lyophilized 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.
Updated 2026-03-31. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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 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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Calculated for the free peptide |
| Molecular weight | About 751.9 g/mol | Derived from the sequence |
| Appearance | White to off-white powder | Typical lyophilised form |
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.
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.
Peptide bonds in selank are susceptible to hydrolysis under strongly acidic or basic conditions, and the terminal proline residues are vulnerable to exopeptidase activity in biological samples. Lyophilized powder stored dry at -20 °C typically remains stable for extended periods, whereas aqueous solutions degrade faster and may lose measurable purity within days to weeks depending on pH, temperature, and microbial load. Repeated freeze-thaw cycles promote aggregation and adsorption to container surfaces. For analytical work, solutions are usually prepared fresh, kept cold, and used within a single working day.
Handling follows standard practice for research peptides. Material is weighed in a low-humidity environment because the powder absorbs atmospheric moisture. Purity is reported as the percentage area of the main peak in a chromatogram, with specifications commonly set at 95 percent or higher; values below that threshold indicate the presence of truncated or modified species. Residual trifluoroacetate from purification is often present and may affect mass balance. Certificates of analysis should state the analytical method, the column and gradient used, and the lot-specific retention time so that results can be compared across suppliers.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
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.
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.
Clinical pathology is a medical specialty that is concerned with the diagnosis of disease based on the laboratory analysis of bodily fluids, such as blood, urine, and tissue homogenates or extracts using the tools of chemistry, microbiology, hematology, molecular pathology, and Immunohaematology. This specialty requires a medical residency. Clinical pathology is a term used in the US, UK, Ireland, many Commonwealth countries, Portugal, Brazil, Italy, Japan, and Peru; countries using the equivalent in the home language of "laboratory medicine" include Austria, Germany, Romania, Poland and other Eastern European countries; other terms are "clinical analysis" (Spain) and "clinical/medical biology (France, Belgium, Netherlands, North and West Africa).
Before the advent of SPPS, solution methods for chemical peptide synthesis relied on tert-butyloxycarbonyl (abbreviated 'Boc') as a temporary N-terminal α-amino protecting group. The Boc group is removed with acid, such as trifluoroacetic acid (TFA). This forms a positively charged amino group in the presence of excess TFA (note that the amino group is not protonated in the image on the right), which is neutralized and coupled to the incoming activated amino acid. Neutralization can either occur prior to coupling or in situ during the basic coupling reaction. The Boc/Bzl approach retains its usefulness in reducing peptide aggregation during synthesis. In addition, Boc/benzyl SPPS may be preferred over the Fmoc/tert-butyl approach when synthesizing peptides containing base-sensitive moieties (such as depsipeptides or thioester moeities), as treatment with base is required during the Fmoc deprotection step (see below). Permanent side-chain protecting groups used during Boc/benzyl SPPS are typically benzyl or benzyl-based groups. Final removal of the peptide from the solid support occurs simultaneously with side chain deprotection using anhydrous hydrogen fluoride via hydrolytic cleavage. The final product is a fluoride salt which is relatively easy to solubilize. Scavengers such as cresol must be added to the HF in order to prevent reactive cations from generating undesired byproducts.
==== Metabolism ==== Doxepin is extensively metabolized by the liver via oxidation and N-demethylation. Its metabolism is highly stereoselective. Based on in vitro research, the major enzymes involved in the metabolism of doxepin are the cytochrome P450 enzymes CYP2D6 and CYP2C19, with CYP1A2, CYP2C9, and CYP3A4 also involved to a lesser extent. The major active metabolite of doxepin, nordoxepin, is formed mainly by CYP2C19 (>50% contribution), while CYP1A2 and CYP2C9 are involved to a lesser extent, and CYP2D6 and CYP3A4 are not involved. Both doxepin and nordoxepin are hydroxylated mainly by CYP2D6, and both doxepin and nordoxepin are also transformed into glucuronide conjugates. The elimination half-life of doxepin is about 15–18 hours, whereas that of nordoxepin is around 28–31 hours. Up to 10% of Caucasian individuals show substantially reduced metabolism of doxepin that can result in up to 8-fold elevated plasma concentrations of the drug compared to normal. Nordoxepin is a mixture of (E) and (Z) stereoisomers similarly to doxepin. Whereas pharmaceutical doxepin is supplied in an approximate 85:15 ratio mixture of (E)- and (Z)-stereoisomers and plasma concentrations of doxepin remain roughly the same as this ratio with treatment, plasma levels of the (E)- and (Z)-stereoisomers of nordoxepin, due to stereoselective metabolism of doxepin by cytochrome P450 enzymes, are approximately 1:1.
== Contraindications == Voriconazole is toxic to the fetus, and thus not used in pregnant women, or women who may become pregnant. People with hereditary intolerance for galactose, Lapp lactase deficiency, or glucose-galactose malabsorption should not take this drug. It should be used cautiously in people with arrhythmias or a long QTc interval. No dose adjustment is necessary for renal impairment or advanced age, but children seem to clear voriconazole faster than adults, and drug levels may need monitoring.
pesos that I'm sure will take making you conceive, which is a good viaticum for an escape.The central idea to threaten them, is the empire, and its immovability. Flatter Gamarra, telling him that he gets the best Duchy, for being the richest, the most civilized, and the most extensive from Santa to the Apurimac: there cannot be a better division. Besides, to La-Fuente, U. says the same thing with respect to his Duchy from Apurimac to Desaguadero; and keep between them, and Eléspuru continuous jealousy. With that seductive idea of perpetuity in their destinies, free from the oscillations of anarchy, we have destroyed that weapon of territorial integrity that would make them work with disgust. Entertained in this way, they will not know the double intention of adding the Duchy of northern Peru to Colombia; although the empire must be one and indivisible (...) Let your main care be that you disarm the Peruvian Force, and the civic, the veteran and the squad. To carry it out, there is the ostensible pretext of the celebrated peace, and of the ruin that the treasury of Peru would experience from the maintenance of an unnecessary army. You know the need to employ people addicted to me in destinations; so you intervene for them together with that government.
Sources: en.wikipedia.org
The Asmara College of Health Sciences is a public college in Asmara, Eritrea. It was founded in 1999 (1999) as one of the faculties at the University of Asmara with the aim of creating competent health professionals to meet the health needs of the nation. The college acquired its present independent status in 2005. The college has five major branches, namely: the School of Allied Health Professions, the School of Nursing, the School of Pharmacy, the School of Public Health, and the Department of Basic and Behavioral Sciences. The college offers BSc degrees in nursing, public health, pharmacy, ophthalmology, midwifery, and clinical laboratory sciences. It also trains technicians to diploma level in pharmacy, dentistry, physiotheraphy, radiology, and laboratory research. Since the college was founded, 3145 students have graduated, of whom 45% are female.
== External links == Equianalgesic Charts American Pain Society Guidelines Clinical Practice Guideline for the Management of Opioid Therapy for Chronic Pain Online opioid equianalgesia calculator Electronic calculator that includes logic for bidirectional and dose-dependent conversions Shaheen, PE; Walsh, D; Lasheen, W; Davis, MP; Lagman, RL (2009). "Opioid equianalgesic tables: are they all equally dangerous?". J Pain Symptom Manage. 38 (3): 409–17. doi:10.1016/j.jpainsymman.2009.06.004. PMID 19735901.
== History == 2,3-Dihydro-LSD was first described in the scientific literature by Charles Gorodetzky and Harris Isbell at the Addiction Research Center of the National Institute of Mental Health (subsequently part of the National Institute on Drug Abuse) by 1964. However, it had first been synthesized and studied in animals by Botand Berde and Rudolph Bircher at Sandoz Pharmaceuticals, but their findings were unpublished. Sandoz Pharmaceuticals supplied the 2,3-dihydro-LSD used by Gorodetzky and Isbell in their clinical study.
President-elect Joe Biden announces he will elevate the White House Office of Science and Technology Policy to a Cabinet-level position, making its nominated director Eric Lander the first biologist in the Cabinet, if confirmed by the U.S. Senate. January 17 – Riley June Williams, a 22-year-old woman suspected of stealing House Speaker Nancy Pelosi's laptop during the January 6 Capitol riot, is charged by the FBI with intent to sell the device to Russian foreign intelligence services. January 18 Vice President-elect Kamala Harris resigns from her U.S. Senate seat. Her chosen successor, former California Secretary of State Alex Padilla, becomes the first Latino to represent California in the Senate. The 1776 Report is released by the 1776 Commission. January 19 COVID-19 pandemic: Nationwide COVID-19 deaths surpass 400,000. On his final full day in office, President Trump issues pardons for 144 people. New York State Office of Court Administration employee Brendan Hunt is arrested by the FBI for encouraging public executions of members of the U.S. Congress on social media. January 20 Joe Biden is sworn in as the 46th president of the United States. Kamala Harris becomes the first woman, first Asian American, and first African American to become Vice President of the United States. Donald Trump becomes the first outgoing president to boycott his successor's inauguration since Andrew Johnson in 1869.
During the separation, the mobile phase composition may stay the same, or change. If it stays the same, the process is termed isocratic (meaning constant composition). The word was coined by Csaba Horvath who was one of the pioneers of HPLC. If it changes, then the process is termed a gradient elution. For example, a gradient can start at 10% methanol in water, and end at 90% methanol in water after 20 minutes. The two components of the mobile phase are typically termed "A" and "B"; A is the "weak" solvent which allows the solute to elute only slowly, while B is the "strong" solvent which rapidly elutes the solutes from the column. In reversed-phase chromatography, solvent A is often water or an aqueous buffer, while B is an organic solvent miscible with water, such as acetonitrile, methanol, THF, or isopropanol. In isocratic elution, peak width increases with retention time linearly according to the equation for N, the number of theoretical plates. This can be a major disadvantage when analyzing a sample that contains analytes with a wide range of retention factors. Using a weaker mobile phase, the runtime is lengthened and results in slowly eluting peaks to be broad, leading to reduced sensitivity. A stronger mobile phase would improve issues of runtime and broadening of later peaks but results in diminished peak separation, especially for quickly eluting analytes which may have insufficient time to fully resolve. This issue is addressed through the changing mobile phase composition of gradient elution.
Sources: en.wikipedia.org
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, commonly written as TKPRPGP. It shares the first four residues with tuftsin and carries three prolines in the chain. The proline-rich tail is the main structural feature that separates it from the parent tetrapeptide.
Selank is a synthetic analogue built on the tuftsin tetrapeptide Thr-Lys-Pro-Arg. Extra proline residues were added to the C-terminus during design work. That modification is intended to make the peptide less vulnerable to rapid enzymatic degradation.
Transliteration from Russian produces variant spellings such as Selanc. Many suppliers avoid the trade-style name entirely and list the peptide sequence. Comparing sequences rather than names is the reliable way to confirm two entries describe the same molecule.
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.