Everything below concerns Enkephalinase. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-01-11. Where a claim depends on a specific study, the study is described rather than over-claimed.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
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.
| Property | Value | Notes |
|---|---|---|
| Typical purity specification | 95 percent or higher by RP-HPLC | Area percentage of the main peak |
| Identity confirmation | Electrospray ionization mass spectrometry | Observed mass compared with the theoretical value near 751.9 Da |
| Recommended dry storage | -20 °C, desiccated | -80 °C for multi-year archival material |
| Solution handling | Prepare fresh; avoid long storage | Sterile filtration reduces microbial load |
| Common synonyms | TKPRPGP; TP-7 | Sequence code and laboratory designation used interchangeably |
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
Pharmacokinetic data are limited. Like most short peptides, Selank is vulnerable to plasma and tissue peptidases, and its measured half-life in circulation is short, on a minutes scale. The Pro-Gly-Pro tail slows this degradation but does not eliminate it. Intranasal administration is the route described in most reports, with absorption through the nasal mucosa and a hypothesized path into the central nervous system that avoids the blood-brain barrier. Direct measurements of human brain exposure are unavailable, so distribution claims rest on inference from animal work.
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
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.
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.
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.
This movement resulted in an intense cultural exchange and resulted in the formation of mestizos (in Spanish) or caboclos (in Portuguese), a social category formed by people with mixture of European and native ancestry, who were an important part of the economy and culture of the region. According to Peter Gow, the ayahuasca shamanism (the use of ayahuasca by a trained shaman to diagnose and cure illnesses) was developed by these mestizos in the processes of colonial transformation. The Amazon rubber cycles (1879–1912 and 1942–1945) sped up these transformations, due to slavery, genocide and brutality against indigenous populations and large migratory movements, specially from the Brazilian Northeast Region as a workforce for the rubber plantations. The mestizo practices became deeply intertwined with the culture of rubber workers, called caucheros (in Spanish) or seringueiros (in Portuguese). Ayahuasca use with therapeutic goals is the main result of this Trans-cultural diffusion, with some practitioners pointing the caucheros as the main responsible for using ayahuasca to cure all sort of ailments of the body, mind and soul, with even some regions using the term Yerba de Cauchero ("rubber-worker herb"). As a result, the ayahuasca shamans in urban areas and mestizo settlements, specially in the regions of Iquitos and Pucallpa (in Peru), became the vegetalistas, folk healers who are said to gain all their knowledge from the plants and the spirits bound to it.
Lipton tea is available in over 150 countries, and particularly popular in Europe, North America, Africa and the Middle East, parts of Asia and Australasia (Australia and New Zealand), as well as Latin America, and the Caribbean. Despite its British origins, Lipton tea (such as Lipton Yellow Label) is not marketed in the United Kingdom, where brand owner Lipton Teas and Infusions sells PG Tips. Lipton Ice Tea, from the Unilever PepsiCo joint venture, is available in the United Kingdom. Lipton tea blends are selected from many different plantations around the world, from well-known producing countries, including Sri Lanka, India, Kenya, and China. Apart from the usual black leaf tea, the brand offers many other varieties, including green leaf teas, flavoured black teas, herbal teas, and milk tea in various Asian markets. The Lipton Tea Innovation & Technology Academy was launched by Lipton Teas and Infusions together with the Government of Kenya and the University of Kabianga in February 2024 to offer training varying from vocational courses to advanced degrees in tea growing and harvesting. In May 2024, Lipton Teas and Infusions announced an agreement to sell its tea estates in Kenya, Tanzania, and Rwanda to Browns Investments with the proceeds reinvested into East Africa’s tea industry.
==== Byzantine writers ==== Physician Oribasius (c. 320–403), personal physician of the emperor and philosopher Julian, compiled all known ancient medical texts of his time by theme into medical encyclopedia. He quotes Galen and Rufus on diabetes, considering it to be a polyuric disease of the kidneys. Various descriptive names are given for the condition, including: chamber-pot dropsy, diarrhea of the urine (diarrhea urinosa), and the thirsty disease. These descriptions, along with a number of other names for the condition ("liuria", "extreme thirst or dipsacus"), were echoed by later Byzantine writers in key encyclopedic texts.
=== Micro BCA assay (for dilute solutions) === The BCA Micro BCA assay is a 3-component protocol which uses concentrated stocks of the Biuret reaction, BCA, and copper(II) reagents. It allows for an improved sensitivity of ~2 - 40 μg/mL vs 20 - 2000 μg/mL of the original BCA assay. However, it has a different, and generally speaking more sensitive, interference from non-protein components. Kits for the Micro BCA assay are available from at least two commercial vendors. Notably, the composition and use of a "Micro BCA Reagent and Protocol" was described in the original manuscript by Smith, and modern kits likely consist of an exact or highly similar formulation. The protocol consists of mixing Micro-Reagent B and the Copper Solution 25:1 to form Micro-Reagent C (MC), which is not shelf stable and should be freshly prepared, and then mixing MC 1:1 with Micro-Reagent A to produce the final (also unstable) assay working solution. Micro-Reagent A, Micro-Reagent B, and Copper Solution are stable indefinitely at room temperature. Micro-Reagent A (MA)
Sources: en.wikipedia.org
=== Other proteins === Zinc serves a purely structural role in zinc fingers, twists and clusters. Zinc fingers form parts of some transcription factors, which are proteins that recognize DNA base sequences during the replication and transcription of DNA. Each of the nine or ten Zn2+ ions in a zinc finger helps maintain the finger's structure by coordinately binding to four amino acids in the transcription factor. In blood plasma, zinc is bound to and transported by albumin (60%, low-affinity) and transferrin (10%). Because transferrin also transports iron, excessive iron reduces zinc absorption, and vice versa. A similar antagonism exists with copper. The concentration of zinc in blood plasma stays relatively constant regardless of zinc intake. Cells in the salivary gland, prostate, immune system, and intestine use zinc signaling to communicate with other cells. Zinc may be held in metallothionein reserves within microorganisms or in the intestines or liver of animals. Metallothionein in intestinal cells is capable of adjusting absorption of zinc by 15–40%. However, inadequate or excessive zinc intake can be harmful; excess zinc particularly impairs copper absorption because metallothionein absorbs both metals. The human dopamine transporter contains a high affinity extracellular zinc binding site which, upon zinc binding, inhibits dopamine reuptake and amplifies amphetamine-induced dopamine efflux in vitro. The human serotonin transporter and norepinephrine transporter do not contain zinc binding sites.
Soviet collectivism and egalitarianism were an important part of Marxist–Leninist ideology in the Soviet Union, where it played a key part in forming the New Soviet man, willingly sacrificing their life for the good of the collective. Terms such as collective and the masses were frequently used in the official language and praised in agitprop literature by Vladimir Mayakovsky (Who needs a "1") and Bertolt Brecht (The Decision and Man Equals Man). The fact that Marxist–Leninist governments confiscated private businesses and landholdings radically increased income and property equality in practice. Income inequality dropped in Russia under the rule of the Soviet Union, then rebounded after its demise in 1991. It also dropped rapidly in the Eastern Bloc after the Soviet takeover of Eastern Europe at the end of World War II. Similarly, inequality went back up after the collapse of the Soviet system. According to Paul Hollander, this was one of the features of Communist states that was so attractive to egalitarian Western intellectuals that they quietly justified the killing of millions of capitalists, landowners and supposedly wealthy kulaks in order to achieve this equality. According to Walter Scheidel, they were correct to the extent that historically only violent shocks have resulted in major reductions in economic inequality. Marxist–Leninists respond to this type of criticism by highlighting the ideological differences in the concept of freedom and liberty.
== Pathology == In males, inadequate embryonal AMH activity can lead to persistent Müllerian duct syndrome (PMDS), in which a rudimentary uterus is present and testes are usually undescended. The AMH gene (AMH) or the gene for its receptor (AMH-RII) are usually abnormal. AMH measurements have also become widely used in the evaluation of testicular presence and function in infants with intersex variations, ambiguous genitalia, and cryptorchidism. Female offspring of pregnant mice injected with AMH develop polyendocrine metabolic ovarian syndrome (PMOS)-like symptoms, including infertility, delayed puberty, and erratic ovulation. Injection of GnRH antagonist cetrorelix prevents the appearance of reproductive defects in this context. This implies excess of AMH may cause PMOS through GnRH signaling.
Sources: en.wikipedia.org
=== Allegations of Forced Recruitment === Amid the political dispute between the TPLF-reinstated regional council and the federally recognized Tigray Interim Administration (TIA), reports emerged in 2026 alleging widespread forced military recruitment across parts of Tigray. On 4 June 2026, Human Rights First Ethiopia (HRFE) released an investigative report claiming that coercive recruitment campaigns and mass roundups (afesa) had occurred in several areas of Tigray, including the Northwestern, Central, and Eastern zones. The report documented testimonies from 27 witnesses, including family members, local officials, former recruits, and individuals who allegedly escaped conscription. According to the report, recruitment efforts targeted former Tigray Defense Forces members, households that had not previously contributed family members during the 2020–2022 conflict, and groups of young people gathered in public locations such as markets, mining sites, entertainment venues, and religious sites. HRFE alleged that some individuals were detained, transported to military facilities, or compelled to join military units against their will. The organization argued that such practices violated provisions of the Ethiopian Constitution, the African Charter on Human and Peoples' Rights, and international human rights instruments concerning arbitrary detention and forced labor.
==== March 2008 hepatitis ==== In March and April 2008, the Community Epidemiology Branch of the San Diego County Health and Human Services Agency traced a hepatitis A outbreak in San Diego County to a single Chipotle restaurant located in La Mesa, California, in which 22 customers were infected with the virus.
The main preparation of the drug commercially available is mixed with cyclizine (Diconal, Wellconal) which has the advantage of reducing nausea, vomiting and histamine release associated with strong opioid therapy. Dipipanone was also available as an oral mixture 10 mg/5 mL without the cyclizine during the 1970s–1980s in the United Kingdom. This form was rare and used normally only in drug trials and in specialist Diconal addiction clinics. Dipipanone is now the only alternative opioid left to use in the UK that is of equal strength to morphine that can be prescribed instead, aside from oxycodone and hydromorphone which are typically the second and third-line alternative to pain relief when morphine is indicated but not tolerated. A fentanyl patch may also be used, especially in cases of renal impairment. One of the limitations of using dipipanone is that it is only produced in one dosage form that is mixed with the anti-emetic and anti-histamine cyclizine at a ratio of 25% dipipanone to 75% cyclizine which limits the dose of dipipanone to an absolute maximum of 3 tablets per dose up to 4–6 times a day. This is a 10 mg dipipanone and 30 mg cyclizine formulation. It is made by the following manufacturers:
The composition and rate of CSF generation are influenced by hormones and the content and pressure of blood and CSF. For example, when CSF pressure is higher, there is less of a pressure difference between the capillary blood in choroid plexuses and CSF, decreasing the rate at which fluids move into the choroid plexus and CSF generation. The autonomic nervous system influences choroid plexus CSF secretion, with activation of the sympathetic nervous system decreasing secretion and the parasympathetic nervous system increasing it. Changes in the pH of the blood can affect the activity of carbonic anhydrase, and some drugs (such as furosemide, acting on the Na-K-Cl cotransporter) have the potential to impact membrane channels.
Sources: en.wikipedia.org
Sealed, desiccated storage at -20 °C or colder is the standard recommendation for research-grade material. Vials should reach room temperature before they are opened, which limits condensation. Repeated temperature cycling is discouraged.
A reported purity value reflects the share of the main peak in one chromatographic run and says nothing about identity. Confirming that the expected sequence is present requires a separate measurement such as mass spectrometry. Purity and identity are distinct questions.
A mass spectrum reports the molecular masses present in a sample and shows whether they match the value expected for selank, near 751.9 Da. It also flags common artifacts such as truncation or adduct formation. It does not establish correct stereochemistry or complete sequence order on its own.
Dry powder is best kept sealed, protected from light, and held at minus 20 degrees Celsius or below. Desiccant packaging helps limit moisture uptake because the material is hygroscopic. A sealed vial should be allowed to equilibrate to room temperature before opening to reduce condensation.