Everything below concerns peptidase. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-04-24. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Primary route studied | Intranasal | Also examined parenterally in animal work |
| Reported plasma half-life | Minutes to tens of minutes | Values vary widely between reports |
| Main model systems | Rodent behavioural and cell assays | Human trials are few and small |
| Principal proposed targets | GABA-A receptor, GABA transaminase | Monoamine and neurotrophic pathways also reported |
| Evidence grade | Preliminary | Limited independent replication |
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
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.
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.
Chalcone synthase or naringenin-chalcone synthase (CHS) is an enzyme ubiquitous to higher plants and belongs to a family of polyketide synthase enzymes (PKS) known as type III PKS. Type III PKSs are associated with the production of chalcones, a class of organic compounds found mainly in plants as natural defense mechanisms and as synthetic intermediates. CHS was the first type III PKS to be discovered. It is the first committed enzyme in flavonoid biosynthesis. The enzyme catalyzes the conversion of 4-coumaroyl-CoA and malonyl-CoA to naringenin chalcone.
Tobacco etch virus (TEV) is a plant virus in the genus Potyvirus and family Potyviridae. Like other members of the genus Potyvirus, TEV has a monopartite positive-sense, single-stranded RNA genome surrounded by a capsid made from a single viral encoded protein. The virus is a filamentous particle that measures about 730 nm in length. It is transmissible in a non-persistent manner by more than 10 species of aphids including Myzus persicae. It also is easily transmitted by mechanical means but is not known to be transmitted by seeds.
Hans von Euler-Chelpin, together with Arthur Harden, received the 1929 Nobel Prize in Chemistry "for their research on sugar fermentation and the role of enzymes in this process." In 1947, both Bernardo Houssay for his discovery of the role of the pituitary gland in carbohydrate metabolism and Carl and Gerty Cori for their discovery of the conversion of glycogen received the Nobel Prize in Physiology or Medicine. For the discovery of sugar nucleotides in carbohydrate biosynthesis, Luis Leloir received the 1970 Nobel Prize in Chemistry. The term glycobiology was coined in 1988 by Raymond Dwek to recognize the coming together of the traditional disciplines of carbohydrate chemistry and biochemistry. This coming together was as a result of a much greater understanding of the cellular and molecular biology of glycans. "Glycoscience" is a field that explores the structures and functions of glycans.
Plasmin is inactivated by proteins such as α2-macroglobulin and α2-antiplasmin. The primary protein responsible for plasmin inhibition is the α2-antiplasmin which is a serpin protein. The C-terminal of the α2-antiplasmin binds plasminogen Kringle domains via lysine residues allowing for the inhibition of plasmin. Another method of plasmin inactivation involves the cleavage of an α2-macroglobulin at the bait region (a segment of the aM that is particularly susceptible to proteolytic cleavage) by plasmin. This initiates a conformational change such that the α2-macroglobulin collapses about the plasmin. In the resulting α2-macroglobulin-plasmin complex, the active site of plasmin is sterically shielded, thus substantially decreasing the plasmin's access to protein substrates. Two additional events occur as a consequence of bait region cleavage, namely (i) a h-cysteinyl-g-glutamyl thiol ester of the α2-macroglobulin becomes highly reactive and (ii) a major conformational change exposes a conserved COOH-terminal receptor binding domain. The exposure of this receptor binding domain allows the α2-macroglobulin protease complex to bind to clearance receptors and be removed from circulation. Plasmin can also be inhibited by inhibiting its activators, inactivating PAI-1 and PAI-2 blocks the production of tPA and uPA which subsequently stop the conversion of plasminogen into plasmin. Defects in the SERPINE1 gene cause deficiencies in PA1-2. PAI-2 is only detectable during pregnancy and lacks a signal sequence it is not secreted by the cell.
Sources: en.wikipedia.org
=== Mechanism of action === Like other dihydropyridine class calcium channel blockers, lercanidipine blocks L-type calcium channels in the smooth muscle cells of blood vessels, relaxing them and thus lowering blood pressure. In contrast to the non-dihydropyridine calcium channel blockers verapamil and diltiazem, it does not significantly act on calcium channels in the atrioventricular node, and therefore does not decrease heart rate, in usual therapeutic doses.
=== Combination hemoglobinopathies === A combination hemoglobinopathy occurs when someone inherits two different abnormal hemoglobin genes. If these are different versions of the same gene, one having been inherited from each parent it is an example of compound heterozygosity. Both alpha- and beta- thalassemia can coexist with other hemoglobinopathies. Combinations involving alpha thalassemia are generally benign. Some examples of clinically significant combinations involving beta thalassemia include:
== History == Bicalutamide as well as all of the other currently marketed NSAAs were derived from structural modification of flutamide, which itself was originally synthesized as a bacteriostatic agent in 1967 at Schering Plough Corporation and was subsequently and serendipitously found to possess antiandrogenic activity. Bicalutamide was discovered by Tucker and colleagues at Imperial Chemical Industries (ICI) in the 1980s and was selected for development from a group of over 2,000 synthesized compounds. It was first patented in 1982 and was first reported in the scientific literature in June 1987. Bicalutamide was first studied in a phase I clinical trial in 1987 and the results of the first phase II clinical trial in prostate cancer were published in 1990. The pharmaceutical division of ICI was split out into an independent company called Zeneca in 1993, and in April and May 1995, Zeneca (now AstraZeneca, after merging with Astra AB in 1999) began pre-approval marketing of bicalutamide for the treatment of prostate cancer in the U.S.. It was first launched in the U.K.Tooltip United Kingdom in May 1995, and was subsequently approved by the U.S. FDA on 4 October 1995, for the treatment of prostate cancer at a dosage of 50 mg/day in combination with a GnRH analogue. Following its introduction for use in combination with a GnRH analogue, bicalutamide was developed as a monotherapy at a dosage of 150 mg/day for the treatment of prostate cancer, and was approved for this indication in Europe, Canada, and a number of other countries in the late 1990s and early 2000s.
=== Diagnostic uses === The transaminase enzymes are important in the production of various amino acids, and measuring the concentrations of various transaminases in the blood is important in the diagnosing and tracking many diseases. For example, the presence of elevated transaminases can be an indicator of liver and cardiac damage. Two important transaminase enzymes are aspartate transaminase (AST), also known as serum glutamic oxaloacetic transaminase (SGOT); and alanine transaminase (ALT), also called alanine aminotransferase (ALAT) or serum glutamate-pyruvate transaminase (SGPT). These transaminases were discovered in 1954 and their clinical importance was described in 1955.
== See also == Devil's Cigarette Lighter – a gas well fire that consumed 16 million cubic meters of gas per day. Environmental impact of war Gulf War oil spill Nuclear winter#Kuwait wells in the first Gulf War
Sources: en.wikipedia.org
=== Uptake === Tau protein has been found in the extracellular environment including Cerebrospinal fluid (CSF) and Interstitial fluid (ISF) under physiological and pathological conditions. Low-density lipoprotein receptor-related protein 1 (LRP1) has been shown as the receptor for Tau internalization into cells. However, studying Tau uptake in human neurons revealed that physiological Tau monomers mainly use LRP1 for internalization, while the uptake of pathological Tau aggregates depend on heparan sulfate proteoglycans.
According to Future Forward PAC, a derivative of his campaign's "Kamala is for they/them, President Trump is for you" attack ad (with commentary by Charlamagne tha God spliced in) was one of the most effective of the campaign, shifting the race 2.7 percentage points in favor of Trump after viewers watched it. However, findings from an RCT study released by Ground Media/GLAAD said that the ad did not have an impact on who viewers intended to vote for.
=== EC 1.21.4 With a disulfide as acceptor === EC 1.21.4.1: D-proline reductase (dithiol) EC 1.21.4.2: glycine reductase EC 1.21.4.3: sarcosine reductase EC 1.21.4.4: betaine reductase EC 1.21.4.5: tetrachlorohydroquinone reductive dehalogenase
. The activation energy represents the energy difference between the initial ideally arranges state and a transition state towards the defective structure. At low defect concentrations, defect formation is entropy driven until a critical concentration of defects allows the activation energy term to compensate for entropy. There is usually an equilibrium defect density indicated at the minimum free energy. The activation energy for defect formation increases this equilibrium defect density.
Sources: en.wikipedia.org
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.
The peptide enters plasma rapidly and is broken down by ordinary proteases into amino acids and shorter fragments. Reported half-lives are short. Whether meaningful amounts of the intact molecule reach the brain is an open question.
Most clinical reports are small, published in Russian and not independently replicated. English-language reviews highlight the absence of large randomised trials. Conclusions about efficacy should be treated as provisional.
Intranasal administration predominates in both animal and human research because it avoids hepatic first-pass metabolism. Injectable and intraperitoneal routes appear in animal work mainly for comparison.