Class
Thymic peptides
Thymic peptides are peptides isolated from, or extracted from, thymus tissue. Several have been studied for effects on immune function, such as T-cell differentiation markers and cytokine release in cell cultures, and immune markers in clinical trials. The group is chemically mixed: it includes a defined peptide, a tissue extract, a dipeptide and a fragment of a protein later recognised mainly for non-immune roles.
How the members differ
- Thymosin alpha-1 is a defined peptide whose synthetic form, thymalfasin, is approved outside the US; its large phase 3 sepsis trial found no mortality difference.
- Thymalin is a polypeptide complex extracted from thymus tissue rather than a single sequence, with activity attributed to the dipeptides Lys-Glu and Glu-Trp.
- Thymagen is most likely Thymogen, the dipeptide Glu-Trp, studied as a haemostimulatory agent by a Moscow group distinct from the St Petersburg bioregulator group.
- TB-500 is an acetylated seven-residue fragment of thymosin beta-4, a protein first isolated from calf thymus but later recognised mainly as an actin-sequestering molecule.
Compounds in this group
Thymosin Alpha-1Limited human data · Approved outside the USThymosin alpha-1 is a 28-amino-acid thymic peptide, and its synthetic form thymalfasin is approved in a number of countries outside the United States. It has been studied in hepatitis, sepsis, and as a vaccine adjunct, with mixed trial findings. It is not FDA-approved.
ThymalinLimited human data · Not approved — research use onlyA short thymic peptide of the bioregulator class, studied in laboratory research on immune function and cellular aging.
TB-500Preclinical research · Not approved — research use onlyTB-500 is a synthetic, acetylated seven-amino-acid fragment of thymosin beta-4, and it is often described as if it were the full protein, which is inaccurate. Evidence for the full protein comes from cell, animal and a few human studies, whereas FDA found no human data for TB-500 itself. It is not approved and is prohibited in sport.
ThymulinPreclinical research · Not approved — research use onlyThymulin is a nonapeptide produced by thymic epithelial cells whose biological activity exists only when the peptide is bound to zinc; it is studied as a biomarker of zinc and thymic status and in animal models of inflammation, with no approved drug use.
ThymagenPreclinical research · Not approved — research use onlyA short thymus-associated bioregulator peptide studied in laboratory research on immune signaling and cellular regulation.
Compare Thymosin Alpha-1, Thymalin, TB-500 side by side
For research use only. Not for human or veterinary use. Not a drug, food, or dietary supplement. Mechanism descriptions summarize published research and are not claims of effect in people.