K4 Elite
K4 Elite
Immune & Inflammation
Thymalin is not a single molecule. It is a mixture of low-molecular-weight polypeptides extracted from calf thymus by acetic-acid extraction and acetone precipitation, developed in the 1970s at the Military Medical Academy in Leningrad by Vladimir Khavinson and Vyacheslav Morozov and registered as a medicine in the Soviet Union in 1982 [1]. It belongs to a family of tissue-specific peptide extracts the same group called “cytomedines”, which also includes Epithalamin (pineal) and Cortexin (cerebral cortex). Because Thymalin is an extract rather than a defined compound, it has no molecular formula, molecular weight or PubChem entry, and its activity is characterised by biological rather than chemical assays. Two dipeptides later isolated from it by reversed-phase HPLC, Glu-Trp (later developed as the drug Thymogen) and Lys-Glu (Vilon), are considered by the developers to be its principal active components [1][2].
The extract is standardised by protein content and by bioassay rather than by identity of individual peptides. Published descriptions state that the majority of the peptide mass lies below 10 kDa. The originating laboratory has argued that short peptides within the complex enter cells and bind DNA to regulate gene expression, and it has published a series of in-vitro reports in support of this model, but no independent group has characterised the full composition of a commercial lot, and lot-to-lot variability has not been reported in the open literature.
The core claim is that Thymalin promotes differentiation and function of T lymphocytes. In a 2020 in-vitro report, Thymalin increased expression of CD5, CD7 and CD28 on cultured human haematopoietic stem cells, which the authors interpreted as activation of T-lymphocyte differentiation [3]. Earlier Russian work reported normalisation of lactate dehydrogenase isoenzyme patterns and cyclic-nucleotide systems in lymphocytes, and increased expression of T-cell differentiation antigens. The dipeptide Glu-Trp isolated from the complex has been tested on its own: in a rat study it was reported to slow ageing-related changes and reduce spontaneous tumour incidence [2]. A 2023 in-silico and cell-culture study examined Lys-Glu and Glu-Trp for interactions with proteins implicated in COVID-19 pathogenesis and reported changes in gene expression and protein synthesis in cultured cells [4].
The most cited human data come from a long-term observational programme in St Petersburg. Khavinson and Morozov reported in 2003 that elderly and very elderly subjects given Thymalin annually over 6 to 8 years had a 2.0- to 2.1-fold lower mortality than untreated comparison groups, with additional reductions when combined with Epithalamin [5]; the study was not blinded or placebo-controlled. A 1997 review from the same authors summarised the earlier clinical use of Thymalin as an immunocorrector and the isolation of Glu-Trp from it [1]. During the COVID-19 pandemic the group published a small open-label series in which Thymalin was added to standard care in hospitalised patients, reporting shorter hospitalisation and changes in lymphocyte counts [6]; there was no randomised control arm.
Almost the entire evidence base originates from the developers and their collaborators, is published in Russian-language or low-impact journals, and lacks blinding, placebo control and independent replication. The 2003 longevity claim comes from a non-randomised observational cohort and cannot support a causal inference. The COVID-19 series was open-label and small. The composition of the extract is undefined, so mechanistic findings for isolated dipeptides cannot simply be attributed to the mixture, and the DNA-binding model of action proposed by the originating group has not been confirmed by independent laboratories. Thymalin is not approved by the FDA or EMA. Because it is a bovine tissue extract, sourcing, prion-safety documentation and lot certification deserve particular scrutiny. This material is supplied for in-vitro laboratory research only.
Format. Lyophilised off-white to pale-yellow powder in a sealed glass vial with rubber stopper and aluminium crimp cap. Content is expressed as total peptide mass, not as a single defined compound.
Reconstitution. Add bacteriostatic water or sterile saline slowly down the side of the vial and swirl gently until dissolved; do not shake. Use the reconstitution calculator to convert vial content to a working concentration, bearing in mind that the figure represents a peptide mixture of undefined molar composition.
Storage. Lyophilised vials: 2–8 °C, protected from light; suitable for longer-term storage at −20 °C. Reconstituted solution: 2–8 °C and use within 7 days; avoid repeated freeze–thaw cycles.
Handling. As a material of bovine tissue origin, handle with the same precautions applied to other animal-derived biologicals. Wear gloves and eye protection; avoid generating dust from the lyophilised cake. For in-vitro laboratory research only — not for human or veterinary use.