RP-HPLC raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2025-10-04. Anything still debated is marked as such rather than presented as settled.
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.
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.
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.
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 |
|---|---|---|
| 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 |
Quality assessment of Selank samples typically combines purity determination with identity confirmation and counter-ion analysis. Purity is usually reported as a percentage by chromatographic area, with values above 95 percent often quoted for research-grade material. Water content and residual solvents are checked in lyophilized batches because they affect both stability and accurate mass determination. A reported purity figure does not by itself establish that a sample is the intended sequence, so orthogonal methods are needed to rule out sequence isomers or truncation products.
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.
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.
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.
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.
Selank is studied chiefly as an animal-model anxiolytic with proposed secondary effects on memory and immune signaling. Reported mechanisms include modulation of the GABA-A receptor complex, inhibition of enkephalin-degrading enzymes, and shifts in monoamine turnover within limbic structures. Some experiments describe increased expression of brain-derived neurotrophic factor in the hippocampus after repeated dosing. No single molecular target has been confirmed, and the peptide does not bind any receptor with the selectivity typical of a conventional small-molecule drug. Mechanism therefore remains a set of hypotheses rather than an established pathway.
MALAT1 (Metastasis Associated Lung Adenocarcinoma Transcript 1) also known as NEAT2 (Nuclear-Enriched Abundant Transcript 2) is an infrequently spliced long non-coding RNA, which is highly conserved amongst mammals and highly expressed in the nucleus. It regulates the expression of metastasis-associated genes. It also positively regulates cell motility via the transcriptional and/or post-transcriptional regulation of motility-related genes. MALAT1 may play a role in temperature-dependent sex determination in the Red-eared slider turtle (Trachemys scripta).
=== Misconduct findings === The editorial board of the Proceedings of the National Academy of Sciences retracted a January 2006 paper coauthored by Fernandez because it had "substantial overlap", without attribution, of figures and text from an article by Fernandez published in Structure the previous month, a form of duplicate publication. An expression of concern was issued in 2013 by the editors of BMC Genomics about a 2011 paper published there by Fernandez. In 2014, geneticist Michael Lynch asked the editors of Nature to remove his name from a 2011 paper he had coauthored with Fernandez, leading the editors there to also publish an expression of concern. The United States Office of Research Integrity (ORI) opened an investigation in 2010 and determined in 2022 that Fernandez had falsified research findings "in 12 published papers, four unpublished manuscripts, one presentation, and three grant applications". ORI proposed a 15-year debarment sanction by the US Department of Health and Human Service. In May 2025, an administrative law judge reviewing that report found that Fernandez's "research misconduct squandered Rice and NIH funds", referring to $1.2 million in grant funding, and recommended upholding the proposed debarment. In May 2026, ORI formally debarred Fernandez for scientific misconduct, for a period of fifteen years, finding that he intentionally fabricated data.
Blackledge-Gair House (at 111 Madison Avenue; added January 9, 1983) Demarest-Atwood House (at 84 Jefferson Avenue; added July 24, 1984) Peter Huyler House (50 County Road; added January 9, 1983) Benjamin P. Westervelt House (at 235 County Road; added January 9, 1983)
Therians took over the medium- to large-sized ecological niches in the Cenozoic, after the Cretaceous–Paleogene extinction event approximately 66 million years ago emptied ecological space once filled by non-avian dinosaurs and other groups of reptiles, as well as various other mammal groups, and underwent an exponential increase in body size (megafauna). The increase in mammalian diversity was not, however, solely because of expansion into large-bodied niches. Mammals diversified very quickly, displaying an exponential rise in diversity. For example, the earliest-known bat dates from about 50 million years ago, only 16 million years after the extinction of the non-avian dinosaurs. Molecular phylogenetic studies initially suggested that most placental orders diverged about 100 to 85 million years ago and that modern families appeared in the period from the late Eocene through the Miocene. However, no placental fossils have been found from before the end of the Cretaceous. The earliest undisputed fossils of placentals come from the early Paleocene, after the extinction of the non-avian dinosaurs. (Scientists identified an early Paleocene animal named Protungulatum donnae as one of the first placental mammals, but it has since been reclassified as a non-placental eutherian.) Recalibrations of genetic and morphological diversity rates have suggested a Late Cretaceous origin for placentals, and a Paleocene origin for most modern clades. The earliest-known ancestor of primates is Archicebus achilles from around 55 million years ago.
=== Anxiety disorders === Panic disorder with or without agoraphobia. Clonazepam has also been found effective in treating other anxiety disorders, such as social phobia, but this is an off-label use. The effectiveness of clonazepam in the short-term treatment of panic disorder has been demonstrated in controlled clinical trials. Some long-term trials have suggested a benefit of clonazepam for up to three years without the development of tolerance.
Sources: en.wikipedia.org
Present in most species pyruvate dehydrogenase and 2-oxoglutarate dehydrogenase (also called α-ketoglutarate dehydrogenase) branched-chain α-keto acid dehydrogenase 2-hydroxyphytanoyl-CoA lyase transketolase Present in some species: pyruvate decarboxylase (in yeast) several additional bacterial enzymes The enzymes transketolase, pyruvate dehydrogenase (PDH), and 2-oxoglutarate dehydrogenase (OGDH) are important in carbohydrate metabolism. PDH links glycolysis to the citric acid cycle. OGDH catalyzes the overall conversion of 2-oxoglutarate (alpha-ketoglutarate) to succinyl-CoA and CO2 during the citric acid cycle. The reaction catalyzed by OGDH is a rate-limiting step in the citric acid cycle. The cytosolic enzyme transketolase is central to the pentose phosphate pathway, a major route for the biosynthesis of the pentose sugars deoxyribose and ribose. The mitochondrial PDH and OGDH are part of biochemical pathways that result in the generation of adenosine triphosphate (ATP), which is the main energy transfer molecule for the cell. In the nervous system, PDH is also involved in the synthesis of myelin and the neurotransmitter acetylcholine.
"In the period 1821–1822, the liberator José de San Martín and Bernardo Monteagudo, his trusted minister, expropriated and squandered the mercantile and economic elite of Lima, without achieving the definitive independence of Peru. Monteagudo had little regard for the level of civilization and the democratic possibilities of Peruvians. His main objective was to eradicate the Spanish threat in independent La Plata and Chile at any cost, including the economic ruin of Peru. He confiscated wealth and other resources to organize local spy networks and covert operations, clearly damaging to gaining the confidence of the local population and their support for the cause of independence. (…) The kidnapping policy inaugurated by Monteagudo further undermined a weak tradition of the right to property and laid the foundations for politically motivated expropriations. The agricultural and urban properties confiscated from royalist Spaniards and Creoles, mainly in the central coast region, were valued at approximately two million pesos. This policy caused greater economic problems and a drop in investment. (...) Eventually, most of the expropriated assets were awarded to military officers who sought compensation and rewards for their patriotic exploits. Among the high-ranking officers who received these rewards we have Antonio José de Sucre, Bernardo O'Higgins, and José Rufino Echenique. Juan Francisco Ryes, Blas Sardeña and José María Plaza, among others. In the provinces, local officials repeated the abuses of power and the plundering committed in the name of the patriot cause.
== Awards and honours == The HGSA honours one eminent member annually by inviting them to present the HGSA Oration at the Annual Scientific Meeting. Additionally, one outstanding mid-career researcher is invited to deliver a presentation at the Annual Scientific Meeting to showcase their work in the Sutherland Lecture, named in honour of Prof Grant Sutherland. Each year, the membership is invited to nominate eminent retiring members to Emeritus Membership of the Society. Nominations are called for members who have contributed significantly to the running and welfare of the Society for a Service Award. HGSA Council scrutinizes and considers these nominations before awarding.
== History == Tiagabine was discovered at Novo Nordisk in Denmark in 1988 by a team of medicinal chemists and pharmacologists under the general direction of Claus Bræstrup. The drug was co-developed with Abbott Laboratories, in a 40/60 cost sharing deal, with Abbott paying a premium for licensing the IP from the Danish company. It was approved for treatment of epilepsy in the United States in September 1997. In 2005, a bolded warning was added to the labeling of tiagabine by the United States Food and Drug Administration cautioning about association of new-onset seizures in people without epilepsy and discouraging off-label use. Tiagabine was previously subject to Risk Evaluation and Mitigation Strategies (REMS) in the United States, which was instituted in 2010. However, this requirement was eliminated in 2012. United States patents on tiagabine listed in the Orange Book expired in April 2016.
The pharmacology of progesterone, a progestogen medication and naturally occurring steroid hormone, concerns its pharmacodynamics, pharmacokinetics, and various routes of administration. Progesterone is a naturally occurring and bioidentical progestogen, or an agonist of the progesterone receptor, the biological target of progestogens like endogenous progesterone. Progesterone also has antimineralocorticoid and inhibitory neurosteroid activity, whereas it appears to have little or no glucocorticoid or antiandrogenic activity and has no androgenic activity. Because of its progestogenic activity, progesterone has functional antiestrogenic effects in certain tissues such as the uterus, cervix, and vagina. In addition, progesterone has antigonadotropic effects due to its progestogenic activity and can inhibit fertility and suppress sex hormone production. Progesterone differs from progestins (synthetic progestogens) like medroxyprogesterone acetate and norethisterone, with implications for pharmacodynamics and pharmacokinetics as well as efficacy, tolerability, and safety. Progesterone can be taken by mouth, in through the vagina, and by injection into muscle or fat, among other routes. A progesterone vaginal ring and progesterone intrauterine device are also available as pharmaceutical products.
Sources: en.wikipedia.org
== Education and early career == LeBlanc received his bachelor's degree in biology from the University of Massachusetts Dartmouth in 1975, followed by a Master's in Biology from Bridgewater State University in 1981. Following his Bachelor's, he started his professional career as an Aquatic Toxicologist at EG&G Bionomics in Wareham, Massachusetts in 1975, a position he held for five years. Subsequently, in 1980, he was appointed as the Director of Toxicology and held that position until 1983. He then joined the University of South Florida in Tampa in 1983 as a Research Associate and received his Ph.D. in biology in 1986. From 1986 to 1989 he served as a Research Fellow in the Department of Biological Chemistry & Molecular Pharmacology and Dana-Farber Cancer Institute at Harvard Medical School where he completed his post-doctoral training.
==== Manifestations of systemic conditions ==== Occasionally systemic conditions may be the sole cause of gingival inflammation rather than merely influencing background plaque-induced gingivitis. Certain mucocutaneous produce gingival inflammation which may manifest as desquamative gingivitis or oral ulceration. Such conditions include lichen planus, pemphigoid, pemphigus vulgaris, erythema multiforme, and lupus erythematosus. Allergic reactions may also trigger gingival lesions. Sources of allergens include toothpastes, mouthwash, chewing gum, foods, additives, medicines, dental restorative materials, mercury, nickel and acrylic, acrylic. Plasma cell gingivitis is a rare condition thought to be a hypersensitivity reaction. Lichenoid lesions may also occur on the gingival mucosa.
In this age group, lorazepam is associated with falls and hip fractures. Due to these concerns, lorazepam use is generally recommended for at most four weeks. Lorazepam was initially patented in 1963 and went on sale in the United States in 1977. It is on the World Health Organization's List of Essential Medicines. It is available as a generic medication. In 2023, it was the 100th most commonly prescribed medication in the United States, with more than 6 million prescriptions.
On Sunday, May 25, 2025, after Filema Duarte still refused to hold elections or resign from office, representative from 117 Cuban Lodges gathered at the National Masonic Temple alongside hundreds of other Freemasons, and demanded his dismissal. Because Filema Duarte had ordered the conference hall to be locked, the Freemasons gathered in the lobby out front of the hall, at the foot of the statue of Carlos Manuel de Céspedes. They sang the National Anthem of Cuba and proceeded to hold the meeting without Filema Duarte or his staff present, and ejected Filema Duarte from the Grand Lodge. Juan Alberto Kessel Linares was reelected as Acting Grand Master of Cuba. Plain-clothes police officers and agents of the State Security Unit were also present at the meeting, capturing photographs and videos of everyone present. Over the course of June, Cuban Freemasons who stood in opposition to Filema Duarte reported that they were under constant surveillance by agents of the government, that their internet was being strategically cut by the government, that power outages were being arranged to target the specific homes of oppositional Freemasons. They also alleged that there were also several "strategic" arrests used as intimidation tactics. On June 14, 2025, Kessel Linares appeared with his Cabinet Elect on the steps of the Grand Lodge of Cuba to hold a press conference, where they denounced the actions of Filema Duarte, of who they said was occupying the office illegally.
Tumor growth (see HP59) Revascularization or neovascularization after trauma, for example, after cardiac ischemia or retinal ischemia Endometriosis - It appears that up to 37% of the microvascular endothelium of the ectopic endometrial tissue originates from endothelial progenitor cells.
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.
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.