Everything below concerns blood-brain barrier. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-08-24. Numbers and descriptions here follow the published literature rather than marketing material.
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.
The compound has a calculated molecular weight near 751.9 daltons and carries a net positive charge at physiological pH because of its arginine residue. It dissolves freely in water and in common aqueous buffers, and typically appears as a white or off-white lyophilized powder. The amide backbone makes the molecule susceptible to peptidases, which limits oral use and favors intranasal or parenteral routes. Nomenclature in the literature varies: the substance is also described by the sequence abbreviation TP-7 and by a Russian trade designation.
Regulatory status differs sharply by region. Selank holds a Russian marketing authorization, where it is supplied mainly as nasal drops, while authorities elsewhere have not approved it for medical use. Material sold internationally is therefore usually labeled as a research chemical rather than a medicine. Peer-reviewed publications come predominantly from Russian laboratories, and sample sizes are generally small. Whether the compound produces comparable effects under independent, well-controlled replication remains an open question that the broader literature has not settled.
Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
| 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 |
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.
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.
Peptide bonds are vulnerable to protease attack, and Selank is no exception. Measured half-life in serum is short, on the order of minutes in several reports, which explains why intranasal administration is the common route described in the literature. Absorption across the nasal mucosa partially bypasses first-pass hepatic metabolism. Quantitative data on human bioavailability remain limited and are difficult to compare across studies.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
Reported pharmacological effects center on reduced anxiety-like behavior in animal models and on measures of memory and learning. Proposed contributing mechanisms include modulation of GABAergic signaling, shifts in monoamine turnover, and changes in the activity of enzymes that degrade neuropeptides. Effects on the expression of genes linked to neuroplasticity have also been described. No single molecular target is widely accepted, and whether the behavioral findings arise from one pathway or several remains an open question.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed as a stabilized analogue of tuftsin, a naturally occurring tetrapeptide fragment derived from the immunoglobulin heavy chain. The additional Pro-Gly-Pro segment at the carboxyl terminus is intended to slow enzymatic cleavage. The compound is usually described in the literature as a synthetic peptide with anxiolytic and cognitive-related activity, a label that reflects a research context rather than an approved therapeutic category.
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.
== History == Norketamine was synthesized by Calvin Lee Stevens in the early 1960s, as part of his team's work on α-aminoketones at Wayne State University. While most research has historically focused on its precursor, researchers have taken notice of norketamine's putative effects. Beginning in the late 1990s, Danish researchers discovered its role as a NMDA receptor antagonist. Later research uncovered its use as an antinociceptive, or "painkiller." Following the 2019 approval of the ketamine enantiomer esketamine by the European Medicines Agency and FDA for use with treatment-resistant depression, researchers and pharmaceutical companies have sought other effective intermediates and metabolites of racemic ketamine. Much of the research examining the potential role of norketamine as a distinct anti-depressant to its precursor began in the mid-2010s. Rodent models have showcased that norketamine crosses the blood-brain barrier, though considerably less efficiently than ketamine. Accordingly, its antidepressant effects are less potent than enantiomers of ketamine, but appear to be as effective as esketamine in its potency and duration. Unlike esketamine, (S)-norketamine does not appear to significantly impact prepulse inhibition (reduction of the startle reflex) and as such appears to have significantly fewer psychotomimetic effects - which may indicate that it could be a safer alternative to ketamine for use as an antidepressant in humans.
=== Antiestrogenic effects === Progesterone, like all progestogens, has antiestrogenic effects in certain tissues such as the uterus, cervix, vagina, and breasts, and possibly also the brain. These effects are mediated by activation of the PR in these tissues. Progesterone does not have antiestrogenic effects in the more conventional sense of binding to and antagonizing the ER or binding to and inhibiting enzymes involved in estrogen biosynthesis. Instead, for instance in the endometrium, progesterone causes downregulation of the ER and upregulation of the estrogen-inactivating enzymes 17β-hydroxysteroid dehydrogenase 2 (converts estradiol into estrone) and estrone sulfotransferase (converts estrone into estrone sulfate). The antiestrogenic effects of progesterone and other progestogens form the basis for their only approved indication in menopausal hormone therapy: prevention of long-term unopposed estrogen-induced endometrial hyperplasia and increased endometrial cancer risk in women with intact uteruses. In the breasts, progesterone and other progestogens downregulate the ER as well as the estrogen-activating enzymes steroid sulfatase (converts estrone sulfate into estrone) and 17β-hydroxysteroid-dehydrogenase 1 (converts estrone into estradiol) and upregulates estrone sulfotransferase. However, other studies suggest that progestogens do not downregulate ER expression in the breasts. When applied directly to the breasts in women, progesterone can block the proliferative effects of estradiol.
state to do so. Following the milestone, Scott announced that the state would lift their restrictions. June 15 COVID-19 pandemic California authorities remove the mask mandate for outdoor activities. The nationwide death toll from the virus exceeds 600,000, equal to the annual cancer death toll. June 16 – Texas Governor Greg Abbott signs Texas House Bill 1927, eliminating the requirement for Texas residents to obtain a license to carry handguns either concealed or openly starting September 1, 2021. June 17 Politico obtains a recording of William Braddock, GOP candidate in a Florida congressional seat, threatening to send "a Russian and Ukrainian hit squad" to fellow Republican opponent Anna Paulina Luna to make her "disappear." The House votes, by 268 to 161, to repeal the Authorization for Use of Military Force Against Iraq Resolution of 2002. President Biden signs a bill making Juneteenth an official federal holiday. June 18 – 2021 NBA playoffs: The Los Angeles Clippers advance to their first NBA Conference Finals after a 131–119 victory against the Utah Jazz in game 6, in which they will play the Phoenix Suns. June 19 COVID-19 pandemic: Indiana reports its first case of the Delta variant of COVID-19. The first Juneteenth under federal holiday status is celebrated. June 20 2021 Arizona wildfires – An outbreak of wildfires begins in Arizona due to thunderstorms producing dry lightning coming through the state from June 14 to June 20. Due to the outbreak, as well as fire danger, many national forests in the state of Arizona are closed to the public.
At pH > 8, silica itself may dissolve. When solutions at extreme pH are needed, the stationary phase can be made of silica polymerized with organic substances, or hydrophobic organic polymers. With such stationary phases, retention time is longer for nonpolar molecules, whereas polar molecules elute more readily (emerge early in the analysis). A chromatographer can increase retention times by adding more water to the mobile phase. Since water is highly polar, it makes the nonpolar analyte interact more strongly with nonpolar stationary phase. Similarly, an investigator can decrease retention time by adding more organic nonpolar solvent to the mobile phase. RP-HPLC operates on the principle of hydrophobic interactions, which originates from the high symmetry in the dipolar water structure and plays the most important role in all processes in life science. RP-HPLC allows the measurement of these interactive forces. The binding of the analyte to the stationary phase is proportional to the contact surface area around the non-polar segment of the analyte molecule upon association with the ligand on the stationary phase. This solvophobic effect is dominated by the force of water for "cavity-reduction" around the analyte and the C18-chain versus the complex of both. The energy released in this process is proportional to the surface tension of the eluent (water: 7.3×10−6 J/cm2, methanol: 2.2×10−6 J/cm2) and to the hydrophobic surface of the analyte and the ligand respectively.
Sources: en.wikipedia.org
Inorganic qualitative analysis generally refers to a systematic scheme to confirm the presence of certain aqueous ions or elements by performing a series of reactions that eliminate a range of possibilities and then confirm suspected ions with a confirming test. Sometimes small carbon-containing ions are included in such schemes. With modern instrumentation, these tests are rarely used but can be useful for educational purposes and in fieldwork or other situations where access to state-of-the-art instruments is not available or expedient.
EMP is marketed in the United States, Canada, and Mexico under the brand name Emcyt, whereas the medication is marketed under the brand name Estracyt in the United Kingdom and elsewhere throughout Europe as well as in Argentina, Chile, and Hong Kong. It has been discontinued in a number of countries, including Australia, Brazil, Ireland, and Norway.
Drug smuggling carries severe penalties in many countries. Sentencing may include lengthy periods of incarceration, flogging and even the death penalty (in Singapore, Malaysia, Indonesia and elsewhere). In December 2005, Van Tuong Nguyen, a 25-year-old Australian drug smuggler, was hanged in Singapore after being convicted in March 2004. In 2010, two people were sentenced to death in Malaysia for trafficking 1 kilogram (2.2 lb) of cannabis into the country. Execution is mostly used as a deterrent, and many have called upon much more effective measures to be taken by countries to tackle drug trafficking; for example, targeting specific criminal organisations that are often also active in the smuggling of other goods (i.e. wildlife) and even people. In many cases, links between politicians and the criminal organisations have been proven to exist. In June 2021, Interpol revealed an operation in 92 countries that shut down 113,000 websites and online marketplaces selling counterfeit or illicit medicines and medical products a month earlier, led to the arrests of 227 people worldwide, recovered pharmaceutical products worth $23 million, and led to the seizure of approximately nine million devices and drugs, including large quantities of fake COVID-19 tests and face masks. In 2025, by executive order, the United States expanded its approach in its counter drug campaign to designate foreign drug cartels as foreign terrorist organizations.
=== Kendrick mass defect analysis of polymers and alternative base units === Because Kendrick mass defect analysis can be carried out by substituting any repeating unit for CH2, KMD analysis is particularly useful for the visualizing the data from polymer mass spectra. For example, a Kendrick mass defect plot of an ethylene oxide/propylene oxide copolymer can be created by using ethylene oxide (C2H4O) as the base unit and calculating the Kendrick mass as:
=== Metabolism === Meloxicam is extensively metabolized in the liver by the enzymes CYP2C9 and CYP3A4 (minor) into four inactive metabolites. Peroxidase activity is thought to be responsible for the other two remaining metabolites.
Sources: en.wikipedia.org
=== Human Diseases and Gene Mutations === Greenspan has conducted various research projects directly on the molecular bases of human diseases. A collaborative study with a group at Jefferson Medical College showed mutations in the COL7A1 gene, for type VII collagen, to be the basis of the disabling and fatal skin disease dystrophic epidermolysis bullosa These studies also led to elucidation of the complete intron-exon structure of COL7A1 which at the time had more exons than any previously described gene. His lab was the first to clone and characterize the α1 chain of type V collagen and was also key in the first demonstration that mutations in a type V collagen gene can cause the heritable connective tissue disorder classic Ehers-Danlos syndrome. Accompanying and following these studies, the Greenspan lab has performed studies on collagen V genes and on the biosynthesis of type V collagen and on the molecular mechanisms whereby mutations in type V collagen result in defects in mammalian tissues. Their studies have also shown autoimmunity against type V collagen to be involved in organ transplant rejection and atherosclerosis, and that induction of immune tolerance to type V collagen can help ameliorate atherosclerosis. The Greenspan lab was also the first to clone and characterize the α3 chain of type V collagen and showed the α3(V) chain to be important to the functioning of certain highly specialized cell types and to be important to tumor growth and survival times in breast cancer.
Ginkgo prefers full sun and grows best in environments that are well-watered and well-drained. The species shows a preference for disturbed sites; in the "semiwild" stands at Tianmu Mountains, many specimens are found along stream banks, rocky slopes, and cliff edges. Accordingly, ginkgo retains a prodigious capacity for vegetative growth. It is capable of sprouting from embedded buds near the base of the trunk (lignotubers, or basal chichi) in response to disturbances, such as soil erosion. Old specimens are also capable of producing aerial roots on the undersides of large branches in response to disturbances such as crown damage; these roots can lead to successful clonal reproduction upon contacting the soil. These strategies are evidently important in the persistence of ginkgo; in a survey of the "semiwild" stands remaining in Tianmushan, 40% of the specimens surveyed were multi-stemmed, and few saplings were present.
=== Radar cross-section (RCS-)reducing metamaterials === Metamaterials have applications in stealth technology, which reduces RCS in any of various ways (e.g., absorption, diffusion, redirection). Conventionally, the RCS has been reduced either by radar-absorbent material (RAM) or by purpose shaping of the targets such that the scattered energy can be redirected away from the source. While RAMs have narrow frequency band functionality, purpose shaping limits the aerodynamic performance of the target. More recently, metamaterials or metasurfaces have been synthesized that can redirect the scattered energy away from the source using either array theory or generalized Snell's law. This has led to aerodynamically favorable shapes for the targets with the reduced RCS.
Sidney Walter Fox (24 March 1912 – 10 August 1998) was a Los Angeles-born biochemist responsible for discoveries on the origins of biological systems. Fox explored the synthesis of amino acids from inorganic molecules, the synthesis of proteinous amino acids and amino acid polymers called "proteinoids" from inorganic molecules and thermal energy, and created what he thought was the world's first protocell out of proteinoids and water. He called these globules "microspheres". Fox believed in the process of abiogenesis where life spontaneously organized itself from the colloquially known "primordial soup;" poolings of various simple organic molecules that existed during the time before life on Earth. He also suggested that his experiments possessed conditions that were similar to those of primordial Earth. In his experiments, Fox demonstrated that it is possible to create protein-like structures from inorganic molecules and thermal energy. Fox went on to create microspheres that he said closely resembled bacterial cells and concluded that they could be similar to the earliest forms of life or protocells.
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.
Selank is a synthetic seven-amino-acid peptide modeled on tuftsin, a fragment of the immunoglobulin G heavy chain. It was designed in Russia to combine anxiolytic and immunomodulatory properties in one molecule.