The short version of electrospray ionization fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-07-21 and is reviewed periodically as new material appears.
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.
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.
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 |
|---|---|---|
| Identity confirmation | Reversed-phase HPLC retention time versus reference standard | Retention depends on column, gradient, and ion-pairing agent |
| Mass confirmation | Electrospray or MALDI mass spectrometry | Doubly protonated ion near m/z 377 is consistent with about 752 Da |
| Typical purity specification | 95 percent or higher by chromatographic peak area | Lower values suggest truncated or modified peptide species |
| Storage of lyophilized powder | -20 °C, desiccated, protected from light | Powder tolerates long storage better than solution |
| Storage of solution | 2-8 °C for short periods | Freeze-thaw cycling promotes aggregation and surface adsorption |
Lyophilized Selank, the dry powder form, is generally stored frozen at minus 20 degrees Celsius or colder for long-term keeping. The solid is hygroscopic and should stay sealed, dry, and protected from light. Once dissolved, the peptide is less stable and is usually held refrigerated at 2 to 8 degrees Celsius for short periods. Repeated freezing and thawing is avoided because it can promote aggregation and loss of activity. Buffers and pH choice also affect how long a solution remains usable.
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
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.
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.
There are many applications for AMS throughout a variety of disciplines. AMS is most often employed to determine the concentration of 14C, e.g. by archaeologists for radiocarbon dating. Compared to other radiocarbon dating methods, AMS requires smaller sample sizes (about 50 mg), while yielding extensive chronologies. MS technology has expanded the scope of radiocarbon dating. Samples ranging from 50,000 years old to 100 years old can be successfully dated using AMS, as other forms of mass spectrometry provide insufficient suppression of molecular isobars to resolve 13CH and 12CH2 from 14C atoms. Because of the long half-life of 14C, decay counting requires significantly larger samples. 10Be, 26Al, and 36Cl are used for surface exposure dating in geology. 3H, 14C, 36Cl, and 129I are used as hydrological tracers. Accelerator mass spectrometry is widely used in biomedical research. In particular, 41Ca has been used to measure bone resorption in postmenopausal women.
MDDMA, or MDDM, also known as 3,4-methylenedioxy-N,N-dimethylamphetamine or as N,N-dimethyl-MDA or N-methyl-MDMA, is a psychoactive drug of the phenethylamine, amphetamine, and MDxx families. It is the N,N-dimethyl analogue of MDA and the N-methyl derivative of MDMA. The drug is a known synthetic impurity of MDMA and has also been described as a possible novel designer drug in 2025. In addition, (R)-MDDMA was characterized as a non-hallucinogenic psychoplastogen with antidepressant-like effects and improved safety relative to MDMA in 2026.
government terminates a deal with Eli Lilly and Company for 350,856 remaining doses of the single antibody bamlanivimab that were scheduled to be delivered by the end of March. The deal will instead be focused on a supply of combined antibodies with etesevimab. Microsoft announces the $20 billion acquisition of AI firm Nuance Communications, the second largest deal in its history, after LinkedIn in 2016. April 15 Chicago police release graphic footage of an officer shooting dead 13-year-old Adam Toledo in a dark alley. Indianapolis FedEx shooting: Nine people are killed, including the shooter, and seven injured, in a mass shooting at a FedEx facility in Indianapolis. April 16 The media reports that U.S. Republican Representatives Marjorie Taylor Greene and Paul Gosar are forming the America First Caucus. It is scrapped within a day, following criticism from other GOP members. COVID-19 drug development: The U.S. Food and Drug Administration (FDA) revokes the emergency use authorization (EUA) for bamlanivimab. COVID-19 pandemic Virginia reports its first two cases of the Lineage P.1 variant, which was originally detected in Brazil. Michigan extends their restrictions on gatherings and dining to May 24 amid a rise of cases. The state also expands their mask mandate to children ages 2–4 years. The number of vaccines administered in the United States exceeds 200 million. April 18 – COVID-19 vaccination: The CDC reports that over 50% of Americans have received at least one dose of a COVID-19 vaccine.
Sources: en.wikipedia.org
=== Precursor to the antioxidant glutathione === Due to the ability of thiols to undergo redox reactions, cysteine and cysteinyl residues have antioxidant properties. Its antioxidant properties are typically expressed in the tripeptide glutathione, which occurs in humans and other organisms. The systemic availability of oral glutathione (GSH) is negligible; so it must be biosynthesized from its constituent amino acids, cysteine, glycine, and glutamic acid. While glutamic acid is usually sufficient because amino acid nitrogen is recycled through glutamate as an intermediary, dietary cysteine and glycine supplementation can improve synthesis of glutathione.
== Polymer-hybrid delivery systems == Coiled-coils are used as non-covalent polymer-drug conjugates to link drugs to polymer backbones. The goal of these types of systems is to attach multiple drugs to a non-toxic backbone such that drugs can be stably transported throughout the body and released at a controlled rate once at the target location. Doxorubicin, paclitaxel, and campothecin are examples of drugs typically used with polymer-drug conjugate systems. Hetero-dimeric coiled-coils motifs can be utilized in such systems, whereby one strand would be conjugated to the polymer backbone network, while the other strand would be conjugated to the drug of choice. The coiled-coils would then oligomerize, followed by the administration of the drug system into the body, whereby the stability of the coiled-coil in physiological conditions would ensure the intact delivery of the drug to the target. Upon cellular uptake at the target site, coiled-coil system would be exposed to a decrease in pH associated with the acidic environments of endosomes and lysosomes, triggering the dissociation of the coiled-coils, resulting in drug release. Dr. Harm-Anton Klok and colleagues were the first to investigate the usage of coiled coils as linkers in polymer-drug conjugate systems, whereby they utilized the parallel heterodimeric E3/K3 coiled-coil system (known for its stability at physiological pH and dissociation at pH 5, resulting in E3 homotrimers along with K3 unimers) to link cargo to a poly(N-(2-hydroxypropyl)methacrylamide) (PHPMA)-based polymer backbone. Klok et al.
The mild acidic and chemoselective post Ugi activation of 5 involving simultaneous indolamide formation and tert-butoxycarbonyl (Boc) removal gives the active amide 6 which allows cyclization to 7 without affecting other peptidic or even ester moieties and with stereochemical retention of the chiral centers.
Monoamines are connected to the pathophysiology of depression. Symptoms may occur because concentrations of neurotransmitters, such as norepinephrine and serotonin, are insufficient, leading to downstream changes. Medications for depression affect the transmission of serotonin, norepinephrine, and dopamine. Older and less selective antidepressants like TCAs and MAOIs inhibit the reuptake or metabolism of norepinephrine and serotonin in the brain, which results in higher concentrations of neurotransmitters. Antidepressants that have dual mechanisms of action inhibit the reuptake of both serotonin and norepinephrine and, in some cases, inhibit with weak effect the reuptake of dopamine. Antidepressants affect variable neuronal receptors such as muscarinic cholinergic, α1- and α2-adrenergic, H1-histaminergic, and sodium channels in the cardiac muscle, leading to decreased cardiac conduction and cardiotoxicity associated particularly with TCAs, and to a lesser extent with SSRIs. Selectivity of antidepressant agents are based on the neurotransmitters that are thought to influence symptoms of depression. Drugs that selectively block the reuptake of serotonin and norepinephrine effectively treat depression and are better tolerated than TCAs. TCAs have comprehensive effects on various neurotransmitters receptors, which leads to lack of tolerability and increased risk of toxicity. SNRIs primarily work by binding to and thus inhibiting the serotonin transporter (SERT) and norepinephrine transporter (NET).
Sources: en.wikipedia.org
==== Distributional effects and inequality ==== The impact of AI is not distributed evenly across the workforce. There is growing evidence of a "hollowing out" of entry-level positions. Data from job platform Adzuna in late 2025 showed a 24.7% year-on-year decline in advertised entry-level jobs in the UK, as businesses increasingly use AI to perform tasks traditionally assigned to junior staff. This raises concerns about the future talent pipeline and the ability of young people to enter the labour market. Furthermore, AI automation poses specific risks to gender equality. A 2026 white paper by the Fawcett Society highlighted that automation and AI could displace up to 40% of women in certain industries by 2030, as women are disproportionately concentrated in administrative and clerical roles highly exposed to automation. The report also warned that AI systems trained on historically unequal labour-market data risk embedding and scaling existing gender pay disparities and occupational segregation.
Furthermore, early outgrowth cells maintain other monocyte functions such as high Dil-Ac-LDL and India ink uptake and low eNOS expression. These original, early outgrowth, CFU-Hill or CACs are also shown to express CD14, a lipopolysaccharide receptor expressed by monocytes but not endothelial cells. Endothelial colony forming cells represent a distinct population that has been found to have the potential to differentiate and promote vessel repair. ECFCs are now known to be tissue-resident progenitor cells in adults that maintain some vasculogenic ability.
=== Cap-dependent translation initiation === The eukaryotic translation initiation factor eIF4E plays a central role in directing ribosomes to the 5′-cap structure of mRNAs, thereby facilitating efficient protein synthesis. Cap-dependent initiation facilitated by eIF4E binding the 5' mRNA cap is considered to be the rate-limiting component of the eukaryotic translation initiation. Many cellular mRNAs depend on eIF4E for translation into protein. In this role, eIF4E functions as part of the eIF4F complex, recruiting eIF4G, eIF4A, and other factors necessary for translation initiation. However, certain viruses bypass this mechanism by cleaving eIF4G to remove the eIF4E-binding domain, thereby enabling cap-independent translation of viral RNAs. Similarly, some cellular mRNAs—such as those encoding heat shock proteins—utilize alternative translation initiation strategies, including internal ribosome entry site (IRES) elements or direct binding by other initiation factors such as eIF3d. In contexts where eIF4E is bypassed or inhibited, other cap-binding proteins such as eIF3D, eIF3I, PARN, and the nuclear cap-binding complex (CBC) can mediate specialized translation pathways.
Sources: en.wikipedia.org
Identity is confirmed by matching the retention time in reversed-phase chromatography against a reference standard and by measuring the molecular mass with mass spectrometry. Tandem mass spectrometry or amino acid analysis can verify the sequence of the seven residues. Because the peptide contains no aromatic amino acids, detection at 280 nm is not useful.
Lyophilized powder is normally stored desiccated at -20 °C, protected from light and moisture. Powder kept under these conditions is generally stable for long periods. Solutions are less stable and are usually prepared immediately before use.
A purity value from one chromatographic method does not capture every possible impurity. Related peptides with similar retention behavior, counterions, and residual solvents may not appear in the same analysis. Independent testing with an orthogonal method provides stronger assurance of identity and content.
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.