A practical reference on batch purity: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-01-16 and is reviewed periodically as new material appears.
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
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.
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.
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.
| 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 |
Most published work on selank originates from a small number of research groups in the Russian Federation. A large share of that record appears in Russian-language journals, which limits access for readers who rely on English-indexed databases. Independent replication by laboratories outside the original research network is sparse in publicly available sources. This concentration of origin and language is a frequently noted feature when the compound is summarized in broader reviews of synthetic peptides.
Reported pharmacological effects center on reduced anxiety-like behavior in animal models and on measures of memory and learning. Proposed contributing mechanisms include modulation of GABAergic signaling, shifts in monoamine turnover, and changes in the activity of enzymes that degrade neuropeptides. Effects on the expression of genes linked to neuroplasticity have also been described. No single molecular target is widely accepted, and whether the behavioral findings arise from one pathway or several remains an open question.
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.
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.
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.
=== Insertion of transgenes === To integrate a gene fragment of interest into the Sendai virus genome, the following protocol might be used. The amplified gene fragment is inserted into a Sendai virus vector lacking the F protein (SeV/ΔF). The recovery and amplification of SeV/ΔF vectors proceed as follows: Transfection: 293T cells are transfected with the pSeV/ΔF template containing the transgene of interest, along with plasmids that encode the T7 RNA polymerase and the viral genes NP, P, F5R (a modified F protein), and L. Cultivation: Post-transfection, the cells are incubated and cultured for 1 to 3 days to produce the initial SeV/ΔF vector. Propagation: The vector is then propagated in LLC-MK2/F7/A cells, a specialized cell line of LLC-MK2 that expresses the Sendai virus F protein, in a medium that includes trypsin. Titer quantification: The titers of the harvested SeV vector are determined by measuring the cell infectious units (CIU) per milliliter through immunostaining with anti-SeV rabbit polyclonal serum.
== Normal amount == In a urinalysis, the normal amount of urinary calcium can be measured in amount per time (commonly per 24 hours). It can also be measured in amount per mass of creatinine, which avails for estimating the urinary calcium excretion in a spot urine sample, because urinary creatinine clearance is relatively unaffected by differences in free water clearance which occurs, for example, in dehydration and which would distort the interpretation of the urinary calcium in a spot urine sample. Normally, in an average adult, the amount of calcium excreted in the urine is 100–250 mg over a 24-hour period. For those on low-calcium diets, there is normally 50–150 mg/24 hours, while those on a calcium-free diet will have 5–40 mg/24 hours. The following reference ranges are for persons with average calcium intake (600–800 mg/day for adults):
These early structural studies were not followed up until recent years with the renewed interest in bottromycin. The structure was confirmed in the 1980s and 1990s to be a cyclic iminopeptide based on NMR studies, with a linear side chain connected to the macrocycle via an amidine linkage. Its absolute stereochemistry, however, was not characterized until 2009. Stereochemistry at carbon 18 and 25 was proposed by comparing predicted conformers obtained using molecular dynamics to experimental constraints obtained through NMR experiments. Stereochemistry at carbon 43 was confirmed by comparing 1H NMR of authentic hydrolysis product to a chemically synthesized sample of the same fragment. Finally, optical rotation, 1H NMR, and HRMS experiments of chemically synthesized bottromycin matched that of biologically produced bottromycin. The three-dimensional solution structure of bottromycin A2 was solved by NMR in 2012. The overall structure was obtained with good resolution (RMSD 0.74±0.59 Å), with a RMSD of 0.09±0.06 Å for the macrocycle. In this study, it was proposed that the methylated proline residue contributed to the restricted conformation of the macrocycle. The methylated proline and β-OMe alanine residues were found to be on the same face of bottroymycin A2 and it was suggested that this characteristic contributed to binding of bottromycin to the ribosomal A site.
=== Leucomatous corneal opacity (leucoma simplex) === Leucomatous corneal opacity is a dense white opacity which results due to scarring of more than half of the stroma. A number of different presentations of leucomatous corneal opacity exist:
== Dietary sources == Good sources of phenylalanine are eggs, chicken, liver, beef, milk, and soybeans. Another common source of phenylalanine is anything sweetened with the artificial sweetener aspartame, such as diet drinks, diet foods and medication; the metabolism of aspartame produces phenylalanine as one of the compound's metabolites.
Sources: en.wikipedia.org
Merck & Co. adapted the 1936 laboratory-scale synthesis, allowing them to manufacture thiamine in Rahway in 1937. However, an alternative route using the intermediate Grewe diamine (5-(aminomethyl)-2-methyl-4-pyrimidinamine), first published in 1937, was investigated by Hoffman La Roche and competitive manufacturing processes followed. Efficient routes to the diamine have continued to be of interest. In the European Economic Area, thiamine is registered under REACH regulation and between 100 and 1,000 tonnes per annum are manufactured or imported there.
=== Preparatory phase === The first five steps of glycolysis are regarded as the preparatory (or investment) phase, since they consume energy to convert the glucose into two three-carbon sugar phosphates (G3P).
(2020), "Metalloids in plants: A systematic discussion beyond description", Annals of Applied Biology, doi:10.1111/aab.12666of Rieske M (1998), "Metalloids", in Encyclopedia of Earth and Physical Sciences, Marshall Cavendish, New York, vol. 6, pp. 758–59, ISBN 0-7614-0551-8 (set) Rochow EG (1966), The Metalloids, DC Heath and Company, Boston Vernon RE (2013), "Which Elements are Metalloids?", Journal of Chemical Education, vol. 90, no. 12, pp. 1703–07, doi:10.1021/ed3008457 —— (2020,) "Organising the Metals and Nonmetals", Foundations of Chemistry, (open access)
===== Mushroom burial ===== Mushroom burial has been developed by Jae Rhim Lee and her colleagues to address the impact traditional burial approaches have on the environment. It is an eco-friendly process which consists of dressing the cadaver in a bodysuit with mushroom spores woven into it, nicknamed the Infinity Burial Suit. Rhim developed her own mushrooms by feeding them her hair, skin, and nails to create a mushroom variety that will best decompose human remains. As the mushrooms grow, they consume the remains within the suit as well as the toxins that are being released by the body. Rhim and her colleagues created this suit as a symbol of a new way for people to think about the relationship between their body after death and the environment.
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.
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, written TKPRPGP in one-letter code. It combines the tetrapeptide tuftsin with a carboxyl-terminal Pro-Gly-Pro extension. This full sequence identifies the molecule more precisely than the research name.