If you have been reading about nootropic and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-05-14. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Typical purity report | 95% or higher by HPLC | Area percentage at 214 nm |
| Identity confirmation | Mass spectrometry | Electrospray or MALDI |
| Powder storage | -20 C, desiccated | Protect from light |
| Solution storage | 2-8 C short term | Freeze aliquots for longer |
| Quality document | Certificate of analysis | States method and value |
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.
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.
=== Infectious hypotheses === One hypothesis suggests that prenatal viral infection may contribute to the development of autism. Prenatal exposure to rubella or cytomegalovirus activates the mother's immune response and may greatly increase the risk for autism in mice. Congenital rubella syndrome is the most convincing environmental cause of autism. Infection-associated immunological events in early pregnancy may affect neural development more than infections in late pregnancy, not only for autism, but also for psychiatric disorders of presumed neurodevelopmental origin, notably schizophrenia. A 2021 meta-analysis of 36 studies suggested a relationship between mothers recalling an infection during pregnancy and having children with autism.
=== Duplication === Sometimes backups are duplicated to a second set of storage media. This can be done to rearrange the archive files to optimize restore speed, or to have a second copy at a different location or on a different storage medium—as in the disk-to-disk-to-tape capability of Enterprise client-server backup.
1-Pyrroline-5-carboxylic acid (systematic name 3,4-dihydro-2H-pyrrole-2-carboxylic acid) is a cyclic imino acid. Its conjugate base and anion is 1-pyrroline-5-carboxylate (P5C). In solution, P5C is in spontaneous equilibrium with glutamate-5-semialdehyde (GSA).
=== Copolymers === It is easy to make mixtures of the monomers or sets of monomers used to make nylons to obtain copolymers. This lowers crystallinity and can therefore lower the melting point. Some copolymers that have been or are commercially available are listed below:
Sources: en.wikipedia.org
=== Legal status === 1P-LSD is unscheduled in the United States and Canada, but may be considered illegal if sold or used for human consumption as an analogue of LSD under the Federal Analogue Act in the United States. 1P-LSD is a prohibited or controlled substance in Australia, France, Finland, Denmark, Germany, Estonia, Japan, Latvia, Norway, Romania, Sweden, Switzerland, United Kingdom, Italy, Singapore, the Czech Republic, and Croatia. 1P-LSD has been illegal in Russia since 2017 as an LSD derivative.
There are few native natural predators of adult emus still extant. Early in its species history it may have faced numerous terrestrial predators now extinct, including the giant lizard Megalania, the thylacine, and possibly other carnivorous marsupials, which may explain their seemingly well-developed ability to defend themselves from terrestrial predators. The main predator of emus today is the dingo, which was originally introduced by Aboriginals thousands of years ago from a stock of semi-domesticated wolves. Dingoes try to kill the emu by attacking the head. The emu typically tries to repel the dingo by jumping into the air and kicking or stamping the dingo on its way down. The emu jumps as the dingo barely has the capacity to jump high enough to threaten its neck, so a correctly timed leap to coincide with the dingo's lunge can keep its head and neck out of danger. Despite the potential prey-predator relationship, the presence of predaceous dingoes does not appear to heavily influence emu numbers, with other natural conditions just as likely to cause mortality. Wedge-tailed eagles are the only avian predator capable of attacking fully-grown emus, though are perhaps most likely to take small or young specimens. The eagles attack emus by swooping downwards rapidly and at high speed and aiming for the head and neck. In this case, the emu's jumping technique as employed against the dingo is not useful. The birds try to target the emu in the open ground so that it cannot hide behind obstacles.
The two substrates of this enzyme are 3-dehydro-L-gulonic acid and oxidised nicotinamide adenine dinucleotide (NAD+). Its products are 2,3-diketogulonic acid, reduced NADH, and a proton. The enzyme can also use the alternative cofactor, nicotinamide adenine dinucleotide phosphate. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is 3-dehydro-L-gulonate:NAD(P)+ 2-oxidoreductase. Other names in common use include 3-keto-L-gulonate dehydrogenase, 3-ketogulonate dehydrogenase, 3-keto-L-gulonate dehydrogenase, and 3-ketogulonate dehydrogenase. This enzyme participates in pentose and glucuronate interconversions and ascorbate and aldarate metabolism.
===== Non-lytic insect cell expression ===== Non-lytic insect cell expression is an alternative to the lytic baculovirus expression system. In non-lytic expression, vectors are transiently or stably transfected into the chromosomal DNA of insect cells for subsequent gene expression. This is followed by selection and screening of recombinant clones. The non-lytic system has been used to give higher protein yield and quicker expression of recombinant genes compared to baculovirus-infected cell expression. Cell lines used for this system include: Sf9, Sf21 from Spodoptera frugiperda cells, Hi-5 from Trichoplusia ni cells, and Schneider 2 cells and Schneider 3 cells from Drosophila melanogaster cells. With this system, cells do not lyse and several cultivation modes can be used. Additionally, protein production runs are reproducible. This system gives a homogeneous product. A drawback of this system is the requirement of an additional screening step for selecting viable clones.
A number of different hydrophobicity scales have been developed. The Expasy Protscale website lists a total of 22 hydrophobicity scales. There are clear differences between the four scales shown in the table. Both the second and fourth scales place cysteine as the most hydrophobic residue, unlike the other two scales. This difference is due to the different methods used to measure hydrophobicity. The method used to obtain the Janin and Rose et al. scales was to examine proteins with known 3-D structures and define the hydrophobic character as the tendency for a residue to be found inside of a protein rather than on its surface. Since cysteine forms disulfide bonds that must occur inside a globular structure, cysteine is ranked as the most hydrophobic. The first and third scales are derived from the physiochemical properties of the amino acid side chains. These scales result mainly from inspection of the amino acid structures. Biswas et al., divided the scales based on the method used to obtain the scale into five different categories.
Sources: en.wikipedia.org
=== Potential pharmaceuticals === Currently there is no widespread use of cysteine proteases as approved and effective anthelmintics but research into the subject is a promising field of study. Plant cysteine proteases isolated from these plants have been found to have high proteolytic activities that are known to digest nematode cuticles, with very low toxicity. Successful results have been reported against nematodes such as Heligmosomoides bakeri, Trichinella spiralis, Nippostrongylus brasiliensis, Trichuris muris, and Ancylostoma ceylanicum; the tapeworm Rodentolepis microstoma, and the porcine acanthocephalan parasite Macracanthorhynchus hirundinaceus. A useful property of cysteine proteases is the resistance to acid digestion, allowing possible oral administration. They provide an alternative mechanism of action to current anthelmintics and the development of resistance is thought to be unlikely because it would require a complete change of structure of the helminth cuticle. In several traditional medicines, the fruits or latex of the papaya, pineapple and fig are widely used for treatment of intestinal worm infections both in humans and livestock.
== Lead-like == During drug discovery, lipophilicity and molecular weight are often increased in order to improve the affinity and selectivity of the drug candidate. As a result, it is often difficult to maintain drug-likeness (i.e., RO5 compliance) during hit and lead optimization. To solve this problem, it has been proposed that members of screening libraries from which hits are discovered should be biased toward lower molecular weight and lipophilicity so that medicinal chemists will have an easier time in delivering optimized drug development candidates that are also drug-like. Hence the rule of five has been extended to the rule of three (RO3) for defining lead-like compounds. A rule of three compliant compound is defined as one that has:
=== Complementary nucleotides === In their modeling, Watson and Crick restricted themselves to what they saw as chemically and biologically reasonable. Still, the breadth of possibilities was very wide. A breakthrough occurred in 1952, when Erwin Chargaff visited Cambridge and inspired Crick with a description of experiments Chargaff had published in 1947. Chargaff had observed that the proportions of the four nucleotides vary between one DNA sample and the next, but that for particular pairs of nucleotides—adenine and thymine, guanine and cytosine—the two nucleotides are always present in equal proportions.
A post hoc analysis from a randomized, placebo-controlled, multi-centre study carried out at 11 secondary care centres, as well as a longitudinal single-centre study on pregnant women in Norway, also determined that metformin had no effect on maternal androgens in pregnancies occurring in the setting of PMOS. One systemic review suggested that polymorphisms in the vitamin D receptor gene are associated with the prognosis of polyendocrine metabolic ovarian syndrome, though this is based on small sample sizes and is debated. Studies have shown benefits for vitamin D supplementation in women with vitamin D deficiency and PMOS. Hyperinsulinemia can increase the production of androgens in the ovaries. One context in which this occurs is HAIR-AN syndrome, a rare subtype of PMOS.
Sources: en.wikipedia.org
Purity is usually reported as an HPLC area percentage, most often measured at 214 nm. Identity is confirmed separately by mass spectrometry. A certificate of analysis should state both the method and the observed value.
Dry powder is kept frozen, desiccated, and shielded from light. Dissolved material is aliquoted and frozen to limit freeze-thaw cycles. Short-term refrigerated storage is common for working solutions.
Russia registers it as a prescription nasal product. Most other markets classify it as a research chemical with no approved medical use. Oversight of purity and labeling is consequently minimal in those markets.
Selank is a synthetic peptide made of seven amino acids. It is modeled on tuftsin, a natural tetrapeptide, with an added three-residue tail. It is not a small-molecule drug.