Antioxidant and immunoregulatory activity of different polysaccharide fractions from tuber of Ophiopogon japonicus

Four sulfated heteropolysaccharide fractions (OJP-1, OJP-2, OJP-3 and OJP-4) were isolated and purified from the tuber of Ophiopogon japonicus by DEAE-Sepharose Fast Flow and Sepharose 6 Fast Flow column chromatography. OJP-1, the least sulfated product, was sulfated synthetically to OJP-1S. Their chemical–physical properties were determined by chemical methods, GC, FT-IR spectroscopy, and HPLC. The antioxidant and immunomodulation activities of these fractions were also investigated. The content of hexuronic acid and sulfate were decreased in the order OJP-4 > OJP-3 > OJP-2 > OJP-1 and OJP-1S > OJP-4 > OJP-3 > OJP-2 > OJP-1, respectively. In comparison with OJP-1, other polysaccharides showed stronger 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and hydroxyl radical scavenging activity. Five polysaccharides also exhibited remarkable macrophage-activating capability by the promotion of phagocytic capacity, energy metabolism rate, NO and interleukin-1 production. It was significantly different between five polysaccharides (P < 0.01) and decreased in the order OJP-1S > OJP-4 > OJP-3 > OJP-2 > OJP-1. Taken together, our results suggested that hexuronic acid and sulfate were effective indicators of antioxidant and immunomodulation activity of polysaccharide.