Thymalin

At a Glance

Classification: Polypeptide extract from calf (bovine) thymus; Khavinson-school peptide bioregulator; immunomodulator registered in Russia

Thymalin is a mixture of peptides extracted from calf thymus. It was developed in the Soviet Union in the 1970s by Vladimir Khavinson and Vyacheslav Morozov at the Military Medical Academy in Leningrad (now St. Petersburg). It is registered in Russia as an immunomodulating medicine. It is the founding product of the "peptide bioregulator" line that later produced short synthetic peptides such as Vilon, Thymogen and Epitalon. Later work by the same group identified short dipeptides in the extract, notably Lys-Glu (KE, sold separately as Vilon) and Glu-Trp (EW, sold separately as Thymogen), and proposed them as some of its active parts. Thymalin is studied for: • Immune support during infections and after immune suppression • Immune aging (immunosenescence) in elderly people • Effects on blood-forming stem cells and T-cell development • Inflammation markers, including in COVID-19 • Long-term mortality in elderly cohorts. Watch the spelling: thymalin is not thymulin. Thymulin is a zinc-dependent thymic hormone with a separate literature. Thymalin is not approved by the FDA or EMA. Almost all published research comes from the developing group and its collaborators, much of it in Russian-language journals.

What Is Thymalin?

Thymalin is a natural extract, not a single defined molecule. Calf thymus tissue ↓ acid extraction and purification ↓ a complex of small peptides and polypeptides (Thymalin) ↓ in which short peptides such as KE and EW have been identified. Because it is an extract, its exact composition is less defined than a single synthetic peptide. The developers later made single short peptides (for example Vilon and Thymogen) partly to address this.

What Are Researchers Studying?

How Does It Work?

Proposed mechanisms (mainly from the developing group's cell and animal work): Thymalin peptides ↓ act on immune precursor cells ↓ encourage hematopoietic stem cells toward T-cell development (for example, more CD28+ cells in culture) ↓ adjust cytokine production (reduced IL-1β, IL-6 and TNF-α in some cell experiments) ↓ proposed "restoration" of thymus-dependent immunity in aging or immune suppression. The group also proposes that short peptides enter cells and bind DNA, regulating gene expression. That theory is not widely tested by independent labs.

What Does the Research Show?

Notable Studies

What We Still Don't Know

• Whether the lifespan and immune benefits hold up in randomized, blinded, independently run trials • Exactly which components of the extract are active, and how consistent batches are • Whether the proposed DNA-binding mechanism is real • Human pharmacokinetics of the peptide mixture • Long-term safety, including risks typical of animal-tissue extracts (immune reactions, contamination) • How results compare with modern immune therapies • Whether "thymalin" sold outside Russian pharmacies matches the registered product. Most of the evidence comes from one research school, and much is published in Russian.

Related Compounds

Sources & References

1. Khavinson VKh, Morozov VG. Peptides of pineal gland and thymus prolong human life. Neuro Endocrinol Lett. 2003;24(3-4):233–240.
2. Khavinson VKh, Morozov VG. [Geroprotective effect of thymalin and epithalamin]. Adv Gerontol. 2002;10:74–84. (Russian.)
3. Khavinson VK, Linkova NS, Kvetnoy IM, et al. Thymalin: Activation of Differentiation of Human Hematopoietic Stem Cells. Bull Exp Biol Med. 2020;170(1):118–122.
4. Khavinson VK, Kuznik BI, Trofimova SV, et al. Results and Prospects of Using Activator of Hematopoietic Stem Cell Differentiation in Complex Therapy for Patients with COVID-19. Stem Cell Rev Rep. 2021;17(1):285–290.
5. Kuznik BI, Shapovalov KG, Smolyakov YN, et al. [Morphological compound and indicators of the blood clotting system in severe COVID-19 patients of middle aged...]. Adv Gerontol. 2022;35(3):368–374. (Russian.)
6. Linkova N, Khavinson V, Diatlova A, et al. The Influence of KE and EW Dipeptides in the Composition of the Thymalin Drug on Gene Expression and Protein Synthesis. Int J Mol Sci. 2023;24(17).