Synthesis and immunomodulatory activity of [60]fullerene–tuftsin conjugates

Immunomodulating peptide tuftsin (Thr-Lys-Pro-Arg) was covalently conjugated to fullerene C60 by two different ways to prepare NH2–tuftsin–C60 and C60–tuftsin–COOH. The two new compounds were intensively characterized. The synthetic C60–tuftsin conjugates were assayed for their stability against leucine aminopeptidase degradation. And the immunostimulating activities to murine peritoneal macrophages were investigated in vitro. Compared with the natural tuftsin, significant enhancement of phagocytosis, chemotaxis activities and major histocompatibility complex class II (MHC II) molecule expression were observed in macrophages stimulated by both of the conjugates. The two conjugates also exhibit complete resistance to enzymatic hydrolysis, and they are non-toxic to macrophages in the tested concentrations. On all accounts, these results suggest that the C60–tuftsin conjugates can be used as potential candidates of immunomodulators and vaccine adjuvants.