peptidase is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2025-09-24. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Pharmacokinetic data are sparse and largely derived from animal work. After intranasal administration the peptide appears in plasma within minutes, and reported half-lives are short, on the order of minutes to tens of minutes. Degradation proceeds through ordinary proteolytic cleavage into constituent amino acids and smaller fragments. Direct evidence that intact Selank reaches brain tissue in meaningful amounts is limited, and the extent of blood-brain barrier penetration is debated. Some authors argue that fragments, not the parent peptide, carry much of the observed activity.
Published clinical work is concentrated in Russian-language journals and generally involves small samples without independent replication. Systematic reviews in English note the shortage of randomised, placebo-controlled trials and the difficulty of verifying methods from translated reports. Outcome measures vary between studies, which complicates pooling of results. Interest in the compound as a cognitive or anxiolytic agent therefore rests on a thinner evidence base than the volume of citations suggests. Replication in well-powered trials with preregistered endpoints would be needed before firm conclusions about efficacy can be drawn.
Proposed mechanisms centre on the GABAergic system. Animal and tissue studies report changes in GABA-A receptor expression and reduced activity of GABA transaminase, the enzyme that degrades GABA. Effects on monoamine turnover, including serotonin and dopamine pathways, are also described, and a separate line of work links the peptide to increased expression of brain-derived neurotrophic factor in hippocampal tissue. Most of these findings come from rodent models and cell preparations. How the individual observations combine into a single coherent mode of action is not settled.
| 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 |
Naming conventions place Selank in the same research family as Semax, another Russian-developed peptide investigated for cognitive effects. The two compounds share a lineage but differ in sequence and in the biological systems proposed as their targets. Semax descends from ACTH fragments, whereas Selank descends from tuftsin. Publications sometimes identify Selank by its full peptide sequence or by laboratory codes rather than one uniform trade name. Because replication outside Russia is limited, reports on its properties are best read alongside the study design and the purity of the material tested.
Selank is a synthetic heptapeptide developed in Russia during the 1990s. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences designed it as a stabilized analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The compound has been studied primarily for its reported anxiolytic and nootropic effects. It remains largely unknown in Western pharmacology and is not approved as a medicine by major regulators such as the FDA or the EMA.
The primary structure of Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro, corresponding to the molecular formula C33H57N11O9 and a monoisotopic mass of roughly 751.9 daltons. The N-terminal threonine and the arginine residue in the fourth position are shared with tuftsin, which carries the sequence Thr-Lys-Pro-Arg. The three additional residues at the C-terminus, Pro-Gly-Pro, extend the chain and are associated with greater resistance to enzymatic degradation. This extension also separates Selank from the shorter parent 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.
Etorphine (M99) is a semi-synthetic opioid possessing an analgesic potency approximately 1,000–3,000 times that of morphine. It was first prepared in 1960 from oripavine, which does not generally occur in opium poppy extract but rather the related plants Papaver orientale and Papaver bracteatum. It was reproduced in 1963 by a research group at MacFarlan Smith in Edinburgh, led by Kenneth Bentley. It can be produced from thebaine.
Overall, 24 out of 25 patients treated with brentuximab vedotin and AVD achieved complete remission. Brentuximab vedotin is also being investigated as a substitute for vincristine (another mitotic inhibitor which prevents tubulin polymerization) in patients with being treated with CHOP (a combination of cyclophosphamide, hydroxydaunorubicin, vincristine, prednisone or prednisolone) for a non-Hodgkin lymphoma. A phase III clinical trial comparing the two combination therapies (CHOP and CHP-brentuximab vedotin) was completed in October 2020, with results published in 2021. The ECHELON-1 phase 3 trial compared brentuximab vedotin with bleomycin both in combination with adriamycin, vinblastine, dacarbazine (AVD) chemotherapy as a firstline treatment for advanced classical Hodgkin lymphoma. The outcome of the trial resulted in a positive recommendation by the Committee for Medicinal Products for Human Use (CHMP) as part of a combination treatment in adults with previously untreated CD30+ stage 3 Hodgkin lymphoma.
"Cooks in the early Navy were left to their own imaginations when it came to preparing meals. In the main, this resulted in whatever was on the official ration for that day of the week being tossed in a ship's coppers and boiled until meal time. The first official Navy cook book was produced by Paymaster F. T. Arms and published by the Bureau of Supplies and Accounts in 1902. It contained five recipes for soup, six for fish, thirty-four for meats, fowl, and eggs, and several for desserts, including "plum duff"."
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Sources: en.wikipedia.org
=== Effectiveness === Even though it is not a cure for kidney failure, dialysis is a very effective treatment. Survival rates of kidney failure are generally longer with dialysis than without (having only conservative kidney management). However, from the age of 80 and in elderly patients with comorbidities there is no difference in survival between the two groups.
Evidence from the study of the organization of mineral nanocrystals in teeth of extant and extinct hominins and other primates, indicating that enamel nanocrystal misorientation in hominin teeth changed in conjunction with dietary shifts of members of the human lineage (including the introduction of meat and agricultural products into their diet), is presented by Gilbert et al. (2026). Gat, Subsol & Braga (2026) compare the development of the cortical bone in the mandible during the early ontogeny of extant chimpanzees and humans and in fossil hominins, linking the robust morphology of the mandible of Paranthropus to a distinct developmental trajectory. Orr et al. (2026) provide a catalog of isolated postcranial remains of hominins from Drimolen (South Africa) collected between 1994 and 2015. New postcranial fossil material of hominins is reported from the Kromdraai fossil site (South Africa) by DeSilva et al. (2026). Alemseged et al. (2026) report the discovery of fossil material of Paranthropus from the Mille-Logya research area determined to be between 2.5 and 2.9-million-years-old, representing the first record of the genus in the Afar region of Ethiopia and one of the oldest records of a member of the genus reported to date. Rak & Kimbel (2026) interpret the prognathism observed in the specimen KNM WT 17000 as a derived rather than primitive trait, and interpret Australopithecus/Paranthropus aethiopicus as the probable sister taxon of Australopithecus/Paranthropus boisei. Critical reevaluation of the study of Zanolli et al.
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=== Other industrial uses === The most common water-based antifreeze solutions used in electronics cooling are mixtures of water and either ethylene glycol (EGW) or propylene glycol (PGW). The use of ethylene glycol has a longer history, especially in the automotive industry. However, EGW solutions formulated for the automotive industry often have silicate based rust inhibitors that can coat and/or clog heat exchanger surfaces. Ethylene glycol is listed as a toxic chemical requiring care in handling and disposal. Ethylene glycol has desirable thermal properties, including a high boiling point, low freezing point, stability over a wide range of temperatures, and high specific heat and thermal conductivity. It also has a low viscosity and, therefore, reduced pumping requirements. Although EGW has more desirable physical properties than PGW, the latter coolant is used in applications where toxicity might be a concern. PGW is generally recognized as safe for use in food or food processing applications, and can also be used in enclosed spaces. Similar mixtures are commonly used in HVAC and industrial heating or cooling systems as a high-capacity heat transfer medium. Many formulations have corrosion inhibitors, and it is expected that these chemicals will be replenished (manually or under automatic control) to keep expensive piping and equipment from corroding.
=== Pharmaceuticals === Sorbitan monooleate is used as a wetting agent and dispersant in lipophilic pharmaceutical bases. It is extensively used as a wetting agent and dispersant for materials such as zinc oxide, calamine and penicillin in lipophilic pharmaceutical bases. It is also employed in drug delivery systems to improve the bioavailability of lipophilic compounds. In research, sorbitan monooleate has been used in a study to assess transfersomes as a transdermal delivery system for sertraline. It has also been used in a study to investigate the dominant factors affecting the stability of nanoemulsions through the use of artificial neural networks.
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.
Reports describe modulation of GABA signalling, changes in monoamine turnover and effects on neurotrophic factor expression. These observations come mainly from animal and cell studies. A single unifying mechanism has not been demonstrated.