The short version of certificate of analysis fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-11-13. Anything still debated is marked as such rather than presented as settled.
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.
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.
Lyophilized material is generally stable for extended periods when kept dry at or below minus twenty degrees Celsius. Working solutions are less stable, and common practice is to aliquot and freeze them so that repeated freeze-thaw cycles are avoided. Aqueous solutions are sensitive to pH extremes and to microbial growth, so short-term storage at refrigerator temperature is typical. Oxidation and hydrolysis are the principal degradation routes. Reconstitution with sterile water or a mild buffer is standard, and solutions should be protected from light.
| 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 |
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, 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.
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. Its four N-terminal residues reproduce tuftsin, a tetrapeptide fragment of the immunoglobulin heavy chain, while the C-terminal Pro-Gly-Pro extension is a synthetic addition. The peptide has a molecular mass near 752 daltons and carries a net positive charge at physiological pH because of the arginine and lysine side chains. Published indexes list it under the name Selank and the sequence abbreviation TKPRPGP. Solid-phase peptide synthesis is the standard production route for research quantities.
Development took place at the Institute of Molecular Genetics of the Russian Academy of Sciences, where a series of short peptides were designed in the 1980s and 1990s. Selank was selected from variants of tuftsin that showed resistance to plasma peptidases. Russian regulatory approval covers it as an anxiolytic agent given intranasally. Outside that market the compound is normally handled as a research chemical rather than a medicine, and no widely recognised international pharmacopoeial monograph exists. The name Selank is a coined trade designation rather than a systematic chemical name.
Enzymatic stability motivates the extra three residues at the carboxyl end. Native tuftsin is cleaved quickly by circulating aminopeptidases and carboxypeptidases, which limits its duration of action and its usefulness as a tool compound. Extending the chain with proline-rich segments is a common design tactic because proline constrains the backbone and slows proteolysis. The same Pro-Gly-Pro motif appears in other Russian-developed peptides of the era. Whether the full seven-residue chain is required for activity, or whether it acts mainly as a prodrug releasing tuftsin, remains unresolved.
Natural fibers or natural fibres (see spelling differences) are fibers that are produced by geological processes or obtained from the bodies of plants or animals. They can be used as a component of composite materials, where the orientation of fibers impacts the properties. Natural fibers can also be matted into sheets to make paper or felt. The earliest evidence of humans using fibers is the discovery of wool and dyed flax fibers found in a prehistoric cave in the Republic of Georgia that date back to 36,000 BP. Natural fibers can be used for high-tech applications, such as composite parts for automobiles and medical supplies. Compared to composites reinforced with glass fibers, composites with natural fibers have advantages such as lower density, better thermal insulation, and reduced skin irritation. Furthermore, unlike glass fibers, natural fibers can be broken down by bacteria once they are no longer used. Natural fibers are generally renewable and biodegradable, and they tend to decompose faster than synthetic fibers, although decomposition rates and environmental impacts vary by fiber type. Natural fibers are good water absorbents and can be found in various textures. Cotton fibers made from the cotton plant, for example, produce fabrics that are light in weight, soft in texture, and which can be made in various sizes and colors. Clothes made of natural fibers such as cotton are often preferred over clothing made of synthetic fibers by people living in hot and humid climates.
This version of the song, which features Maynard James Keenan (from Tool and A Perfect Circle) and guitarist John Frusciante (of the Red Hot Chili Peppers), was praised by Aicher as "Dark, brooding, sad, and twitchy".
== Etymology == The scientific name Crotalus is derived from Ancient Greek: κρόταλον, romanized: krótalon, lit. 'castanet'. The name Sistrurus is the Latinized form of the Greek for "tail rattler" (Σείστρουρος, Seístrouros) and shares its root with the ancient Egyptian musical instrument the sistrum, a type of rattle.
Sources: en.wikipedia.org
== Analogues == Several growth hormone analogues featuring amino acid substitutions, deletions, and extensions have been developed, resulting in variants with distinct pharmacokinetic and pharmacodynamic profiles.
Statistics from 1998 show that there were wide racial disparities in arrests, prosecutions, sentencing and deaths. African-American drug users made up for 35% of drug arrests, 55% of convictions, and 74% of people sent to prison for drug possession crimes. Nationwide African-Americans were sent to state prisons for drug offenses 13 times more often than other races, even though they supposedly constituted only 13% of regular drug users. Human Rights Watch's report, "Race and the Drug War" (2000), provided extensive documentation of racial disparities, citing statistics and case studies highlighting the unequal treatment of racial and ethnic groups by law enforcement agencies, particularly in drug arrests. According to the report, in the US in 1999, compared to non-minorities, African Americans were far more likely to be arrested for drug crimes, and received much stiffer penalties and sentences. Reporting on the effects of state initiatives, the Department of Justice found that, from 1990 through 2000, "the increasing number of drug offenses accounted for 27% of the total growth among black inmates, 7% of the total growth among Hispanic inmates, and 15% of the growth among white inmates." In Malign Neglect – Race Crime and Punishment in America (1995), criminologist Michael Tonry wrote, "The War on Drugs foreseeably and unnecessarily blighted the lives of hundreds and thousands of young disadvantaged black Americans and undermined decades of effort to improve the life chances of members of the urban black underclass."
=== Polyendocrine metabolic ovarian syndrome === GLP-1 agonists are effective in reducing body weight in people with obesity and polyendocrine metabolic ovarian syndrome, but the effectiveness in polyendocrine metabolic ovarian syndrome without obesity is uncertain.
Naltrexone itself produces little or no psychoactive effect in normal research volunteers even at high doses, which is remarkable given that the endogenous opioid system is important in normal hedonic functioning. Because endogenous opioids are involved in the brain reward system, it would be reasonable to hypothesize that naltrexone might produce anhedonic or dysphoric effects. Although some evidence from small, early trials suggested that patients with a history of opiate dependence might be susceptible to dysphoric effects in response to naltrexone (Crowley et al. 1985; Hollister et al. 1981), reports of such effects have been inconsistent. Most large clinical studies of recovering opioid-dependent individuals have not found naltrexone to have an adverse effect on mood (Greenstein et al. 1984; Malcolm et al. 1987; Miotto et al. 2002; Shufman et al. 1994). Some studies have actually found improvements in mood during the course of treatment with naltrexone (Miotto et al. 1997; Rawlins and Randall 1976). Based on available evidence, naltrexone seems to have minimal untoward effects in the aforementioned areas, at least with long-term therapy. It has been suggested that differences in findings between acute and longer-term studies of naltrexone treatment might be related to altered function in the opioid system with chronic administration of naltrexone. For example, marked upregulation of opioid receptors and hyper-sensitivity to opioids have been observed with naltrexone in preclinical studies.
Sources: en.wikipedia.org
== Odd-chain fatty acids == Odd-chain fatty acids (OCFAs) are those fatty acids that contain an odd number of carbon atoms. The most common OCFAs are the saturated C15 and C17 derivatives, respectively pentadecanoic acid and heptadecanoic acid. The synthesis of even-chained fatty acid synthesis is done by assembling acetyl-CoA precursors, however, propionyl-CoA instead of acetyl-CoA is used as the primer for the biosynthesis of long-chain fatty acids with an odd number of carbon atoms.
== See also == Oxides, e.g., Al2O3, CaO, Fe2O3, MgO, MnO, P2O5, K2O, SiO2 Carbonates: Na2CO3 (soda ash), K2CO3 (potash) Bicarbonates, e.g., NaHCO3 (baking soda) Sulfates: sulfate ash, according to Ph. Eur. Inductively coupled plasma emission spectrometry Atomic absorption spectroscopy
This is done in cases where distention (swelling) has a greater chance of occurring. In many cases, an embalmer may select to perform what is known as a pre-injection. A pre-injection is a solution of chemicals that do not contain any preservative chemicals, but rather chemicals that encourage vasodilation, help disperse blood clots, and act as chelating agents. The focus of this "pre-injection" is to allow for a more complete drainage and better distribution of the arterial embalming solution. Cavity treatment/embalming refers to the removal of internal fluids inside body cavities via the use of an aspirator and trocar. The embalmer pushes the trocar through the abdominal wall near the navel (two inches superior and two inches to the right) and into the abdominal and chest cavities. This first punctures the hollow organs and aspirates their contents. The embalmer then fills the cavities with concentrated chemicals (known as cavity chemicals) that may contain formaldehyde, which are delivered to the chest cavity via the trocar inserted through the diaphragm. The incision is either sutured closed (commonly using the purse-string or 'N' suture methods) or a "trocar button" is secured into place. Hypodermic embalming is a supplemental method which refers to the injection of embalming chemicals into tissue with a hypodermic needle and syringe, which is generally used as needed on a case-by-case basis to treat areas where arterial fluid has not been successfully distributed during the main arterial injection.
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.
Purity is usually reported as an HPLC area percentage, most often measured at 214 nm. Identity is confirmed separately by mass spectrometry. A certificate of analysis should state both the method and the observed value.