anxiolytic raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-01-30 and is reviewed periodically as new material appears.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Common route | Intranasal | Also injected in some animal work |
| Solubility class | Freely soluble in water | Solid form is hygroscopic |
| Typical storage | About -20 degrees Celsius | Keep desiccated and dark |
| Purity method | Reverse-phase HPLC | Reported as area percent |
| Confirmatory method | Mass spectrometry | Verifies expected molecular mass |
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.
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.
Characterization of Selank in laboratory settings relies on standard peptide analytical techniques. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities and degradation products, while mass spectrometry confirms molecular identity through accurate mass measurement. Amino acid analysis and peptide sequencing verify the primary structure when reference material is unavailable. Because Selank is a short chain, fragmentation-based analysis produces a diagnostic ion pattern that supports confident identification.
Peptide stability depends strongly on temperature, moisture, and pH. Lyophilized Selank is generally most stable when stored cold and dry, with freezer temperatures commonly used for long-term storage. In solution, the compound is susceptible to hydrolysis and to microbial growth if it is not handled aseptically. The C-terminal proline-rich extension appears to slow enzymatic cleavage relative to tuftsin, though quantitative degradation rates vary with the matrix and the conditions tested. Published stability data specific to Selank remain sparse.
Cortisol follows a circadian rhythm, and to accurately measure cortisol levels is best to test four times per day through saliva. An individual may have normal total cortisol but have a lower than normal level during a certain period of the day and a higher than normal level during a different period. Therefore, some scholars question the clinical utility of cortisol measurement. Cortisol is lipophilic, and is transported bound to transcortin (also known as corticosteroid-binding globulin (CBG)) and albumin, while only a small part of the total serum cortisol is unbound and has biological activity. This binding of cortisol to transcortin is accomplished through hydrophobic interactions in which cortisol binds in a 1:1 ratio. Serum cortisol assays measures total cortisol, and its results may be misleading for patients with altered serum protein concentrations. The salivary cortisol test avoids this problem because only free cortisol can pass through the blood-saliva barrier. Transcortin particles are too large to pass through this barrier, that consists of epithelial cell layers of the oral mucosa and salivary glands. Cortisol may be incorporated into hair from blood, sweat, and sebum. A 3 centimeter segment of scalp hair can represent 3 months of hair growth, although growth rates can vary in different regions of the scalp. Cortisol in hair is a reliable indicator of chronic cortisol exposure. Automated immunoassays lack specificity and show significant cross-reactivity due to interactions with structural analogs of cortisol, and show differences between assays.
== Animal dentin == Elephant ivory is solid dentin. The structure of the dentinal tubules contributes to both its porosity and its elasticity. Elephant tusks are formed with a thin cap of enamel, which soon wears away, leaving the dentin exposed. Exposed dentin in humans causes the symptom of sensitive teeth. Dentin is best known for its occurrence in teeth, but in early vertebrates, it was an important part of the dermal skeleton that covered most of the body, and it persists today in a few taxa such as the coelacanth. Because dentin is less mineralized than enamel, it wears away more quickly than enamel. Some mammalian teeth exploit this phenomenon, especially herbivores such as horses, deer or elephants. In many herbivores, the occlusal (biting) surface of the tooth is composed of alternating areas of dentin and enamel. Differential wearing causes sharp ridges of enamel to be formed on the surface of the tooth (typically a molar), and to remain during the working life of the tooth. Herbivores grind their molars together as they chew (masticate), and the ridges help to shred tough plant material. In xenarthrans, enamel is generally absent, with the tooth instead consisting of alternating orthodentine and vasodentine. A material similar to dentin forms the hard material that makes up dermal denticles in sharks and other cartilaginous fish.
== Pathophysiology == Overproduction of collagen is thought to result from an autoimmune dysfunction, in which the immune system starts to attack the kinetochore of the chromosomes. This would lead to genetic malfunction of nearby genes. T cells accumulate in the skin; these are thought to secrete cytokines and other proteins that stimulate collagen deposition. Stimulation of the fibroblast, in particular, seems to be crucial to the disease process, and studies have converged on the potential factors that produce this effect.
Sources: en.wikipedia.org
Evidence from the study of extant and extinct canids interpreted as supporting Bergmann's rule in the studied group at the interspecific level is presented by Chaves-Silveira et al. (2026). Evidence from the study of the fossil record of canids from the John Day Formation, indicative of stronger links of dietary behavior of the studied canids (as indicated by tooth wear) with lineage duration than with tooth morphology, is presented by Tanis, DeSantis & Terry (2026). Kort, Cavin & Wang (2026) describe the anatomy of the postcranial skeleton of Mesocyon coryphaeus, finding no evidence of cursorial adaptations seen in later canids, and interpret the studied canid as a likely ambush predator. Kropczyk & Marciszak (2026) report the discovery of fossil material of the corsac fox from the late Pleistocene strata from the Rogóżka Cave (Poland). Fossil material of Xenocyon lycaonoides representing one of the earliest records of this species worldwide is described from the early Pleistocene strata from the Gonghe Basin (Tibetan Plateau; China) by Huang et al. (2026). Frosali et al. (2026) interpret the shape and size of the frontal sinus in Canis etruscus, Canis mosbachensis and Canis borjgali as primarily influenced by the ecology of the studied canids, and interpret the morphology of the frontal sinus of the latter two species as indicative of higher proportion of meat in their diets compared to C. etruscus.
So far, four species from the genus Pediococcus have been isolated in wines and grape must, P. inopinatus, P. pentosaceus, P. parvulus, and P. damnosus, with the last two being the species most commonly found in wine. All Pediococcus species are Gram-positive with some species being micro-aerophilic while others utilizing mostly aerobic respiration. Under the microscope, Pediococcus often appear in pairs of pairs or tetrads which can make them identifiable. Pediococci are homofermenters, metabolizing glucose into a racemic mixture of both L- and D-lactate by glycolysis. However, in the absence of glucose, some species, such as P. pentosaceus, begin using glycerol, degrading it into pyruvate which later can be converted to diacetyl, acetate, 2,3-butanediol and other compounds that can impart unfavorable characteristics to the wine. Most Pediococcus species are undesirable in winemaking due to the high levels of diacetyl that can be produced, as well as increased production of biogenic amines that has been implicated as one potential cause for red wine headaches. Many species of Pediococcus also have the potential to introduce off odors or other wine faults to the wine such as the bitter-tasting "acrolein taint" that comes from degradation of glycerol into acrolein which then reacts with phenolic compounds in the wine to produce a bitter-tasting compound. One species, P.
=== Product invention === As recently as July 21, 2011, LifeVantage credited McCord as the creator of Protandim on its website. At a 2011 conference for LifeVantage distributors, McCord stated, "I was presented with a list of 41 potential ingredients for a product they wanted to call Protandim, and I went through the list and penciled out, rapidly, about 36 of those ingredients," leaving the 5 ingredients in the current formulation of Protandim. In March 2009, former LifeLine Therapeutics executive, Paul Myhill stated, "We initially decided to hide that fact [that Myhill derived the core composition for Protandim] for marketing purposes and instead rely on the impeccable background of Dr. McCord." In April, 2005, Myhill produced a signed letter from McCord in which McCord stated, "I do not honestly feel that I have made contributions to the intellectual property, up to this point, that would qualify me as an inventor...I must congratulate you and Paul for having framed the concept of Protandim so close to its final embodiment, prior to the beginnings of our association."
Sources: en.wikipedia.org
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.
Reported human trials are few, brief and originate mainly from one country. They describe effects on anxiety-related measures, but sample sizes are small and reporting is limited. The results are widely regarded as preliminary rather than confirmed.
Reverse-phase liquid chromatography is used to assess purity and separation of related impurities. Mass spectrometry confirms that the observed molecular mass matches the expected peptide. A certificate of analysis from the supplier is the usual document of record.
Selank is a synthetic heptapeptide designed as a stabilized analog of the natural tetrapeptide tuftsin. It has been investigated mainly for anxiolytic and cognitive effects. It is not an approved pharmaceutical in most countries.