RESUMO
A polyhydric alcohol (PAL) was isolated from Taxus cuspidata and its immunostimulatory activities were assessed. The primary monosaccharide composition of the PAL was determined to be glucose, where HPAEC analysis showed no significant amount of any other sugars. However, glycerol and xylitol were identified as the main sugar alcohols. Fourier-transform infrared (FT-IR) analysis indicated that the purified PAL is a complex glycitol, which structurally contains significant amount of hydroxyl groups. MALDI-TOF mass spectroscopy also demonstrated that PAL is a complex glycitol built in hexose polymerization. Enzyme linked immunosorbent assay showed that the PAL stimulates the release of the proinflammatory cytokines TNF-α and IL-6 in a dose-dependent manner. Furthermore, treatment of RAW 264.7 cells with PAL for 24h remarkably increased the phosphorylation levels of ERK, p38 and JNK in a dose-dependent manner, whereas the total protein levels of ERK (t-ERK), p38 (t-p38) and JNK (t-JNK) remained unchanged. These results clearly demonstrate that PAL stimulates the immune response in RAW 264.7 cells through the activation of MAPKs (ERK, p38 and JNK) signaling pathway. To the best of our knowledge, this is the first study to demonstrate the primary structure and immune-stimulating activities of PAL from the fruit of T. cuspidata.