A defined oral peptide fraction prepared from porcine brain tissue, marketed as a nutraceutical analog of intravenous Cerebrolysin for cognitive support.
Abstract
N-PEP-12 is a porcine-brain-derived peptide preparation developed by Ever Neuro Pharma (the manufacturer of Cerebrolysin) as a defined orally bioavailable analog of the parent intravenous nootropic. Cerebrolysin itself is a complex hydrolysate of porcine cerebral cortex containing approximately 25 percent free amino acids and 75 percent low-molecular-weight peptides (less than 10 kDa) administered by daily intravenous or intramuscular injection in courses of 10 to 30 days for vascular dementia, Alzheimer’s disease, ischemic stroke recovery, and traumatic brain injury indications across approximately 50 jurisdictions (Europe, Asia, Russia, South America). The intravenous administration is operationally restrictive; N-PEP-12 was developed to provide a similar peptide profile in a daily oral capsule format suitable for outpatient and over-the-counter use. The published characterization describes a peptide molecular weight distribution of 1 to 10 kDa with similar amino acid composition to Cerebrolysin and shared neurotrophic activity in cortical neuron culture (BDNF and IGF-1 mimetic effects, neurite outgrowth, protection against amyloid-beta and glutamate excitotoxicity). Clinical evidence is more limited than for Cerebrolysin: published randomized trials in mild cognitive impairment (MCI) and age-associated memory impairment report modest cognitive improvements over 90 days in single-center studies. The compound is not FDA-approved; it is marketed as a dietary supplement in the United States and as a nutraceutical or medicinal food in European jurisdictions. The principal limitation on the strength of the evidence is the small number of independent clinical trials and the dominance of the manufacturer-sponsored published record. Reconstitution is not required; oral capsules contain approximately 60 mg of peptide blend.
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Selective alpha-7 nicotinic acetylcholine receptor full agonist
A quinuclidine benzofuran-2-carboxamide developed at Targacept as a selective alpha-7 nicotinic full agonist with a binding affinity of 1.4 nanomolar at the human alpha-7 receptor, advanced through Phase 2 development for cognitive impairment and negative symptoms of schizophrenia with a positive 12-week exploratory trial followed by a negative larger 24-week confirmatory trial, subsequently licensed to Anvylic Therapeutics for Tourette syndrome and other indications.
Abstract
Bradanicline (development codes TC-5619 and ATA-101) is a small-molecule, highly selective full agonist of the homopentameric alpha-7 subtype of the neuronal nicotinic acetylcholine receptor (alpha-7 nAChR), originated at Targacept Pharmaceuticals (Winston-Salem, North Carolina) from a quinuclidine benzofuran-2-carboxamide chemistry program in the mid-2000s and advanced through Phase 1 and Phase 2 clinical development for cognitive impairment associated with schizophrenia. The compound binds the human alpha-7 nicotinic receptor with a Ki of approximately 1.4 nanomolar, slightly higher affinity than encenicline (Ki approximately 4 nanomolar) and substantially higher affinity than tropisetron at the alpha-7 site, and exhibits functional intrinsic activity of approximately 80 to 90 percent of the acetylcholine maximum response in heterologous expression systems, placing it in the high-efficacy stratum of alpha-7 ligands as a full agonist rather than the partial-agonist class that encenicline and tropisetron occupy. The full-agonist intrinsic activity is the principal medicinal-chemistry differentiator of bradanicline within the broader quinuclidine-amide chemical class. Selectivity over alpha-4-beta-2, alpha-3-beta-4, alpha-3-beta-2, and other neuronal nicotinic subtypes is approximately 100-fold or greater. The compound was advanced through an exploratory Phase 2 trial in 185 schizophrenia patients (Lieberman et al. 2013) at 5 milligrams once daily for 12 weeks, with statistically significant improvement on the Groton Maze Learning Task and on the Scale for Assessment of Negative Symptoms compared to placebo, and a statistically significant drug effect on working memory in the tobacco-using subgroup. A larger confirmatory Phase 2 trial (Walling et al. 2016) in 477 schizophrenia outpatients across 64 sites at 5 or 50 milligrams once daily for 24 weeks did not support a benefit on negative or cognitive symptoms compared to placebo. Targacept terminated the cognitive impairment program in 2013 and the compound was subsequently licensed to Catalyst Biosciences and to Anvylic Therapeutics for Tourette syndrome and selected other neurological indications. The compound represents a useful research-clinical reference for the alpha-7 nicotinic full-agonist class and for the assessment of whether higher functional intrinsic activity at the receptor produces greater clinical benefit. Bradanicline did not produce the severe gastrointestinal toxicity that triggered the September 2015 FDA clinical hold on encenicline; the safety profile in Phase 2 was well-tolerated with no clinically noteworthy findings reported. The compound is supplied as a research-grade reagent (greater than 98 percent purity) by multiple chemical suppliers and continues to serve as a reference alpha-7 nicotinic full agonist for fundamental pharmacology research. This monograph reviews the chemistry, synthesis, and stereochemistry of bradanicline; the receptor pharmacology in detail; the human pharmacokinetic record; the indication-by-indication clinical evidence base; and a structured comparative assessment of five alpha-7 nicotinic acetylcholine receptor candidates against bradanicline on five competency standards.
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A 15-residue synthetic peptide modeled on the second fibronectin-like domain of neural cell adhesion molecule, an FGFR1 partial agonist with neuroprotective and pro-cognitive activity in rodent models.
Abstract
FGL (FG Loop peptide; Glu-Val-Tyr-Val-Val-Ala-Glu-Asn-Gln-Gln-Gly-Lys-Ser-Lys-Ala; sometimes called the FGL peptide or NCAM-derived FGFR agonist; molecular weight approximately 1622 Da) is a synthetic 15-residue peptide modeled on the second fibronectin type III repeat (FnIII) domain of neural cell adhesion molecule (NCAM), specifically the Phe-Gly loop responsible for fibroblast growth factor receptor 1 (FGFR1) interaction. NCAM is a transmembrane glycoprotein expressed at high levels in developing and adult nervous system tissue that mediates cell-cell adhesion through homophilic NCAM-NCAM binding and signals across the membrane through cis-binding to FGFR1. The FGL peptide was designed at the University of Copenhagen by Elisabeth Bock and Vladimir Berezin as a small-molecule mimetic of the NCAM-FGFR interaction, capable of activating FGFR1 signaling without the broad effects of full NCAM ectodomain or full-length FGF ligands. Reported activities include neurite outgrowth promotion in primary cortical and hippocampal neurons, protection against glutamate excitotoxicity, anxiolysis and pro-cognitive effects in rodent fear conditioning and Morris water maze paradigms, and recovery promotion in models of traumatic brain injury and stroke. Routes studied include subcutaneous, intraperitoneal, and intranasal administration. Plasma half-life is short (approximately 30 minutes); the central nervous system exposure after intranasal administration is substantially higher than after parenteral routes, owing to direct olfactory and trigeminal pathway transport. The compound advanced through ENKAM Pharmaceuticals (a University of Copenhagen spin-out) into early clinical development for Alzheimer’s disease and cognitive impairment in the late 2000s; clinical development has not produced a marketed agent. The principal limitation on the strength of the evidence is the dominance of the originating laboratory’s publications and the absence of independent replication of key behavioral findings.
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Type I positive allosteric modulator of the alpha-7 nicotinic acetylcholine receptor
An isoxazole-acrylamide chemical entity originally developed at the University of California Irvine as compound CCMI and licensed through multiple owners to Anvylic Therapeutics, representing the most mechanistically distinct alpha-7 nicotinic candidate in clinical development through its Type I positive allosteric modulator mechanism that preserves the spatiotemporal specificity of endogenous cholinergic neurotransmission.
Abstract
AVL-3288 (also known as UCI-4083, CCMI, Anvylic-3288, and XY-4083) is a small-molecule, orally bioavailable Type I positive allosteric modulator (PAM) of the homopentameric alpha-7 subtype of the neuronal nicotinic acetylcholine receptor (alpha-7 nAChR). The compound is mechanistically distinct from the partial-agonist (tropisetron, encenicline, GTS-21) and full-agonist (bradanicline, PHA-543613) classes that have dominated alpha-7 nicotinic receptor drug development. Type I PAMs bind the alpha-7 receptor at an allosteric site distinct from the orthosteric (acetylcholine) binding site, do not directly activate the receptor in the absence of agonist, and enhance the potency and efficacy of endogenous acetylcholine signaling at the receptor. Critically, Type I PAMs preserve the rapid desensitization kinetics of the alpha-7 channel and therefore preserve the spatiotemporal specificity of cholinergic neurotransmission, in contrast to direct agonists which prolong receptor activation and may produce non-physiological signaling. This mechanistic profile is the principal scientific argument for the AVL-3288 approach as an alternative to direct agonist development in cognitive applications, particularly in light of the September 2015 FDA clinical hold and March 2016 Phase 3 termination of encenicline (a partial agonist) for severe gastrointestinal toxicity. The compound was originated at the University of California Irvine in the laboratory of Kelvin Gee in the early 2000s as part of an academic medicinal-chemistry program for novel alpha-7 nicotinic receptor modulators, was licensed through several commercial owners (Bionomics, Anvylic Therapeutics), and was advanced through a first-in-human Phase 1a single-ascending-dose study in 21 healthy non-smokers (Gee et al. 2017) and a Phase 1b randomized double-blind placebo-controlled triple-cross-over study in 24 non-smoking medicated outpatients with schizophrenia or schizoaffective disorder (Freedman et al. 2020) at 10 milligrams and 30 milligrams oral doses. The Phase 1a study reported safety, dose-proportional pharmacokinetics, and exploratory cognitive signals at 10 and 30 milligrams. The Phase 1b study in schizophrenia patients reported P50 auditory evoked potential gating biomarker effects at 30 milligrams (consistent with alpha-7 receptor target engagement), exploratory cognitive performance signals, and acceptable tolerability across the studied doses. The compound has not advanced to Phase 2 as of the most recent monograph revision; future development depends on commercial-funding decisions. AVL-3288 represents the most mechanistically novel of the alpha-7 nicotinic receptor candidates and is the principal contemporary alternative therapeutic concept for the alpha-7 nicotinic target. This monograph reviews the chemistry, synthesis, and structural class of AVL-3288; the receptor pharmacology of Type I PAM mechanism in molecular and electrophysiological detail; the limited human pharmacokinetic record from Phase 1a and Phase 1b; the clinical evidence base in healthy volunteers and schizophrenia outpatients; sourcing, reconstitution, and stack-interaction considerations; the safety record; and a structured comparative assessment of five alpha-7 nicotinic acetylcholine receptor candidates against AVL-3288 on the five competency standards.
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Synthetic tetrapeptide bioregulator with testicular tissue-specific epigenetic and steroidogenesis-modulating activity
A synthetic tetrapeptide (Lys-Glu-Asp-Gly) developed at the Saint Petersburg Institute of Bioregulation and Gerontology as the defined active sequence of the testicular polypeptide complex Testoluten, proposed to modulate steroidogenic gene expression and Leydig cell function through direct peptide-DNA interaction and chromatin remodeling in testicular endocrine tissue.
Abstract
Testagen, the synthetic tetrapeptide Lys-Glu-Asp-Gly (one-letter code KEDG; molecular formula C17H29N5O9; molecular weight 447.44), is a testicular-derived bioregulatory peptide synthesized and characterized by Vladimir Khavinson and colleagues at the Saint Petersburg Institute of Bioregulation and Gerontology (IBG) beginning in the early 2000s. The compound belongs to the Khavinson class of ultrashort (two to seven residue) peptide bioregulators, a family of synthetic sequences modeled on tissue-specific peptide fragments isolated from organ extracts by acid-pepsin hydrolysis and ultrafiltration, and is the defined synthetic analog of the active component of the testicular polypeptide complex preparation Testoluten [1, 2]. Testagen is distinguished within the Khavinson bioregulator family by a testicular tissue-directed pharmacological profile that centers on three proposed activities: first, modulation of steroidogenic gene expression in Leydig cells, with reported effects on expression of genes encoding steroidogenic acute regulatory protein (StAR), cholesterol side-chain cleavage enzyme (CYP11A1), 3-beta-hydroxysteroid dehydrogenase (3-beta-HSD), and 17-beta-hydroxysteroid dehydrogenase, the principal rate-limiting enzymes in the testosterone biosynthetic cascade from cholesterol to testosterone [3, 4]; second, epigenetic modulation through direct peptide-DNA interaction and chromatin remodeling, consistent with the broader Khavinson hypothesis that ultrashort peptides act as sequence-specific regulators of gene expression through complementary electrostatic interactions with DNA in gene promoter regions [5, 6]; and third, normalization of hypothalamic-pituitary-gonadal (HPG) axis signaling in aged animal models, with reported restoration of luteinizing hormone receptor expression on Leydig cells and normalization of the testosterone-to-luteinizing hormone ratio [7, 8]. The compound shares the general Khavinson bioregulator mechanism of cell and nuclear membrane penetration, direct interaction with histone proteins and double-stranded DNA, and modulation of gene transcription, a framework supported by fluorescence microscopy tracking of labeled peptide analogs into cell nuclei and by electrophoretic mobility shift assays demonstrating peptide-DNA complex formation [5, 6]. Structurally, Testagen differs from the closely related Khavinson bioregulators Epithalon (Ala-Glu-Asp-Gly, pineal-derived), Livagen (Lys-Glu-Asp-Ala, liver-derived), and Cortagen (Ala-Glu-Asp-Pro, brain-derived) by single residue substitutions that are proposed to confer tissue-specificity through differential DNA sequence recognition [9]. The substitution of lysine at position 1 (versus alanine in Epithalon) and glycine at position 4 (versus alanine in Livagen) produces a distinct charge distribution and hydrogen-bonding pattern that molecular modeling studies have associated with preferential interaction with promoter sequences of testicular steroidogenic genes [5, 10]. No formal pharmacokinetic studies have been published for Testagen. The compound, as a linear tetrapeptide with unprotected termini, is expected to undergo rapid proteolytic degradation by aminopeptidases and carboxypeptidases in plasma and gastrointestinal fluid, with a predicted plasma half-life on the order of minutes. No human clinical trials of the synthetic KEDG tetrapeptide have been registered on ClinicalTrials.gov or on major international trial registries. The clinical evidence base is limited to a single uncontrolled Russian-language clinical study and to ex vivo human cell studies. The parent polypeptide complex Testoluten has been used in Russian gerontological clinical practice for age-related testosterone decline and male subfertility, but the synthetic tetrapeptide does not hold separate pharmaceutical registration in any jurisdiction. Testagen is not approved by the United States Food and Drug Administration, the European Medicines Agency, or any major Western regulatory authority. It is supplied as a research-grade lyophilized powder by multiple peptide suppliers at greater than 95 percent purity by high-performance liquid chromatography. This monograph reviews the chemistry, synthesis, and structural characterization of Testagen; the proposed epigenetic, steroidogenic, and HPG axis mechanisms in molecular detail; the available pharmacokinetic considerations; the preclinical pharmacology across testicular aging and reproductive models; the limited clinical evidence; sourcing and quality verification; reconstitution and handling; stack-interaction considerations; adverse-event and safety signal; and a comparative assessment of five male reproductive or endocrine candidates against Testagen on five competency standards (novelty, effect size, promising potential, side-effect profile, and overall validation).
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Selective alpha-7 nicotinic acetylcholine receptor full agonist (preclinical research compound)
A quinuclidine furo[2,3-c]pyridine-5-carboxamide developed at Pfizer in the mid-2000s as a brain-penetrant, orally bioavailable selective alpha-7 nicotinic full agonist with substantial preclinical pharmacology in rodent cognitive models. The principal high-potency selective alpha-7 nicotinic agonist in current research use as a tool compound, with no advancement to human clinical trials but extensive use in fundamental and combination-pharmacology studies including the recent presenilin double-knockout mouse model of Alzheimer disease and synergistic combination work with memantine in aged rats.
Abstract
PHA-543613 is a small-molecule, brain-penetrant, orally bioavailable selective full agonist of the homopentameric alpha-7 subtype of the neuronal nicotinic acetylcholine receptor, originated at Pfizer Global Research and Development in the mid-2000s as part of an alpha-7 nicotinic receptor medicinal-chemistry program for cognitive enhancement applications. The compound is a quinuclidine furo[2,3-c]pyridine-5-carboxamide, structurally related to the quinuclidine-amide alpha-7 family that includes encenicline (a quinuclidine benzothiophene-2-carboxamide) and bradanicline (a quinuclidine benzofuran-2-carboxamide), distinguished by the fused furo[2,3-c]pyridine bicyclic system in the amide-bearing aryl group. The chemistry was disclosed in the seminal Wishka et al. (2006) Journal of Medicinal Chemistry report from Pfizer, which described the structure-activity relationship study, the optimization to PHA-543613 as the lead compound, and the preliminary pharmacology supporting brain penetration, oral bioavailability, and alpha-7 selectivity [1]. The compound has not been advanced to human clinical trials; the published pharmacology is principally preclinical (rodent species). PHA-543613 binds the human alpha-7 nicotinic receptor at the orthosteric (acetylcholine) site with low-nanomolar affinity (Ki approximately 8 nanomolar at human alpha-7 expressed in heterologous systems) and acts as a full agonist with intrinsic functional activity of approximately 80 to 90 percent of the acetylcholine maximum response in Xenopus oocyte and cell-line expression systems, comparable to bradanicline and substantially higher than encenicline (60 to 70 percent), tropisetron (25 to 40 percent), and GTS-21 (30 to 50 percent). Selectivity over other neuronal nicotinic subtypes (alpha-4-beta-2, alpha-3-beta-4) is approximately 100-fold or greater. The compound exhibits good oral bioavailability and high brain penetration in rodent species (brain-to-plasma ratio approximately 5 to 10), supporting central nervous system pharmacology at oral doses of 0.3 to 10 milligrams per kilogram. The principal published pharmacology comprises rodent behavioral studies in scopolamine-induced cognitive impairment, MK-801-induced cognitive impairment, beta-amyloid-induced cognitive deficit (the Aฮฒ25-35 mouse model), aged-rat working memory paradigms, and the recent Hijazi et al. (2023) presenilin 1 and presenilin 2 conditional double knockout mouse model of familial Alzheimer disease [2, 3, 4]. The compound has demonstrated reversal of cognitive deficits across these models with effect sizes substantially exceeding the alpha-7 partial agonists tested in parallel comparisons (notably exceeding galantamine in head-to-head comparisons in the aged-rat model). Substantial recent work has characterized the synergistic combination of PHA-543613 with memantine (an NMDA receptor antagonist, the FDA-approved Alzheimer disease drug) in aged rats, with the combination demonstrating greater cognitive benefit than either compound as monotherapy at clinically translatable doses [4]. The combination work supports a contemporary research-clinical hypothesis that combination pharmacology of alpha-7 nicotinic full agonism (PHA-543613-class) with NMDA receptor antagonism (memantine) and acetylcholinesterase inhibition (donepezil-class) may produce cognitive benefits exceeding those achievable with monotherapy in any single mechanism class. PHA-543613 has not been licensed to a clinical-development entity for human trials as of the most recent monograph revision; the compound therefore serves as a research tool rather than as a clinical candidate. Research-grade PHA-543613 is widely available from chemical suppliers at moderate cost and is one of the most extensively used alpha-7 nicotinic receptor agonist tool compounds in contemporary fundamental pharmacology research. This monograph reviews the chemistry, synthesis, and stereochemistry of PHA-543613; the receptor pharmacology in molecular and electrophysiological detail; the preclinical pharmacokinetic record in rodent species; the comprehensive preclinical pharmacology across cognitive enhancement, neuroprotection, and combination pharmacology applications; sourcing, reconstitution, and stack-interaction considerations; the safety record (preclinical only); and a structured comparative assessment of five alpha-7 nicotinic acetylcholine receptor candidates against PHA-543613 on the five competency standards.
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Synthetic cardioprotective tetrapeptide bioregulator with epigenetic gene-regulatory and anti-apoptotic activity targeting cardiomyocytes
A synthetic tetrapeptide (H-Ala-Glu-Asp-Arg-OH; AEDR) developed at the Saint Petersburg Institute of Bioregulation and Gerontology as an ultrashort peptide bioregulator with cardioprotective, anti-apoptotic, and epigenetic chromatin-regulatory activity targeting cardiomyocytes, cardiac fibroblasts, and myocardial gene expression programs.
Abstract
Cardiogen (H-Ala-Glu-Asp-Arg-OH; AEDR tetrapeptide; molecular formula C18H31N7O9; molecular weight 489.48 g/mol) is a synthetic tetrapeptide bioregulator developed by Vladimir Khavinson and colleagues at the Saint Petersburg Institute of Bioregulation and Gerontology as the cardiac-specific member of the Khavinson ultrashort peptide bioregulator family [1, 2]. The compound belongs to a class of synthetic two-to-seven-residue peptide sequences modeled on tissue-specific peptide fragments isolated from mammalian organ extracts, and is designated as the cardiovascular system bioregulator within this peptide family. Cardiogen shares the Ala-Glu-Asp tripeptide core with the cortical bioregulator Cortagen (Ala-Glu-Asp-Pro) and the pineal bioregulator Epithalon (Ala-Glu-Asp-Gly), differing from these compounds by the fourth-position arginine residue, a single amino acid substitution that determines cardiac tissue specificity within the Khavinson classification system [3, 4]. The principal molecular mechanism of Cardiogen, characterized through molecular modeling, cell culture, and organotypic myocardial tissue studies, is epigenetic regulation of gene expression through direct interaction of the tetrapeptide with double-stranded DNA in gene promoter regions and with histone proteins (H1, H2B, H3, H4), producing chromatin decondensation and reactivation of transcriptional programs in cardiac cells [5, 6, 7]. The cardioprotective activity, characterized in organotypic myocardial tissue cultures, embryonic fibroblast cultures, and coronary artery ligation animal models, includes stimulation of cardiomyocyte proliferation with concurrent suppression of cardiomyocyte apoptosis through p53 protein downregulation, upregulation of cytoskeletal proteins (actin, vimentin, tubulin) by up to five-fold and nuclear matrix proteins (lamin A, lamin C) by up to 2.5-fold relative to control, preservation of myocardial glycogen stores and cellular energy production structures under ischemic conditions, and a reported threefold reduction in mortality following experimental coronary artery ligation in treated versus control groups [8, 9, 10, 11]. In a separate line of investigation, Cardiogen demonstrated tumor-modifying activity against transplanted M-1 sarcoma in senescent rats, with dose-dependent inhibition of tumor growth mediated by hemorrhagic necrosis and stimulation of tumor cell apoptosis through a vascular mechanism rather than direct cytostatic effect [12]. The compound has been characterized in the context of the senescence-associated secretory phenotype of cardiovascular system cells and inflammaging, with evidence that the AEDR tetrapeptide regulates molecules involved in the inflammatory pathways contributing to age-related cardiovascular decline [13]. No formal pharmacokinetic studies have been published for Cardiogen as the isolated synthetic AEDR tetrapeptide. As a linear tetrapeptide with unprotected termini, the compound is expected to undergo rapid proteolytic degradation by aminopeptidases and carboxypeptidases in plasma and gastrointestinal fluid; however, molecular modeling studies have demonstrated that ultrashort peptides are substrates of the proton-coupled oligopeptide transporter (PEPT1/PEPT2) family carriers, supporting intestinal absorption and cellular uptake through active transport mechanisms [14, 15]. No human clinical trials have been published. The compound is not approved by the United States Food and Drug Administration, the European Medicines Agency, or any major Western regulatory authority. Cardiogen is registered in the Russian Federation as a biologically active additive and is commercially available there in capsule and sublingual formulations. It is supplied internationally as a research-grade lyophilized peptide by multiple peptide synthesis vendors at greater than 95 percent purity by high-performance liquid chromatography. This monograph reviews the chemistry, synthesis, and structural characterization of Cardiogen; the discovery and development history within the Khavinson bioregulatory peptide program; the molecular pharmacology including peptide-DNA binding, histone interaction, and cardiac gene expression modulation; the pharmacokinetic considerations for ultrashort peptides; the preclinical pharmacology across cardiac, inflammatory, and aging cell models; the clinical evidence base (absent); sourcing and quality verification; reconstitution and handling; stack interactions and combinations; adverse events and safety signal; and a comparative assessment of five cardioprotective or cardiac-repair peptide candidates (Vesugen, Thymosin beta-4, BPC-157, Cortagen, GHK-Cu) against Cardiogen on five competency standards.
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A four-residue synthetic peptide developed by the Khavinson group as a cerebral cortex bioregulator, part of the Russian short-peptide bioregulator class.
Abstract
Cortagen (Ala-Glu-Asp-Pro; CAS 254749-42-7; molecular weight 414.41) is a four-residue synthetic peptide developed at the St. Petersburg Institute of Bioregulation and Gerontology by Vladimir Khavinson as a representative of the short-peptide bioregulator class derived from cortexin (a porcine cerebral cortex extract registered as a medicine in the Russian Federation). The Khavinson program isolated active fragments from organ-specific peptide extracts and characterized synthetic tetrapeptide and tripeptide analogs as the molecular basis of the parent extract’s activity, including Cortagen for cerebral cortex, Pinealon (Glu-Asp-Arg) for pineal/CNS, Epitalon (Ala-Glu-Asp-Gly) for pineal, Vilon (Lys-Glu) for thymus, and several others. The proposed mechanism is direct DNA binding of the short peptides at promoter regions of tissue-specific genes, modulating transcription in a cell-type-restricted manner; published Russian-language work characterizes binding to specific GC-rich regulatory regions and effects on transcription factor recruitment. Pro-cognitive and neuroprotective activities of Cortagen are reported in rodent models of cerebral hypoxia, traumatic brain injury, and stress; Russian clinical reports describe efficacy in vegetative-vascular dystonia, post-traumatic asthenia, and discirculatory encephalopathy at intramuscular doses of 5 to 10 mg over 5 to 10 day courses. The Khavinson bioregulator class is registered as medicines in the Russian Federation and a small number of CIS jurisdictions; FDA, EMA, and most Western regulatory authorities have not reviewed the class. The principal limitation on the evidence base is the dominance of the originating laboratory’s publications and the limited scale of clinical evidence relative to what would be required for Western regulatory approval. Investigators should weight the evidence accordingly.
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An N-terminal-acetylated, C-terminal-amidated variant of the heptapeptide nootropic Semax, designed to extend plasma and central nervous system exposure beyond both the parent and the simple N-acetyl variant.
Abstract
NA-Semax Amidate (N-acetyl-Met-Glu-His-Phe-Pro-Gly-Pro-NH2) is a doubly modified variant of Semax (the seven-residue ACTH(4-10) analog Met-Glu-His-Phe-Pro-Gly-Pro) developed at the Russian Academy of Sciences as a long-acting analog. Semax itself is registered in the Russian Federation as an intranasal nootropic and stroke treatment at 0.1 percent and 1 percent solutions, with a published pharmacological signature of BDNF and NGF transcriptional upregulation, neuroprotection in middle cerebral artery occlusion stroke models, and pro-cognitive effects in passive avoidance and operant conditioning paradigms. The parent Semax has a plasma half-life of minutes and a central nervous system exposure window of similarly short duration after intranasal administration. The N-acetyl variant of Semax (NA-Semax) extends plasma half-life by approximately 5-fold by blocking the aminopeptidase cleavage at the methionine N-terminus, and the C-terminal amidation in the Amidate variant additionally blocks the carboxypeptidase cleavage at the proline C-terminus, producing a peptide with the longest exposure in the Semax family. Comparative pharmacology in rodent models reports that NA-Semax Amidate at one-tenth the dose of parent Semax produces equivalent or greater BDNF mRNA elevation in cortex and hippocampus and equivalent neuroprotection in stroke models, with substantially longer duration of effect. Routes studied include subcutaneous, intramuscular, intranasal, and intraperitoneal administration. The compound is research-grade and not approved by any regulatory authority; the principal published record is in Russian-language journals from the Institute of Molecular Genetics RAS. Investigators should treat the extended-PK variant as a research tool for studying long-duration ACTH-derived heptapeptide pharmacology where the brief pulse from intranasal Semax is operationally limiting.
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Synthetic hepatoprotective tripeptide bioregulator of the Khavinson ultrashort peptide class
A synthetic tripeptide (Glu-Asp-Leu) developed at the Saint Petersburg Institute of Bioregulation and Gerontology as a tissue-specific epigenetic bioregulator targeting hepatic and gastrointestinal gene expression, distinguished from conventional hepatoprotective agents by a proposed mechanism of direct nuclear peptide-DNA interaction and chromatin remodeling rather than receptor-mediated signal transduction.
Abstract
Ovagen is a synthetic tripeptide composed of L-glutamic acid, L-aspartic acid, and L-leucine (Glu-Asp-Leu; single-letter code EDL) and belongs to the Khavinson class of ultrashort peptide bioregulators developed at the Saint Petersburg Institute of Bioregulation and Gerontology under the direction of Vladimir Khavinson. The compound is classified as a liver and gastrointestinal tract bioregulator within the Cytogen (synthetic short-chain peptide) product line and is proposed to exert its biological activity through direct interaction with nuclear DNA and chromatin rather than through conventional membrane receptor signaling. The molecular weight of Ovagen is 375.37 daltons (molecular formula C15H25N3O8), a size that places it within the ultrashort peptide category (2 to 7 amino acid residues) characterized by resistance to gastrointestinal peptidase degradation, oral bioavailability without enteric coating in some formulations, and the capacity to cross cellular membranes and localize to the nucleoplasm without receptor-mediated endocytosis. The principal proposed mechanism of action involves sequence-specific binding of the EDL tripeptide to double-stranded DNA in the promoter regions of hepatocyte genes governing cell proliferation, antioxidant defense, apoptosis, and inflammatory signaling. In aged rat liver tissue, Ovagen administration has been reported to produce an approximately 18-fold increase in Ki-67 expression (a marker of cellular proliferation) and an approximately 6-fold decrease in p53 expression (a marker of apoptotic signaling and cellular senescence), suggesting a shift from senescent to proliferative hepatocyte phenotype [1, 2]. In preclinical models of chemically induced hepatotoxicity (carbon tetrachloride and paracetamol), Ovagen administration over 14 to 28 days reduced serum liver enzyme elevation, decreased hepatocyte necrosis and inflammatory cell infiltration on histological examination, and normalized hepatic antioxidant status [3, 4]. A secondary research application involves gastrointestinal mucosal support, with preclinical data suggesting that Ovagen strengthens epithelial barrier function, increases tight junction protein expression, and reduces intestinal permeability in aging models [5]. The compound has not been approved by any national regulatory authority for therapeutic use. No published, peer-reviewed human clinical trials of Ovagen exist as of the date of this monograph. The evidence base is entirely preclinical (cell culture and rodent models) and is derived predominantly from the Khavinson laboratory and collaborating Russian institutions. The peptide bioregulator framework within which Ovagen was developed has produced a substantial body of Russian-language and English-language literature, including a 2021 systematic review of peptide regulation of gene expression published in the journal Molecules [6], but the framework has not been independently validated by Western regulatory-standard clinical trials. Investigators considering Ovagen for research applications should weight the evidence accordingly, noting the predominantly single-laboratory provenance of the preclinical data, the absence of human pharmacokinetic characterization to Western regulatory standards, and the mechanistic novelty of the proposed direct peptide-DNA interaction pathway. This monograph reviews the chemistry, proposed mechanism of action, preclinical pharmacology, available pharmacokinetic considerations, sourcing and quality verification, reconstitution and handling, stack-interaction considerations, adverse-event signal, and a comparative assessment of five hepatoprotective or liver-bioregulatory candidates against Ovagen on five competency standards.
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