The short version of certificate of analysis fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-06-16 and is reviewed periodically as new material appears.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilised solid form |
| Solubility class | Freely soluble in water | Hydrophilic heptapeptide |
| Dry storage temperature | -20 degrees Celsius or lower | Sealed, desiccated, protected from light |
| Solution storage | 2 to 8 degrees Celsius short term | Avoid repeated freeze-thaw cycles |
| Common identification method | Reversed-phase HPLC with mass spectrometry | Confirms purity and molecular mass |
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.
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.
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.
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.
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.
Downstream processing refers to purification of chemicals, pharmaceuticals and food ingredients produced by fermentation or synthesized by plant and animal tissues, for example antibiotics, citric acid, vitamin E, and insulin. Fractionation refers to a purification strategy in which some relatively inefficient purification method is repeatedly applied to isolate the desired substance in progressively greater purity. Electrolysis refers to the breakdown of substances using an electric current. This removes impurities in a substance that an electric current is run through Sublimation is the process of changing of any substance (usually on heating) from a solid to a gas (or from gas to a solid) without passing through liquid phase. In terms of purification - material is heated, often under vacuum, and the vapors of the material are then condensed back to a solid on a cooler surface. The process thus in its essence is similar to distillation, however the material which is condensed on the cooler surface then has to be removed mechanically, thus requiring different laboratory equipment. Bioleaching is the extraction of metals from their ores through the use of living organisms. Separation process From Crystallization
== Ethylene derivatives == These are generally mustard oils, which are characterized by a burning taste; their principal occurrence is in mustard and Tropaeolum seeds. Sinigrin, or the potassium salt of inyronic acid not only occurs in mustard seed, but also in black pepper and in horseradish root. Hydrolysis with barium hydroxide, or decomposition by the ferment myrosin, gives glucose, allyl mustard oil and potassium hydroxide. Sinalbin occurs in white pepper; it decomposes to the mustard oil, glucose and sinapin, a compound of choline and sinapic acid. Jalapin or Scammonin occurs in scammony; it hydrolyses to glucose and jalapinolic acid.
Aiello was a Professor of Anthropology at UCL; Indonesian Teuku Jacob, of Gadjah Mada University claimed that the hominid was a Homo Sapiens pygmy, with microcephaly; the skeleton was examined at the Mallinckrodt Institute of Radiology with a CT scan; neuroanthropologist Dean Falk of Florida State University looked at the brain, with Charles Floyd Hildebolt (1944-2024), a Professor of Radiology, and Kirk Smith; Homo erectus was thought to have colonised the island 800,000 years ago; it was believed that the species arrived on the island by raft; the Brodmann area 10 part of the brain, was larger in the hominid, than Homo erectus; John Gurche made a model of the hominid face; Gerrit van den Bergh, of the University of Wollongong, discussed whether the Ebu gogo were the same species.
== Structure == Cyclotides have a well-defined three-dimensional structure due to their interlocking disulfide bonds and cyclic peptide backbone. Backbone loops and selected residues are labeled on the structure to help orientation. The amino acid sequence (single-letter amino acid representation) for this peptide is indicated on the sequence diagram to the right. One of the interesting features of cyclic peptides is that knowledge of the peptide sequence does not reveal the ancestral head and tail; knowledge of the gene sequence is required for this. In the case of kalata B1 the indicated glycine (G) and asparagine (N) amino acids are the terminal residues that are linked in a peptide bond to cyclize the peptide.
A positron emission tomography study found that a single low dose of 10 mg clomipramine to healthy volunteers resulted in 81.1% occupancy of the SERT, which was comparable to the 84.9% SERT occupancy by 50 mg fluvoxamine. In the study, single doses of 5 to 50 mg clomipramine resulted in 67.2–94.0% SERT occupancy while single doses of 12.5 to 50 mg fluvoxamine resulted in 28.4 to 84.9% SERT occupancy. Chronic treatment with higher doses was able to achieve up to 100.0% SERT occupancy with clomipramine and up to 93.6% SERT occupancy with fluvoxamine. Other studies have found 83% SERT occupancy with 20 mg/day paroxetine and 77% SERT occupancy with 20 mg/day citalopram. These results indicate that very low doses of clomipramine are able to substantially occupy the SERT and that clomipramine achieves higher occupancy of the SERT than SSRIs at comparable doses. Moreover, clomipramine may be able to achieve more complete occupancy of the SERT at high doses, at least relative to fluvoxamine. If the ratios of the 80% SERT occupancy dosage and the approved clinical dosage range are calculated and compared for SSRIs, SNRIs, and clomipramine, it can be deduced that clomipramine is by far the strongest SRI used medically. The lowest approved dosage of clomipramine can be estimated to be roughly comparable in SERT occupancy to the maximum approved dosages of the strongest SSRIs and SNRIs. Because their mechanism of action was originally not known and dose-ranging studies were never conducted, first-generation antipsychotics were dramatically overdosed in patients.
Sources: en.wikipedia.org
Aticaprant, also known by its developmental codes JNJ-67953964, CERC-501, and LY-2456302, is a κ-opioid receptor (KOR) antagonist which was under development for the treatment of major depressive disorder and other conditions. Aticaprant is taken orally. Side effects of aticaprant include itching, among others. Aticaprant acts as a selective antagonist of the KOR, the biological target of the endogenous opioid peptide dynorphin. The medication has decent selectivity for the KOR over the μ-opioid receptor (MOR) and other targets, a relatively long half-life of 30 to 40 hours, and readily crosses the blood–brain barrier to produce central effects. Aticaprant was originally developed by Eli Lilly, was under development by Cerecor for a time, and is now under development by Janssen Pharmaceuticals. In July 2022, it was in phase III clinical trials for major depressive disorder. In March 2025, Johnson & Johnson discontinued development of aticaprant for major depressive disorder due to lack of effectiveness in phase III trials. Aticaprant was also under development for the treatment of alcoholism, cocaine use disorder, and nicotine withdrawal, but development for these indications was discontinued as well.
=== Lifestyle === Weight loss is the most effective treatment for MASLD and MASH. A loss of 5% to 10% body weight is recommended and has shown regression of liver damage, with 10% to 40% weight loss completely reversing MASH without cirrhosis. A weight loss of greater than 10% was associated with the resolution of MASH in 90% of people in a biopsy-based study. A structured weight loss program helps people with MASLD lose more weight compared with advice alone. This type of program also leads to improvements in MASLD measured by blood tests, ultrasound, imaging, or liver biopsies. Although fibrosis improves with lifestyle interventions and weight loss, there is limited evidence for improvement in cirrhosis. A combination of improved diet and exercise, rather than either alone, appears to help manage MASFLD and reduce insulin resistance. Motivational support, such as with cognitive behavioral therapy, is helpful, as most people with MASLD do not perceive their condition as a disease, and thus have a low motivation to change. Higher-intensity behavioral weight loss therapies (diet and exercise combined) may produce greater weight loss than lower-intensity ones. A 2019 systematic review suggested updating the guidelines to recommend these therapies for MASLD management. Weight loss is associated with improvements in biomarkers, MASLD severity, and a lower risk of MASH, but its effect on long-term health is not known.
=== Badger's rule === For many kinds of samples, the assignments are known, i.e. which bond deformation(s) are associated with which frequency. In such cases further information can be gleaned about the strength on a bond, relying on the empirical guideline called Badger's rule. Originally published by Richard McLean Badger in 1934, this rule states that the strength of a bond (in terms of force constant) correlates with the bond length. That is, increase in bond strength leads to corresponding bond shortening and vice versa.
In 2025, CBSE decided to conduct two board examinations from the academic year 2025–26 to ease the pressure on students. CBSE has also rationalised much of the content in its syllabus after the COVID period to ease the children
Sources: en.wikipedia.org
Skin whitening, also known as skin lightening and skin bleaching, is the practice of using chemical substances in an attempt to lighten the skin or provide an even skin color by reducing the melanin concentration in the skin. Several chemicals have been shown to be effective in skin whitening, while some have proven to be toxic or have questionable safety profiles. This includes mercury compounds which may cause neurological problems and kidney problems. In a number of African countries, above 25% of women regularly use skin-whitening products. In Asia, this number is around 40%. In India, over 50% of skin-care product sales are attributed to skin-lightening formulations. In Pakistan, where skin lightening products are popular, creams have been found to contain toxic levels of hydroquinone and mercury. Efforts to lighten the skin date back to at least the 16th century in Asia. While a number of agents — such as kojic acid and alpha hydroxy acid — are allowed in cosmetics in Europe, a number of others such as hydroquinone and tretinoin are not. While some countries do not allow mercury compounds in cosmetics, others still do, and they can be purchased online.
=== Other lymphomas and squamous-cell carcinoma === In September 2022, the FDA announced new information regarding other types of cancers related to breast implants, based on medical device reports (MDRs) of cases of patients with squamous-cell carcinoma or various lymphomas found in the scar tissue around breast implants. The agency reported 10 MDRs about squamous-sell carcinoma found in the capsule scar tissue and 12 MDRs about various lymphomas also in the scar tissue around the breast implants. These new cases do not overlap with cases of BIA-ALCL. SCC and other lymphomas have been found in smooth-surface and textured implants as well as silicone-gel-filled and saline-filled implants. Patients who reported symptoms specified swelling, pain, lumps, and changes to their skin. As of 2022, neither the incidence rate nor prevalence is known.
=== Post-Streich years === In March 2024, it was announced that Streich's assistant coach, Julian Schuster, would take over as head coach of the club. During the 2024–25 season, Freiburg reached the Champions League spots, climbing to fourth place after a crucial away win against Wolfsburg on matchday 31. However, a 3–1 home defeat to Eintracht Frankfurt on the final matchday saw them drop to fifth place and Europa League qualification, narrowly missing out on the Champions League for the fifth time following 2001, 2013, 2022, and 2023. In Schuster's second season, the club reached the Europa League final, the first European final in the club's history. In the final in Istanbul, they however lost 3-0 to English Aston Villa.
The most favourable season for taking these [shellfish] is after the rising of the Dog-star, or else before spring; for when they have once discharged their waxy secretion, their juices have no consistency: this, however, is a fact unknown in the dyers' workshops, although it is a point of primary importance. After it is taken, the vein [i.e. hypobranchial gland] is extracted, which we have previously spoken of, to which it is requisite to add salt, a sextarius [about 0.54 L, 19 imp fl oz, 18 US fl oz] to every hundred pounds of juice. It is sufficient to leave them to steep for a period of three days, and no more, for the fresher they are, the greater virtue there is in the liquor. It is then set to boil in vessels of tin [or lead], and every hundred amphorae ought to be boiled down to five hundred pounds of dye, by the application of a moderate heat; for which purpose the vessel is placed at the end of a long funnel, which communicates with the furnace; while thus boiling, the liquor is skimmed from time to time, and with it the flesh, which necessarily adheres to the veins. About the tenth day, generally, the whole contents of the cauldron are in a liquefied state, upon which a fleece, from which the grease has been cleansed, is plunged into it by way of making trial; but until such time as the colour is found to satisfy the wishes of those preparing it, the liquor is still kept on the boil. The tint that inclines to red is looked upon as inferior to that which is of a blackish hue.
Soon after the revised Blount Study was released, Robert Utiger, a doctor with the Harvard Institute of Medicine, testified before the US Congress and stated: "I continue to believe that that reference dose, 0.007 milligrams per kilo (24.5 ppb), which includes a factor of 10 to protect those who might be more vulnerable, is quite adequate." In 2014, a study was published, showing that environmental exposure to perchlorate in pregnant women with hypothyroidism is associated with a significant risk of low IQ in their children.
Sources: en.wikipedia.org
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.
Reversed-phase HPLC establishes purity, while mass spectrometry confirms the expected molecular mass. Sequence confirmation may use tandem mass spectrometry or peptide mapping. A certificate of analysis typically reports these results alongside the analytical method applied.
In Russia it is a registered medicine available by prescription. In many other countries it is not approved for human use and is supplied only as a research chemical. Import and possession rules differ by jurisdiction, and buyers are responsible for checking local requirements.
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.