Maturin acetate from Psacalium peltatum (Kunth) Cass. (Asteraceae) induces immunostimulatory effects in vitro and in vivo.

Maturin acetate (MA) is one of main constituents in Psacalium peltatum. The cytotoxic effects of MA on tumorigenic cells were evaluated using the MTT assay. The in vitro immunostimulatory effects of maturin acetate (MA) were evaluated on the viability of murine splenocytes and macrophages, and human peripheral blood mononuclear cells (PBMC). The effects of MA on the production of nitrous oxide, pinocytosis and lysosomal enzyme activity were assayed in murine macrophages RAW 264.7. The effects of MA on the NK cell activity were also assayed. The in vivo immunostimulatory activities of MA were evaluated on BALB/c mice immunosuppressed with cyclophosphamide (CY). MA lacks cytotoxic activity against human cancer cells (IC50>200 μM). In the absence of LPS, MA 10 μM or higher stimulated significantly (P≤0.05), compared to untreated cells (-LPS), the viability of murine macrophages and splenocytes. In the absence of LPS, MA 10 μM or higher stimulated significantly (P≤0.05), compared to untreated cells (-LPS), the lysosomal enzyme activity and pinocytosis. In immunosuppressed mice, MA increases significantly (P≤0.05), compared to CY-treated mice, the production of IL-2 and IL-15 and IFN-γ. In conclusion, MA exerts immunostimulatory activities in vitro and in vivo.