Thymalin Peptide

Research Overview

The Thymalin peptide complex is isolated from calf thymus by mild acid extraction, first characterized in the 1970s by Vladimir Khavinson and Vyacheslav Morozov at what is now the Saint Petersburg Institute of Bioregulation and Gerontology. It is the founding member of the thymic branch of the Khavinson peptide family and the parent preparation from which the synthetic dipeptide Thymogen (Glu-Trp) was later isolated and reproduced. In the research literature Thymalin is used as a reference thymic-peptide preparation for investigating T-cell differentiation, cytokine regulation in immune cell cultures, and the organ-specific peptide bioregulation hypothesis.

Thymalin should not be confused with Thymulin, which is a single synthetic nonapeptide (serum thymic factor) with a defined sequence and molecular weight. The two share a name root and a thymic origin but are different materials, and this catalog carries them as separate products.

Composition and Molecular Characteristics

Thymalin is not a single molecule. It is a mixture of low-molecular-weight polypeptides recovered from thymus tissue, so it carries no single CAS registry number, molecular formula, or molecular weight, and none is stated here. Published work on its composition has identified two active dipeptide constituents: Lys-Glu (KE, the sequence later supplied synthetically as Vilon) and Glu-Trp (EW, supplied synthetically as Thymogen). Morozov and Khavinson reported the isolation of Glu-Trp from Thymalin by reversed-phase HPLC, and a 2023 study from the same institute examined the contribution of the KE and EW dipeptides to the activity of the complex.

A note on registry lookups: a name search for “Thymalin” in PubChem returns the record for nonathymulin (Thymulin), because the two names are listed as synonyms there. That record describes the nonapeptide pGlu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn, which is the material sold on this site as Thymulin, not the thymus extract sold on this page. Researchers characterizing this product should rely on the batch Certificate of Analysis rather than a registry record.

Place in the Khavinson Peptide Family

The Khavinson program produced two generations of research compounds. The first generation consists of organ-specific polypeptide complexes extracted from calf tissues: Thymalin from thymus, Epithalamin from pineal gland, Cortexin from cerebral cortex, and others. The second generation consists of short synthetic peptides designed from the amino-acid composition of those extracts, such as Epitalon (Ala-Glu-Asp-Gly), Pinealon (Glu-Asp-Arg), Cardiogen, Vilon (Lys-Glu), and Thymogen (Glu-Trp). Thymalin is the natural-extract counterpart to the synthetic thymic dipeptides, and comparative studies of the natural complex against its synthetic derivatives are a recurring design in this literature.

Research Applications

Hematopoietic stem cell differentiation

Khavinson and colleagues examined Thymalin in cultures of human hematopoietic stem cells and reported a two- to three-fold decrease in the stem-cell marker CD44 and the intermediate-stage marker CD117 alongside a 6.8-fold increase in CD28, a marker of mature T lymphocytes. The authors interpreted this as evidence that the complex promotes differentiation of CD117-positive progenitors toward CD28-positive T cells in vitro.

Cytokine regulation in immune cell cultures

In a lipopolysaccharide-stimulated model using human peripheral blood mononuclear cells, Thymalin and its KE and EW dipeptide constituents reduced the synthesis of IL-1β, IL-6, and TNF-α by 1.4 to 6 times. A separate study in the THP-1 monocyte/macrophage cell line compared Thymalin with four synthetic Khavinson peptides and found that all five modulated mitogen-activated kinase phosphorylation, reduced LPS-stimulated TNF and IL-6 expression in differentiated cells, and reduced monocyte adhesion to activated endothelial cells.

Organotypic tissue culture and B-cell markers

In organotypic cultures of thymus tissue from young and old rats, Thymalin was among seven tissue-specific polypeptide preparations that selectively stimulated growth of the matching tissue at 20 to 50 ng/mL, with increased PCNA and decreased p53 expression. Thymalin additionally activated expression of CD5 and CD20, markers of B-cell differentiation.

Thymus morphology in animal models

Work from the Rostov Research Institute of Oncology examined thymus microstructure in outbred rats bearing transplanted sarcoma 45 under an activation-therapy protocol and reported increased lymphoproliferative activity and higher counts of tissue basophils and plasma cells in the thymic lobules. Immunomorphological studies have also detected Thymalin-reactive material in human epidermis and fetal reticuloepithelium, with the layer of reactive cells thinning with age.

Natural versus synthetic thymic peptides

Morozov and Khavinson compared the natural Thymalin complex with the synthetic dipeptides Thymogen and Vilon across T-cell differentiation, cyclic nucleotide composition, and cytokine release in blood lymphocytes. The synthetic dipeptides reproduced several activities of the complex but differed from it in antioxidant response in thymocytes, a finding that keeps the natural extract in use as a comparator in this line of research.

Product Format and Storage

Thymalin is supplied as a white to off-white lyophilized (freeze-dried) powder in a 10 mg size, where the stated mass refers to the total peptide content of the vial. The lyophilized format limits solution-phase degradation during storage and supports precise gravimetric preparation of research standards at the point of use.

The sealed lyophilized powder is stored at -20°C or below, protected from light and moisture, and kept desiccated. A Certificate of Analysis accompanies the product.

Quality Assurance and Analytical Testing

Because Thymalin is a peptide mixture rather than a single compound, its analytical profile is a fingerprint rather than a single purity figure. The methods below are those commonly used to characterize a thymic polypeptide fraction of this class:

• Reversed-phase HPLC — chromatographic profile of the peptide fraction and total peptide content.
• Electrospray-ionization mass spectrometry — mass distribution of the constituent peptides.
• Amino-acid analysis — overall amino-acid composition of the fraction, the same measurement the Khavinson group used to design the synthetic dipeptides.
• Karl Fischer titration — residual moisture in the lyophilized powder.
• Residual solvent analysis by GC — solvents carried over from extraction and purification.

Compliance and Safety Information

Thymalin is offered strictly as a research chemical for in vitro laboratory investigation. It is not a drug, dietary supplement, cosmetic, or food, and it is not intended for human or veterinary use. Purchasers are responsible for ensuring that handling, storage, and disposal comply with the regulations applicable to their jurisdiction and institution.

Peptides.GG is a chemical supplier and is not a compounding pharmacy under 503A or 503B. Statements have not been evaluated by the US FDA. Products are not intended to diagnose, treat, cure, or prevent any disease. For research use only — not for human consumption.