Thymalin

Thymalin is a peptide bioregulator — a low-molecular-weight polypeptide mixture extracted from the thymus glands of calves — developed in the Soviet Union during the 1970s and 1980s by Vladimir Khavinson, Vladimir Morozov, and colleagues at what is now the St. Petersburg Institute of Bioregulation and Gerontology. Unlike fully synthetic peptides, Thymalin is a natural extract containing multiple small peptides that together are thought to restore thymic signaling, with Khavinson's group identifying short di- and tripeptide sequences (including Lys-Glu and related fragments) as the probable active components. In Russia and some Eastern European countries, Thymalin has a long history of prescription clinical use, where it is licensed as an immunomodulator. Outside those markets it is not approved by the FDA, EMA, or most Western regulators and is classified as a research compound. The biological rationale is straightforward: the thymus involutes progressively from early adulthood, contributing to a decline in naïve T-cell output and immune competence that is considered a central feature of immunosenescence (age-related immune decline). Restoring thymic peptide signaling is hypothesized to slow or partially reverse this process. Published studies report improvements in immune parameters, reductions in age-associated disease incidence, and reduced mortality in elderly cohorts treated over many years — findings that are biologically plausible but come almost entirely from one institution and have not been replicated in independent, double-blind, placebo-controlled trials in Western literature. This entry is a research reference only. It is not medical advice and does not endorse human use.