Pinealon: A Research Overview

Introduction

Pinealon is a synthetic tripeptide composed of L-glutamic acid, L-aspartic acid, and L-arginine, denoted by the single-letter amino acid sequence Glu-Asp-Arg or, in one-letter code, EDR. The compound belongs to a class of short synthetic peptides developed at the St. Petersburg Institute of Bioregulation and Gerontology under the direction of Vladimir Kh. Khavinson, and is part of a peptide bioregulator research program spanning more than four decades. Published research on Pinealon has concentrated on its behavior in neural cell systems and in rodent models of hypoxic and oxidative injury, with findings appearing in both English-language and translated Russian-language peer-reviewed journals.

Background

Interest in short bioactive peptides corresponding in sequence to peptides found in mammalian pineal tissue arose within Soviet-era biomedical research programs. Vladimir Kh. Khavinson and colleagues at the St. Petersburg Institute of Bioregulation and Gerontology pursued a hypothesis that peptide sequences inferred from organ extracts could, when synthesized in short oligopeptide form, engage nuclear and chromatin targets and modulate gene expression in tissue-specific ways [1].

The broader peptide bioregulator program produced compounds for a range of tissue types. For the pineal lineage, earlier work had characterized a polypeptide complex designated Epithalamin, extracted from bovine pineal tissue, before attention turned toward identifying and synthesizing the discrete active short peptide sequences within such preparations [1]. This research lineage places Pinealon within a family of short peptides that includes Epithalon (Ala-Glu-Asp-Gly), which shares overlapping sequence elements and has been studied in related research contexts. The EDR sequence was subsequently characterized through molecular docking as capable of interacting with DNA promoter regions, providing a structural basis for the gene-regulatory hypotheses advanced by the Khavinson group.

Chemistry and Structure

Pinealon has the chemical name L-glutamyl-L-aspartyl-L-arginine and the amino acid sequence Glu-Asp-Arg. Its CAS registry number is 175175-23-2, the molecular formula is C₁₅H₂₆N₆O₈, and the approximate molecular weight is 418.4 Da. The three constituent residues provide a net acidic charge at physiological pH from the two carboxylate-bearing amino acids (glutamate and aspartate) partially offset by the basic guanidinium group of the arginine side chain.

Because of its small size (three residues), Pinealon lacks the secondary structural motifs common to larger peptides. Research from the Khavinson group reported, using fluorescence-labeled analogs, that short peptides of this size class are capable of crossing lipid bilayers and entering the cell nucleus of HeLa cells, where they were observed to interact with deoxyribooligonucleotide targets in vitro [2]. This membrane permeability characteristic distinguishes Pinealon from larger peptide research compounds that require receptor-mediated or transporter-mediated cellular entry.

Pharmacological Classification

Pinealon is classified in the literature as a peptide bioregulator with reported in vitro neuroprotective and antioxidant properties. It is not an agonist of a defined cell-surface receptor, and it is not categorized within conventional receptor-pharmacology classes such as G-protein-coupled receptor agonists, ion-channel modulators, or enzyme inhibitors. The primary mechanistic hypothesis, described in peer-reviewed publications, is that the EDR tripeptide enters cells and nuclei and interacts directly with promoter-region DNA sequences, thereby modulating transcriptional output of multiple target genes [3].

Pinealon has been grouped in Russian-language and translated literature under the broader heading of "cytomedicines" or "cytogens" — a classification scheme originating with the Khavinson group to designate synthetic peptides reflecting the tissue-regulatory functions of organ-derived polypeptide complexes. This classification scheme is distinct from standard international pharmacological taxonomy.

Regulatory Status

Pinealon is not approved by the US Food and Drug Administration (FDA) as a drug for any therapeutic indication and does not appear in the FDA Orange Book (Approved Drug Products with Therapeutic Equivalence Evaluations). No marketing-authorization application for Pinealon as a medicinal product has been identified in European Medicines Agency or member-state public regulatory databases.

In Russia, the compound has been distributed in formulations designated for use in geriatric and neurological research contexts. Its specific regulatory categorization under Russian pharmaceutical law has not been fully described in Western-accessible English-language regulatory documentation.

Researchers working with Pinealon are responsible for determining applicable regulations in their jurisdictions.

Discovery History

The synthetic EDR sequence emerged from a research program that began with the isolation of peptide complexes from bovine organ tissue, a program described in peer-reviewed reviews covering work spanning several decades [1]. Khavinson and Morozov published work describing effects of pineal-derived polypeptide preparations through the 1970s into the 1990s in Soviet-era and Russian-language publications. The transition from complex organ extracts to defined short synthetic peptides — including identification of EDR as an active sequence — was described in English-language review articles summarizing the program [1,3].

A 2011 publication in Rejuvenation Research by Khavinson and colleagues formally characterized Pinealon's in vitro effects on cell viability, reactive oxygen species (ROS) accumulation, and proliferative processes in cerebellar granule cells, neutrophils, and pheochromocytoma-derived PC12 cells, representing one of the first detailed English-language characterizations of the isolated tripeptide [4]. Subsequent work examined Pinealon in rodent models of prenatal hyperhomocysteinemia [5] and experimentally induced ischemia [6], and molecular docking analyses further elaborated potential gene-regulatory interactions [3]. The synthesis and purity verification processes for the research compound are described in detail in the Pinealon sourcing and quality article.

References

1. Anisimov VN, Khavinson VKh. Peptide bioregulation of aging: results and prospects. Biogerontology. 2010;11(2):139–149. doi: 10.1007/s10522-009-9249-8. PMID: 19830585.

2. Fedoreyeva LI, Kireev II, Khavinson VKh, Vanyushin BF. Penetration of short fluorescence-labeled peptides into the nucleus in HeLa cells and in vitro specific interaction of the peptides with deoxyribooligonucleotides and DNA. Biochemistry (Moscow). 2011;76(11):1210–1219. doi: 10.1134/S0006297911110022.

3. Khavinson V, Linkova N, Kozhevnikova E, Trofimova S. EDR Peptide: Possible Mechanism of Gene Expression and Protein Synthesis Regulation Involved in the Pathogenesis of Alzheimer's Disease. Molecules. 2020;26(1):159. doi: 10.3390/molecules26010159. PMID: 33396470.

4. Khavinson V, Ribakova Y, Kulebiakin K, Vladychenskaya E, Kozina L, Arutjunyan A, Boldyrev A. Pinealon increases cell viability by suppression of free radical levels and activating proliferative processes. Rejuvenation Research. 2011;14(5):535–541. doi: 10.1089/rej.2011.1172.

5. Arutjunyan A, Kozina L, Stvolinskiy S, Bulygina Y, Mashkina A, Khavinson V. Pinealon protects the rat offspring from prenatal hyperhomocysteinemia. International Journal of Clinical and Experimental Medicine. 2012;5(2):179–185. PMID: 22567179. PMCID: PMC3342713.

6. Mendzheritskiĭ AM, Karantysh GV, Ivonina KO. Effects of introduction of short peptides before carotid artery occlusion on behaviour and caspase-3 activity in the brain of old rats. Advances in Gerontology. 2011;24(1):74–79. PMID: 21809624.