This is a working overview of Certificate of analysis, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-10-16 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.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
Lyophilized Selank, the dry powder form, is generally stored frozen at minus 20 degrees Celsius or colder for long-term keeping. The solid is hygroscopic and should stay sealed, dry, and protected from light. Once dissolved, the peptide is less stable and is usually held refrigerated at 2 to 8 degrees Celsius for short periods. Repeated freezing and thawing is avoided because it can promote aggregation and loss of activity. Buffers and pH choice also affect how long a solution remains usable.
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
| 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 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.
Development took place at the Institute of Molecular Genetics of the Russian Academy of Sciences, where a series of short peptides were designed in the 1980s and 1990s. Selank was selected from variants of tuftsin that showed resistance to plasma peptidases. Russian regulatory approval covers it as an anxiolytic agent given intranasally. Outside that market the compound is normally handled as a research chemical rather than a medicine, and no widely recognised international pharmacopoeial monograph exists. The name Selank is a coined trade designation rather than a systematic chemical name.
Enzymatic stability motivates the extra three residues at the carboxyl end. Native tuftsin is cleaved quickly by circulating aminopeptidases and carboxypeptidases, which limits its duration of action and its usefulness as a tool compound. Extending the chain with proline-rich segments is a common design tactic because proline constrains the backbone and slows proteolysis. The same Pro-Gly-Pro motif appears in other Russian-developed peptides of the era. Whether the full seven-residue chain is required for activity, or whether it acts mainly as a prodrug releasing tuftsin, remains unresolved.
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.
Most published work on selank originates from a small number of research groups in the Russian Federation. A large share of that record appears in Russian-language journals, which limits access for readers who rely on English-indexed databases. Independent replication by laboratories outside the original research network is sparse in publicly available sources. This concentration of origin and language is a frequently noted feature when the compound is summarized in broader reviews of synthetic peptides.
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.
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.
Klein C, Entian KD (1994). "Genes involved in self-protection against the lantibiotic subtilin produced by Bacillus subtilis ATCC 6633". Appl. Environ. Microbiol. 60 (8): 2793–801. Bibcode:1994ApEnM..60.2793K. doi:10.1128/aem.60.8.2793-2801.1994. PMC 201725. PMID 8085823. JJ; Roelse, J; Howard, JC; Butcher, GW; Hämmerling, GJ; Neefjes, JJ (1994). "Selectivity of MHC-encoded peptide transporters from human, mouse and rat". Nature. 367 (6464): 648–51. Bibcode:1994Natur.367..648M. doi:10.1038/367648a0. PMID 8107849. Binet R, Letoffe S, Ghigo JM, Delepelaire P, Wandersman C (1997). "Protein secretion by Gram-negative bacterial ABC exporters-a review". Gene. 192 (1): 7–11. doi:10.1016/S0378-1119(96)00829-3. PMID 9224868.
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syndrome Bazex–Dupré–Christol syndrome (Bazex syndrome, follicular atrophoderma and basal cell carcinomas) Beare–Stevenson cutis gyrata syndrome Bloom syndrome (Bloom–Torre–Machacek syndrome) Blue rubber bleb nevus syndrome Brittle hair–intellectual impairment–decreased fertility–short stature syndrome Cantú syndrome Cardio-facio-cutaneous syndrome (cardiofaciocutaneous syndrome) Cartilage–hair hypoplasia (McKusick type metaphyseal chondrodysplasia) Cerebral dysgenesis–neuropathy–ichthyosis–keratoderma syndrome Childhood tumor syndrome Chondrodysplasia punctata Cicatricial junctional epidermolysis bullosa Craniosynostosis–anal anomalies–porokeratosis syndrome Cockayne syndrome Colobomas of the eye–heart defects–ichthyosiform dermatosis–mental retardation–ear defects syndrome (CHIME syndrome, Zunich neuroectodermal syndrome, Zunich–Kaye syndrome) Congenital hemidysplasia with ichthyosiform erythroderma and limb defects syndrome (CHILD syndrome) Conradi–Hünermann syndrome (Conradi–Hünermann–Happle syndrome, Happle syndrome, X-linked dominant chondrodysplasia punctata) Costello syndrome Cronkhite–Canada syndrome Crouzon syndrome Cutis verticis gyrata Darier's disease (Darier–White disease, dyskeratosis follicularis, keratosis follicularis) DeSanctis–Cacchione syndrome Disseminated superficial actinic porokeratosis Disseminated superficial porokeratosis Dolichol kinase deficiency Dominant dystrophic epidermolysis bullosa Dyskeratosis congenita (Zinsser–Cole–Engman syndrome) Dystrophic epidermolysis bullosa Ectodermal dysplasia Ectodermal dysplasia with corkscrew hairs Ectrodactyly–ectodermal dysplasia–cleft syndrome (EEC syndrome, split hand–split foot–ectodermal dysplasia–cleft syndrome) Epidermolysis bullosa herpetiformis (Dowling–Meara epidermolysis bullosa simplex) Epidermolysis bullosa simplex Epidermolysis bullosa simplex of Ogna Epidermolysis bullosa simplex with mottled pigmentation Epidermolysis bullosa simplex with muscular dystrophy Epidermolytic hyperkeratosis (bullous congenital ichthyosiform erythroderma, bullous ichthyosiform erythroderma) Erythrokeratodermia with ataxia (Giroux–Barbeau syndrome) Familial benign chronic pemphigus (familial benign pemphigus, Hailey–Hailey disease) Fanconi syndrome (familial pancytopenia, familial panmyelophthisis) Fibrodysplasia ossificans progressiva Focal dermal hypoplasia (Goltz syndrome) Follicular atrophoderma Franceschetti–Klein syndrome (mandibulofacial dysostosis) Gardner's syndrome (familial colorectal polyposis) Gastrocutaneous syndrome Generalized atrophic benign epidermolysis bullosa Generalized epidermolysis bullosa simplex (Koebner variant of generalized epidermolysis bullosa simplex) Generalized trichoepithelioma Giant axonal neuropathy with curly hair Gingival fibromatosis with hypertrichosis Haber syndrome Hallerman–Streiff syndrome Harlequin-type ichthyosis (harlequin baby, harlequin fetus, harlequin ichthyosis, ichthyosis congenita, ichthyosis congenita gravior) Hay–Wells syndrome (AEC syndrome, ankyloblepharon filiforme adnatum–ectodermal dysplasia–cleft palate syndrome, ankyloblepharon–ectodermal defects–cleft lip and palate syndrome, ankyloblepharon–ectodermal dysplasia–clefting syndrome) Hereditary sclerosing poikiloderma Heterochromia iridum Holocarboxylase synthetase deficiency Hypohidrotic ectodermal dysplasia (anhidrotic ectodermal dysplasia, Christ–Siemens–Touraine syndrome) Hypotrichosis–acro-osteolysis–onychogryphosis–palmoplantar keratoderma–periodontitis syndrome Hypotrichosis–lymphedema–telangiectasia syndrome Ichthyosis–brittle hair–impaired intelligence–decreased fertility–short stature syndrome (IBIDS syndrome, sulfur-deficient brittle hair syndrome, Tay's syndrome, trichothiodystrophy, trichothiodystrophy with ichthyosis) Ichthyosis bullosa of Siemens (ichthyosis exfoliativa) Ichthyosis follicularis (ichthyosis follicularis with alopecia and photophobia syndrome) Ichthyosis linearis circumflexa Ichthyosis prematurity syndrome Ichthyosis vulgaris (autosomal dominant ichthyosis, ichthyosis simplex) Ichthyosis with confetti Neonatal ichthyosis–sclerosing cholangitis syndrome (ichthyosis–sclerosing cholangitis syndrome, NISCH syndrome) Incontinentia pigmenti achromians (hypomelanosis of Ito) Immune dysfunction–polyendocrinopathy–enteropathy–X-linked syndrome Jaffe–Campanacci syndrome Johanson–Blizzard syndrome Johnson–McMillin syndrome Joubert syndrome Junctional epidermolysis bullosa Junctional epidermolysis bullosa gravis (epidermolysis bullosa letalis, Herlitz disease, Herlitz epidermolysis bullosa, Herlitz syndrome, lethal junctional epidermolysis bullosa) Junctional epidermolysis bullosa with pyloric atresia Kabuki syndrome (Kabuki makeup syndrome, Niikawa–Kuroki syndrome) Keratolytic winter erythema (erythrokeratolysis hiemalis, Oudtshoorn disease, Oudtshoorn skin) Keratosis follicularis spinulosa decalvans (Siemens-1 syndrome) Keratosis linearis with ichthyosis congenita and sclerosing keratoderma syndrome Keratosis pilaris atrophicans faciei (folliculitis rubra, keratosis pilaris rubra atrophicans faciei, lichen pilare, lichen pilaire ou xerodermie pilaire symmetrique de la face, ulerythema ophryogenes, xerodermi pilaire symmetrique de la face) Keratosis pilaris Kindler syndrome (acrokeratotic poikiloderma, bullous acrokeratotic poikiloderma of Kindler and Weary, congenital poikiloderma with blisters and keratoses, congenital poikiloderma with bullae and progressive cutaneous atrophy, hereditary acrokeratotic poikiloderma, hyperkeratosis–hyperpigmentation syndrome, Weary–Kindler syndrome) Klinefelter syndrome Klippel–Feil syndrome Lamellar ichthyosis (collodion baby) Legius syndrome (neurofibromatosis type 1-like syndrome) Lelis syndrome Lenz–Majewski syndrome Leschke syndrome Lethal acantholytic epidermolysis bullosa Lhermitte–Duclos disease Linear and whorled nevoid hypermelanosis (linear nevoid hyperpigmentation, progressive cribriform and zosteriform hyperpigmentation, reticulate and zosteriform hyperpigmentation, reticulate hyperpigmentation of Iijima and Naito and Uyeno, zebra-like hyperpigmentation in whorls and streaks, zebra-line hyperpigmentation) Linear Darier disease (acantholytic dyskeratotic epidermal nevus) Linear porokeratosis Localized epidermolysis bullosa simplex (Weber–Cockayne syndrome, Weber–Cockayne variant of generalized epidermolysis bullosa simplex) Mandibuloacral dysplasia Marinesco–Sjögren syndrome McCune–Albright syndrome McCusick syndrome Metageria Microphthalmia–dermal aplasia–sclerocornea syndrome Mitis junctional epidermolysis bullosa (nonlethal junctional epidermolysis bullosa) Mitochondrial myopathy–encephalopathy–lactic acidosis–stroke syndrome Multiple lentigines syndrome (cardiocutaneous syndrome, Gorlin syndrome II, lentiginosis profusa syndrome, LEOPARD syndrome, progressive cardiomyopathic lentiginosis) Multiple pterygium syndrome Multiple sulfatase deficiency (Austin disease, mucosulfatidosis) Naegeli–Franceschetti–Jadassohn syndrome (chromatophore nevus of Naegeli) Netherton syndrome Neurofibromatosis type 1 (von Recklinghausen's disease) Neurofibromatosis type 3 (neurofibromatosis mixed type) Neurofibromatosis type 4 (neurofibromatosis variant type) Neutral lipid storage disease (Dorfman–Chanarin syndrome) Nonbullous congenital ichthyosiform erythroderma (congenital ichthyosiform erythroderma) Noonan syndrome Oculocerebrocutaneous syndrome (Delleman–Oorthuys syndrome) Oculodentodigital dysplasia Odonto-tricho-ungual-digital-palmar syndrome Oliver–McFarlane syndrome Orofaciodigital syndrome Pachydermoperiostosis (idiopathic hypertrophic osteoathorpathy, Touraine–Solente–Gole syndrome) Peeling skin syndrome (acral peeling skin syndrome, continual peeling skin syndrome, familial continual skin peeling, idiopathic deciduous skin, keratolysis exfoliativa congenita) Pfeiffer syndrome Photosensitivity–ichthyosis–brittle sulfur-deficient hair–impaired intelligence–decreased fertility–short stature syndrome Pityriasis rotunda (pityriasis circinata, tinea circinata) Plate-like osteoma cutis Plaque-type porokeratosis (classic porokeratosis, porokeratosis of Mibelli) Polyneuropathy–organomegaly–endocrinopathy–monoclonal gammopathy–skin changes syndrome (Crow–Fukase syndrome) Polyostotic fibrous dysplasia (Albright's disease) Popliteal pterygium syndrome Porokeratosis Porokeratosis palmaris et plantaris disseminata Prader–Willi syndrome Progeria (Hutchinson–Gilford progeria syndrome, Hutchinson–Gilford syndrome, progeria syndrome) Progressive osseous heteroplasia Progressive symmetric erythrokeratodermia (erythrokeratodermia progressiva symmetrica) Proteus syndrome Proteus-like syndrome Punctate porokeratosis Rapp–Hodgkin syndrome (Rapp–Hodgkin ectodermal dysplasia syndrome) Recessive dystrophic epidermolysis bullosa (Hallopeau–Siemens variant of epidermolysis bullosa, Hallopeau–Siemens disease) Refsum's disease (heredopathia atactica polyneuritiformis, phytanic acid storage disease) Relapsing linear acantholytic dermatosis Restrictive dermopathy Rhizomelic chondrodysplasia punctata (autosomal recessive chondrodysplasia punctata type 1, chondrodystrophia calcificans punctata, peroxisomal biogenesis disorder complementation group 11) Rombo syndrome Rothmund–Thomson syndrome (poikiloderma congenitale) Rud syndrome Say syndrome Scalp–ear–nipple syndrome (Finlay–Marks syndrome) Schindler disease (Kanzaki disease, alpha-N-acetylgalactosaminidase deficiency) Schinzel–Giedion syndrome Scleroatrophic syndrome of Huriez (Huriez syndrome, palmoplantar keratoderma with scleroatrophy, palmoplantar keratoderma with sclerodactyly, scleroatrophic and keratotic dermatosis of the limbs, sclerotylosis) Segmental neurofibromatosis Senter syndrome (Desmons' syndrome) Shabbir syndrome (laryngo–onycho–cutaneous syndrome) Silver–Russell syndrome Sjögren–Larsson syndrome Skin fragility syndrome (plakophilin 1 deficiency) Smith–Lemli–Opitz syndrome 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Zimmermann–Laband syndrome
In seemingly rare cases, medications such as SSRIs, isotretinoin (Accutane) and finasteride (Propecia) are reported to induce long-lasting iatrogenic disorders characterized by sexual dysfunction symptoms, including erectile dysfunction in males; these disorders are known as post-SSRI sexual dysfunction (PSSD), post-retinoid sexual dysfunction/post-Accutane syndrome (PRSD/PAS), and post-finasteride syndrome (PFS). These conditions remain poorly understood and lack effective treatments, although they have been suggested to share a common etiology.
Sources: en.wikipedia.org
=== 2019 revision of the SI === The definition of the dalton was not affected by the 2019 revision of the SI, that is, 1 Da in the SI is still 1/12 of the mass of a carbon-12 atom, a quantity that must be determined experimentally in terms of SI units. However, the definition of a mole was changed to be the amount of substance consisting of exactly 6.02214076×1023 entities, and the definition of the kilogram was changed as well. As a consequence, the molar mass constant (Mu) remains close to but no longer exactly 1 g/mol, meaning that the mass in grams of one mole of any substance remains nearly but no longer exactly numerically equal to the average mass of an entity in daltons, although the relative standard uncertainty of 4.5×10−10 at the time of the redefinition is insignificant for all practical purposes. Letting ent denote one entity, the smallest amount of any substance (retaining its chemical properties), one mole is an aggregate of an Avogadro number of entities, i.e. 1 mol = N0 ent ≈ (g/Da) ent. This means that the appropriate atomic-scale unit for molar mass is dalton per entity (Da/ent), equal to the constant Mu, very nearly equal to 1 g/mol. For Da/ent to be exactly equal to g/mol, the dalton would need to be redefined exactly in terms of the (fixed-h) kilogram and the Avogadro number so that 1 Da = (1/N0) g, satisfying the relationships N0 = g/Da and 1 mol = N0 ent = (g/Da) ent, thus conforming to the original mole concept—that the Avogadro number is the gram-to-dalton mass unit ratio.
== Side effects == Nicotinamide has minimal side effects. Acute liver toxicity has been documented in at least one case with doses over 3000mg, with recommended maximum intake in non liver-impaired individuals being 1500mg. Normal doses are safe during pregnancy. Nicotinamide is contraindicated in individuals diagnosed with liver disease, and/or may cause possible drug interactions.
== Early life and career == Kahn was born in Louisville, Kentucky. He received his undergraduate and medical degree from the University of Louisville in 1964 and 1968. He became interested in pursuing diabetes research while serving in several positions at the National Institutes of Health (NIH) from 1970 to 1981. He moved to Boston in 1981 when he was appointed Associate Professor of Medicine at Harvard Medical School and Research Director of the Joslin Diabetes Center. By 1984, he was promoted to Professor of Medicine and named the Mary K. Iacocca Professor of Medicine at Harvard Medical School in 1986.
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.
Reverse-phase HPLC is the usual method and gives a percentage purity value. Mass spectrometry then confirms the molecular mass. Together they provide a basic identity and purity profile for a lot.