What is thymalin?
Thymalin, also spelled timalin or thymaline, is not a single defined molecule. Primary papers describe it as a polypeptide preparation. It is made from calf thymus by mild acid extraction. Its creators called it a complex of peptides, not one compound (Morozov and Khavinson, 1997). Two short peptides were later separated from that extract and made into defined substances.
One is the dipeptide Glu-Trp, sold as thymogen (Anisimov et al., 2000). The other is the dipeptide Lys-Glu (Khavinson et al., 2021). Our product page lists a 10MG lyophilized research vial. It gives no sequence, formula, molecular weight or CAS number. That is consistent with a mixture. Disguised Alpha supplies it for laboratory research use only, and nothing on this page is guidance for use in people.
Thymalin reference data
| Property | Value |
|---|---|
| Name | Thymalin |
| Aliases | Timalin, thymaline; described as a thymus polypeptide complex |
| Sequence | Not applicable: the literature describes a polypeptide preparation, not one defined molecule |
| Formula, molecular weight, CAS number | None stated on the product page |
| PubChem | A name search for "thymalin" resolves to CID 3085284, titled Nonathymulin (C₃₃H₅₄N₁₂O₁₅, 858.9 g/mol, registry number 63958-90-7). That record is a different substance: see the note below. |
| Form | Lyophilized powder |
| Size carried | 10MG |
| Testing | Third-party tested. The certificate for each lot is published on the product page and in the COA portal |
The PubChem name clash matters. CID 3085284 is the nine-residue peptide pGlu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn. Its sequence was worked out from pig serum. It was named facteur thymique sérique, later thymulin (Pleau et al., 1977). Its activity in those assays needed a bound zinc ion (Dardenne et al., 1985; Bach and Dardenne, 1989). "Thymalin" appears there only as a synonym. The extract in the thymalin papers is not that nonapeptide. The product page gives no formula or weight, so there is nothing to compare. For quantitative work, use the measured content printed on your lot's certificate.
What the research covers
Published work falls into four areas. Each summary below states the model used. Two caveats apply to the whole field. First, the work is older and more concentrated than its size suggests. A PubMed search for the name variants returns about 300 records. Roughly 101 list V. Kh. Khavinson or V. G. Morozov as an author.
About 268 are in Russian or Ukrainian, with only 31 in English. More than three quarters date from the 1980s and 1990s. Second, the material is a preparation, not a molecule. So effects credited to "thymalin" in one paper may not refer to the same mixture as in another. Several studies also test it alongside thymogen or vilon.
What the preparation is and what came out of it
The founding group described thymic peptides extracted from calf thymus. They also described how the dipeptide Glu-Trp was separated from that extract by reversed-phase chromatography. The thymogen product was based on that dipeptide. Both the extract and the synthetic dipeptides were reported to affect T-cell differentiation. They were also reported to affect cyclic nucleotide composition in blood lymphocytes.
But their effects on antioxidant responses in thymocytes differed (Morozov and Khavinson, 1997; characterization also in Safronov et al., 1984). An independent review of the period places it in a crowded field. That field included thymosins and thymulin. It also included thymopoietin and thymopentin. The review notes that these are hard to compare (Arion et al., 1997).
Rodent and explant models
Several 1980s studies looked at colony-forming units from bone marrow, spleen and blood. They used mice whose thymus had been removed, plus sham-operated mice. They reported stimulation of granulocytic colonies from splenic colony-forming units. This was seen in both animals and culture. The effect on bone marrow colony-forming units showed up only in animals (Val'kovich et al., 1986; Popov and Ergakova, 1985).
Work from the same period reported less platelet aggregation in intact rats. Aortic antiaggregation activity did not change (Kuznik et al., 1986). Organ-culture work from the Pavlov Institute compared the extract with synthetic peptides derived from it. It used explants of rat thymus and spleen.
The extract boosted explant growth at about 5 ng/mL in tissue from 21-day-old rats. Vilon and thymogen inhibited growth in explants from 1-day-old animals (Chalisova et al., 1999). A companion paper compared five tissue extracts, each on explants of its own source organ. The thymus extract was active at the lowest concentration of the set (Chalisova et al., 2000).
A separate line of work used antibodies raised against the extract. These found immunoreactive material in human fetal reticuloepithelium, epidermis and developing respiratory organs. That epidermal layer thinned by about age 70 (Khlystova et al., 2002; Khlystova et al., 2003). Those are findings about an antibody target in tissue sections, not about the product.
Recent cell-culture work, including independent groups
One study used cultures of human hematopoietic stem cells from cord blood. The extract was reported to lower CD44 and CD117 expression by two to three times. It was also reported to raise CD28 by 6.8 times. The authors read this as a shift along the differentiation pathway (Khavinson et al., 2020).
An Italian group worked with the founding author. They tested five of these peptides, including the thymalin complex, in the human THP-1 monocyte line. They reported more tyrosine phosphorylation of mitogen-activated kinases. Stimulated cells showed lower tumor necrosis factor and interleukin-6 expression. Adhesion to activated endothelial monolayers fell (Avolio et al., 2022).
A 2023 study paired two methods. It used molecular docking of the Lys-Glu and Glu-Trp dipeptides against double-stranded DNA. It also ran an in vitro inflammation model in blood mononuclear cells from four donors. It reported 1.4 to 6.0 times lower interleukin-1 beta, interleukin-6 and tumor necrosis factor alpha (Linkova et al., 2023).
Three independent lines of work exist. One found fewer cysticerci in a mouse Taenia crassiceps model (Hermánek and Prokopic, 1989). Another is a Vladivostok comparison with a squid-derived peptide preparation (Kuznetsova et al., 2013). The third is rat mandible bone-defect models from Ukrainian groups (Boiko et al., 2024).
Registration in Russia and the clinical literature
Thymalin is registered as a medicine in the Russian Federation. Its registration number is LS-000267, dated 26 February 2010, as stated by the founding group (Khavinson et al., 2020). It is not approved in the United States. The human studies behind that registration come almost entirely from the institute that created it. The most-cited report followed 266 elderly participants in St Petersburg and Kiev for 6 to 8 years.
It described lower mortality in the groups given the thymic and pineal preparations (Khavinson and Morozov, 2003). The same material appears in an earlier paper (Khavinson and Morozov, 2002). Later reports came from that group with hospital partners. They describe its use alongside standard care in patients with COVID-19 (Khavinson et al., 2021). The independent animal tumor work comes from a single oncology institute (Zhukova et al., 2018). None of the human work has been repeated elsewhere.
Key studies
- Safronov BN, et al. "Experimental and clinical study of the thymus polypeptide factor thymalin." Hum Physiol. 1984. PMID 6336212. Mouse and human work from the originating institute.
- Popov BV, Ergakova EV. "Differentiation characteristics of circulating and bone marrow hematopoietic stem cells and the effect of thymus factors." Biull Eksp Biol Med. 1985. PMID 3839146. Mouse model: colony-forming units in thymectomized animals.
- Hermánek J, Prokopic J. "Influence of thymic preparations on the result of experimental infection with Taenia crassiceps (Zeder, 1800) in ICR mice." Folia Parasitol. 1989. PMID 2488049. Independent mouse parasitology model.
- Chalisova NI, et al. "Effect of thymus polypeptide fractions on the development of rat thymus and spleen in organ culture." Tsitologiia. 1999. PMID 10591126. Organotypic rat explant culture.
- Kuznetsova TA, et al. "Comparative study of immunomodulatory activity of peptides, tinrostim and thymalin." Antibiot Khimioter. 2013. PMID 24734422. Independent group: mouse and human cell immunoassays.
- Khavinson VK, et al. "Thymalin: Activation of Differentiation of Human Hematopoietic Stem Cells." Bull Exp Biol Med. 2020. PMID 33237528. DOI 10.1007/s10517-020-05016-z. Human hematopoietic stem cell culture.
- Avolio F, et al. "Peptides Regulating Proliferative Activity and Inflammatory Pathways in the Monocyte/Macrophage THP-1 Cell Line." Int J Mol Sci. 2022. PMID 35408963. DOI 10.3390/ijms23073607. Human THP-1 monocyte culture.
- Linkova N, et al. "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." Int J Mol Sci. 2023. PMID 37686182. DOI 10.3390/ijms241713377. Molecular docking plus an in vitro inflammation model in human blood cells.
Handling and storage of lyophilized thymalin
General lab practice for this material:
- Store the powder at -20°C, away from light, until use. Storage guidance is on the product page. Let the sealed vial reach room temperature before opening, so moisture does not condense on the powder.
- Molar concentrations cannot be calculated for a preparation. Published cell and explant work reports mass per volume, on the order of nanograms per milliliter (Chalisova et al., 1999). So plan comparisons on a mass basis.
- Prepare stock solutions in water or a neutral buffer, and record the pH. If a solution needs clearing, filter it rather than heat it. Processing can change the makeup of an extract.
- Never assume these are the same: this preparation, the defined dipeptides separated from it, and the nonapeptide on PubChem CID 3085284. Log each as a separate material.
- Once the powder is dissolved, keep solutions at 2 to 8°C and away from light. Split stock into single-use aliquots to avoid freeze/thaw cycles.
- Record the lot number and keep its certificate with your notes. Use its measured content, not the label mass.
Frequently asked questions
What is thymalin, and does it have a molecular weight?
It is a polypeptide preparation extracted from calf thymus. Primary papers describe it as a complex of peptides, not one defined molecule (Morozov and Khavinson, 1997). Neither the product page nor the published work gives it a molecular weight. PubChem does return a record for the name: CID 3085284 at 858.9 g/mol. But that is the nine-residue thymulin peptide sequenced from pig serum (Pleau et al., 1977). It is a different substance that carries "thymalin" only as a synonym. Do not quote that weight for this material.
Is thymalin the same as thymosin alpha-1 or thymogen?
No. Thymosin alpha-1 is a defined 28-residue peptide from a different extraction program. Our thymosin alpha-1 research guide covers it. Thymogen is the Glu-Trp dipeptide separated from the thymalin extract (Anisimov et al., 2000).
Is thymalin registered as a medicine anywhere?
Yes, in the Russian Federation, under registration number LS-000267 dated 26 February 2010 (Khavinson et al., 2020). It is not approved in the United States. The material sold here is a research chemical, not that medicine, and not for use in people.
How much of the thymalin literature comes from one group?
A large share. About 101 of roughly 300 records list V. Kh. Khavinson or V. G. Morozov as an author. About 268 are in Russian or Ukrainian, and most date from the 1980s and 1990s. The independent work is narrow. It covers a mouse parasitology model (Hermánek and Prokopic, 1989) and comparative immunoassays (Kuznetsova et al., 2013). It also covers THP-1 cell work (Avolio et al., 2022) and a rat mandible model (Boiko et al., 2024).
How should thymalin powder be stored?
Keep the lyophilized powder at -20°C and away from light. Once dissolved, store the solution at 2 to 8°C, away from light. Avoid freeze/thaw cycles. These steps are listed on the product page.
Where can researchers buy thymalin?
Disguised Alpha sells it for laboratory research. It is third-party tested, with the certificate published on the product page: Thymalin (10MG).
Related compounds and guides
- Thymosin Alpha-1: a defined 28-residue thymic peptide, and its research guide.
- Epitalon: the Ala-Glu-Asp-Gly tetrapeptide from the same St Petersburg program, and its research guide.
- Pinealon and its research guide.
- Cartalax and Vesugen: more short peptides from the same research.
- Cardiogen and its research guide.
- COA portal: every published certificate, by lot.
This product is for research use only. It has not been evaluated for safety or effectiveness in humans. Not for human consumption. All products are intended for laboratory research purposes only.