Thymalin: What the Thymus Bioregulator Research Shows

Thymalin is the oldest product in the bioregulator family and the odd one out: most bioregulators are synthetic peptides of two to four amino acids, while Thymalin is a tissue extract. This article explains what that means, how it relates to the synthetic thymus peptides that followed, what the studies report and in which models, and how much weight the evidence can bear.

What Thymalin is

Thymalin is a complex of peptides with molecular masses up to about 10 kDa, obtained from calf thymus by mild acid extraction. It has no single sequence, formula or molecular weight; in a 2013 interview Khavinson described it as containing more than 50 peptides. In the programme's terminology it is a cytomedin, a peptide complex from an organ, as distinct from the later synthetic short peptides the group calls cytogens.

The work began in 1973 at the S.M. Kirov Military Medical Academy in Leningrad, together with a drug factory at the city's meat-processing plant. The stated aim was to make military personnel more resilient to radiation, toxic substances, injury, hypoxia and severe stress, on the theory that stress suppresses the thymus and pineal gland. Thymalin, developed by Khavinson with his fellow student Vyacheslav Morozov, was registered as a medicine in 1982 and is still made in St Petersburg.

Thymalin and the synthetic thymus peptides

An extract is hard to standardise and does not show which component does the work, so the group looked for short sequences to stand in for it. Two dipeptides are linked to Thymalin.

• Thymogen (Glu-Trp, also called oglufanide): isolated from Thymalin by reversed-phase chromatography and then made synthetically. It was approved in the USSR in 1990, and the group describes it as the country's first synthetic peptide medicine.
• Vilon (Lys-Glu): its origin is less clear. The group's 1997 overview describes it as a newly synthesised immunomodulatory dipeptide. Later reviews say Lys-Glu was detected in Thymalin by chromatography and mass spectrometry, but the source they cite is a 1997 Russian patent rather than a published analysis, and a 2023 paper calls KE and EW the active substances of Thymalin.

The distinction matters: results with the single, defined dipeptides cannot simply be transferred to the extract, or the reverse. The 1997 overview itself reported a difference: the natural extract affected the antioxidant response of thymus cells, while the synthetic dipeptides did not.

The proposed mechanism

The original idea was replacement: thymus peptides would support T-cell maturation when stress or age suppresses the thymus. The group now explains Thymalin's action in bioregulator terms, through short components such as KE and EW that are proposed to enter cells and adjust gene expression. That is a hypothesis layered on a mixture: the published work does not establish which component accounts for which effect in a living organism.

What the studies show

• Immune cells (cell culture): in human haematopoietic stem cell cultures, Thymalin lowered the stem cell markers CD44 and CD117 and raised CD28, a marker of mature T-cells, 6.8-fold, which the authors read as a push towards T-cell maturation. In blood immune cells from four donors stimulated with bacterial lipopolysaccharide, Thymalin and the dipeptides KE and EW lowered the inflammatory cytokines IL-1β, IL-6 and TNF-α by 1.4 to 6.0 times.
• Rats: most animal work comes from the originating network, much of it in Russian. One independent example, from universities in Kyiv and Kharkiv in 2024, used 48 rats with jaw bone defects: Thymalin treatment was associated with more T-cells, B-cells and macrophages in the healing tissue, and a shift from M1 towards M2 macrophages.
• Older people: the most cited human study, by researchers in St Petersburg and Kyiv, followed 266 older people for six to eight years. Mortality was reported to be 2.0 to 2.1 times lower in the Thymalin group than in controls, alongside fewer acute respiratory illnesses. The abstract does not describe how participants were allocated or whether anyone was blinded.
• COVID-19: a single-centre, open-label randomised trial in 92 patients compared Thymalin plus standard care (42 patients) with standard care alone (50). IL-6, C-reactive protein and D-dimer fell faster with Thymalin; there were no deaths in either group.

How strong is the evidence?

Thymalin has the longest track record of any bioregulator and the loosest definition. Three things limit what its literature can show.

• Identity: a mixture defined by its source and extraction method cannot be specified like a single peptide, so a result from one preparation cannot be assumed for another.
• One network: nearly all studies come from Khavinson's institute and its long-standing collaborators, and independent work is scattered and small.
• Trial design: the human studies are small, open-label or not described as randomised, and unreplicated. Khavinson has himself recalled that early human work in the Soviet Union took place with no ethics committee and few restrictions.

A fair summary: Thymalin is a historically important thymus extract with consistent immune-marker findings in the originating group's work, but there is no independent, blinded human evidence for it.

Where Thymalin fits

Thymalin is the parent of the thymus-linked synthetic peptides, including Vilon, and it was often studied alongside Epithalamin, the pineal extract behind Epitalon. Despite the similar names, it is a different substance from Thymosin alpha-1, a single 28-amino-acid peptide, and from Thymulin, a zinc-dependent thymic hormone. For how all the bioregulators fit together, see our guide to the Khavinson bioregulator peptides and the evidence behind them.

References

1. Morozov VG, Khavinson VK. (1997). "Natural and synthetic thymic peptides as therapeutics for immune dysfunction." International Journal of Immunopharmacology. PubMed 9637345
2. Khavinson VKh. (2020). "Peptide medicines: past, present, future." Klinicheskaya Meditsina (in Russian). doi:10.30629/0023-2149-2020-98-3-165-177
3. Khavinson V. (2013). "'I think that the small peptides are the best for healthy ageing...', an interview with Vladimir Khavinson. Interview by Suresh I. S. Rattan." Biogerontology. PubMed 23377892
4. Khavinson VK. (2001). "Tissue-specific effects of peptides." Bulletin of Experimental Biology and Medicine. PubMed 11713572
5. Linkova N, et al. (2023). "The Influence of KE and EW Dipeptides in the Composition of the Thymalin Drug on Gene Expression and Protein Synthesis Involved in the Pathogenesis of COVID-19." International Journal of Molecular Sciences. PubMed 37686182
6. Khavinson VK, et al. (2020). "Thymalin: Activation of Differentiation of Human Hematopoietic Stem Cells." Bulletin of Experimental Biology and Medicine. PubMed 33237528
7. Boiko AA, et al. (2024). "Expression features of T-lymphocytes, B-lymphocytes and macrophages in the post-traumatic regenerate of the mandible rats under conditions of filling a bone defect with hydroxyapatite-containing osteotropic material and thymalin injecting the surrounding soft tissues." Polski Merkuriusz Lekarski. PubMed 38642352
8. Khavinson VKh, Morozov VG. (2003). "Peptides of pineal gland and thymus prolong human life." Neuro Endocrinology Letters. PubMed 14523363
9. Khavinson VK, et al. (2021). "Results and Prospects of Using Activator of Hematopoietic Stem Cell Differentiation in Complex Therapy for Patients with COVID-19." Stem Cell Reviews and Reports. PubMed 33575961
10. Goldstein AL, et al. (1977). "Thymosin alpha1: isolation and sequence analysis of an immunologically active thymic polypeptide." Proceedings of the National Academy of Sciences of the USA. PubMed 265536
11. Bach JF, Dardenne M. (1989). "Thymulin, a zinc-dependent hormone." Medical Oncology and Tumor Pharmacotherapy. PubMed 2657247