tuftsin, a natural tetrapeptide, with an added three-residue tail. It is not a small-molecule drug.