Comparison
While Semax is used clinically in Russia for ischemic stroke and cognitive disorders; in models it improves learning, protects dopaminergic neurons, and modulates stress responses without significant endocrine ACTH-like effects166174, TB-500 is studied for enhancing musculoskeletal and cardiac repair, wound healing, and promoting cell migration and differentiation via actin cytoskeleton remodeling21255.
While Semax works as a synthetic heptapeptide, Met-Glu-His-Phe-Pro-Gly-Pro (MEHFPGP), that is an analog of ACTH(4–10) with a Pro-Gly-Pro extension and exerts neurotrophic and neuroprotective actions partly via upregulation of BDNF and modulation of dopaminergic and glutamatergic systems40162165174, TB-500 is a synthetic peptide comprising the LKKTETQ actin-binding motif of thymosin beta-4 that binds G-actin, sequesters actin monomers, and promotes cell migration, angiogenesis, and tissue repair1255.
Semax is 7 amino acids long, whereas TB-500 is the same length as it has a length of 7 amino acids. Semax is made up of a sequence of Methionine, Glutamic acid, Histidine, Phenylalanine, Proline, Glycine, Proline. TB-500 is made up of a sequence of Lysine, Lysine, Lysine, Threonine, Glutamic acid, Threonine, Glutamine.
Semax
Targets are not fully defined; interacts with melanocortin-related pathways and inhibits certain peptidases, but no single dominant receptor has been established174
TB-500
Binds monomeric actin (G-actin) rather than a classical cell-surface receptor, modulating actin polymerization at barbed and pointed ends55
Semax
POMC
TB-500
TMSB4X