This is a working overview of RP-HPLC, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-03-01 and is reviewed periodically as new material appears.
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.
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
| 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 |
The compound was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences during the 1980s and 1990s. The stated design goal was to retain the immunomodulatory and central nervous system activity attributed to tuftsin while improving resistance to enzymatic breakdown. Adding a proline-rich tail to the short parent peptide was a deliberate strategy, because proline residues restrict the conformations available to many peptidases. The same laboratory produced Semax, an ACTH fragment analog, and both compounds were developed in parallel as short, enzymatically stabilized peptides intended for intranasal use.
Selank is not a naturally occurring peptide and has no known endogenous counterpart in human physiology. Russian-language sources frequently call it TP-7, while English-language sources use the name Selank almost exclusively. Database indexing is uneven, partly because early reports appeared in regional journals that are not widely cataloged. Some summaries describe the material as a tuftsin analog and others as a synthetic heptapeptide; the labels overlap rather than conflict. Citing the primary sequence resolves ambiguity more reliably than the research or trade name alone.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter notation. Its structure consists of the immunomodulatory tetrapeptide tuftsin, Thr-Lys-Pro-Arg, extended at the carboxyl terminus by a Pro-Gly-Pro segment. The molecular formula is commonly given as C33H57N11O9, corresponding to a monoisotopic mass near 751.4 Da and an average molecular mass near 751.9 Da. All seven residues are proteinogenic amino acids, and the molecule carries no modified side chains or non-natural linkages.
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.
Peptide stability depends strongly on temperature, moisture, and pH. Lyophilized Selank is generally most stable when stored cold and dry, with freezer temperatures commonly used for long-term storage. In solution, the compound is susceptible to hydrolysis and to microbial growth if it is not handled aseptically. The C-terminal proline-rich extension appears to slow enzymatic cleavage relative to tuftsin, though quantitative degradation rates vary with the matrix and the conditions tested. Published stability data specific to Selank remain sparse.
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.
Pharmacokinetic data are sparse and largely derived from animal work. After intranasal administration the peptide appears in plasma within minutes, and reported half-lives are short, on the order of minutes to tens of minutes. Degradation proceeds through ordinary proteolytic cleavage into constituent amino acids and smaller fragments. Direct evidence that intact Selank reaches brain tissue in meaningful amounts is limited, and the extent of blood-brain barrier penetration is debated. Some authors argue that fragments, not the parent peptide, carry much of the observed activity.
Published clinical work is concentrated in Russian-language journals and generally involves small samples without independent replication. Systematic reviews in English note the shortage of randomised, placebo-controlled trials and the difficulty of verifying methods from translated reports. Outcome measures vary between studies, which complicates pooling of results. Interest in the compound as a cognitive or anxiolytic agent therefore rests on a thinner evidence base than the volume of citations suggests. Replication in well-powered trials with preregistered endpoints would be needed before firm conclusions about efficacy can be drawn.
Proposed mechanisms centre on the GABAergic system. Animal and tissue studies report changes in GABA-A receptor expression and reduced activity of GABA transaminase, the enzyme that degrades GABA. Effects on monoamine turnover, including serotonin and dopamine pathways, are also described, and a separate line of work links the peptide to increased expression of brain-derived neurotrophic factor in hippocampal tissue. Most of these findings come from rodent models and cell preparations. How the individual observations combine into a single coherent mode of action is not settled.
Chinese premier Wen Jiabao apologised to the nation, saying he felt "extremely guilty" about the poisoned milk products, in the same way he had previously asked the people's pardon for the deaths of coal miners, polluted drinking water, and train passengers stranded by the authorities' inadequate response to the severe snowstorm during the New Year.
== Properties == N-Methylethanolamine is a clear, colorless, hygroscopic, amine-like smelling liquid which is miscible with water and ethanol in any ratio. Aqueous solutions react strongly basic and are therefore corrosive. The substance is easily biodegradable and has no potential of bioaccumulation due to its water miscibility. NMEA is not mutagenic, but in the presence of nitrite, carcinogenic nitrosamines can be formed from the compound, as it is a secondary amine.
The fruit bodies of Boletus edulis can grow singly or in small clusters of two or three specimens. The mushroom's habitat consists of areas dominated by pine (Pinus spp.), spruce (Picea spp.), hemlock (Tsuga spp.) and fir (Abies spp.) trees, although other hosts include chestnut, chinquapin, beech, Keteleeria spp., Lithocarpus spp., and oak. In California, porcini have been collected in a variety of forests, such as coastal forests, dry interior oak forests and savannas and interior high-elevation montane mixed forests, to an altitude of 3,500 m (11,500 ft). In northwestern Spain, they are common in scrublands dominated by the rock rose species Cistus ladanifer and Halimium lasianthum. In the Midi region of south-west France, they are especially favoured and locally called cèpe de Bordeaux after the town from which they are traded to the north and abroad. Boletus edulis has a cosmopolitan distribution, concentrated in cool-temperate to subtropical regions. It is common in Europe—from northern Scandinavia, south to the extremities of Greece and Italy—and North America, where its southern range extends as far south as Mexico. It is well known from the Borgotaro area of Parma, Italy, and has PGI status there. The European distribution extends north to Scandinavia and south to southern Italy and Morocco. In North America, it can be found from May to October inland and August to January on the West Coast. In China, the mushroom can be found from the northeastern Heilongjiang to the Yunnan–Guizhou Plateau and Tibet.
Sources: en.wikipedia.org
== Optical resolution in racemic amino acids == No theory explains the prevalence of L-amino acids. If one takes, for example, alanine, which has a small methyl group, and phenylalanine, which has a larger benzyl group, a simple question is in what aspect, L-alanine resembles L-phenylalanine more than D-phenylalanine, and what kind of mechanism causes the selection of all L-amino acids, because it might be possible that alanine was L and phenylalanine was D.
Prolyl 4-hydroxylase subunit alpha-1 is an enzyme that in humans is encoded by the P4HA1 gene. This gene encodes a component of prolyl 4-hydroxylase, a key enzyme in collagen synthesis composed of two identical alpha subunits and two beta subunits. The encoded protein is one of several different types of alpha subunits and provides the major part of the catalytic site of the active enzyme. In collagen and related proteins, prolyl 4-hydroxylase catalyzes the formation of 4-hydroxyproline that is essential to the proper three-dimensional folding of newly synthesized procollagen chains. Alternatively spliced transcript variants encoding different isoforms have been described.
=== Fibrosis quantization === Collagen (particular case, but widely studied in SHG microscopy), can exist in various forms : 28 different types, of which 5 are fibrillar. One of the challenge is to determine and quantify the amount of fibrillar collagen in a tissue, to be able to see its evolution and relationship with other non-collagenous materials. To that end, a SHG microscopy image has to be corrected to remove the small amount of residual fluorescence or noise that exist at the SHG wavelength. After that, a mask can be applied to quantify the collagen inside the image. Among other quantization techniques, it is probably the one with the highest specificity, reproductibility and applicability despite being quite complex.
== Post-band projects == Masters continues to create music, often of an experimental nature. His first project after Pale Saints was Spoonfed Hybrid with former A.C. Temple member Chris Trout. They released their self-titled debut album in 1993 and their second album, Hibernation Shock, in 1996. In 1994, Masters, recording under the name Pail Saint, released the album Noise Bucket on Time Stereo, the label run by His Name Is Alive auteur Warren Defever. Masters and Defever then teamed up and began to release music as ESP Summer. In autumn 1998, Masters released a 7-inch EP under the name Friendly Science Orchestra entitled Miniature Album, which became an NME 'Single of the Week'. As of 2005, Masters lived in Japan. His projects, including Wingdisk with Mark Tranmer of Gnac and the Montgolfier Brothers, can be viewed on his website, The Institute of Spoons. Naysmith and Cooper formed Lorimer, and later continued working together in the Leeds band the Terminals. The band released a single in December 2006, entitled "Dictator", on Double Dragon Records. The band changed their name again to Cyanide Pills and by 2011 had released five singles and one album on Damaged Goods Records. Naysmith and Cooper worked on a new project of atmospheric instrumental music under the name The Program. Naysmith soon formed the X-Rays Eyes alongside Cooper's bandmate Sy Shields. Naysmith died on 4 April 2024. Barham has gone on to record melodic electronica under the name Kuchen.
Sources: en.wikipedia.org
Evidence from the study of the pelvis and hindlimbs of Cyonasua, indicative of morphological similarities to bones of scansorial and terrestrial generalist carnivorans such as members of the genera Galictis, Meles and Arctictis, is presented by Tarquini et al. (2026). Tseng (2026) describes the first known partial skeleton of Leptarctus wortmani from the Hemphillian strata from the Rome Beds (Oregon, United States), providing evidence of morphology of the postcranial skeleton similar to those of extant badgers belonging to the genus Meles. Lopatin et al. (2026) describe a molar of a member of the genus Mellivora from the Pleistocene strata from the Tham Hai Cave, representing the first known record of Mellivorinae in Southeast Asia. A new specimen of Cernictis hesperus, providing new information on the anatomy of members of this species, is described from the (probably late Hemphillian) strata of the Pinole Tuff Formation (California, United States) by Tseng (2026). A well-preserved cranium of a Pleistocene sable is described from the Ogorokha Site (Sakha Republic, Russia) by Boeskorov et al. (2026). Sotnikova et al. (2026) report the discovery of new fossil material of large-bodied wolverines from the Pleistocene strata from the Indigirka River basin and New Siberia (Sakha Republic, Russia), and interpret their large size as likely to be physiological adaptation to the mammoth steppe environment. Rule et al.
Global Fossil Infrastructure Tracker API – the trade association of the US oil industry. (American Petroleum Institute) U.S. Energy Information Administration U.S. Department of Energy EIA – World supply and consumption Joint Organisations Data Initiative | Oil and Gas Data Transparency U.S. National Library of Medicine: Hazardous Substances Databank – Crude Oil "Petroleum" . The American Cyclopædia. 1879. "A Short History of Petroleum", Scientific American, August 10, 1878, p. 85
A bouillon cube (also known as a stock cube) is dehydrated broth or stock formed into a small cube or other cuboid shape. The most common format is a cube about 13 mm (1⁄2 in) wide. It is typically made from dehydrated vegetables or meat stock, a small portion of fat, MSG, salt, and seasonings, shaped into a small cube. Vegetarian and vegan types are also made. Instant bouillon is also available in granular, powdered, liquid, and paste forms.
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.
Most published work uses intranasal application, either as drops or as a nasal spray. Injection routes appear in a smaller set of animal experiments. Oral use is uncommon in the literature because peptide breakdown and poor absorption limit this route.